Russia Defence Forum

Would you like to react to this message? Create an account in a few clicks or log in to continue.

Military Forum for Russian and Global Defence Issues


    Single vs. Twin Engine Fighters

    LMFS
    LMFS

    Posts : 1949
    Points : 1949
    Join date : 2018-03-04

    Single vs. Twin Engine Fighters Empty Single vs. Twin Engine Fighters

    Post  LMFS on Sat Aug 22, 2020 6:49 am

    An old topic... we can post here arguments and data in favour or against each option

    I start linking this argumentation by Piccard578, contained in a blog entry where he compares different engines:

    https://defenseissues.net/2014/12/06/fighter-aircraft-engine-comparision

    He explains the argument that I have tried to convey regarding mass & drag distribution differences between twin and single engine fighters, only much better than myself:

    This is one of reasons why single engined fighters typically have better peformance than twin engined fighters despite lower thrust-to-weight ratio. Engine frontal area is one of major contributors to drag in all “normal” flight conditions. Taking two engines that use same technology and general design, frontal area – and drag – will increase with square of dimensions’ increase, while weight – and thus thrust – will increase with cube of dimensions’ increase. Engine that is 20% larger in all three dimensions will have 44% greater frontal area and 72,8% more weight and thrust – thus its thrust-to-drag ratio will be 20% greater than that of the smaller engine. If engines are of the same size and characteristics, then twin engined aircraft will be larger and have higher inertia and inferior transient performance. This of course assumes identical design goals and avaliable technology. For example, F-119 is 239% larger in volume than the EJ200, has 59% greater frontal area and 15% better thrust-to-drag ratio.

    kvs
    kvs

    Posts : 6799
    Points : 6946
    Join date : 2014-09-11
    Location : Canuckistan

    Single vs. Twin Engine Fighters Empty Re: Single vs. Twin Engine Fighters

    Post  kvs on Sat Aug 22, 2020 9:36 am

    The form drag is being belaboured in the above quote. It makes it sound like, for example, the cross sectional frontal area of the Su-2x,3x,5x
    and Mig-29 jets is significantly increased by having two engines. The only thing substantial is the air intake and if you consider the F-16, it
    accounts for a substantial part of the cross section even though it is a single-engine jet.

    If it was as bad as it is being made to sound, then both the Sukhoi and the Mig-29 jets would be cramming the engines like the F-18. Instead
    they are deliberately spread apart to give better maneuvering capability.

    So a better assessment would consider fuel use and operational time.

    GarryB
    GarryB

    Posts : 25949
    Points : 26495
    Join date : 2010-03-30
    Location : New Zealand

    Single vs. Twin Engine Fighters Empty Re: Single vs. Twin Engine Fighters

    Post  GarryB on Sat Aug 22, 2020 12:23 pm

    But the engines are almost never the same size and same characteristics.

    For a ground vehicle I agree that two engines makes the transmission more complex so unless there is simply no other choice or it makes economic sense then it simply is not done.

    The BTR-60 is an example where a very cheap and very widely used truck engine was used as a power plant... but because of its lack of power they put two into the vehicle made sense at the time, but we can see that later on they changed to a single engine because of the chronic transmission problems it created... it made them cheap and easy to service but it also meant they constantly needed servicing.

    With an aircraft however things are a bit different, yet the real world has shown that single engined fighters are not that widely used these days and those that are used are not by any stretch of the imagination cheap.

    There are lots of factors that lead to operational costs but having a second engine is not a significant one... in fact many countries that fly over water insist on there being two engines a lot of the time.

    Honestly you could waste a lot of time going back over aircraft designs suggesting this or that change might have saved some dollars, or could have made it faster or higher flying or more manouverable, but at the end of the day if you want cheap single engined fighters buy that Chinese MiG-21 variant, but if you want it to be useful then make it slightly bigger and heavier and more capable like a MiG-35. russia Razz
    LMFS
    LMFS

    Posts : 1949
    Points : 1949
    Join date : 2018-03-04

    Single vs. Twin Engine Fighters Empty Re: Single vs. Twin Engine Fighters

    Post  LMFS on Tue Aug 25, 2020 8:05 pm

    kvs wrote:The form drag is being belaboured in the above quote.   It makes it sound like, for example, the cross sectional frontal area of the Su-2x,3x,5x
    and Mig-29 jets is significantly increased by having two engines.

    Well, that is a fact. According to Paralay, F-16 has 4.25 sqm cross sectional area, which is less than half of Su-27 (10 sqm) and the MiG-29 has 6.8 sqm. They may have more thrust, but one has to remember that excess power and not simply thrust is the relevant parameter. I will try to double check those values if I find the time, but they don't seem too far off for me.


    The only thing substantial is the air intake and if you consider the F-16, it accounts for a substantial part of the cross section even though it is a single-engine jet.

    The F-16 is built pretty much as tight around the unavoidable factors of frontal cross section (engine, cockpit, intake) as it gets. Engine in the center in a frontal view, cockpit protruding slightly above and ventral intake protruding slightly below. Two side intakes would have higher drag and can suffer pressure distortions when turning.

    Single vs. Twin Engine Fighters Yf-16e10

    If it was as bad as it is being made to sound, then both the Sukhoi and the Mig-29 jets would be cramming the engines like the F-18.   Instead
    they are deliberately spread apart to give better maneuvering capability.

    I assume, but have no proof, that they were designed that way because of the integral aero layout (BWB) they use. Also keep in mind that neither myself nor Piccard578 are saying that single engine has not downsides, because it tends to make longer fuselages that will be heavier and have bigger pitch moments. In the case of heavy fighters like the Sukhoi, a single engine would mean it would be really big, which makes logistics and maintenance more difficult.

    So a better assessment would consider fuel use and operational time.

    The argument was limited to the effects of single or twin engines on thrust, weight and drag. Of course there are many other aspects, I agree.

    I think it is relevant to notice that, the bigger the airframe, the longer the range, because the fuel amount increases cubically with linear dimensions and the cross sectional area quadratically. So a smaller airframe will have lower tolerance to increased cross sectional area than a bigger one, that translates very nicely into the commonly seen reality that twin engine makes lots of sense for heavy fighters, but IMHO not so much for lighter ones.

    GarryB wrote:There are lots of factors that lead to operational costs but having a second engine is not a significant one... in fact many countries that fly over water insist on there being two engines a lot of the time.

    The tables below illustrate class A mishaps in single and twin engine fighters. As reliability of engines has improved, both configurations have come to similar mishap rates:

    https://www.safety.af.mil/Portals/71/documents/Aviation/Engine%20Statistics/USAF%20Single%20Engine.pdf
    https://www.safety.af.mil/Portals/71/documents/Aviation/Engine%20Statistics/USAF%20Twin%20Engine.pdf


    Last edited by LMFS on Tue Aug 25, 2020 8:42 pm; edited 1 time in total
    LMFS
    LMFS

    Posts : 1949
    Points : 1949
    Join date : 2018-03-04

    Single vs. Twin Engine Fighters Empty Re: Single vs. Twin Engine Fighters

    Post  LMFS on Tue Aug 25, 2020 8:34 pm

    More by Piccard578, his preferences are clear, but he makes good arguments too:

    https://defenseissues.net/2014/08/09/single-vs-twin-engined-fighters/
    GarryB
    GarryB

    Posts : 25949
    Points : 26495
    Join date : 2010-03-30
    Location : New Zealand

    Single vs. Twin Engine Fighters Empty Re: Single vs. Twin Engine Fighters

    Post  GarryB on Wed Aug 26, 2020 11:48 am

    Well, that is a fact. According to Paralay, F-16 has 4.25 sqm cross sectional area, which is less than half of Su-27 (10 sqm) and the MiG-29 has 6.8 sqm.

    Yeah, but the F-16 also has a simpler lighter air intake design because it is not designed to fly faster than Mach 2 like the other two aircraft you mention... and you are being selective because the longer ranged model F-16 has conformal fuel tanks because it lacked fuel range... something the Su-27 never had a problem with and later model MiG-29s have enlarged backs and the number of wet areas inside the fuselage increased to solve that problem.

    They may have more thrust, but one has to remember that excess power and not simply thrust is the relevant parameter. I will try to double check those values if I find the time, but they don't seem too far off for me.

    Having an enormous power to weight ratio is no compensation when your wings stall and you can't do anything with that power... you need TVC to maintain controlled flight even in a superstall... which model F-16 have TVC engines?

    The F-16 is built pretty much as tight around the unavoidable factors of frontal cross section (engine, cockpit, intake) as it gets. Engine in the center in a frontal view, cockpit protruding slightly above and ventral intake protruding slightly below. Two side intakes would have higher drag and can suffer pressure distortions when turning.

    So now you are saying if a single engined aircraft has two side mounted air intakes then it loses its reduced drag advantage... does that apply to the F-5?

    Or the MiG-23/27?

    The argument was limited to the effects of single or twin engines on thrust, weight and drag. Of course there are many other aspects, I agree.

    Instead of making artificial comparisons and then cherry picking measures that make your preferred choice look good, would it not be better to examine each design and try to work out why the choices made were selected and if other choices like making them a single engined aircraft would make them better or worse.

    I think it is relevant to notice that, the bigger the airframe, the longer the range, because the fuel amount increases cubically with linear dimensions and the cross sectional area quadratically. So a smaller airframe will have lower tolerance to increased cross sectional area than a bigger one, that translates very nicely into the commonly seen reality that twin engine makes lots of sense for heavy fighters, but IMHO not so much for lighter ones.

    And that is what I am trying to say to you... with a modern stealth fighter where weapons now have to be internal and of course fuel as well how can you justify a smaller lighter fighter jet becuase that is bound to leave it short of fuel and very limited in normal weapon load without breaking the stealth and going for external weapons.

    It has been shown by Israel in Syria that the F-35 still has to hide with stand off weapons so essentially they could be doing the same job with F-16s or F-15s much more cheaply and those 4th gen fighters could carry more standoff weapons and also self defence weapons too because their larger payload performance for any given flight range and speed.

    Single engined tiny stealth fighters are a stupid idea... you will end up with no fuel and no payload, or to achieve one or both of those you carry it externally and lose your stealth... in other words bloody useless.

    The tables below illustrate class A mishaps in single and twin engine fighters. As reliability of engines has improved, both configurations have come to similar mishap rates:

    So the most inefficient aircraft in the USAF fleet would be the B-52 with its 8 unreliable engines that all need servicing... yet I would suspect if that were true it would be the B-52 being retired or upgraded to a twin jet, and the B-1B and B-2 would be their bombers going forward...

    The B-52 does not have 8 engine safety... if all four on one side fail it is in trouble even if the other four are working normally.

    More by Piccard578, his preferences are clear, but he makes good arguments too:

    His first paragraph...
    Single engined fighters have typically been favored due to their low procurement and operational costs, ease of maintenance and assumed better air-to-air performance. Yet there is also a belief that single-engined fighters are inherently less survivable and lower-performance than twin-engined fighters.

    Really... are F-35s cheap to buy and cheap to operate and are easy to maintain and have a good air to air record?

    The new Russian stealth fighter is going to be twin engined clearly because they don't want the lightest cheapest plane they can get... they want internal volume for fuel and weapons to be carried internally... it doesn't matter if it is a bit cheaper to buy and maintain if it does not have enough fuel or weapon capacity to get the job done...

    Comments about WWII are irrelevant.... he mentions twin engined fighters like the Me-110 and the P-38... what about the Me-262?

    The F-4 was never designed to dogfight (hinted at by the lack of a gun) and considering the level modern short range missiles have gotten to a light cheap dogfighter is going to be even more useless.

    The west worked out in the 1990s that dogfighting is suicide... things will only get worse.

    Single engined fighters have typically been favored due to their low procurement and operational costs, ease of maintenance and assumed better air-to-air performance. Yet there is also a belief that single-engined fighters are inherently less survivable and lower-performance than twin-engined fighters.

    the difference in operational and maintainence costs between singles and twins would generally be explained by the fact that the twins are bigger heavier aircraft... there is the same difference in costs between the Su-27 and MiG-29... which are both twins.

    His logic at to why the F-5 was a front line fighter is very amusing and also rubbish... the countries that used the F-5 were US aligned but were deemed by the US to not be needing a better aircraft like an F-16... it was very rare such countries would get any real choice.

    BTW if his logic was sound why isn't Russia using its Yak-130 as a frontline fighter too?


    The F-16s roll rate being similar to the F-22 is no surprise, the engines on the F-22 are too close together to get any practical benefit from its TVC... though I could use that as an argument to show that the weight distribution of the F-22s shorter wider located engine mounts are compensated for by being close together and using TVC nozzles.

    I would suggest that mounting them further apart as on the MIG and Sukhoi twins the added rotation force from the engine separation should allow an even faster roll rate would you not agree?

    LMFS
    LMFS

    Posts : 1949
    Points : 1949
    Join date : 2018-03-04

    Single vs. Twin Engine Fighters Empty Re: Single vs. Twin Engine Fighters

    Post  LMFS on Wed Aug 26, 2020 7:41 pm

    @Garry: I am not trying to make this a contest of who is stronger or something like that, just giving data and trying to understand each layout's advantages and problems and why certain planes are designed in one way or another.

    GarryB wrote:Yeah, but the F-16 also has a simpler lighter air intake design because it is not designed to fly faster than Mach 2 like the other two aircraft you mention...

    That has nothing or at best minimum impact on the cross sectional area

    and you are being selective because the longer ranged model F-16 has conformal fuel tanks because it lacked fuel range... something the Su-27 never had a problem with and later model MiG-29s have enlarged backs and the number of wet areas inside the fuselage increased to solve that problem.

    I was just answering kvs' claim. As a matter of fact, the single engine plane has way smaller cross sectional area, I was not going into the fuel aspect. In that regard, the Flanker is very well equipped, while the original MiG-29 was significantly worse than the original F-16 (0.31 fuel / empty weight compared to 0.43 for the F-16A).

    Having an enormous power to weight ratio is no compensation when your wings stall and you can't do anything with that power... you need TVC to maintain controlled flight even in a superstall... which model F-16 have  TVC engines?

    No operational MiG-29 has them either... again it has nothing to do with the issue at hand.

    The F-16 was designed with two tails in mind as the picture I linked shows. The final design with only one was decided because of costs if I am not wrong, an that limits high AoA performance. Sukhois and MiGs have been doing >90º AoA for ages without TVC.

    So now you are saying if a single engined aircraft has two side mounted air intakes then it loses its reduced drag advantage... does that apply to the F-5?

    No, why the reductionism? I even provided a nice picture where you can see they difference it made in the case of the F-16 program.

