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    Su-57 Stealth Fighter: News #6

    GarryB
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    Post  GarryB on Wed Nov 18, 2020 12:30 pm

    Most of my disagreements are in the access panel itself. If it's hinged at the V of the bay, then it needs to have some pretty solid hinges that not only open and close it but are capable of holding the panel from being ripped off the bay with all the airspeed happening at the time. I would think that is a legitimate point, no? So far I haven't seen anything in the patent that shows where the panel opens or is hinged, just that there is a missile in there and that it has a trapeze mechanism that allows the missile to protrude head first at an angle of between 20 to 70 degrees to the plain of the fuselage? I think that's how it's worded. So I'm just trying to find out more info that convinces me, that's all.

    So you accept that the two centrally mounted main weapons bays will have bay doors and actuators that open and close those doors in flight in a range of speeds.

    Why do you think they could design actuators and doors over the main weapon bays but not smaller wing mounted bays.

    Wouldn't it be logical that a much smaller wing mounted bay door would need less powerful actuators to open and close it?

    They don't open like wind brakes, the airflow would be moving down the edge of the doors and most of the actuators will be internal... and new electric actuators are quite powerful... they are replacing heavy hydraulic actuators with electric ones on new planes these days... would you agree that the wind force on those all moving vertical tail surfaces would be pretty damn fierce at high flight speeds... yet it clearly moves the entire vertical tail portion for flight control purposes...

    Also if an F-22 is supercruising at 1.8M, could it be possible that the airframe is heated enough from air friction for Russian OLS-35 IRST to detect it at over 100km? AFAIK, there is physically no way to reduce heat signature of an airframe at supersonic speeds, even with whatever composite materials americans put on their fighters.

    There are three bands of IR where the atmosphere allows transmission over reasonable distances... called imaginatively long, medium, and short wave IR.

    Showing short wave IR or SWIR cameras for the Armata tank, unlike normal thermal imagers it can see through water or glass... or cloud...

    Combinations of the different waves offers different advantages and problems... just like having IRST and Ku and Ka band AESA radar and L band radar in your best fighters... with a bit of processing power you get much better results than any one technology on its own...

    Of course high speed creates more aerodynamic heating, the idea with those kinematically superior planes is that, weapons being equal and even if you can see them, they can shoot you down while staying out of the range of your missiles. To improve performance in IR you would need highly thermally conductive materials to spread the heat all over the airframe and coat with materials of low emissivity, but of course a very hot fuselage is still going to be more visible than a colder one.

    An Su-30 flying along detects a target ahead closing at a speed of mach 1.5 should be able to launch an R-27ET... the IR signature and high closing speed should make a kill highly likely...

    Su-57 can supercruise with AL-41 at the speed of 1600km/h, which is about 1.5Mach.

    Nice.

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    kvs
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    Post  kvs on Wed Nov 18, 2020 9:53 pm

    The F-22 supercruises at 1.5M and not 1.8M. Where did the 1.8M number come from?

    Isos
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    Post  Isos on Wed Nov 18, 2020 10:27 pm

    kvs wrote:The F-22 supercruises at 1.5M and not 1.8M.   Where did the 1.8M number come from?


    Fanboy propaganda.
    Isos
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    Post  Isos on Wed Nov 18, 2020 10:38 pm

    https://www.af.mil/About-Us/Fact-Sheets/Display/Article/104506/f-22-raptor/

    According to this description, f-22 with two external tanks has a ferry range of 1600 nautical miles. It represents 11900kg of fuel.

    Internal fuel only is 8200kg.

    This means without fuel tanks, it has a ferry range of (8200×1600)÷11900 = 1102 nm = 2040 km.

    It gives it a radius of 1000km and even less if it need to fight or go at lower altitudes.

    Supercruise should also take much more fuel for the same distance and reduce it even more.

    That's similar to mig-35 rather than su-35/su-57.

    Destroy tankers with r-37 and suicide drone by spetznaz inside the enemy territory, then they will need to bring them closer at least 600km from the frontline and just use iskanders with real time satellite spotting a recalibrating the iskander in flight.
    LMFS
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    Post  LMFS on Wed Nov 18, 2020 11:32 pm

    Isos wrote:Fanboy propaganda.

    From your source:

    The F-22 engines produce more thrust than any current fighter engine. The combination of sleek aerodynamic design and increased thrust allows the F-22 to cruise at supersonic airspeeds (greater than 1.5 Mach) without using afterburner -- a characteristic known as supercruise.

    I don't have time now to look for references, but pilots are the source for those values, from what I remember.

    The normal speed can be 1.5 M, we talk about max cruising speed.

    According to this description, f-22 with two external tanks has a ferry range of 1600 nautical miles. It represents 11900kg of fuel.

