5th gen light mulltirole fighter/Mikoyan LMFS

Actually that is a good thing... with no promise to buy 3,500 then they will need to have a product that is not too expensive and actually works...

Would prefer to see them reduce the requirement for top speed down to something like mach 1.5 because most fighters... even mach 2.3 fighters rarely actually fly that fast and the reduced speed requirements means potentially more internal fuel and weapons volume which means it stays stealthy more often...

It doesn't need a huge payload of 7 tons or anything, but the ability to carry a few weapons would be valuable... perhaps some rear facing torpedo tube like weapon bays for rearward firing AAMs like Verba or Igla-S or something or 9M100. A few upwards facing mortar launchers for 250kg bombs or fuel cells when bombs are not needed... which would leave the main weapon bay for other stuff...

24 tons sounds a bit heavy to me..., though that is MTOW, so normal weight would be 18 tons or so I suspect... which would make it quite nippy with 11 ton thrust engines.

I have heard those engines being called VK-10M but also RD-44... not sure if they are real designations or not...

SAP-2027 will be adjusted anyway. SAP-2020 was adjusted what, thrice?

If the jet comes out, which I doubt, and it's cheap enough, then the Russian MoD may revise their budget and procurement plans to purchase these jets.

Right now, majority of the money is still going towards strategic weapon systems (Ballistic missiles and cruise missiles) while the rest are getting upgrades and odd orders here and there.

So if the price is right, they may opt for more of these than let's say Su-35 as it would be a good buy. Only if price is right. Su-35's are cheap.

I don't think they even want an all stealth fleet, but having 300-400 light fighters boosts their fighter numbers to reasonable values for any front.

To be honest they might only buy 100 manned versions and use the other 200-300 as unmanned drone versions that they can put into storage and take out and use when needed... in which case a fully modular design would be valuable... perhaps a dual nose mount for either a new type of radar or EW device or ESM sensor where they all weigh about the same so if not fitted with radar you could mount something cheaper but still useful... some sort of optronics package or MMW radar like those carried on helicopters and CAS aircraft maybe.

Their ten year plans are supposed to be regularly revised and updated depending on what has happened since the plan was drawn up... for instance in 2010 they would have no idea exports of western equipment will be banned in 2014 so a revision of the 2010 plan included domestic production of critical components first but latter all foreign parts from Russian military equipment.

If this light fighter is successful and affordable then they will change the number of other types they order, but as I said I really don't think they want an all stealthy fleet... even if its stealth levels are good MiG-35 and Su-35s will remain useful aircraft... their external payload capacity means they are useful as bomb trucks at the very least and therefore are force multipliers... and with L band radar they can detect stealth aircraft and weapons... so new types of air to air weapon for use against stealthy targets will be useful to both them and to stealthy fighters...

It's probably meant as an export driven project. A light and relatively cheap stealthy fighter for smaller countries. Sort of a MiG-21 for the 21st century.

Doesn't look like the Rus AF is interested in light fighters these days

But it is not a light fighter.

With a MTOW of 24 tons it is the same weight as the MiG-29/35 so it is a medium weight fighter...

Personally I don't think it makes sense to try to make a light weight stealth fighter... it will never actually be cheap to buy or operate... the cheap light fighter like the MiG-21 and F-5 are likely now either MiG-21 or F-5 knockoffs or evolved aircraft or they will be drone missile trucks for carrying bundles of missiles or bombs... and an auto pilot and fuel... and nothing else.

Imagine wasting your time making an F-16 replacement now... an LMFS in an unmanned model with all the latest missiles and self defence systems able to pull 30 g turns would kick the arse of any manned aircraft...

Well, light compared to the Su-57

GarryB wrote:But it is not a light fighter.

With a MTOW of 24 tons it is the same weight as the MiG-29/35 so it is a medium weight fighter...

Personally I don't think it makes sense to try to make a light weight stealth fighter... it will never actually be cheap to buy or operate... the cheap light fighter like the MiG-21 and F-5 are likely now either MiG-21 or F-5 knockoffs or evolved aircraft or they will be drone missile trucks for carrying bundles of missiles or bombs... and an auto pilot and fuel... and nothing else.

Imagine wasting your time making an F-16 replacement now... an LMFS in an unmanned model with all the latest missiles and self defence systems able to pull 30 g turns would kick the arse of any manned aircraft...