    Instead of making artificial comparisons and then cherry picking measures that make your preferred choice look good, would it not be better to examine each design and try to work out why the choices made were selected and if other choices like making them a single engined aircraft would make them better or worse.

    I don't have general preferences between single and twin, but you still don't get it... and I am bringing data instead of complaining.

    If you want to examine each design and analyse their merit indexes we can do it, where do you want to start?

    And that is what I am trying to say to you... with a modern stealth fighter where weapons now have to be internal and of course fuel as well how can you justify a smaller lighter fighter jet becuase that is bound to leave it short of fuel and very limited in normal weapon load without breaking the stealth and going for external weapons.

    I have already explained what I consider the minimum size that is workable with 5G fighters. It is still doable with one engine of the Al-31 size class.

    Single engined tiny stealth fighters are a stupid idea... you will end up with no fuel and no payload, or to achieve one or both of those you carry it externally and lose your stealth... in other words bloody useless.

    Do the exercise, bring numbers to the table. I actually took the pain and the results do not suggest what you say. And to make it even worse, I reached almost the same conclusions design bureaus have reached too...

    So the most inefficient aircraft in the USAF fleet would be the B-52 with its 8 unreliable engines that all need servicing... yet I would suspect if that were true it would be the B-52 being retired or upgraded to a twin jet, and the B-1B and B-2 would be their bombers going forward...

    Now you are making it silly. What the table shows is that older single engine jet fighters had significantly more issues than twin engine, but modern ones are more or less in the same ballpark, because once the engine gets very reliable its contribution to the mishaps gets lower. This is the information planers need to have to decide whether a single engine jet can be safe enough for service.

    the difference in operational and maintainence costs between singles and twins would generally be explained by the fact that the twins are bigger heavier aircraft... there is the same difference in costs between the Su-27 and MiG-29... which are both twins.

    What is that difference between those two? I have no data.

    The F-16s roll rate being similar to the F-22 is no surprise, the engines on the F-22 are too close together to get any practical benefit from its TVC...

    Main TVC use is not to contribute to roll, first of all. And then, both planes have very high roll rate, because their mass is concentrated close to the roll axis.

    I would suggest that mounting them further apart as on the MIG and Sukhoi twins the added rotation force from the engine separation should allow an even faster roll rate would you not agree?

    First, TVC as in Flankers creates yaw moment that needs to be compensated when deflecting differentially, I don't know what burden that places on the FCS and the rest of the control surfaces. In general, I think their effectiveness would depend of the airspeed. Close to corner velocity the elevators create a lot of roll moment, while the podded engine layout increases the roll moment of inertia and hence makes rolling more difficult. In general I have not seen MiGs or Sukhois rolling faster than other planes like F-16 or Rafales, I cannot tell if they are superior. At low airspeeds the TVC should provide an advantage, at high speed it may not compensate the mass layout disadvantage.

    GarryB
    GarryB

    Posts : 25949
    Points : 26495
    Join date : 2010-03-30
    Location : New Zealand

    Single vs. Twin Engine Fighters Empty Re: Single vs. Twin Engine Fighters

    Post  GarryB on Thu Aug 27, 2020 12:57 pm

    @Garry: I am not trying to make this a contest of who is stronger or something like that, just giving data and trying to understand each layout's advantages and problems and why certain planes are designed in one way or another.

    I understand you are trying to suggest one particular configuration of aircraft is supposed to be superior for small light fighters... what I am trying to get across is that while a tiny country like New Zealand might benefit from such a cheap simple fighter, that countries like Russia need something more.

    You complain that the MiG-35 is obsolete yet suggest a smaller and lighter single engined cheap fighter might somehow be better...

    The MiG-35 is significantly cheaper than the Rafale, which makes the Su-30MKI look cheap, yet the complaints about the Flanker are heard over the complaint non existent complaints regarding the Rafale.... but then they are only just getting the latter into service... so what criticism could there be yet.

    That has nothing or at best minimum impact on the cross sectional area

    The requirement to be faster would necessitate it being heavier and more complicated and require more maintenance.

    In that regard, the Flanker is very well equipped, while the original MiG-29 was significantly worse than the original F-16 (0.31 fuel / empty weight compared to 0.43 for the F-16A).

    You do understand the MiG-29 was designed for a job and was never intended to be put side by side against the American plane in some sort of fanboy stats competition... You also understand that compensating for that lack of fuel meant East German MiG-29s kept centreline fuel tanks as standard restricting their max g to about 5 or 6, leading to a 100% kill ratio against all HATO aircraft of the time.
    You do understand that aircraft designed to operate from rough air strips that are heavier will always give lower fuel ratios no matter what because a fuel mass to empty weight comparison is always going to go against the aircraft that has a higher empty weight...

    Apart from that it is meaningless because either aircraft will be used to the range its fuel allows it to... being able to fly slightly greater ranges does not win any prizes, or make the plane special.

    Having Flankers for longer ranged work meant the MiG-29s didn't need long range... when you need a long range plane use a Flanker.

    The Soviets didn't need an F-16... they needed a MiG-29.

    No operational MiG-29 has them either... again it has nothing to do with the issue at hand.

    Roll rate is not that important. They clearly don't think it is worth the extra cost and maintenance... yet they put up with two engines on every fighter... perhaps that is not the problem you try to suggest it is.

    The F-16 was designed with two tails in mind as the picture I linked shows. The final design with only one was decided because of costs if I am not wrong, an that limits high AoA performance. Sukhois and MiGs have been doing >90º AoA for ages without TVC.

    I don't ever remember seeing those models before... the point of the two tails and their position is to catch the vortex air off the leading edge root extensions... having two meant they could be made smaller than a single fin, whose performance would be made worse by the turbulence created by the nose radome.

    No, why the reductionism? I even provided a nice picture where you can see they difference it made in the case of the F-16 program.

    You claim single engined fighters have lower drag but then you admit that when twin intakes are used then logically that increases frontal area... I merely asked if that means the F-5 and MiG-23 also suffer enlarged frontal area because of their twin air intakes... the MiG-23 more so because each air intake needs to be fully articulated for supersonic air flow, which makes each intake more complex and heavy compared with one designed for lower speeds like the simpler MiG-27 design...


    I don't have general preferences between single and twin, but you still don't get it... and I am bringing data instead of complaining.

    So it was not you that suggested the new MiG designed 5th gen fighter be single engined?


    I have already explained what I consider the minimum size that is workable with 5G fighters. It is still doable with one engine of the Al-31 size class.

    And if I paint tits on a sheep I have the makings of a great whore house in the Aussie outback, but what if I want better quality than that?

    You say western engines have gotten to the level where they are reliable enough that having one or having two does not make any difference, but have you cross referenced Soviet and Russian experience and know for a fact that Russian and Soviet jet engines working in much harsher conditions from rough airstrips match that record?

    The Soviet and Russian approach to airfields is rather different from those in the west, and making all sorts of claims based on western data is being very short sighted in my view.


    Do the exercise, bring numbers to the table. I actually took the pain and the results do not suggest what you say. And to make it even worse, I reached almost the same conclusions design bureaus have reached too...

    The MiG and Sukhoi design bureaus... or a sweedush one?


    Now you are making it silly. What the table shows is that older single engine jet fighters had significantly more issues than twin engine, but modern ones are more or less in the same ballpark, because once the engine gets very reliable its contribution to the mishaps gets lower. This is the information planers need to have to decide whether a single engine jet can be safe enough for service.

    So you must have screeds of information about Russian and Soviet aircraft engines to make that assumption, because obviously if French fighters that live in heated air conditioned shelters and operate from airfields that are walked every day with all debris removed by hand have no problems with foreign object ingestion then of course the same will obviously be true for a MiG-29 operating in the middle of Sibera sitting out in the open at minus 40 degrees, where no one goes outside unless they have to let alone pace up and down a runway and apron looking for small stones and bits of metal...

    Who is being silly... they have said MiG is making a new 5th gen twin jet fighter.


    What is that difference between those two? I have no data.

    So how the F can you say a single engined aircraft is cheaper to operate?

    Again... you are discussing from a position of ignorance.

    Of course companies that sell single engined fighters will say they are the best and they are cheaper... because they are clearly not more capable...

    Main TVC use is not to contribute to roll, first of all. And then, both planes have very high roll rate, because their mass is concentrated close to the roll axis.

    So no benefit from being single engined in that case...

    In general I have not seen MiGs or Sukhois rolling faster than other planes like F-16 or Rafales, I cannot tell if they are superior.

    A high roll rate is irrelevant... what is critical is being able to roll while in a stall, which is what TVC provides...

    At low airspeeds the TVC should provide an advantage, at high speed it may not compensate the mass layout disadvantage.

    At low or no airspeed it means you can roll and they can't... at high speed it is not that important.



    kvs
    kvs

    Posts : 6799
    Points : 6946
    Join date : 2014-09-11
    Location : Canuckistan

    Single vs. Twin Engine Fighters Empty Re: Single vs. Twin Engine Fighters

    Post  kvs on Thu Aug 27, 2020 7:47 pm

    It's always apples to oranges and even cucumbers in these sorts of discussions. The relevant criteria for the design are never laid out.
    This gives us the "designers are stupid" BS since the goal posts are not only moving, they are not even there.

    The graph posted above is clearly not universal and applies only to the two US models in wind tunnel tests. Russian aircraft designers
    are aware of wind tunnels and in fact have institutes working with them for decades. The west has nothing to teach Russia about
    form drag, boundary layer separation and turbulence. Both in the air and in the water.

    Garry brought up a killer point. The fuel tank capacity of some single engine jet like the F-16 is deficient and for marginal "losses"
    in terms of drag, a larger twin engine design gets you more range. So what is the point of the single engine design? The drag
    does not limit the top speed of the twin engine jet since it can actually have more thrust than a single engine jet.

    I will cite crappy-pedia but in this case it is not that bad:

    F-16:


    Empty weight: 18,900 lb (8,573 kg)
    Gross weight: 26,500 lb (12,020 kg)
    Max takeoff weight: 42,300 lb (19,187 kg)
    Fuel capacity: 7,000 pounds (3,200 kg) internals[4]
    Powerplant: 1 × General Electric F110-GE-129 afterburning turbofan (Block 50), 17,155 lbf (76.31 kN) thrust dry, 29,500 lbf (131 kN) with afterburner
    Powerplant: 1 × Pratt & Whitney F100-PW-229 afterburning turbofan (Block 52), 17,800 lbf (79 kN) thrust dry, 29,160 lbf (129.7 kN) with afterburner

    Maximum speed: Mach 2.05 at altitude, clean[4]
    Mach 1.2, 800 kn (921 mph; 1,482 km/h) at sea level[71]
    Combat range: 295 nmi (339 mi, 546 km) on a hi-lo-hi mission with 4x 1,000 lb (454 kg) bombs
    Ferry range: 2,277 nmi (2,620 mi, 4,217 km) with drop tanks
    Service ceiling: 50,000[315][316] ft (15,000 m) plus
    g limits: +9.0 (limited by flight control system)
    Rate of climb: +50,000[317][318] ft/min (250 m/s)
    Wing loading: 88.3 lb/sq ft (431 kg/m2)
    Thrust/weight: 1.095 (1.24 with loaded weight & 50% internal fuel)[319]

    Mig-29


    Empty weight: 11,000 kg (24,251 lb)
    Gross weight: 14,900 kg (32,849 lb)
    Max takeoff weight: 18,000 kg (39,683 lb)
    Fuel capacity: 3,500 kg (7,716 lb) internal
    Powerplant: 2 × Klimov RD-33 afterburning turbofan engines, 81.59 kN (18,340 lbf) with afterburner

    Maximum speed: 2,400 km/h (1,500 mph, 1,300 kn) at high altitude
    Maximum speed: Mach 2.25
    Range: 1,430 km (890 mi, 770 nmi) with maximum internal fuel[257]
    Ferry range: 2,100 km (1,300 mi, 1,100 nmi) with 1x drop tank
    Service ceiling: 18,000 m (59,000 ft)
    g limits: +9
    Rate of climb: 330 m/s (65,000 ft/min) [258]
    Wing loading: 403 kg/m2 (83 lb/sq ft)
    Thrust/weight: 1.09

    I am not seeing the advantages of the F-16 in spite of its theoretical lower drag numbers. Also, the posted drag differences above
    are what one would call marginal. And clearly they have no impact on parameters that matter. Any attempt to attribute the
    lack of any noticeable impact of drag on these parameter due to design differences simply proves the point that they are a non-issue.
    Designers have multiple other parameters to deal with other than marginal drag differences.

    BTW, when you do a Google search for these numbers you will find comparisons of the Mig-29 and the F-15 which is just retarded.


    LMFS
    LMFS

    Posts : 1949
    Points : 1949
    Join date : 2018-03-04

    Single vs. Twin Engine Fighters Empty Re: Single vs. Twin Engine Fighters

    Post  LMFS on Thu Aug 27, 2020 8:51 pm

    GarryB wrote:I understand you are trying to suggest one particular configuration of aircraft is supposed to be superior for small light fighters...

    Not exactly. The intent of this thread is for proponents of one or other layout to contribute arguments, technical and/or authoritative if possible, for or against. It is an old discussion that percolates many other subjects and threads and I thought it would be much more constructive to focus on the topic itself and research it properly, so that we can form an informed opinion, even if we will probably never settle the discussion itself.

    As to my position, I will state it once again: I think the light fighter (or medium-light, depending on what criteria is used) configured as roughly half the size of a heavy one and with one engine where the heavy has two is a very logical choice, technically sound and economically advantageous. But this thread is not about me repeating that over and over but rather about providing data on the intrinsic characteristics and performances of both layouts.

    what I am trying to get across is that while a tiny country like New Zealand might benefit from such a cheap simple fighter, that countries like Russia need something more.

    I get that. Interestingly, my opinion is rather the opposite. A small country that has no heavy fighters is probably going to place more demands on their eventual light(er) ones. Light and heavy fighters make most sense together as part of the hi-lo mix of the countries that created them. A F-16 may not be the best choice if you need an attack plane with range and payload capacity, but maybe you cannot sustain a fleet with them and also F-15E. But ok that is just my opinion.

    You complain that the MiG-35 is obsolete yet suggest a smaller and lighter single engined cheap fighter might somehow be better...

    First I don't complain. As a matter of fact, older platforms lose relevance and need to be substituted. A modern one with state of the art aero, layout, and system integration technology is going to have advantages. Do you think the new 5G MiG fighter will use the same MiG-29 air vehicle?

    Second, since I don't share your opinion that light, single engine fighter = crap, I don't share your conclusion either. It can be better in many ways that are not strictly performance related, it can be cheaper to operate for instance and do its job as intended.