    Internal fuel only is 8200kg.

    This means without fuel tanks, it has a ferry range of (8200×1600)÷11900 = 1102 nm = 2040 km.

    It gives it a radius of 1000km and even less if it need to fight or go at lower altitudes.

    You cannot calculate range on internal fuel from ferry range without removing the drag effect of the EFTs, which is very substantial both as DI and as increase in AoA. That does not mean you are not right in that F-22's fuel consumption does not allow to sustain supercruising for very long, Su-57 is supposed to be noticeably better.

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    Isos
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    Post  Isos on Wed Nov 18, 2020 11:48 pm

    Pilots are not reliable since they say what the AF tells them to say. Same debat happens with Typhoon supercruise capability with pilots saying total different figures compared to the engineers that made the aircraft and tested it.


    I know about the drag but it gives a good estimation. Note that those data are for very high flying altitude where drag is smaller than at medium to low altitudes and probably without weapons. In actual war it will be anyway much smaller and they will need to send them 500-700km from the frontline so in range of Iskanders.
    LMFS
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    Post  LMFS on Thu Nov 19, 2020 12:09 am

    Isos wrote:Pilots are not reliable since they say what the AF tells them to say. Same debat happens with Typhoon supercruise capability with pilots saying total different figures compared to the engineers that made the aircraft and tested it.

    But you quote the AF which is supposedly telling them to lie, why should it be reliable? We quote pilots, Russian pilots also, many times. BTW, how do you know the F-22 cruises at 1.5 M?

    I know about the drag but it gives a good estimation.

    Not really
    thegopnik
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    Post  thegopnik on Thu Nov 19, 2020 12:55 am

    Guess any real estimates on fuel range without external tanks would be deemed as embarrassing for LM so they have not included it but are reliant on tanks to only post info with the tanks included as their marketing preference Some users here which I cant understand why are hell bent for a little Mach 0.1-0.3 to add on super cruise as more important than having an aircraft that literally already has 75% more range than the other in a internal fuel consumption range(not including drag). Than of course some users here(you know who you are and there is more than 1 stating this) put a lot of emphasis on how much drag greatly effects like if it didn't have those tanks it will still be close to the advertised external fuel tank range  but are not giving any numerical value to calculate the drag but believe it is that bad Rolling Eyes? Even if we all pretend that the 12000kg is the internal fuel range which of course it isn't the fuel efficiency is still higher than the afterburner speed efficiency the F-22 has over the Su-57 anyway dunno

    I mean they could design a higher thrust engine to begin with on the 1st stage but the fuel efficiency is a no-go to monitor the airspace of a very big country. Not to hit a nerve but I believe there  is a good reason why LM advertises the external tank range over the internal fuel range What a Face But either way we are comparing fruits to vegetables and that is no way to predict a country's engine technology(as some are drawing conclusions based on that, on who is ahead in aircraft engines). For example if the F-22 did not go for high thrust numbers but numbers similar to the Su-57 1st stage or Su-35 engine would it have better internal fuel consumption of those 2 aircrafts? If the Su-57 or Su-35 did prioritize higher thrust similar to the F-22 would it still have a better internal fuel consumption(and lockheed not feeling too embarrassed to disclose the internal fuel range to compare them)?

    Please copy and paste this shit to other forums because as meaningless as this 1st stage su-57 vs F-22 engine debate is. I am sure the future argument will be a izdelie 30 vs F-35 ADVENT(which is not going to work for debate anyways). and far future argument will be mig-41 ramjet detonation engines vs whatever the F/A-XX program is doing and it would be a god send if they are nearly the same in some aspects to make more fair comparisons than what this board is currently doing.
    GarryB
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    Post  GarryB on Thu Nov 19, 2020 6:00 am

    The fact that they even bother to talk about a ferry range is interesting.... surely being a stealth fighter they would develop internal bladder type fuel tanks to fill the internal weapon bays with zero increase in RCS and yet boosting flight range... but obviously in the real world they would just put weapons in the weapons bays and have the jet use inflight refuelling to extend range for patrol or deployment.

    For external tanks to make sense using they would have to extend flight range by a significant value in the subsonic flight regime where the extra drag wont render the extra fuel they carry irrelevant.

    Generally Ferry Range exceeds normal operational range of the aircraft despite the extra drag...
    LMFS
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    Post  LMFS on Thu Nov 19, 2020 11:35 am

    thegopnik wrote:Guess any real estimates on fuel range without external tanks would be deemed as embarrassing for LM so they have not included it but are reliant on tanks to only post info with the tanks included as their marketing preference Some users here which I cant understand why are hell bent for a little Mach 0.1-0.3 to add on super cruise as more important than having an aircraft that literally already has 75% more range than the other in a internal fuel consumption range(not including drag). Than of course some users here(you know who you are and there is more than 1 stating this) put a lot of emphasis on how much drag greatly effects like if it didn't have those tanks it will still be close to the advertised external fuel tank range  but are not giving any numerical value to calculate the drag but believe it is that bad Rolling Eyes? Even if we all pretend that the 12000kg is the internal fuel range which of course it isn't the fuel efficiency is still higher than the afterburner speed efficiency the F-22 has over the Su-57 anyway dunno

    I mean they could design a higher thrust engine to begin with on the 1st stage but the fuel efficiency is a no-go to monitor the airspace of a very big country.  But either way we are comparing fruits to vegetables and that is no way to predict a country's engine technology(as some are drawing conclusions based on that, on who is ahead in aircraft engines). For example if the F-22 did not go for high thrust numbers but numbers similar to the Su-57 1st stage or Su-35 engine would it have better internal fuel consumption of those 2 aircrafts? If the Su-57 or Su-35 did prioritize higher thrust similar to the F-22 would it still have a better internal fuel consumption(and lockheed not feeling too embarrassed to disclose the internal fuel range to compare them)?

    Please copy and paste this shit to other forums because as meaningless as this 1st stage su-57 vs F-22 engine debate is. I am sure the future argument will be a izdelie 30 vs F-35 ADVENT(which is not going to work for debate anyways). and far future argument will be mig-41 ramjet detonation engines vs whatever the F/A-XX program is doing and it would be a god send if they are nearly the same in some aspects to make more fair comparisons than what this board is currently doing.

    What a mess of a post

    1. US normally provides aircraft ranges either as combat radius for a given profile or as ferry range, for F-22 and for the rest of their planes. Russia provides range on internal fuel. Those metrics are tricky to compare.

    2. The "some users" BS is unnecessary, if you are referring to me say it clearly. Supercruise is something Russians have been trying to implement since the 80's, it was the intent of the original MFI and associated AL-41 engine on which they spent massively. You failing to understand why has actually zero relevance once every serious airforce out there knows its value and is ready to invest heavily and sacrifice other aspects to obtain it. US did take the "easy" way with a low bypass engine that is not good for subsonic range, we will need to see what Russia does. I hope and actually expect them going the same way they went already 30 years ago with the original AL-41 which was a VCE, but it has not been disclosed in an explicit way.

    3. When I am referring to EFTs and their drag I, differently to you, am not making a politic argument but a technical one. You cannot pretend doing calculations to disguise a 30% error because your entry data is garbage. The original calculation by Isos is not even remotely accurate, that is all. Nobody is saying range with and without EFT is the same, that is absurd.

    are not giving any numerical value to calculate the drag but believe it is that bad Rolling Eyes

    Do you a remote idea of what the drag index is? Have you taken an actual look to flight manual DI / range calculations? If you would have done you would not be making such silly statements

    Even if we all pretend that the 12000kg is the internal fuel range which of course it isn't the fuel efficiency is still higher than the afterburner speed efficiency the F-22 has over the Su-57 anyway dunno

    What the hell are you talking about?

    I mean they could design a higher thrust engine to begin with on the 1st stage but the fuel efficiency is a no-go to monitor the airspace of a very big country. Not to hit a nerve but I believe there  is a good reason why LM advertises the external tank range over the internal fuel range What a Face

    That is called low BPR engine and is one of the routes to supercruising. The other is VCE as said. You are not hitting any nerve, you rather seem completely lost.

    But either way we are comparing fruits to vegetables and that is no way to predict a country's engine technology(as some are drawing conclusions based on that, on who is ahead in aircraft engines).

    There are certain technological parameters like TIT or OPR that very clearly indicates who is "ahead". An engine like the F135 is a 3,600 °F (1,980 °C; 2,260 K) machine that is head, shoulders and waist above what we know, at least in the public space, about other engines. The jury is still out regarding izd. 30 and even izd. 117, but the advantage is massive regarding all other operational engines, essentially anywhere. Again, if all is a big lie and the TIT is false and the thrust is false, well, bad luck and we know nothing. I as anyone out there have to work with open sources.

    For example if the F-22 did not go for high thrust numbers but numbers similar to the Su-57 1st stage or Su-35 engine would it have better internal fuel consumption of those 2 aircrafts?

    Depends on the engine. If it had used a high BPR engine it could have better SFC than the Sukhois, since better OPR and TIT mean better efficiency, but no supercruise. They preferred a low BPR engine because the supercruise was considered a priority. They could also have used the YF120, which could have provided both good SFC and supercruise, but probably thought it was high risk.