    The requirement to be faster would necessitate it being heavier and more complicated and require more maintenance.

    But the topic was cross sectional area. F-16 is a 2 M class fighter regardless. Sometimes a fast acceleration can matter more than top speed, this is also relevant to be kept in mind.

    EDIT: I remembered there was in fact a design of an intake with variable ramps for the F-16. See there is no apparent change to the inlet's external dimensions:

    Single vs. Twin Engine Fighters Scan0010

    You do understand the MiG-29 was designed for a job and was never intended to be put side by side against the American plane in some sort of fanboy stats competition...  

    Yes, it was you who brought up the fuel issue and claimed the F-16 needed CFTs. I just demonstrated you it was still better in that regard than the MiG.

    Having Flankers for longer ranged work meant the MiG-29s didn't need long range... when you need a long range plane use a Flanker.

    One of the claims of MiG's team regarding their new MiG-29 family is that they have increased internal fuel by a 50% so that might be perceived now as shortcoming of the original design. This relates to the point I made above, for the USSR to have MiGs taking off from rough airfields in point defence role may be all they needed in the 80's, for export customers and even VKS today that seems not to be the case anymore.

    Roll rate is not that important. They clearly don't think it is worth the extra cost and maintenance...

    Make up your mind, below you say TVC for roll authority is relevant, but here you say the MiGs don't have it installed because they couldn't bother since it odes not compensate?

    yet they put up with two engines on every fighter... perhaps that is not the problem you try to suggest it is.

    What problem? I just say it makes more sense to use one type of engine than two and to profit from the advantages of different layouts when composing the fleet. I don't think two engine layout is "problematic"

    I don't ever remember seeing those models before... the point of the two tails and their position is to catch the vortex air off the leading edge root extensions... having two meant they could be made smaller than a single fin, whose performance would be made worse by the turbulence created by the nose radome.

    One fin of course remains in the shadow of the nose at high AoA and now it is also not acceptable due to LO design issues. Most single tail planes have AoA limitations.

    You claim single engined fighters have lower drag but then you admit that when twin intakes are used then logically that increases frontal area...

    For the same capture surface it is lighter and marginally less draggy to have one big intake than two smaller ones. If this is relevant or not is difficult to say, that is why I posted the image with real figures. It is not a world of difference, but all needs to add up in order to get the best possible design.

    I merely asked if that means the F-5 and MiG-23 also suffer enlarged frontal area because of their twin air intakes... the MiG-23 more so because each air intake needs to be fully articulated for supersonic air flow, which makes each intake more complex and heavy compared with one designed for lower speeds like the simpler MiG-27 design...

    I don't know exactly. The marginal disadvantage can be compensated or justified considering the whole design.

    So it was not you that suggested the new MiG designed 5th gen fighter be single engined?

    That is my personal opinion, from the perspective of someone that is not in the VKS or Russian MIC. I will sleep very well if they develop a twin engine fighter and will try to understand why they did it.  It is not some kind of religious belief you know?

    but have you cross referenced Soviet and Russian experience and know for a fact that Russian and Soviet jet engines working in much harsher conditions from rough airstrips match that record?

    Who says the new fighter will operate from rough airstrips? The dorsal intakes are not there anymore in the new MiGs...

    Data from Western sources are WAY easier to come by than Russian ones, that is one thing. The other is that Russian engines on a technological level similar to Western ones are only now starting to emerge (AL-41F1S, RD-33MK) so there is less experience with them. I consider, given the operational life and overhaul intervals, that Russian engines have roughly caught up with the state of the art in that regard. This is BTW a must for them, because otherwise their sales in the export market would suffer.

    The Soviet and Russian approach to airfields is rather different from those in the west, and making all sorts of claims based on western data is being very short sighted in my view.

    Ok be my guest, you are invited to better that data. But to make assumptions without figures to back them is not exactly better than at least finding analogues as I am doing. The thread is not limited to Russian planes BTW.

    The MiG and Sukhoi design bureaus... or a sweedush one?

    Ok I get it: I "just" managed to get, by basic application of common sense, the same basic results professionals in Saab also came to, but that means nothing because you magically know Sukhoi or and MiG think different... respect.

    There have been all sorts of projects both by MiG and Sukhoi for single engine, light (and not so light) 4G/5G fighter projects. Do you think they were very different to what I propose? Do you want to see some of them?

    So how the F can you say a single engined aircraft is cheaper to operate?

    Again... you are discussing from a position of ignorance.

    Ok prove you are not doing the same... where is the data? I have some indirect ones, but you do seem to know a lot about the issue, since you are correcting me.

    So no benefit from being single engined in that case...

    The more concentrated the weight, the better in that regard. Single engine is optimal, two engines can be similar if placed very close. But then any serious damage (i.e. a broken turbine blade) means there is a good change of the other engine failing too. I guess Russians value having two engines apart in order to minimize the influence from one on the other.

    A high roll rate is irrelevant... what is critical is being able to roll while in a stall, which is what TVC provides...

    Banking is crucial to turn, and doing it fast is indeed a good thing. Rolling in a stall with zero airspeed or fuselage inertia is non critical (why would it be?) and until the TVC came as said Sukhois and MiGs and all other planes have been more than ok without it. Stall recovery is relevant though, and it is guaranteed with TVC even if no differential or even 3D deflection is available, normal 2D are ok for that.


    Last edited by LMFS on Fri Aug 28, 2020 3:36 am; edited 1 time in total
    LMFS
    LMFS

    Posts : 1949
    Points : 1949
    Join date : 2018-03-04

    Single vs. Twin Engine Fighters Empty Re: Single vs. Twin Engine Fighters

    Post  LMFS on Fri Aug 28, 2020 2:30 am

    kvs wrote:It's always apples to oranges and even cucumbers in these sorts of discussions.   The relevant criteria for the design are never laid out.
    This gives us the "designers are stupid" BS since the goal posts are not only moving, they are not even there.

    The idea behind this thread is precisely to analyse the aspects related to single and twin engine design in a way as structured as possible instead of mixing the topic in other threads in a messy way. The result is up to us.

    The graph posted above is clearly not universal and applies only to the two US models in wind tunnel tests.   Russian aircraft designers
    are aware of wind tunnels and in fact have institutes working with them for decades.   The west has nothing to teach Russia about
    form drag, boundary layer separation and turbulence.   Both in the air and in the water.  

    Why would I question the Russian designers' prowess?? On the contrary... The idea was just to give a quantitative dimension to the argument made. It is specific to that case and all, still it gives some idea of the order of magnitude of the differences we are discussing (6% difference in L/D is not insignificant I would say). But in any case that related only to the type of intake, not to the issue of the number of engines. A single engine plane can have two intakes and a twin engine plane can have just one intake.

    Garry brought up a killer point. The fuel tank capacity of some single engine jet like the F-16 is deficient and for marginal "losses"
    in terms of drag, a larger twin engine design gets you more range.
       

    I just demonstrated it is the opposite of what you claim, considering a twin engine jet which is actually far larger, like the MiG-29, that should have substantially more range but has little more fuel and clearly less range.

    F-16A: weight empty 7,317 kg / internal fuel 3,162 kg (ratio fuel to weight is 0.43)
    MiG29: weight empty 11,001 kg /internal fuel 3,453 kg (0.31)

    50% more cross sectional area is not a "marginal" difference in drag by any measure.

    The drag does not limit the top speed of the twin engine jet since it can actually have more thrust than a single engine jet.

    It always depends. In terms of thrust, F-16's TWR is better than that of a MiG-29. But as I said, that is just a part of the problem and can actually be misleading. The parameter that determines the dynamic performance of the plane in terms of acceleration, climb and sustained turning is excess power, which is thrust minus drag. There the F-16 is also better, based on the information I have.

    Beyond that, having a lot of thrust to compensate for a lot of drag is always a bad idea, because it will make you spend your fuel faster.

    The article in fact went beyond what I am saying in stating that thrust escalates with the cube of the linear dimensions of the engine (so to say that engine's thrust to weight for a given technology and design is constant despite size changes). This is not so obvious and actual relationship is non linear in reality (weight can be estimated as 2.7 * Thrust ^0.75 for a range of commercial turbofans). Therefore I am not using this assumption myself.

    I am not seeing the advantages of the F-16 in spite of its theoretical lower drag numbers.

    You should use F-16A values instead, those are the ones against which MiG-29 was designed. And of course this is a case of apples vs oranges since those wiki values are far too superficial in one hand and given in different conditions for each plane, to make an assessment. You need EM charts, fuel rate tables and so on. If not, at least a good info source to start with is this:

    http://www.aerospaceweb.org/aircraft/fighter/
    GarryB
    GarryB

    Posts : 25949
    Points : 26495
    Join date : 2010-03-30
    Location : New Zealand

    Single vs. Twin Engine Fighters Empty Re: Single vs. Twin Engine Fighters

    Post  GarryB on Fri Aug 28, 2020 7:08 pm

    I think the light fighter (or medium-light, depending on what criteria is used) configured as roughly half the size of a heavy one and with one engine where the heavy has two is a very logical choice, technically sound and economically advantageous.

    Yet has it ever been implemented?

    The Mig-23 does not use an Al-31 engine, and the F-16 does use the engine or the F-15 but is it half the maintenance bill? ... is there any single engined fighter anywhere that actually uses a single engine that is also used on a heavier twin engined fighter that can be considered cheaper?

    Perhaps the Me-110 uses two engines used in a Bf109 variant?

    Not really a good example though is it?

    I get that. Interestingly, my opinion is rather the opposite. A small country that has no heavy fighters is probably going to place more demands on their eventual light(er) ones. Light and heavy fighters make most sense together as part of the hi-lo mix of the countries that created them. A F-16 may not be the best choice if you need an attack plane with range and payload capacity, but maybe you cannot sustain a fleet with them and also F-15E. But ok that is just my opinion.

    If you ignore the HATO bullshit 99% of countries really don't need fighter aircraft... do you think the sky would fall if Germany announced it was going to give up having an air force and that a civilian police authority would start using civilian aircraft modified with a few gun pods and air to air missiles for policing duties and customs roles... what do German fighter planes actually contribute anywhere and in any way?

    Here in New Zealand we had an outstanding single engined jet fighter that you totally ignore... the Skyhawk.... it was so cheap even we could afford to operate it... it had wide variety of ordinance and could carry a huge payload for its size and could operate from aircraft carriers if needed...  give it a modern radar and R-73s  and it would be outstanding...

    You could probably put a decent light radar set in a Buccaneer and a helmet mounted sight and give it R-73s and R-77Ms and have an amazing little fighter that could also operate from carriers... not amazingly manouverable but faster and longer ranged than an F-16 at low altitude with two nuclear bombs as a payload.

    But you are fixated with the electric jet.... the first fighter that needed computers to fly and was always intended to be simple but was always going to be expensive because all of the computer hardware it needed to be so simple.

    First I don't complain. As a matter of fact, older platforms lose relevance and need to be substituted. A modern one with state of the art aero, layout, and system integration technology is going to have advantages. Do you think the new 5G MiG fighter will use the same MiG-29 air vehicle?

    They are just doing what they did with everything else... the T-90 is based on the T-72... to you they are idiots because not only have they upgraded the T-72 and the T-90 they have not replaced everything with Armata T-14s.

    T-14s are not cheap. They will certainly be rather better than T-90s and upgraded T-72s, but so what... most of the jobs they will need them for an upgraded T-54 is probably able to get the job done... why send an expensive T-14 to do a job an upgraded T-72 can do just as well?

    Older platforms might not have the same drag figures, they might be less expensive to operate and also do the job of getting the weapon to the right place in space to launch at the target and get the kill.

    Now lets look at Israel... the cost of getting a standoff munition into the air over Lebenon and launch it towards Syria for it to be shot down outside Damascus... right now it might take an F-35 2 hours to perform the mission, at 80K per hour, while 5 years ago the mission would have been performed by an obsolete type like an F-16 at perhaps 15K per hour. They might have caught glimpses of the F-16, but then they might have caught glimpses of the F-35 too... all that really matters is that the F-35 is expensive for what it is and what it can achieve and the fact that it uses a single engine doesn't make it cheaper or better in any way at all.

    The existence of the F-35 and Rafale suggests to me that it is the F-16 that is obsolete.

    Second, since I don't share your opinion that light, single engine fighter = crap, I don't share your conclusion either. It can be better in many ways that are not strictly performance related, it can be cheaper to operate for instance and do its job as intended.

    Well that is the thing, I think the evidence is clear that the idea that a single engined fighter is cheap = crap... F-35, F-16... assuming claims of the Gripen being cheap are true then if it is then its capability is poor compared with its twin engined competition, which means it is a poor alternative to having a better fighter.

    A light single engine fighter is great... if it is unmanned. Then it can actually be made cheap.

    S-70 suggests the Russians agree.


    EDIT: I remembered there was in fact a design of an intake with variable ramps for the F-16. See there is no apparent change to the inlet's external dimensions:

    That bleed slot would be terrible for RCS, as would the ramp moving up and down...

    Plus... if it moves down and restricts the airflow... where does the excess air go?

    Was it tested at all, or just a what if drawing?

    Didn't you just tell MiG off for their promises that never make it to metal?

    Yes, it was you who brought up the fuel issue and claimed the F-16 needed CFTs. I just demonstrated you it was still better in that regard than the MiG.

    Did you?  What conformal fuel tanks does MiG use?

    One of the claims of MiG's team regarding their new MiG-29 family is that they have increased internal fuel by a 50% so that might be perceived now as shortcoming of the original design.

    They also have TVC engine nozzles as an option which suggests manouverability is a problem yet no customers took up that option... confusing...

    This relates to the point I made above, for the USSR to have MiGs taking off from rough airfields in point defence role may be all they needed in the 80's, for export customers and even VKS today that seems not to be the case anymore.

    They have air intake grid protectors to reduce the risk of FOD, and they still train from motorways... as shown recently with Il-76s and Su-34s.

    Make up your mind, below you say TVC for roll authority is relevant, but here you say the MiGs don't have it installed because they couldn't bother since it odes not compensate?

    You said it was important because you thought the roll rate of single engined aircraft was better than twins. When I pointed out with TVC it isn't, you said only at low speed... which as I pointed out is when it is most relevant... ie in stalls.

    I also said roll rate in general is not that critical... it only matters for a split second... you do understand that rolling on its own is not really an evasive manouver and a missile about to hit you cannot be evaded by continuously rolling because you are basically pivoting around the same point and maintaining your direction of flight. A roll to allow a hard turn only lasts for a fraction of a second and whether it takes 0.1 of a second or 0.05 of a second is not really that important...