    If the Su-57 or Su-35 did prioritize higher thrust similar to the F-22 would it still have a better internal fuel consumption(and lockheed not feeling too embarrassed to disclose the internal fuel range to compare them)?

    The Su-35 and arguably the Su-57 have substantially more internal fuel than the F-22, so they would normally have more range even if they had the same type of low BPR engine.

    Please copy and paste this shit to other forums because as meaningless as this 1st stage su-57 vs F-22 engine debate is. I am sure the future argument will be a izdelie 30 vs F-35 ADVENT(which is not going to work for debate anyways). and far future argument will be mig-41 ramjet detonation engines vs whatever the F/A-XX program is doing and it would be a god send if they are nearly the same in some aspects to make more fair comparisons than what this board is currently doing.

    Yeah, cry me a river

    GarryB wrote:For external tanks to make sense using they would have to extend flight range by a significant value in the subsonic flight regime where the extra drag wont render the extra fuel they carry irrelevant.

    Of course. That does not mean that the range of the plane can be calculated linearly based on the fuel amount disregarding the presence of the EFTs.

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    Isos
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    Post  Isos on Thu Nov 19, 2020 12:10 pm

    LMFS wrote:
    Isos wrote:Pilots are not reliable since they say what the AF tells them to say. Same debat happens with Typhoon supercruise capability with pilots saying total different figures compared to the engineers that made the aircraft and tested it.

    But you quote the AF which is supposedly telling them to lie, why should it be reliable? We quote pilots, Russian pilots also, many times. BTW, how do you know the F-22 cruises at 1.5 M?

    I know about the drag but it gives a good estimation.

    Not really

    I'm quoting them for fuel data.

    The pilots giving different values are also documented for the typhoon.

    The drag is insignificant compare to what the fuel tanks add in terms of range. Those dataare also for clean fighter. Without fuel tanks but with weapins it compensates the loss of drag induced by fuel tanks.

    So yeah it give a theorical range of around 1000km on internal fuel. Not perfect but it is a good figure.
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    Post  LMFS on Thu Nov 19, 2020 12:17 pm

    Isos wrote:So yeah it give a theorical range of around 1000km on internal fuel. Not perfect but it is a good figure.

    I am not questioning the bottom line of your reasoning, just the numbers. I agree the range is a bit short an if high speed cruising is added, then substantial IFR availability is a need. So the speed is phenomenal, if we believe the figures, but the legs are still short.
    Isos
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    Post  Isos on Thu Nov 19, 2020 12:43 pm

    LMFS wrote:
    Isos wrote:So yeah it give a theorical range of around 1000km on internal fuel. Not perfect but it is a good figure.

    I am not questioning the bottom line of your reasoning, just the numbers. I agree the range is a bit short an if high speed cruising is added, then substantial IFR availability is a need. So the speed is phenomenal, if we believe the figures, but the legs are still short.

    I never said it is 1000km range radius with supercruising.

    I just used the data provided on the link which should be for a subsonic fuel efficient speed and it falls in the category of mig-35 which has a ferry range of 2000km.

    Supercruising should reduce it. And since they can't use it at its limit and will keep a safe amount of fuel for return to base but also plan to fly low for a part of the trip or fight and use afterburber then it is even more reduced. Which is true for any fighter.

    Take out their tanker and they will need to use them from airfields in range of iskander from the frontline.
    thegopnik
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    Post  thegopnik on Thu Nov 19, 2020 4:56 pm

    LMFS why that attitude? Where am I insulting you? just because users here have disagreements does not mean you should be giving such attitude towards them. I cant copy and paste on this phone.
    right now I will just make direct responses.

    1.not really have you looked at any f-16s, f-15s or f-35s? They do give max ranges on internal fuels I just cant figure out why they are not doing the same for the f-22.

    2.i am referring to you and secretprojects. Do you have any sources that they have tried to implement supercruise speeds that of the F-22? You got to also realize the countries that you are probably referencing wanting to obtain high supercruise do not have bigger countries than Russia where range is more significantly important to cover a big country.

    3. Yes drag is important but what are the ranges you are looking at between 2049kms to 3000kms? I dont want you to pull a Ronny at secretprojects by turning this thread into a bottomless pitt(what I am trying to avoid with you) but the majority here will continue on having disagreements with you because it's going to be a I believe in Santa claus to I believe in the leprechaun more kind of arguement at this rate which is already pointless.

    Now since I cannot quote you on this phone. I do know what drag index is but what is your numerical estimate between 2049 to 3000kms? That is all if you can't provide this but still insist the range is barely effected without the tanks than this thread is going to turn into a bottomless pitt. The 12000kg is the f-22 included with carrying 2 external fuel tanks. Do you also have proof(doubt you have any) that if the f-22 had a high BPR that its fuel range would be better than the 1st stage? I do know that the su-35 and su-57 have more internal fuel but the f-22 has more fuel than both with 2 external fuel tanks but still less the range. We can still calculate it having the same 10,000kg fuel as either the su-35 and su-57 1st stage but that will probably give it a 2500km something range where your going to be all like no no dont forget the drag while not giving any numerical estimates in return hence creating bottomless pitt thread with other users here and me. I am also crying that river because I find it funny that the same users will get dragged into that same river of pointless rants like what's going on right now.

    LMFS dont worry I will still like you after this but there are times where we will have disagreements like this from time to time.
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    Post  LMFS on Thu Nov 19, 2020 5:37 pm

    thegopnik wrote:LMFS why that  attitude? Where am I insulting you?

    Am I insulting you?

    1.not really have you looked at any f-16s, f-15s or f-35s? They do give max ranges on internal fuels I just cant figure out why they are not doing the same for the f-22.

    From af.mil, the only of those planes you mention where range on internal fuel is given is F-35 (guess why) and that is something new.
    F-15:
    Range: 3,450 miles (3,000 nautical miles) ferry range with conformal fuel tanks and three external fuel tanks
    F-16:
    Range: more than 2,002 miles ferry range (1,740 nautical miles)

    Bottomless pit over, believe what you want.
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    Post  Mindstorm on Thu Nov 19, 2020 11:51 pm

    LMFS wrote:
    Mindstorm wrote:
    That statement about this parameter is false only assuming that over-ocean CLAIMS about the same paramters was initially true......do you know in the same way of some others: such as an effective area of dispersion in 0,0001 square meters or almost absent IR signature preventing its detection and even lock-on even at reduced ranges....and today guys like М. Толбоев have plenty of hard and coherent data coming from reality confirming how much ridiculous technical disinformation were present in those CLAIMS about F-22

    Its assertion is not that Rolls-Royce or Pratt & Whitney ,or any other engine maker at world, had not developed an engine capable to pull a particular airframe over mach 1 at maximum military power regime, but instead that neither of them was capable until now ,matched with any airframe now existing at world, to pull a fighter aircraft at a speed of 1600 km/h in this regime.

    That statement is true by any available information outside public domain.

    I am limited to open sources, so I have no way of knowing such details, but I know the following:

    > Revealing the true capacities of the Su-57 on an interview would normally cause the person in question to be prosecuted. Sometimes data a re purposefully leaked, but Russian official sources have been very secretive regarding that particular parameter and never provided values.
    > Given the known / reasonably expected values of izd. 117 based on izd. 117S and older comments from Pogosyan, its military power values should be very inferior to those of the F119. By a 20-30% actually, given the different technologies but specially due to different BPR of both engines. It would require an aerodynamic miracle for the Su-57 to be faster with so much less thrust. I am accounting for the advantages in pressure recovery that the variable intakes provide, but still I see it very difficult
    > If the Su-57 was already faster than the F-22 in cruising speed, then there would be no real need for the izd. 30 and the officials and designers talking about it being the engine that really provides the plane with proper supercruising would also make no sense.
    > There are planes with lower performance engines and not so optimized overall design like Eurofighter where reliable data informs about 1.4 M cruising speed, very close already to the value reported by Tolboyev as a record and so 1.5 M should perfectly be thinkable for the F-22
    > I agree that US information is in general not trustworthy. The supercruising speed of the F-22 has been discussed several times and quotes are abundant for speeds of 1.8 M and even one pilot stating >1.9 M. This is not something that surprises me specially: if you compare the provided uninstalled mil thrust values of the F119 you can see they are actually comparable to AB values of older generation engines used in similarly sized / shaped planes for speeds well above 2M. Granted AB can be more effective at high speed, but still I don't think it is a far fetched claim. Initial flights of the YF-22 and YF-23 already reported supercruising @1.6 M in early program dates, then the YF-22 was actually re-shaped and further optimized for supercruising and became the current F-22. If all is a big lie then at least this time they lied coherently for a change
    > Some Russian source spoke (sorry I don't remember the name but he was a military expert) claimed cruising speeds of 2 M and top 2.4 M for the second stage Su-57, now it remains to be seen how much more powerful it would be compared to F119 to understand if the US claims regarding the cruising speed of the F-22 are feasible or not.

    So in this case I personally don't think the US claim is that far fetched, but still I can be totally wrong. You would need developer level access to the program to check with real Cl, Cd and installed thrust values to know for sure. Can the Su-57 already supercruise at 1.5M with the izd. 117? It sounds a bit optimistic but maybe it can, I don't know. Pogosyan said in the past that the plane with the first stage engines already fulfilled the requirements, interestingly that 1.5 M is what I am repeating here as the value originally defined for supercruising, so it is actually thinkable that they already tried to achieve exactly that with the first iteration and the second one was in order to surpass F-22.