    What problem? I just say it makes more sense to use one type of engine than two and to profit from the advantages of different layouts when composing the fleet. I don't think two engine layout is "problematic"

    Russia is just leaving a situation where it does not have enough different engine types... considering the variety of aircraft sizes and weights they have, just having one fighter engine type makes no sense at all...

    One fin of course remains in the shadow of the nose at high AoA and now it is also not acceptable due to LO design issues. Most single tail planes have AoA limitations.

    Indeed, but not every plane suffers for that... if you have that issue then don't fly in situations where AoA is a problem... or accept a little agro when you fly in the tattered parts of the envelope...

    For the same capture surface it is lighter and marginally less draggy to have one big intake than two smaller ones. If this is relevant or not is difficult to say, that is why I posted the image with real figures. It is not a world of difference, but all needs to add up in order to get the best possible design.

    But drag is only one issue... what about sucking shit up off the runway with a chin mounted air intake?

    The square intakes of the Tu-22M3 actually increased RCS by 25% over the intakes like the MiG-23 used on the Tu-22M2... they kept them because if the difference in engine performance it resulted in meaning flight range and top speed increased dramatically.

    I don't know exactly. The marginal disadvantage can be compensated or justified considering the whole design.

    Despite its problems it was clearly considered superior to the nose mounted air intake of the MiG-21 that preceded it.

    That is my personal opinion, from the perspective of someone that is not in the VKS or Russian MIC. I will sleep very well if they develop a twin engine fighter and will try to understand why they did it.  It is not some kind of religious belief you know?

    Maybe they like the fact that any increase in engine power is doubled in a twin jet, but also did you notice a pattern.

    There are single engined aircraft and there are twin, but the only three engined aircraft I know of are commercial airliners that use the extra often tail mounted engine for a boost at takeoff and then cruise the rest of the flight. Then there are four and six and even eight engined aircraft... but no five engined ones and very few three engined ones... the vast majority are one, two or four.

    Do you think that is an accident?

    I would say there are obvious reasons to be a single engined plane but the fact that they are not the most common suggests very good reasons for that.

    The MiG-21 is probably the best Soviet single jet fighter, but things have moved on and such a small plane simply does not have much growth potential or space for everything needed today...

    The worst planes I know of are the VSTOL fighters.. the Yak-38s and Yak-38Ms and the Yak-141s... which actually had three engines each... which sounds super safe except it was the opposite... if any one of those engines failed during landing the result will be a crash and an ejected pilot... so safety wasn't improved with three engines... it was three times less safe than a single engined fighter... (the ejection systems on those aircraft were automatic because of the narrow safety margin... lost a lot of planes but fewer pilots were lost).

    Who says the new fighter will operate from rough airstrips? The dorsal intakes are not there anymore in the new MiGs...

    The intake doors are grids that allow air to flow through them so they don't need the upper louvers...

    I consider, given the operational life and overhaul intervals, that Russian engines have roughly caught up with the state of the art in that regard. This is BTW a must for them, because otherwise their sales in the export market would suffer.

    Yeah, cause there is no way they could survive not charging their customers for their 30 million dollar engines separately like the US does...

    A customer in Africa asked if they want D-30K engines at 14 tons thrust at 800K US dollars for their Il-76 or if they want PS-90A engines at $6 million each but 16 tons thrust and reduced fuel consumption I am pretty sure what most will choose...

    Ok be my guest, you are invited to better that data. But to make assumptions without figures to back them is not exactly better than at least finding analogues as I am doing. The thread is not limited to Russian planes BTW.

    If we are going to only use western data then anything we come up with is pretty useless anyway isn't it?

    How can you look a customer in the face and say single engined fighters are cheaper?

    When you need three Gripens instead of one Rafale or Typhoon to get the job done... is it actually cheaper?

    And do I have to mention F-35?

    What other new single engined fighter is an option?  Chinese... well of course they are cheaper...

    There have been all sorts of projects both by MiG and Sukhoi for single engine, light (and not so light) 4G/5G fighter projects. Do you think they were very different to what I propose? Do you want to see some of them?

    I am familiar with most of them, and all of them failed, because Russia does not need or want a light single engined fighter... it wants a capable affordable fighter.

    It does not matter if you take a little longer checking the engines because there are two... and because there are two you don't need to be as thorough because of one fails you still have the other to get you home. With a single you better be sure everything is good because there is no backup.

    Ok prove you are not doing the same... where is the data? I have some indirect ones, but you do seem to know a lot about the issue, since you are correcting me.

    How about the data for the F-16 and F-15? Instead of pointless comparisons with the totally unrelated MIG-29, how about a comparison of the P&W F-100 engine that powers both the F-16 and the F-15?

    I would have thought that would be the obvious place to start to be honest...

    You already said:

    The tables below illustrate class A mishaps in single and twin engine fighters. As reliability of engines has improved, both configurations have come to similar mishap rates:

    Except similar mishap rates is a bad thing for single engined fighters doesn't it?

    I guess Russians value having two engines apart in order to minimize the influence from one on the other.

    It has nothing to do with guessing and everything to do with body lift that is accentuated with engine trunks and two jet engines at the rear...

    Try it yourself.

    Get a plastic shopping bag and flatten it so there is no air inside. Put the plastic bag around your lips and blow as hard as you can... the tiny amount of air in your lungs is nothing like what is needed to fill the bag with air. Flatten it out again and this time hold the bag a few centimetres from your face and blow again letting the air around you flow in too and you will more likely fill the bag much more than the last time.

    Having two engines facing backwards with a fuselage forming a sort of wing with the engines drawing air through and over the fuselage enhances the lifting performance of the aircraft body.

    Banking is crucial to turn, and doing it fast is indeed a good thing.

    Doing it fast and doing it super fast is not that much of a difference... but having twin tails and twin engines and being able to pull high AoA means the turn itself can be more useful than rolling fast.

    Rolling in a stall with zero airspeed or fuselage inertia is non critical (why would it be?)

    Because stall recovery will either be gravity or engine power and being able to roll to enhance either one could be important... certainly being able to point your nose where you want is critical in a superstall and being able to roll so that you can direct your yaw to where you want your nose to be and hold it is the difference between fighting and falling.

    and until the TVC came as said Sukhois and MiGs and all other planes have been more than ok without it. Stall recovery is relevant though, and it is guaranteed with TVC even if no differential or even 3D deflection is available, normal 2D are ok for that.

    Even without TVC having two engines you can throttle gives you some control a single engined aircraft or closely coupled twins don't have.


    I just demonstrated it is the opposite of what you claim, considering a twin engine jet which is actually far larger, like the MiG-29, that should have substantially more range but has little more fuel and clearly less range.

    F-16A: weight empty 7,317 kg / internal fuel 3,162 kg (ratio fuel to weight is 0.43)
    MiG29: weight empty 11,001 kg /internal fuel 3,453 kg (0.31)

    You are not getting it... the MiG-29 and the F-16 were not made by the same company for the same contract... comparing their empty weight and their fuel fraction means nothing at all... if they were working for the same contract and the range was specified then the fuel fraction of the MiG would be much higher to meet that range requirement, but the fact that they were intended for totally different roles means a comparison is meaningless.

    If you were really serious you would be comparing the YF-17 numbers to the YF-16 because they did compete together for the same job... the YF-17 lost and eventually became the F-18... perhaps the discussion should be why a single engined fighter design won the AF competition but such a plane was not even considered for a naval job if it is so fantastic and cheap and simple...

    50% more cross sectional area is not a "marginal" difference in drag by any measure.

    Not enough to make it slower.

    BTW the F-16 can carry a 7 ton payload... does that cross sectional area include that?

    In terms of thrust, F-16's TWR is better than that of a MiG-29.

    So what. The TWR of an F-16 is probably better than that of a MiG-31... which one is faster... which one is suitable for operating over the arctic with 500kg AAMs as its primary weapon?

    Beyond that, having a lot of thrust to compensate for a lot of drag is always a bad idea, because it will make you spend your fuel faster.

    Fuel is cheap enough.

    You should use F-16A values instead, those are the ones against which MiG-29 was designed.

    Was it?

    And of course this is a case of apples vs oranges since those wiki values are far too superficial in one hand and given in different conditions for each plane, to make an assessment. You need EM charts, fuel rate tables and so on. If not, at least a good info source to start with is this:

    Why would Russia care about fuel rate tables? Are they running out of oil?

    I am sure the Red Baron would tell you the best fighter has the lowest fuel burn rate...

    I am sure the fuel burn rate of a single like a Gripen or an F-16 or even an F-35 would be much more impressive than the fuel burn rate of an Su-35.
    LMFS
    LMFS

    Posts : 1949
    Points : 1949
    Join date : 2018-03-04

    Single vs. Twin Engine Fighters Empty Re: Single vs. Twin Engine Fighters

    Post  LMFS on Fri Aug 28, 2020 10:30 pm

    GarryB wrote:Yet has it ever been implemented?

    It was really close with the F-16 and F-15. Then USAF started pumping more and more into the low part of the mix as it usually happens and they spoiled the concept a bit. Now engines are more powerful and electronics smaller, so I think it could be implemented. We have to see whether this is going to happen though, as "loyal wingmans" are entering the stage and may take the lo part of the mix for themselves.

    and the F-16 does use the engine or the F-15 but is it half the maintenance bill?

    Between 2.4 and 3 times cheaper, depending on the version and based in the information I gathered. Numbers change a bit every year.

     ... is there any single engined fighter anywhere that actually uses a single engine that is also used on a heavier twin engined fighter that can be considered cheaper?

    Apart from F-16? Maybe J-10... but what do China and USAF know? Very Happy

    to you they are idiots because not only have they upgraded the T-72 and the T-90 they have not replaced everything with Armata T-14s.

    Oh boy...

    That bleed slot would be terrible for RCS, as would the ramp moving up and down...

    Like the one in every adjustable intake, including the Su-57???

    Plus... if it moves down and restricts the airflow... where does the excess air go?

    Garry, this is literally like every adjustable ramp intake in the world.

    Was it tested at all, or just a what if drawing?

    I don't know, but the F-16 has been used for many experiments, XL, TVC, DSI intake etc.

    Did you?  What conformal fuel tanks does MiG use?

    Yes. The MiG has some beautiful dorsal CFTs in some versions, BTW.

    They also have TVC engine nozzles as an option which suggests manouverability is a problem yet no customers took up that option... confusing...

    May be confusing for you. MiG has not make it an option not to have more fuel in the newer MiG-29 family.

    They have air intake grid protectors to reduce the risk of FOD, and they still train from motorways... as shown recently with Il-76s and Su-34s.

    There are some interesting stories about those FOD screens, namely that they gather dirt and stones and when they are open they release them into the engines... I have to research that further. But a highway is not a dirt airstrip. Even if the screens would work, the amount of dust and small stones thrown into ventral intakes by the front wheel is insane and I assume dorsal intakes are a need to operate like that. Hence the need for that kind of operation is not perceived anymore. Feel free to correct me, if you have proof they operate from dirt airstrips.

    A roll to allow a hard turn only lasts for a fraction of a second and whether it takes 0.1 of a second or 0.05 of a second is not really that important...

    Roll rate and onset times are relevant, better dont make up numbers.

    just having one fighter engine type makes no sense at all...

    We disagree then

    Indeed, but not every plane suffers for that... if you have that issue then don't fly in situations where AoA is a problem... or accept a little agro when you fly in the tattered parts of the envelope...

    You will notice Russians tend to avoid cornering themselves like that, and it is correct IMO. The more flexible the plane, the more options you have, the more difficult for the enemy to devise and train tactics to counter you. Pilots appreciate F-35 and F-18 having more nose authority than the F-16. All newer planes have two tails, due to that and LO.

    But drag is only one issue... what about sucking shit up off the runway with a chin mounted air intake?

    On the contrary... an intake placed in front of the wheel runs in clean air, unlike ventral intakes in the wake of the front wheel...

    You can see this in Il-65 , C-17 or Su-25 operating from dirt airstrips

    The square intakes of the Tu-22M3 actually increased RCS by 25% over the intakes like the MiG-23 used on the Tu-22M2... they kept them because if the difference in engine performance it resulted in meaning flight range and top speed increased dramatically.

    What do you mean?

    Despite its problems it was clearly considered superior to the nose mounted air intake of the MiG-21 that preceded it.

    Such an intake is unnecessarily long, adds lots of weight, complicates radar and area ruling... it is logical that planes are not designed like that anymore.

    Maybe they like the fact that any increase in engine power is doubled in a twin jet,

    If you have two engines with 15% more power each, you have 15% more thrust overall, the same as if you have one engine 15% more powerful...

    There are single engined aircraft and there are twin, but the only three engined aircraft I know of are commercial airliners that use the extra often tail mounted engine for a boost at takeoff and then cruise the rest of the flight. Then there are four and six and even eight engined aircraft... but no five engined ones and very few three engined ones... the vast majority are one, two or four.

    The trend that I see is that no new airliner has 4 engines and neither have they 3. As I said, engine reliability has come a long way in the last decades, in fact has advanced proportionally more than engine performance. And so planes with more than 2 engines are not designed anymore.

    Do you think that is an accident?

    I would say there are obvious reasons to be a single engined plane but the fact that they are not the most common suggests very good reasons for that.

    Twin propeller planes are much more expensive to insure than single engines, do you think it is an accident? They are difficult to control when one engine fails and unless the pilot is quite competent they simply tend to crash. There is also a quite lengthy list of twin engine fighters fatal accidents caused by failure of one engine, for the same reason. Real life is a bitch...

    The MiG-21 is probably the best Soviet single jet fighter, but things have moved on and such a small plane simply does not have much growth potential or space for everything needed today...

    MiG-21 is extremely small. Today it would need to be bigger, but the good thing is that engines are way more powerful too...

    The intake doors are grids that allow air to flow through them so they don't need the upper louvers...

    I don't think so, see above...

    A customer in Africa asked if they want D-30K engines at 14 tons thrust at 800K US dollars for their Il-76 or if they want PS-90A engines at $6 million each but 16 tons thrust and reduced fuel consumption I am pretty sure what most will choose...

    Yeah you are right, they should close UEC and just keep manufacturing jet engines of the 50's, things just went downhill afterwards Rolling Eyes

    If we are going to only use western data then anything we come up with is pretty useless anyway isn't it?

    No, there are trends based on technology and constraints that are the same all over the world. There exists a risk to misunderstand things, of course.

    How can you look a customer in the face and say single engined fighters are cheaper?

    If the data supports it, why not? The analysis I have done suggests that light single engine fighters are quite cheaper than medium or heavy twin engine, at least in western world.