    LMFS i think you have not understood to what refere the statement of М. Толбоев......it refere to initial trials of the second stage engine and it has merely revealed what the aircraft had already achieved in those early tests (nothing that over-ocean collagues was not already aware of ,not differently than us with theirs).

    Sustained horizontal supercruise - i repeat sustained - at speed greater than 1500 km/h at different wing's angle of attack, from typical operational maneuvering, is very difficult to achieve mostly for typical air flow fluctuations around engine's inlets and low-time compressor stalls that suddenly lower the thrust yield.


    The US firm that was more near to realize real supercruise at those kind of regimes was General Electric with its YF-120, like you probably well know this variable cycle engine was sensibly superior in comparison to Pratt & Whitney's F119 just in supercruise capabilities to the point that when matched with most efficient glider for high supersonic flight's regimes among the two - the YF-23 - (lower frontal cross section and flattened cord shape) it managed even to reach a cruise speed in the area of 1.6 Mach.

    Is important to remember obviously that both those flying demonstrator models was sensibly lighter, devoid of several drag-generating stealth-related finitures, any kind of RAM and all the self-defense electronic stuffing and consumables and therefore those kind of limit achievements was completely irreproduceable in serial models.

    Not a single radar, including OTH, or radar and optical satelitte on this planet has ever recorded an F-22 sustaining speeds even very far from those ridiculous circulating on it; maybe if a modenized GE YF-120 would have produced, by today someone could see a serial F-22 supercruise at speed of 1.5-1.6.



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    Post  Gomig-21 on Fri Nov 20, 2020 3:01 am

    GarryB wrote:So you accept that the two centrally mounted main weapons bays will have bay doors and actuators that open and close those doors in flight in a range of speeds.

    Why do you think they could design actuators and doors over the main weapon bays but not smaller wing mounted bays.

    Wouldn't it be logical that a much smaller wing mounted bay door would need less powerful actuators to open and close it?

    They don't open like wind brakes, the airflow would be moving down the edge of the doors and most of the actuators will be internal... and new electric actuators are quite powerful... they are replacing heavy hydraulic actuators with electric ones on new planes these days... would you agree that the wind force on those all moving vertical tail surfaces would be pretty damn fierce at high flight speeds... yet it clearly moves the entire vertical tail portion for flight control purposes...


    Saw this today on another forum it made me crack up a little. Very Happy

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    Post  LMFS on Fri Nov 20, 2020 10:05 am

    @Mindstorm:

    Yes I was understanding those statements as referred to izd. 117 not to izd. 30. As said I have no way of knowing whether the true max cruising speed of F-22 is 1.6 or 1.8 M, even trying to make good calculations you would find problems when real values for key aero / engine parameters of the plane are needed. I have indeed heard standard supersonic cruising speed for it is 1.5 M.

    I don't quite understand though what you are meaning with "at speed greater than 1500 km/h at different wing's angle of attack, from typical operational maneuvering,", is it related to supersonic meanouvering instead of level flight?

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    Post  Mindstorm on Fri Nov 20, 2020 1:11 pm

    LMFS wrote:I don't quite understand though what you are meaning with "at speed greater than 1500 km/h at different wing's angle of attack, from typical operational maneuvering,", is it related to supersonic meanouvering instead of level flight?


    Partially.

    At those speed (obviously at altitudes greater than 15.000 meters) in not afterburner mode also banking of few degrees ,necessary to follow ground based or AWACS commands towards enemy airborne targets, can cause a sensible lowering of the thrust yield , this effect is highly dependent from the glider's aerodynamics design and inlet and air intake's arrangement.
     
    Usually this effect is counterbalanced with transient use of afterburner ,that obviously negate the advantage of supercruise.
    Different aircraft with different propulsions  (low bypass turbofan being only a compromise solution) show different speed thresholds for this effect.

    In supersonic maneuvring at high altiutudes instead (fundamental to ascertain the anti-missile maneuvering potential of a modern aircraft, particularly against air -to-air ones with limited warhead's potential) another important role play supersonic trim drag, this is one of the reasons both the supersonic optimized F-22 and domestic products have included thrust vectoring solutions.

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    Post  marcellogo on Fri Nov 20, 2020 2:04 pm

    There is sort of prize awarded for not using AF during a mission?

    It seems me that supercruise is seen here as a thing in itself and not as a mean to an end as it should be.