    When you need three Gripens instead of one Rafale or Typhoon to get the job done... is it actually cheaper?

    First, a light fighter may not be able to do what a heavy one can do, in any numbers, hence the complementarity in the fleet. For instance, if your radar detection range is half of that of the bigger plane, no number of light fighters will get it doubled.

    Second, what the CPFH showed is that you can operate three Gripen for the price of the other two. The Swiss report did not conclude that you would need three Gripen for each Rafale / Eurofighter, and it was besides badly flawed by trying to compare planes that do not occupy the same category as if they were analogue.

    What other new single engined fighter is an option?  Chinese... well of course they are cheaper...

    Well, then a Russian one is definitely missing Razz

    Single vs. Twin Engine Fighters Mig_iz10

    I am familiar with most of them, and all of them failed, because Russia does not need or want a light single engined fighter... it wants a capable affordable fighter.

    That remains your opinion, until you manage to bring to the table authoritative and clear statements from Russian designers and military planers saying as much.

    Except similar mishap rates is a bad thing for single engined fighters doesn't it?

    Class A mishap means loss of the plane or at least serious damage, so it is not substantially worse for single engine plane sin this case.

    It has nothing to do with guessing and everything to do with body lift that is accentuated with engine trunks and two jet engines at the rear...

    I get what you say, but integral aerodynamic design does not mandate podded design, wing roots could be made thicker too, for more fuel as Su-57, MiG-29, Tu-160, F-16 do. With two ventral intakes you have a thick nose for a big radar and simplified / lighter air ducts, plus the enhanced safety and the lift body you mention in the space between them. You increase wetted area, interference drag and some other problematic aspects. I will see whether I manage to find an authoritative opinion about the reasons for the podded design.

    Because stall recovery will either be gravity or engine power and being able to roll to enhance either one could be important... certainly being able to point your nose where you want is critical in a superstall and being able to roll so that you can direct your yaw to where you want your nose to be and hold it is the difference between fighting and falling.

    Rolling does not point your nose or alter yaw.

    You are not getting it... the MiG-29 and the F-16 were not made by the same company for the same contract...

    Gripen and Eurofighter are also a product of different programs and you keep comparing them. If you don't want to be proven wrong, don't bring the supposed fuel superiority issue, easy.

    if they were working for the same contract and the range was specified then the fuel fraction of the MiG would be much higher

    And yet you slip your unsubstantiated opinion about fuel superiority again lol1

    If you were really serious you would be comparing the YF-17 numbers to the YF-16 because they did compete together for the same job... the YF-17 lost and eventually became the F-18... perhaps the discussion should be why a single engined fighter design won the AF competition but such a plane was not even considered for a naval job if it is so fantastic and cheap and simple...

    Why the "inherently superior" twin engine lost the USAF program would be also an interesting aspect don't you think? We can check YF-17 and YF-16 if you want to.

    BTW the F-16 can carry a 7 ton payload... does that cross sectional area include that?

    Is this a joke?

    Fuel is cheap enough.

    Fuel onboard a jet fighter that allows to fulfil a mission is actually quite an expensive commodity.

    Was it?

    F-15 and F-16 of course.

    I am sure the fuel burn rate of a single like a Gripen or an F-16 or even an F-35 would be much more impressive than the fuel burn rate of an Su-35.

    F-16 does 0.25 nm/lb, what about the Su-35?
    GarryB
    GarryB

    Posts : 25949
    Points : 26495
    Join date : 2010-03-30
    Location : New Zealand

    Single vs. Twin Engine Fighters Empty Re: Single vs. Twin Engine Fighters

    Post  GarryB on Sat Aug 29, 2020 2:43 pm

    It was really close with the F-16 and F-15.

    Not even nearly.... for your idea to actually work both planes have to be made by the same company.... otherwise who is going to make the light fighter and keep it cheap and simple when they can add features and capabilities and make it heavier and more expensive and complex...

    But having the high and low fighters made by the same company creates the same monopoly the F-35 is currently enjoying... and what was the ultimate response to that...

    We have to see whether this is going to happen though, as "loyal wingmans" are entering the stage and may take the lo part of the mix for themselves.

    Which makes much more sense... but they will likely be over engineered in the US too... why stop now?

    Between 2.4 and 3 times cheaper, depending on the version and based in the information I gathered. Numbers change a bit every year.

    Which is not good enough... the F-15 is ancient and should have been dropped from the inventory decades ago like the F-14 was... and more importantly in terms of performance the F-16 is not 2.4 to 3 times better.

    Apart from F-16? Maybe J-10... but what do China and USAF know?

    USAF are experts in pissing away money and China simply does not have that many engines to choose from... but lets check and see how successful either will be?

    I don't know, but the F-16 has been used for many experiments, XL, TVC, DSI intake etc.

    Never heard of any faster than Mach 2, so I guess vapourware.

    Yes. The MiG has some beautiful dorsal CFTs in some versions, BTW.

    The SMT uses an enlarged back, not scabbed on conformal fuel tanks.

    May be confusing for you. MiG has not make it an option not to have more fuel in the newer MiG-29 family.

    Might be confusing to you that the MiG-29 was never meant to compete with the Flanker, it was supposed to compliment the Flanker, so long range was not a problem for the Soviets, only for export customers who asked for more range. I realise it is very unwestern to listen to customers or ask what they want, but MiG are funny like that... pretty much every upgrade of the MiG-29 included more fuel capacity... I am surprised you noticed because they are all the same aren't they?

    I realise using figures and numbers from the very first MiG-29 and the F-16A suits your view, but both aircraft have moved on.

    There are some interesting stories about those FOD screens, namely that they gather dirt and stones and when they are open they release them into the engines... I have to research that further.

    Of course... that is why they fit them... didn't you know Russian engines can't start properly until they have had breakfast... some porridge or some muesli... they had solid doors that did the job and then replaced them with gridfin doors because obviously they don't work... no Russian grid fin system works on anything it is all a big conspiracy... it will only take ten minutes of looking through US Navy stats to show they tried it once 50 years ago and it didn't make any difference because after they had the entire staff at the air base pick up all the stones and bits of wire on the airfield the grid fins didn't do anything except reduce the airflow into the engine so they ditched it. Rolling Eyes

    But a highway is not a dirt airstrip. Even if the screens would work, the amount of dust and small stones thrown into ventral intakes by the front wheel is insane and I assume dorsal intakes are a need to operate like that. Hence the need for that kind of operation is not perceived anymore. Feel free to correct me, if you have proof they operate from dirt airstrips.

    If they all are designed to operate from pristine paved air strips why do all their fighters have mudguards on the nose wheel... why do they have grid fin doors over their air intakes... has HATO made a promise that if a real war starts in europe that they wont attack Russian airfields?

    Roll rate and onset times are relevant, better dont make up numbers.

    Roll rate means nothing if the turn is slow because of AoA limitations.... taking half a second or three quarters of a second to roll to the angle you want to pull turn away from your current flight direction is not really very important...

    We disagree then

    A heavy fighter will get heavier over time and need an increase in power to maintain performance... look at the F-14A and F-14D, or the Su-27 and the Su-35, or the first model Su-57 and later models...

    The light fighter shouldn't change weight at all so increased thrust engines will burn more fuel meaning a higher fuel fraction will be needed to maintain performance in terms of range.

    Pilots appreciate F-35 and F-18 having more nose authority than the F-16. All newer planes have two tails, due to that and LO.

    The F-35 and Gripen are the only single engined new fighters and only one is intended to be a light fighter... all the other Eurocanards and Russian planes and the "new" F-15s all have twin engines... isn't that a trend too?

    On the contrary... an intake placed in front of the wheel runs in clean air, unlike ventral intakes in the wake of the front wheel...

    You do understand that during takeoff with the engine generally running at full power there is no need for a wheel in front to kick stuff up into the air to get it to go into an engine intake... We are talking about the 21st century... the main reason that stopped Harriers from operating from supermarket carparks was that plastic shopping bags are not good for jet engines either.

    What do you mean?

    Just what I said... the MiG-25 type intakes of the Tu-22M3 were chosen because of the effect on engine performance and not RCS for which they are terrible.

    There are lots of reasons for choosing design solutions and not all of them are based on drag or roll rate.

    Such an intake is unnecessarily long, adds lots of weight, complicates radar and area ruling... it is logical that planes are not designed like that anymore.

    It also moves the air intake in front of the nose wheel... and means the airflow has access to the engine intake at higher AoA.


    If you have two engines with 15% more power each, you have 15% more thrust overall, the same as if you have one engine 15% more powerful...

    Bullshit. If you increase thrust by 1 ton per engine then a single gets one ton of extra thrust to play with, while a twin gets two tons of extra thrust.

    Smaller lighter engines are easier to increase in power than engines that are already big and powerful.

    And so planes with more than 2 engines are not designed anymore.

    Both the Il-106 and the Slon transports will most likely have four engines each...

    Twin propeller planes are much more expensive to insure than single engines, do you think it is an accident?

    Twin propeller planes are generally larger much longer ranged and more expensive so of course they cost more to insure.

    They are difficult to control when one engine fails and unless the pilot is quite competent they simply tend to crash.

    I would expect when one engine fails they would be easier to control because there is only one engine, and they are more likely to crash in a single engined aircraft when that engine fails... instead of tends to, it should be will crash.

    There is also a quite lengthy list of twin engine fighters fatal accidents caused by failure of one engine, for the same reason. Real life is a bitch...

    The job of the designers is to make the best and safest plane they can... accidents are accidents.


    MiG-21 is extremely small. Today it would need to be bigger, but the good thing is that engines are way more powerful too...

    And twin engines is a quick way to make it bigger without needing a huge expensive engine....

    I don't think so, see above...

    MiG said of their experience in Syria that they adopted the grid fin intake doors used on the Flankers to protect the engines of their SMTs.

    Yeah you are right, they should close UEC and just keep manufacturing jet engines of the 50's, things just went downhill afterwards

    A lot of customers couldn't give a shit about slightly more power or better fuel consumption... for a plane like an Il-76 do you think four new engines at 800K each, or 3.2 million for a set of four engines but burns more fuel is the biggest sticking point for the country operating the plane. Four new engines at 6 million dollars a pop for which their existing spare parts pool is now useless and they need to retrain all their ground crew including sending them to university to learn how to look after these new engines that are going to cost 24 million dollars per plane just for the engines and with no spare parts at all.

    Most of MiGs problems have been trying to make the best planes they can instead of what the Russian Air Force wanted... the SMT model didn't need to be multirole... they just wanted a short range interceptor... they made the MiG-29K they made it fully multirole too which made it almost as expensive as the Su-33 which was an Su-27 with folding wings and a tail hook and some strengthening... their problem has been that they have been trying to make their plane too capable, which has been pushing up the price and the Air Force just thinks for a similar price they can get the Su-30.

    No, there are trends based on technology and constraints that are the same all over the world.

    If that were true then the new MiG will be a single engine VSTOL fighter that is overpriced...

    The analysis I have done suggests that light single engine fighters are quite cheaper than medium or heavy twin engine, at least in western world.

    There are not cheap western fighters.

    First, a light fighter may not be able to do what a heavy one can do, in any numbers, hence the complementarity in the fleet. For instance, if your radar detection range is half of that of the bigger plane, no number of light fighters will get it doubled.

    Radar range is largely irrelevant though isn't it... that is the job of the IADS to get you close enough to the target and in position for an attack they wont know is coming.

    The Swiss report did not conclude that you would need three Gripen for each Rafale / Eurofighter, and it was besides badly flawed by trying to compare planes that do not occupy the same category as if they were analogue.

    The Swiss report seemed to be to show the Gripen couldn't do the job in any numbers and was not worth considering for the job...

    Well, then a Russian one is definitely missing

    Why would Russia want a useless short range nothing of a plane... they are already buying plenty of twin engine types and funding a new stealth fighter... the last thing they need would be another single engined fighter.


    That remains your opinion, until you manage to bring to the table authoritative and clear statements from Russian designers and military planers saying as much.

    The planes they currently operate and the new plane they are funding does not include any single engined fighters.

    Class A mishap means loss of the plane or at least serious damage, so it is not substantially worse for single engine plane sin this case.

    I would say there is a considerable difference between the loss of a plane and serious damage...

    I will see whether I manage to find an authoritative opinion about the reasons for the podded design.

    Underbody bodywing fences?

    Rolling does not point your nose or alter yaw.

    I know, but not being able to roll in a super stall means even with TVC you can only move your nose up and down... a plane going past means you can't roll to align your up and down with their flight path and keep your nose pointed at them as they go by.... it also limits your choices to exit the stall you are in most efficiently...

    Which makes you more predictable and easier to target...

    Gripen and Eurofighter are also a product of different programs and you keep comparing them. If you don't want to be proven wrong, don't bring the supposed fuel superiority issue, easy.

    The MiG-29 has more internal space... you said so yourself. The first models could not take advantage of that because of the structure of the aircraft meant to put fuel in a compartment you had to put a fuel tank in there... which added weight and some spaces were simply not suitable. The current method of construction means the skin of the aircraft becomes the outer wall of the fuel tank which is lighter and simpler and cheaper.
    It should also reduce dry weight BTW.

    Comparisons between a single engined fighter designed to steal from poor countries and murder anyone who refuses their new colonial overlords, and a twin engined fighter intended for self defence is not accurate because one requires range and the other one does not.

    The newer models all have increased fuel levels as well as enlarged external fuel tank options and inflight refuelling so fuel is not a problem nor an advantage of a single jet fighter.

    And yet you slip your unsubstantiated opinion about fuel superiority again

    Bigger heavier fighters are able to carry more fuel... you yourself described the MiG-29 more as a medium fighter and the F-16 as being light...

    Why the "inherently superior" twin engine lost the USAF program would be also an interesting aspect don't you think? We can check YF-17 and YF-16 if you want to.

    I would have thought that would be the first place you would look, but I suspect you will be disappointed... fighter aircraft contracts don't always go to the best design.

    Fuel onboard a jet fighter that allows to fulfil a mission is actually quite an expensive commodity.

    When invading the colonies yes.... but fuel weight and fuel burn are not random occurrances, during mission planning you can often determine that some inflight refuelling might be needed, or buddy tanking perhaps... or even just using a bigger aircraft perhaps... sometimes light fighters are not the first choice for deep strike missions...

    F-16 does 0.25 nm/lb, what about the Su-35?

    Don't know but will convert it into arshins for you.... you are clearly interested in archaic measures... Wink
    LMFS
    LMFS

    Posts : 1949
    Points : 1949
    Join date : 2018-03-04

    Single vs. Twin Engine Fighters Empty Re: Single vs. Twin Engine Fighters

    Post  LMFS on Sat Aug 29, 2020 10:53 pm

    GarryB wrote:Not even nearly.... for your idea to actually work both planes have to be made by the same company

    In Russia they will do what they are told to. VKS can write the TTZ and set the acceptable prices and that's it.

    But having the high and low fighters made by the same company creates the same monopoly the F-35 is currently enjoying... and what was the ultimate response to that...

    Allowing two companies to do them would actually be an incentive to have different layouts and approaches which would help getting complementary designs.

    Which is not good enough...

    Who says that?

    and more importantly in terms of performance the F-16 is not 2.4 to 3 times better.

    Being cheaper it means it could be much worse and still pay off...

    USAF are experts in pissing away money and China simply does not have that many engines to choose from... but lets check and see how successful either will be?

    Both are superpowers and have people, money and resources to make a very informed planning of their armed forces. I would not take them for fools.

    Never heard of any faster than Mach 2, so I guess vapourware.

    A technical idea not implemented by some external reason has not the negative connotations of "vapourware". Probably it was simply not deemed necessary.

    Might be confusing to you that the MiG-29 was never meant to compete with the Flanker

    It is quite clear to me, the same F-16 or Gripen do not try to compete with F-111 or F-15. Still you keep comparing them with medium and heavy fighters with completely different acquisition and operational costs.

    I realise using figures and numbers from the very first MiG-29 and the F-16A suits your view, but both aircraft have moved on.

    It is the most reasonable approach because those planes have moved on in quite different circumstances, and the old data are easy to to come by. But we can compare latest versions if you want to... just find the data for the MiG.

    If they all are designed to operate from pristine paved air strips why do all their fighters have mudguards on the nose wheel

    Not all...

    ... why do they have grid fin doors over their air intakes...

    New MiGs dont have that anymore

    A heavy fighter will get heavier over time and need an increase in power to maintain performance... look at the F-14A and F-14D, or the Su-27 and the Su-35, or the first model Su-57 and later models...

    The light fighter shouldn't change weight at all so increased thrust engines will burn more fuel meaning a higher fuel fraction will be needed to maintain performance in terms of range.

    Those considerations apply both to light and heavy fighters.

    The F-35 and Gripen are the only single engined new fighters and only one is intended to be a light fighter... all the other Eurocanards and Russian planes and the "new" F-15s all have twin engines... isn't that a trend too?

    You are right, if you ignore J-10, JF-17, Tejas, F-35, F-16 still being sold...

    You do understand that during takeoff with the engine generally running at full power there is no need for a wheel in front to kick stuff up into the air to get it to go into an engine intake...

    Il-76, Su-25 or C-17 have no screens in front of their engines and they take off from places no-one has seen the MiGs using.

    It also moves the air intake in front of the nose wheel... and means the airflow has access to the engine intake at higher AoA.

    With a ventral intake the nose and fuselage forces the air into the engine at high AoA, no issue there.

    Bullshit. If you increase thrust by 1 ton per engine then a single gets one ton of extra thrust to play with, while a twin gets two tons of extra thrust.

    Smaller lighter engines are easier to increase in power than engines that are already big and powerful.

    Rolling Eyes

    You still seem to think a plane with two engines has twice the relative thrust of a single engined one, right?

    As to the point that small engines can be improved and big ones don't... I think anyone can see that makes no sense at all. Why would you use a bad small engine on your new twin engined fighter to start with?

    That is why talking is cheap but what is actually needed is to let the numbers talk. Don't be lazy and bring up numbers to prove your point. What are those small engines that can be upgraded and those big ones that cannot?

    Both the Il-106 and the Slon transports will most likely have four engines each...

    We were talking about airliners. A twin-engined Slon would need a 70 tf engine  Shocked

    I would expect when one engine fails they would be easier to control because there is only one engine, and they are more likely to crash in a single engined aircraft when that engine fails... instead of tends to, it should be will crash.

    Just read about it and you will see what happens in reality.

    MiG said of their experience in Syria that they adopted the grid fin intake doors used on the Flankers to protect the engines of their SMTs.

    Do you have a link? I though the mesh doors were already there.

    Most of MiGs problems have been trying to make the best planes they can instead of what the Russian Air Force wanted... the SMT model didn't need to be multirole... they just wanted a short range interceptor... they made the MiG-29K they made it fully multirole too which made it almost as expensive as the Su-33 which was an Su-27 with folding wings and a tail hook and some strengthening... their problem has been that they have been trying to make their plane too capable, which has been pushing up the price and the Air Force just thinks for a similar price they can get the Su-30.

    You are making the perfect case against the medium fighter. I fully agree, 0% sarcasm.

    Radar range is largely irrelevant though isn't it... that is the job of the IADS to get you close enough to the target and in position for an attack they wont know is coming.

    Great, you just need to convince all AFs in this world that GCI is back and they can save billions in radars for fighters and in trying so hard to increase their ranges.

    The Swiss report seemed to be to show the Gripen couldn't do the job in any numbers and was not worth considering for the job...

    And that only proves they were pitting together planes that were not designed for the same functions and were dead wrong trying to use light cheap fighters for roles that demand heavy ones. They are at fault, not the Gripen. It is like you using an air gun to hunt elephants and saying the gun is rubbish...

    Again: the light fighter is to complement the heavy one.

    The planes they currently operate and the new plane they are funding does not include any single engined fighters.

    Until you get proof that they are doing that for the reasons you say, it remains your opinion. Tomorrow they could change their mind. They have been talking about single engine fighters very recently.  It is not even clear that the ongoing studies for a twin engine fighter are the only ones being done, or that they are not being done just to make the development cheaper, basing it in the MiG-29, or for industrial base reasons (supporting Klimov). It remains speculation only.

    I know, but not being able to roll in a super stall means even with TVC you can only move your nose up and down... a plane going past means you can't roll to align your up and down with their flight path and keep your nose pointed at them as they go by.... it also limits your choices to exit the stall you are in most efficiently...

    This use is marginal at best, a plane does not fight completely stopped in mid air, and if it happens you should be already positioned in terms of roll to follow the opponent. If you get there, use TVC to get yaw or pitch as needed and recover airspeed. Only Su-35 and 57 can do this trick currently and they are not making a trend anywhere else. It is a "nice to have" feature IMHO, nothing that you need to impose over other more important design considerations that are going to be relevant all the time and not only in very "pathological" situations.

    Which makes you more predictable and easier to target...

    Stopped in mid air you are dead meat, no matter if you want to make it more aesthetically pleasant by rolling around yourself  Laughing

    The MiG-29 has more internal space... you said so yourself.

    They managed to free some space, yes. I don't know exactly how much did they get from the dorsal intakes. Su-35 also got more than 2 extra tons of fuel over Su-27, so there is gain from other optimizations. The result in the MiG-35 is a plane with a more or less normal amount fuel available (4.5 - 5 t fuel for medium fighters like Rafale or Eurofighter), when before it was clearly substandard. F-35 has almost twice that, but it is more strike oriented so it would be a bit unfair to compare it to the others.

    Comparisons between a single engined fighter designed to steal from poor countries and murder anyone who refuses their new colonial overlords, and a twin engined fighter intended for self defence is not accurate because one requires range and the other one does not.

    This is the same emotional narrative I read from carrier detractors... it has nothing to do with the case. Flankers have more range than any "colonial" fighter. A small single engine fighter should have a range similar to MiG-35 (2,000 km on internal fuel) or a bit better if possible.

    The newer models all have increased fuel levels as well as enlarged external fuel tank options and inflight refuelling so fuel is not a problem nor an advantage of a single jet fighter.

    Thanks, that is what I am saying for a while.

    Bigger heavier fighters are able to carry more fuel... you yourself described the MiG-29 more as a medium fighter and the F-16 as being light...

    Light fighters consume much less. So in absolute terms they are more economical to operate in that regard, in relative terms you need to see what plane makes more distance based in the fuel they carry and their consumption, it is not so obvious to say before making numbers, because of the very reduced cross sectional area of small single engine planes. In principle as said, the bigger plane has a general advantage in range due tot eh way fuel and drag increase with linear dimensions.

    fighter aircraft contracts don't always go to the best design.

    Does it apply to the new 5G jet too?  Razz

    When invading the colonies yes.... but fuel weight and fuel burn are not random occurrances, during mission planning you can often determine that some inflight refuelling might be needed, or buddy tanking perhaps... or even just using a bigger aircraft perhaps... sometimes light fighters are not the first choice for deep strike missions...

    BS, range is always useful. You need time on afterburner to do a push and launch your missiles, to disengage or to egress after a strike, to address a new threat, to outrun a missile. You need to climb or to maneouver. The only planes that don't use EFTs normally are the Flankers, the rest use them for almost any mission.

    Don't know but will convert it into arshins for you.... you are clearly interested in archaic measures...   Wink

    As far as you get the data of the MiG-35 for us, it can be in middle age units if you want thumbsup
    kvs
    kvs

    Posts : 6799
    Points : 6946
    Join date : 2014-09-11
    Location : Canuckistan

    Single vs. Twin Engine Fighters Empty Re: Single vs. Twin Engine Fighters

    Post  kvs on Sun Aug 30, 2020 12:18 am

    TLDR;

    I see that my statement about "marginal" got under the skin of the single engine advocate.   I was using the C_D numbers you posted yourself.
    If a 50% cross-sectional area difference gives a 5% C_D difference at cruise then it is a misleading number to tout.

    Single inlet ( Mach = 0.8 ) : 0.0318
    Dual inlet   ( Mach = 0.8 ) : 0.0337
    LMFS
    LMFS

    Posts : 1949
    Points : 1949
    Join date : 2018-03-04

    Single vs. Twin Engine Fighters Empty Re: Single vs. Twin Engine Fighters

    Post  LMFS on Sun Aug 30, 2020 1:21 am

    kvs wrote:TLDR;

    I see that my statement about "marginal" got under the skin of the single engine advocate.   I was using the C_D numbers you posted yourself.
    If a 50% cross-sectional area difference gives a 5% C_D difference at cruise then it is a misleading number to tout.

    Single inlet ( Mach = 0.8 ) : 0.0318
    Dual inlet   ( Mach = 0.8 ) : 0.0337

    kvs, I think you are mixing two different things:

    - The single vs double intake effect was illustrated by the early YF-16 wind tunnel model; there, differences of roughly 5-9% are to be seen in the parameters, in favour of the single ventral intake. We are talking here about the same airframe and the same intake capture area. This is unrelated to the single vs. twin engine discussion.

    - The 50% cross sectional area difference was related to F-16 vs MiG-29, different airframes with different engine layouts. Such difference is substantial and should lead to very different fuel flow rates in almost any flight regime. You claimed the single engine plane would have a marginal advantage in drag:

    The fuel tank capacity of some single engine jet like the F-16 is deficient and for marginal "losses" in terms of drag, a larger twin engine design gets you more range.
    GarryB
    GarryB

    Posts : 25949
    Points : 26495
    Join date : 2010-03-30
    Location : New Zealand

    Single vs. Twin Engine Fighters Empty Re: Single vs. Twin Engine Fighters

    Post  GarryB on Sun Aug 30, 2020 2:04 pm

    In Russia they will do what they are told to.

    Yah... In nazi Russia ve do az ve r told, ver as in pez luving U S ov A zay do az zay pleez... anyzing zey like. Rolling Eyes

    Meanwhile, in the real world every MIC builds what their customer demands or a different bureau gets the contract.

    In fact that is totally not true.... Tupolev essentially forced the Russian Air Force to take Mach 2 theatre bombers instead of the much bigger much more expensive mach 3 bombers they were demanding... but that was a minor hiccup... the only other case of a design bureau I can remember going their own way was with the Su-25.

    For the High Low mix of fighters to work the low fighter has to stay cheap and simple and short ranged, which would be fine for Russia or the US, but for exports other countries are probably using teh low fighter as their primary fighter so they want all the bells and whistles, so eventually the low fighter becomes and complex and expensive as the big plane when they upgrade.... Russia essentially avoided that simply by continuing to use the old model MiG-29s.

    MiG actually catered to that with the SMT upgrades to actually reduce the operating costs of the older planes which the Russian AF essentially rejected... they didn't want to spend money to save money... they had plenty of spare parts.

    Allowing two companies to do them would actually be an incentive to have different layouts and approaches which would help getting complementary designs.

    HAHAHAHAHAHAHAHAHAHHAHAAHHAHAHAHAHAHAHAHHAHHHAHAHAHHAHHAHAHHAHHAHAHA....

    Su-9/11 interceptors and Su-7 strike aircraft of the same generation as the MiG-21... most western reporters can't tell them apart... Flanker family and Fulcrum family.... many western reporters still can't tell them apart.

    The solution for a problem is normally the same depending on the technical capability and materials. The requirements for high and low fighters are not that much different... the low needs to be smaller and lighter and cheaper.

    Who says that?

    I did...

    Being cheaper it means it could be much worse and still pay off...

    The Sukhoi solution is that an Su-30 is less well equipped than an Su-35 which makes it rather cheaper to buy... not much cheaper to operate but a significant chunk of operational costs are fuel costs, which is nothing for a state that runs several energy companies...

    I think the MiG-29M2 makes rather more sense being smaller and lighter and cheaper but in many ways with a lot of comparable features... similar speed for example and good manouver performance.

    Both are superpowers and have people, money and resources to make a very informed planning of their armed forces. I would not take them for fools.

    Common sense has nothing to do with this... the US system is run by greed... we spend 10 times more money than Russia yet they have better air defence systems and are better in a lot of other areas too... we need to spend more... not sure about you but that looks like the solution of a fool... their politicians are not better... our sanctions have not worked to make putin conform to what we want him to do so the solution is more sanctions...

    China does not have a lot of experience to fall back on, but I rate them to be rather more sensible than the americans have proven themselves to be when there is 10 years of no red menace they turn on anything and everything... I would be taking my kids out of that day care centre...

    [quoteA technical idea not implemented by some external reason has not the negative connotations of "vapourware". Probably it was simply not deemed necessary.[/quote]

    That is the source of vapourware isn't it? Surplus to requirements... no money to throw away at it...

    It is quite clear to me, the same F-16 or Gripen do not try to compete with F-111 or F-15. Still you keep comparing them with medium and heavy fighters with completely different acquisition and operational costs.

    That is the core of your problem... neither the F-16 nor Gripen are cheap to buy, and do anything to piss off the US and you can't get spare parts anyway...


    It is the most reasonable approach because those planes have moved on in quite different circumstances, and the old data are easy to to come by. But we can compare latest versions if you want to... just find the data for the MiG.