    Let's make an example: a Typhoon is credited as able to hit supersonic speed in less than 30 seconds after the beginning of take off and to reach 1,6 mach and 11000 meters of quote in less than 2 minutes and an half, that obviously using AF.

    Now, how much 30 or even 150 seconds of full AF would impact the total autonomy of such a plane, assuming it would be able to (Typhoon is not with current engines) at such speed and quote ?

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    Post  LMFS on Fri Nov 20, 2020 2:22 pm

    Mindstorm wrote:Partially.

    At those speed (obviously at altitudes greater than 15.000 meters) in not afterburner mode also banking of few degrees ,necessary to follow ground based or AWACS commands towards enemy airborne targets, can cause a sensible lowering of the thrust yield , this effect is highly dependent from the glider's aerodynamics design and inlet and air intake's arrangement.

    I have always found very interesting the huge size of the Su-57 intakes (way bigger than those of the F-22), besides them being fully variable for absolute best possible performance. They are both complex, heavy and challenging to design in a low RCS way, so the incentive needs to have been very powerful for them to follow that path. At high altitude the air density is very low and it is indeed challenging to get high thrust from an engine so an oversized intake helps. The downside with a conventional engine is obviously spillage in subsonic flight, I wonder how this issue is addressed now and whether the izd. 30 is a VCE that could help reducing substantially such loses.
     

    Usually this effect is counterbalanced with transient use of afterburner ,that obviously negate the advantage of supercruise.
    Different aircraft with different propulsions  (low bypass turbofan being only a compromise solution) show different speed thresholds for this effect.

    Certainly VCE is the right approach and from what I have read from Russian sources, there seems to be a clear understanding among them that a true supercruising aircraft needs such an engine. First because the subsonic range of a low bypass engine is not good, second because the VCE has an inherently higher specific thrust once VABIs are closed.

    In supersonic maneuvring at high altiutudes instead (fundamental to ascertain the anti-missile maneuvering potential of a modern aircraft, particularly against air -to-air ones with limited warhead's potential) another important role play supersonic trim drag, this is one of the reasons both the supersonic optimized F-22 and domestic products have included thrust vectoring solutions.

    The tendency of the plane to lower the nose at supersonic speeds is best compensated by forward lift than by rear downforce, maybe this is one further reason for the LEVCONS that can modify the lift profile of the fuselage and therefore contribute more efficiently than the nozzles. In any case this should be considered against the background of the plane being unstable and therefore having a certain margin, maybe even in supersonic flight, until such trimming is needed. That means, maybe the nozzles can be kept pointing very sightly down to trim the plane and create lift an that possibility only disappears well inside supersonic flight regime.

    Reading all this, my opinion that the Su-57 is a very ambitious supercruiser only grows stronger...

    @Marcellogo:

    We discussed this not long ago, the time on AB a normal plane has is actually quite reduced, therefore a platform that aims at high persistence should avoid using it as much as possible and in any case reserve it for high energy demand situations where AB is a must. Supercruising allows for tactics that are not possible for other planes and massively reduces the footprint of AD and A2A missiles.

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    Post  Backman on Fri Nov 20, 2020 7:03 pm

    [quote="Mindstorm"][quote="LMFS"]
    Mindstorm wrote:
    That statement about this parameter is false only assuming that over-ocean CLAIMS about the same paramters was initially true......do you know in the same way of some others: such as an eitney's F119 just in supercruise [/b]capabilities to the point that when matched with most efficient glider for high supersonic flight's regimes among the two - the YF-23 - (lower frontal cross section and flattened cord shape) it managed even to reach a cruise speed in the area of 1.6 Mach.

    Is important to remember obviously that both those flying demonstrator models was sensibly lighter, devoid of several drag-generating stealth-related finitures, any kind of RAM and all the self-defense electronic stuffing and consumables and therefore those kind of limit achievements was completely irreproduceable in serial models.

    Not a single radar, including OTH, or radar and optical satelitte on this planet has ever recorded an F-22 sustaining speeds even very far from those ridiculous circulating on it; maybe if a modenized GE YF-120 would have produced, by today someone could see a serial F-22 supercruise at speed of 1.5-1.6.




    When comparing the speed of all these aircraft, it bares knowing which ones have variable intakes or not. Some ppl say that the F-22 does have some variable intake systems, others say it doesn't.