    The fact that there is no current data for the MiG doesn't stop you criticising it and writing it off as flawed, yet you admit it is just your opinion.

    New MiGs dont have that anymore

    They added them to the SMTs after experience in Syria.... what evidence do you have they don't have them on their current models?

    A mesh screen used for takeoff means the engine runs at full power on the ground... which makes me think it could also be used in normal flight as a radar blocker if it was properly optimised...


    You are right, if you ignore J-10, JF-17, Tejas, F-35, F-16 still being sold...

    F-35 is not a light fighter, and late model F-16s are not either... the other planes... really...

    40 years ago there were plenty of single engine light planes... Mirage IIIs, Mirage 2000s, Saab Drakens, Su-17 family, MiG-21, MiG-23... now they are mostly replaced with twin engined larger heavier multirole aircraft...

    Get over it.

    Il-76, Su-25 or C-17 have no screens in front of their engines and they take off from places no-one has seen the MiGs using.

    Hahahaha.... when the Aussies got their C-17s they were told if they use them from rough air strips they will invalidate the warranty for airframe and engine life...

    Operating Il-76s and Su-25s from rough airstrips means they must have rough airstrips which means there will be times when they need to operate fighters there too... the engine intakes of the MiG-29 are much closer to the ground than any of those types you mention...

    You still seem to think a plane with two engines has twice the relative thrust of a single engined one, right?

    If the engine is the same engine then yes.

    They don't build planes and then design engines for them... most of the time they look at the engines they have and the engines they are developing and they design an aircraft around those engines.

    As to the point that small engines can be improved and big ones don't... I think anyone can see that makes no sense at all. Why would you use a bad small engine on your new twin engined fighter to start with?

    Don't know what you are talking about here...

    That is why talking is cheap but what is actually needed is to let the numbers talk. Don't be lazy and bring up numbers to prove your point. What are those small engines that can be upgraded and those big ones that cannot?

    Now you are making shit up.

    You have two engines of the same generation built to the same standard... one is big like an Al-31 and the other is smaller like an RD-33. Neither engine is crap, they are different sizes and different thrust classes. A new technology comes along that allows an increase in thrust for both engines of 1 ton thrust, so the Al-31 as a single engine improves the thrust in its aircraft by 1 ton without changing weight, it does however mean at the higher thrust setting it will burn more fuel. In a twin engined aircraft with two RD-33s that means an increase of 2 tons thrust.

    Both aircraft will probably continue to use the same thrust setting for cruising, because that is the fuel efficient setting used as normal, but when accelerating or climbing or both the extra power will improve performance, though it wont effect top speed that much... which would take so long to get to and burn too much fuel to achieve they likely wont find out anyway.

    Making a fictional single engined aircraft with a single Al-31 means the smaller lighter aircraft gets less of a thrust increase over the Flanker with two engines, because both engines are the same so the twin engined aircraft gets a double improvement in thrust because it has two engines.


    We were talking about airliners. A twin-engined Slon would need a 70 tf engine

    777s have gotten lost and shot down... how safe are they... or indeed Boeings in general... it is likely any new large airliner the Russians make will be a four engined aircraft.


    Do you have a link? I though the mesh doors were already there.

    The Flankers always used mesh doors, the MiGs had solid doors.

    You are making the perfect case against the medium fighter. I fully agree, 0% sarcasm.

    Many posters here and many people in Russia think they don't need smaller lighter fighters like the MiG-29 family, and that the Su-30 is the perfect solution to making an all Flanker Air Force affordable...

    Great, you just need to convince all AFs in this world that GCI is back and they can save billions in radars for fighters and in trying so hard to increase their ranges.

    HATO and the rest of the world don't have a ground based defensive IADS to support their aircraft... HATO has an air based system they can use to go to other countries to destroy and then rape, rob and pillage... sorry... spread peace and democracy... or is that Pepsi and Cocacola...

    Again: the light fighter is to complement the heavy one.

    So Saab don't understand their own aircraft...

    Until you get proof that they are doing that for the reasons you say, it remains your opinion.

    What proof do I need... they are talking about a new programme for a light cheaper (but obviously not actually cheap) 5th gen stealth fighter... if they were going to start making single engined fighters this would be it... and they said it will be a twin.

    It remains speculation only.

    The Russian military has ordered production of the MiG-35... there have been delays with its radar.... are you suggesting that in actual fact the radar is not the problem but they actually have a single engined fighter they want the Russian Military to buy instead except they are keeping it totally secret so they get no funding or support to make this new aircraft...

    Good luck with that...

    This use is marginal at best, a plane does not fight completely stopped in mid air, and if it happens you should be already positioned in terms of roll to follow the opponent. If you get there, use TVC to get yaw or pitch as needed and recover airspeed. Only Su-35 and 57 can do this trick currently and they are not making a trend anywhere else. It is a "nice to have" feature IMHO, nothing that you need to impose over other more important design considerations that are going to be relevant all the time and not only in very "pathological" situations.

    Call it a trick all you want but launching your missiles directly at the enemy plane means the shortest period of time before impact and the sooner he is dead the less time he has to launch anything at you... pointing your nose at him... even if you are flying backwards means you missile will be accelerating at him all the way getting max speed and energy from its fuel... continuing to fly nose forward with enemy aircraft behind you making your missiles pull a 180 degree turn on launch radically reduces the range and speed of your missiles.

    A target behind you and the last thing you want to continue doing is to keep flying forward and straight... a 150 degree flip... launch a missile and then continue the flip to descend and full AB to accelerate and roll over to get the right way up again would be the most efficient way to deal with a threat on your tail...


    Stopped in mid air you are dead meat, no matter if you want to make it more aesthetically pleasant by rolling around yourself

    Not at all... I am not suggesting doing it with the enemy plane 1km behind you and with you lined up for a cannon shot...

    The result in the MiG-35 is a plane with a more or less normal amount fuel available (4.5 - 5 t fuel for medium fighters like Rafale or Eurofighter), when before it was clearly substandard.

    Fighters like the Typhoon and Rafale are it... there is no bigger aircraft above them, so they need the range. The MiG-29 has the Su-27, which I am sure you will agree has plenty of fuel...

    Flankers have more range than any "colonial" fighter.

    Russia is a big country to defend. Which countries got inflight refuelling widely deployed first...

    Thanks, that is what I am saying for a while.

    If anything their single engined fighter... MiG-21 lacked range. Their bigger more expensive MiG-23 was still a single engined fighter but had rather better range, but was certainly not cheap to buy or operate.

    Light fighters consume much less. So in absolute terms they are more economical to operate in that regard, in relative terms you need to see what plane makes more distance based in the fuel they carry and their consumption, it is not so obvious to say before making numbers, because of the very reduced cross sectional area of small single engine planes. In principle as said, the bigger plane has a general advantage in range due tot eh way fuel and drag increase with linear dimensions.

    Again, I will say fuel is not a problem so a bigger aircraft just makes more sense.

    Does it apply to the new 5G jet too?

    In the case of the F-35 I would say it is the example that proves the rule... by including a Harrier replacement it was totally ruined as a light fighter.

    It could have been a stealthy F-16, and instead it is a stealthy Buccaneer... which is fine for light strike, but not so good as a fighter.

    BS, range is always useful. You need time on afterburner to do a push and launch your missiles, to disengage or to egress after a strike, to address a new threat, to outrun a missile. You need to climb or to maneouver. The only planes that don't use EFTs normally are the Flankers, the rest use them for almost any mission.

    If you are always carrying EFTs then you really needed a bigger plane.... like a Flanker. EFTs are for extra missions... if you are carrying EFTs as well as missiles of course you need to use more fuel to accelerate to launch your missiles, but MiG is designed to carry a centreline tank if it needs one which keeps the wing pylons free for weapons...

    As far as you get the data of the MiG-35 for us, it can be in middle age units if you want

    I don't actually work for MiG, and it is pretty clear it is information they are not prepared to release just yet...

    LMFS
    LMFS

    Posts : 1949
    Points : 1949
    Join date : 2018-03-04

    Single vs. Twin Engine Fighters Empty Re: Single vs. Twin Engine Fighters

    Post  LMFS on Sun Aug 30, 2020 9:20 pm

    GarryB wrote:For the High Low mix of fighters to work the low fighter has to stay cheap and simple and short ranged, which would be fine for Russia or the US, but for exports other countries are probably using teh low fighter as their primary fighter so they want all the bells and whistles, so eventually the low fighter becomes and complex and expensive as the big plane when they upgrade....

    Two comments:

    - Short range for the low side of the mix: it needs to be > 2,000 km in order to avoid EFTs in short range tactical missions. With BWB this is doable. Interestingly both my proposal and Saab's one had very similar fuel capacities > 6t for an empty weight of ca. 10 t. Together with reduced drag this should allow for ranges in excess of 2500 km on internal fuel, which would be nice both for the VKS and for a foreign customer which would, as you rightly say, use the plane as their main fighter and would greatly benefit from a decent range.

    - The foreign customers may indeed want all avionics refinements and best performance possible, since as we see the market frequently compares "apples vs oranges". The domestic version may use simpler versions of that equipment and even not have them installed altogether and operate based on the heavy, high end fighters of the fleet, a bit like the "loyal wingmans" will do. This should save lots of money, because avionics today are enormously expensive and in many cases regardless of the plane's size.

    HAHAHAHAHAHAHAHAHAHHAHAAHHAHAHAHAHAHAHAHHAHHHAHAHAHHAHHAHAHHAHHAHAHA....

    I am happy that you have fun man...

    The requirements for high and low fighters are not that much different... the low needs to be smaller and lighter and cheaper.

    I see you are not understanding much of what I post here... different layouts result in different aero profiles with different advantages.

    The fact that there is no current data for the MiG doesn't stop you criticising it and writing it off as flawed, yet you admit it is just your opinion.

    I am not writing it off. And of course there is data about the new MiG family, only it is not complete. But what is available points to a heavier airframe.

    They added them to the SMTs after experience in Syria.... what evidence do you have they don't have them on their current models?

    I was referring to dorsal intakes gone since the M version, if you mean the mesh screens then they are indeed in place.

    A mesh screen used for takeoff means the engine runs at full power on the ground... which makes me think it could also be used in normal flight as a radar blocker if it was properly optimised...

    The PAK-FA patent has info on those blockers and how they work, a mesh which is thin enough to block the radar is not good for the airflow.

    Operating Il-76s and Su-25s from rough airstrips means they must have rough airstrips which means there will be times when they need to operate fighters there too... the engine intakes of the MiG-29 are much closer to the ground than any of those types you mention...

    And crucially they are placed in the wake of the front wheel...

    You have two engines of the same generation built to the same standard... one is big like an Al-31 and the other is smaller like an RD-33. Neither engine is crap, they are different sizes and different thrust classes. A new technology comes along that allows an increase in thrust for both engines of 1 ton thrust, so the Al-31 as a single engine improves the thrust in its aircraft by 1 ton without changing weight, it does however mean at the higher thrust setting it will burn more fuel. In  a twin engined aircraft with two RD-33s that means an increase of 2 tons thrust.

    Wow that is a serious misconception... thrust increase is always proportional to the original thrust of the engine. For instance, if you have AL-31 vs AL-41F1S, you have and improvement of 12% max thrust. RD-33MK vs RD-33 is 8% more thrust. No fixed increases for each engine, regardless of its size or original thrust, that is utter nonsense. So if your plane had originally X thrust and the new engines get improved by a Y%, your thrust will be improved by that Y% the same whether you are single engine or twin engine...

    Making a fictional single engined aircraft with a single Al-31 means the smaller lighter aircraft gets less of a thrust increase over the Flanker with two engines, because both engines are the same so the twin engined aircraft gets a double improvement in thrust because it has two engines.

    Seriously... If the lighter fighter has exactly half the weight the bigger one, with one engine it will have the same original TWR and the same proportional increase with newer engines than the twin engine. This is kindergarten level maths for gods sake  scratch

    it is likely any new large airliner the Russians make will be a four engined aircraft.

    They are going to make the Il-96 twin engined, go figure.

    Many posters here and many people in Russia think they don't need smaller lighter fighters like the MiG-29 family, and that the Su-30 is the perfect solution to making an all Flanker  Air Force affordable...

    And I think the MiG-29 is not different enough from Flankers in terms of cost but too different in terms of capabilities, so it has no real appeal for the VKS. The new family will at least improve range, still the basic design is very limiting. I will post below a rough calculation I made with drawings to scale. You will see how the cross sectional area of those two, F-16 and MiG-29, is very different. But if you look at the length of the fuselage proper, it is very similar. The result is that the MiG probably creates a lot of lift, which is very good for manoeuvring, but it has little internal fuel and a lot of drag. That is why I said that as a multirole fighter it is a bit burdened by the original design requirements, which called for a very specialised role.

    HATO and the rest of the world don't have a ground based defensive IADS to support their aircraft...

    Tikhomirov designed the Irbis with 20 kW power for huge range despite not being HATO, and Phazotron is burning stages in their AESA development to come from 130 to 260 km range. So yes, radar range matters for fighter jets, IADS or not.

    So Saab don't understand their own aircraft...

    Saab would like every housewife to buy a Gripen, what do they care about they actually needing them? And as you said it yourself, many countries do not need an air force at all, come on, what are the huge dangers threatening Switzerland? Invasion by Liechtenstein? They know as well as anyone that for many countries fighters are just toys for big children and they will use every possible opportunity to sell them, this is just standard corporate behaviour.

    if they were going to start making single engined fighters this would be it... and they said it will be a twin.

    That does not mean they do it because of what you say.

    Not at all... I am not suggesting doing it with the enemy plane 1km behind you and with you lined up for a cannon shot...

    I already explained why I consider this a very marginal gain.

    If anything their single engined fighter... MiG-21 lacked range.

    Wait, MiG-29 lacked range too and you just said it is irrelevant...

    If you are always carrying EFTs then you really needed a bigger plane.... like a Flanker.
     
    Or simply a plane with bigger fuel fraction and less drag, designed from the onset as multirole and not as point defence fighter.

    I don't actually work for MiG, and it is pretty clear it is information they are not prepared to release just yet...

    By the way you defend them it seems you work for them or at least hold shares  Rolling Eyes

    Now seriously, that is one of the reasons I am using older data for the most accurate comparisons. NATO got their hands on the plane and you have every data you may want. For the F-16 we have as many charts as you may wish for in every configuration possible. That is a treasure trove for anyone wanting to make a serious analysis.

    Ok, I did the following, since the data I had about cross sectional areas was not so reliable to me. I took blueprints of both F-16 and MiG-29, scaled them and calculated the cross sectional area in a fast but not too imprecise way. Given the big differences between both designs and the many error sources involved in the estimation, I think this is reasonably decent. Result is 40% more cross section for the MiG (old version), 6,22 vs 4,44 sqm

    Single vs. Twin Engine Fighters Cross_10
    GarryB
    GarryB

    Posts : 25949
    Points : 26495
    Join date : 2010-03-30
    Location : New Zealand

    Single vs. Twin Engine Fighters Empty Re: Single vs. Twin Engine Fighters

    Post  GarryB on Mon Aug 31, 2020 2:31 pm

    Together with reduced drag this should allow for ranges in excess of 2500 km on internal fuel, which would be nice both for the VKS and for a foreign customer which would, as you rightly say, use the plane as their main fighter and would greatly benefit from a decent range.

    The Russians are getting what they want...can't you get it through your head that while a single engined aircraft might have lower drag that this means nothing at all if it can't do the job?

    A missile has even less drag so why not retire all light aircraft and just have 3,000km range missiles?

    They have MiG-35s slowly entering service... you can bitch all you want about how long it has taken but MiG was happy to make them 13 years ago and you keep harping on about.

    They have OKed development for a new 5th gen fighter to compliment the Su-57... there is no room for another light fighter for Russia... any mission that might perform will likely be achieved with armed single engined drones.

    The light single engined fighter is what is obsolete.

    - The foreign customers may indeed want all avionics refinements and best performance possible, since as we see the market frequently compares "apples vs oranges".

    Lets be realistic... most foreign customers already know what they want when they start their competitions... the purpose is just to confirm what they have already decided and so unless the aircraft of choice screws up it will win... unless the price doesn't come down or match the competition requirements...

    This should save lots of money, because avionics today are enormously expensive and in many cases regardless of the plane's size.

    That is the problem... that is why light manned fighters are not cheap.... avionics and self defence suites and engines and radar do not scale well... all these things for a smaller aircraft half the weight of the big one are not half the price... and economies of scale don't apply to engines the way you seem to think they do... having half the number of engines doesn't matter when you have three or four times more planes...

    I see you are not understanding much of what I post here... different layouts result in different aero profiles with different advantages.

    You are not understanding what I post here either... having one engine in a fighter might give some benefits in drag and weight, but some customers prefer twin engined planes. MiG has designed plenty of single engined planes... most of their early fighters are all singles, but it is the Russian Air Force that sets the requirements and they want twins.

    I am not writing it off. And of course there is data about the new MiG family, only it is not complete.

    Calling it obsolete is writing it off.

    But what is available points to a heavier airframe.

    Only you are claiming this. General trends with increased composite materials and increased stealth suggest empty weight should be less than older models not more.

    I was referring to dorsal intakes gone since the M version, if you mean the mesh screens then they are indeed in place.

    Clearly you are not listening... I said quite some time ago that they removed the dorsal intakes when they changed from solid intake doors to mesh intake screens... which is pretty obvious.

    The PAK-FA patent has info on those blockers and how they work, a mesh which is thin enough to block the radar is not good for the airflow.

    You might want to alert the Americans then because their F-117 stealth strike aircraft had mesh screens in their air intakes specifically as radar blockers...

    And crucially they are placed in the wake of the front wheel...

    And even more crucially anything that was kicked up by the front wheel hit the solid intake doors and bounced away and could not bounce forward two metres and be carried up into the air and over the wing into the dorsal air intakes to have any chance of getting any where near the engines...


    Wow that is a serious misconception... thrust increase is always proportional to the original thrust of the engine. For instance, if you have AL-31 vs AL-41F1S, you have and improvement of 12% max thrust. RD-33MK vs RD-33 is 8% more thrust. No fixed increases for each engine, regardless of its size or original thrust, that is utter nonsense. So if your plane had originally X thrust and the new engines get improved by a Y%, your thrust will be improved by that Y% the same whether you are single engine or twin engine...

    You are the one demanding engine commonality so a 10% thrust increase with one engine in a single means a 20% total thrust increase for a twin using the SAME ENGINE.

    The new engine they are working on for the new fighter will be a 12 ton thrust engine... which is 3 tons more thrust than the current 9 ton thrust model.

    Seriously... If the lighter fighter has exactly half the weight the bigger one, with one engine it will have the same original TWR and the same proportional increase with newer engines than the twin engine. This is kindergarten level maths for gods sake

    And taking it further a 14 year old boxer improves by 10% and still can only fight other 14 year old boxers, because Mike Tyson improves by 5% but put in a ring with that feather weight will kick his arse. The 14 year old boxers fees wont cover his hospital bill. You might need a payment plan to cover Mikes fees but it would be worth it.

    They are going to make the Il-96 twin engined, go figure.

    But didn't you say a twin with one engine out is hard to fly... surely the main reason the B-52 is not currently a twin is because the loss of one engine would make it unflyable... why has that changed?

    And I think the MiG-29 is not different enough from Flankers in terms of cost but too different in terms of capabilities, so it has no real appeal for the VKS.

    I agree, but we are not talking about the MiG-29 here, we are talking about a MiG-35.

    But by all means list the costs and capabilities of Flankers and MiG-35s and you can show me clearly why it is not worth it.

    The new family will at least improve range, still the basic design is very limiting.

    Oh please... the old family never had a problem with range... if they did then the SMT models would have replaced them... the T in SMT means fuel for fucks sake.

    And what is so limiting by the basic design that is not being used in the new models?

    I will post below a rough calculation I made with drawings to scale. You will see how the cross sectional area of those two, F-16 and MiG-29, is very different.

    I don't need a drawing to show me that...

    So what?

    But if you look at the length of the fuselage proper, it is very similar.

    Again... so what?

    The result is that the MiG probably creates a lot of lift, which is very good for manoeuvring, but it has little internal fuel and a lot of drag.

    Wow... you have found their secret... so what you are saying is that inherently the MiG manouvers better but has shorter range and likes to wear womens clothes...

    For a plane with a lower thrust to weight ratio and higher drag it is both faster than the F-16 and also has a much much higher climb rate.

    That is why I said that as a multirole fighter it is a bit burdened by the original design requirements, which called for a very specialised role.

    Its role is to basically be a shorter ranged Su-35 multirole fighter bomber... why would a single engined fighter be better at that?

    Tikhomirov designed the Irbis with 20 kW power for huge range despite not being HATO, and Phazotron is burning stages in their AESA development to come from 130 to 260 km range. So yes, radar range matters for fighter jets, IADS or not.

    So the plane this plane will be operating with has one of the best radars available and a new radar is on the way for it but you complain anyway.

    Bitching and moaning is easy... but you do realise if you want a brand new single engined designed 5th gen stealthy fighter to be developed it will take probably 15-20 years too.

    Wait, MiG-29 lacked range too and you just said it is irrelevant...

    It only lacked range for export customers, if the domestic model was considered short of range then the SMT upgrade had the most internal fuel of any model and could be applied to existing models so if the design was short of range for their needs they could have easily solved that problem.

    The reality is that before they had fighters with inflight refuelling probes their Su-27s were taking off with quarter tank fuel weights simply because they didn't need any more than that...

    The Russian planes had an area to cover and that area was based on the range of the planes that operated there... extra fuel was useful for transfers and exercises but that didn't happen very often at all.

    Or simply a plane with bigger fuel fraction and less drag, designed from the onset as multirole and not as point defence fighter.

    Looking at the current MiG-35s and M2s with enlarged dorsal areas and increased wet areas around the aircraft it seems they were able to greatly increase fuel fraction without needing to resort to scabbed on conformal fuel tanks like they did with the F-16 and F-15.

    Extra fuel was not a huge priority despite being improved with every upgrade...

    That is a treasure trove for anyone wanting to make a serious analysis.

    Meaningless... it might as well be about a different plane.... the information they had was about the MiG-29B...

    But I look forward to your explanation as to why the high drag super heavy MiG has a sea level climb rate of 350m/s and the low drag high thrust to weight ratio F-16C/D model has a climb rate of 250m/s at sea level...

    Other aspects like the MiG A and B would kick F-16A arse because the F-16A didn't have any air to air missile except the Sidewinder, which tests with German MiGs showed were easily fooled with Flares. US flares didn't work against R-73.

    Why do I defend MiG?

    Why do I defend Communist Soviet Union when western revisionists try to make out that Germany was really not the bad guy... nazism and Germany are not the same thing but communism and the soviet union was Russia and it was all their fault because Hitler would have been nice if Stalin had not forced him to invade Poland...

    I am sure when western F-16 pilots were getting their arses handed to them in exercises against East German MiGs they will feel better knowing their F-16s were using less engine power and less fuel to get beaten than those big draggy MiGs were using to win...

    I think a good way to make a decent single engined fighter would be to take the F-5 and take those two little engines out and put an RD-33 into it and update the wing shape and fuselage shape to allow high speed flight... give it a decent little radar and optronics system and fit it to carry R-73s on the wingtips and say four wing pylons for triple R-77-1 missiles... give them excellent communications systems and a decent self defence suite... the optronics could be a centreline pod mounted system.

    That can be Irans low fighter and their high fighter could be a MiG-29M2 which they build in Iran... engine and electronics and radar systems can be directly related to keep costs down.

    These two planes can replace all their F-4s and F-5s currently in service and they could probably make a few extra for neighbours like Syria and Iraq and even Pakistan if they want some... or even India.

    Some Su-30s with upgrades like better radar and self defence avionics could replace the F-14s and with RVV-BD missiles as well as a range of other air to air and air to ground weapons they would be great.

    They can pay for it all with oil and gas to Russia...
    GarryB
    GarryB

    Posts : 25949
    Points : 26495
    Join date : 2010-03-30
    Location : New Zealand

    Single vs. Twin Engine Fighters Empty Re: Single vs. Twin Engine Fighters

    Post  GarryB on Mon Aug 31, 2020 2:47 pm

    One thing I don't think you understand is that single or twin engined fighters are designed... one does not inherently become cheap and simple and the other complex and expensive.

    Fuel fractions are design choices... aircraft length and width are design choices too...

    F-35s show a single engined fighter can be eye wateringly expensive... F-5 and Yak-130 shows they can be made light and relatively cheap, but if you read what I write about LIFTs being fighters you find I am at least consistant...

    Lead In Fighter Trainers should never be used as light fighters.

    Most LIFTS being considered for such roles are often not actually that cheap anyway to start with, and when you add more powerful engines and radars and self defence suites the price is going to ramp up very very fast and no matter what you get it will never be as good as a custom designed light fighter.... or as I suggest a medium fighter with the expensive stuff simplified.

    A big heavy fighter like a Flanker costs more money to fly around than a MiG-29 of any type... that is just basic physics... you can drive around in a family car for a fraction of the cost of a truck or bus, and if the job is to take two or three people somewhere then obviously the family car is the best choice.

    These days with bombing computing systems that allow altitude bombing with dumb bombs, the Russians are currently doing it with Su-24s, Su-34s, and even Tu-22M3s. It would be much cheaper to do it in a MiG-29SMT, but even cheaper likely to do it in a Yak-130 or L39... it all depends on how often targets come up and what sort of loads are needed... when we see Su-34/24 aircraft they normally have two bombs loaded, while the Tu-22M3s seem to carry 9 to 12 rather heavier bombs... lighter planes might not cope well with range and heavier bomb loads but then a transport plane like an An-12 or the new Il-276 could carry enormous dumb bomb loads they can pick and mix bomb weights to drop and how to drop them.

    Most tactical planes will carry a pair of matched weight weapons... which is probably more effective than one heavier bomb because it spreads the damage making a target kill more likely, but a cargo plane pushing bombs out its rear or having a roof mounted bomb rack/crane that picks up different types of bombs in the cargo bay and then carries them back out the back of the aircraft and drops them out the back... it could carry multiple bomb options on board and decide as it approaches the target which bomb combination it uses... a lighter plane will use less fuel like an Il-114, but in any case flying at 10km altitude it should be safe from most ground fire...
    LMFS
    LMFS

    Posts : 1949
    Points : 1949
    Join date : 2018-03-04

    Single vs. Twin Engine Fighters Empty Re: Single vs. Twin Engine Fighters

    Post  LMFS on Mon Aug 31, 2020 5:46 pm

    @Garry:

    the discussion style has gotten son confrontational and you dismiss my arguments is such a way that I don't feel compelled to invest real effort (those silly drawings that you don't need took some hours work, believe it or not, the same as finding data & relevant flight manuals and charts), maybe you prefer that I engage in a cheap exchange of opinions instead of doing the hard work needed for establishing facts?

    I am not against twin engines and in favour of single ones, I am in favour of both in the right conditions, but you insist in attacking me as an enemy of MiG-29 and twin engine jets and that is a misrepresentation of my position. That does not mean that if you attack single engine jets based on flimsy grounds, I am not going to answer. I am trying to engage in a solid, data based analysis and gain as deep an understanding in propulsion layout and design decisions as possible. And such decisions are never so categoric as "single engine fighters suck".

    That is the problem... that is why light manned fighters are not cheap....

    I said some of those subsystems could be even removed altogether, in combined operation with heavy fighters (i.e. provisions for radar in place but equipment maybe not installed in planes belonging to mixed air regiments). That would make such fighter useless in your opinion, yet you yourself admit the MiG does not need to be as good as a Rafale if it is cheaper and it is covered by Flankers or Su-57, which is exactly my argument for a light fighter... makes me think we are arguing for the sake of arguing  dunno

    Calling it obsolete is writing it off.

    A product in its late operational life approaches obsolescence, that is what I said. This is obvious BTW and said without any bad intention. I have said MANY times there is still time for the MiG-35 to be used despite the huge program delays, but answer with sincerity, how many MiG-29 versions do you think will come after the MiG-35? Answer also frankly, was the development of the -35 not largely delayed compared to other similar planes? When concrete programs for 6G start receiving serious funding all over the world, the writing is on the wall for 4G and all the development in it needs to be finished and brought to the market. Again, I am just stating the obvious.

    Only you are claiming this. General trends with increased composite materials and increased stealth suggest empty weight should be less than older models not more.

    I didn't make up service ceiling data. Reduced service ceiling with increased thrust is not a sign of reduced empty weight. Increased operational life of the airframe isn't either, the same as increased MTOW or payload or increased avionics and equipment. If their data is accurate or not, it is a completely different issue.

    Clearly you are not listening... I said quite some time ago that they removed the dorsal intakes when they changed from solid intake doors to mesh intake screens... which is pretty obvious.

    I may had a confusion there, that does not mean I am not listening.

    Sponsored content

    Single vs. Twin Engine Fighters Empty Re: Single vs. Twin Engine Fighters

    Post  Sponsored content


      Current date/time is Mon Sep 28, 2020 8:52 pm