    The su 57 does have variable intakes. And for high altitude speed, the aircraft with variable intakes is going to be head and shoulders above in this regard



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    Post  Backman on Sat Nov 21, 2020 5:49 am



    Maybe someone posted this already but...

    https://militarywatchmagazine.com/article/algeria-adds-su-57-fighter-artwork-to-defence-ministry-building-near-term-acquisition-of-next-generation-russian-jet-likely

    Algeria has long been speculated to be the first client for Russia’s Su-57 next generation fighter jet - a platform which entered mass production in July 2019 but has yet to join the Russian Air Force. While reports of an Algerian order for the Su-57 have not been verified, a recent image of the country’s Defence Ministry shows Su-57 fighters operating alongside Algerian Su-30 fighters, frigates and T-90 tanks - giving considerable credibility to reports that the country is in fact planning to field the aircraft. Algeria has been a leading client for state of the art Russian arms for decades, many of which entered service in the Algerian Military before they officially entered service in Russia itself. The country’s air force is considered the most modern and capable on the African continent, with Algeria itself ranked as 13th in the world among military powers as of 2020. The backbone of the Algerian Air Force is currently comprised of Su-30MKA heavyweight fighters, MiG-29C medium fighters and Su-24M strike fighters - with a unit of heavily modernised MiG-25 Foxbat interceptors also deployed for air defence.

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    Post  GarryB on Sat Nov 21, 2020 7:38 am

    Saw this today on another forum it made me crack up a little.

    Can't see it.... Sad

    The tendency of the plane to lower the nose at supersonic speeds is best compensated by forward lift than by rear downforce, maybe this is one further reason for the LEVCONS that can modify the lift profile of the fuselage and therefore contribute more efficiently than the nozzles.

    I know what you mean but don't agree. On paper using a canard to lift the nose is theoretically better than using a horizontal tail surface to push the rear of the aircraft down to raise the nose because it technically reduces lift. But in this case the body of the aircraft is contributing body lift and directing engine nozzles down applies lift to the rear of the vehicle too.

    It is better explained with a small boat. When you power up the prop the boat is lifted out of the water to plain near the surface, which allows you to go much faster than if the prop was totally horizontal and the boat stayed in the water.

    With an aircraft of course you are not balancing on two different mediums so lifting out of water and into the air is not really practical because you are not in water...

    But if you think about it you can change the angle of attack of an aircraft... with zero angle of attack meaning cutting straight through the air, while a 20 degree nose high angle would mean high drag from wings and fuselage.

    What TVC engine nozzles lets you do is use the engine nozzles the trim the aircraft into the airflow rather than deflecting tail or canard surfaces... all your control surfaces can be neutral and therefore minimum drag and RCS, while it is your engine nozzles that directs the thrust of the engines to keep the nose and body of the aircraft at the lowest drag angle possible in flight.

    We discussed this not long ago, the time on AB a normal plane has is actually quite reduced, therefore a platform that aims at high persistence should avoid using it as much as possible and in any case reserve it for high energy demand situations where AB is a must. Supercruising allows for tactics that are not possible for other planes and massively reduces the footprint of AD and A2A missiles.

    Factors like giving max energy to missiles launched at the enemy or even just remaining in a tight turn or climb are more important than trying to keep as much fuel as possible to magnify range.

    For many fighters the job is accelerate out to a specific location and fire on what ever is there and then go home and do it again.

    Most aircraft never fly anywhere near their max possible speed because it wastes fuel and dramatically reduces flight range, but for aircraft like the MiG-31 it is normal... you end up with a 50 ton aircraft because you need the fuel, but I would think using a ramjet propulsion mode would actually greatly improve flight speed and flight range...
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    Post  LMFS on Sat Nov 21, 2020 1:21 pm

    GarryB wrote:I know what you mean but don't agree. On paper using a canard to lift the nose is theoretically better than using a horizontal tail surface to push the rear of the aircraft down to raise the nose because it technically reduces lift. But in this case the body of the aircraft is contributing body lift and directing engine nozzles down applies lift to the rear of the vehicle too.

    What TVC engine nozzles lets you do is use the engine nozzles the trim the aircraft into the airflow rather than deflecting tail or canard surfaces... all your control surfaces can be neutral and therefore minimum drag and RCS, while it is your engine nozzles that directs the thrust of the engines to keep the nose and body of the aircraft at the lowest drag angle possible in flight.

    Yeah that is the idea, to trim with the most drag-effective way of creating force, but when the center of lift moves backward at supersonic speeds you would need the nozzles pointing upwards and therefore pushing the tail down to trim the plane. Instead, if the LEVCONs are used to modify the body's airfoil equivalent camber you are creating lift in a drag economical way in front of the CoG to adjust AoA as needed. That is better than pushing the plane down with the TVC.

    But if you think about it you can change the angle of attack of an aircraft... with zero angle of attack meaning cutting straight through the air, while a 20 degree nose high angle would mean high drag from wings and fuselage.

    A plane never flies at 0 deg AoA, that is the question. If you create force downwards with the nozzles as you say above to move the nose up, you are detracting that force from your lift and therefore increasing the needed AoA and associated drag of the plane.

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