Yes I think they need to build an arsneal version of PAK DA, or maybe the IL-76 that will act as a "mother ship" for the drone fighters. It will have mission managers on board and perhaps even act as a refulling plane for the UAVs, although better to have a dedicated refueller. The mothership would also be a AWACs plane to give the drones full situational awareness so they can have smaller radars. It would also be able to deliver its own salvo of BVR missiles. The drones would sacrifice to protect the mothership.

Cyberspec wrote:Here's something more substantial....model of the LMFS getting tested in a wind tunnel at TsAGI....no canards  

is it a recent model?

If Mod doesn't plan on buying LMFS, they have to find a way to keep MiG busy, otherwise the qualified staff will waste away and eventually retire with lesser reason and opportunities for new staff to be trained. The MiG-41 is easily 10-15 years away, I suggest they deeply modernize and even restart the production of the MiG-31M fleet in the meantime. Let's see MiG-31's with a much lighter composite/tintanium (infused with graphene) 3d printed airframe, fitted with avionics, radar, and the 2nd stage engine from the Su-57.

Well, light compared to the Su-57

Not really... the Su-57s MTOW is probably only ten tons heavier at about 35 tons... I would say both would spend most of their operational lives at weights of 18 tons for the MiG and 24 tons for the Sukhoi.... compared with double that... 50 tons for the MiG-31 and possibly more for the MiG-41...

I mean the S-70 is a light drone and it is supposed to have an operational weight of about 20 tons...

Yes I think they need to build an arsneal version of PAK DA, or maybe the IL-76 that will act as a "mother ship" for the drone fighters. It will have mission managers on board and perhaps even act as a refulling plane for the UAVs, although better to have a dedicated refueller. The mothership would also be a AWACs plane to give the drones full situational awareness so they can have smaller radars. It would also be able to deliver its own salvo of BVR missiles. The drones would sacrifice to protect the mothership.

For HATO I would agree, because going to fight in Venezuela or Angola having a mothership makes it all nice and portable, but for Russia they are more interested in defending their own territory so rather than creating a mobile IADS for these drones and light planes... just integrated them into the existing IADS Russia is creating for itself around its territory and military assets...

If Mod doesn't plan on buying LMFS, they have to find a way to keep MiG busy, otherwise the qualified staff will waste away and eventually retire with lesser reason and opportunities for new staff to be trained.

I would think a light stealth fighter aircraft would actually sell rather well... it is in demand right now with the only option for some countries being the F-35 which is losing its appeal because it is supposed to be a lot of things but one of those is cheap and it clearly isn't... so is it stealthy enough?

Maybe Turkey might want to join MiG in developing a new light fighter.

The MiG-41 is easily 10-15 years away, I suggest they deeply modernize and even restart the production of the MiG-31M fleet in the meantime.

Totally disagree here.... MiG has been working on a MiG-31 replacement and a light stealthy fighter for a rather long time... I don't think either will take more than 5 years to get something flying... maybe another 3-4 years to get it working as needed.

The critical think with the MiG-41 will be an engine that can operate from a runway and also accelerate to beyond mach 3 safely and efficiently... a bypass turbofan that uses bypass air as a ramjet perhaps... or perhaps something with a pulse detonation scramjet or more exotic.

It think the first generation MiG-41 will not be hypersonic but will be faster and longer ranged than the MiG-31 and the next engines will make it even faster...

George1 wrote:is it a recent model?

As far as I can tell, the pic was recently released but could be much older...

Maybe someone has more info?

Cyberspec wrote:

George1 wrote:is it a recent model?

As far as I can tell, the pic was recently released but could be much older...

Maybe someone has more info?

The oldest reference I found is from 2015

http://espacial-org.blogspot.com/2015/11/modelos-de-aviones-furtivos-rusos1.html

so it isn't sth new

George1 wrote:so it isn't sth new

It's the best we have to go by on what it might look like. Previously there were only artists impressions that were mostly showing a scaled down version of the MiG 1.44

Trends and fashion have a lot more influence on design than pure maths and sensible thought.

Personally I think the simple plain design of the Tegas is a good thing, but I also think very light planes are too light.

Making a plane a single engined aircraft means a powerful single engine is needed which usually makes it a very expensive engine... not a good way to start making a cheap plane.

They would not work at high AoA because the shadow of the fuselage would deprive them of the airflow. So that solution is used in aircraft for which maneouverability is not important, like very stealthy flying wing bombers and UCAVs, but not on fighters.

You argued that, but you also argued for single engined aircraft which would eliminate 3D-TVC, which would weakened AoA ability far more so than the above fuselage intakes. Also you notice something about dogfighting is that fighter pilots are trained to make turns inwardly on curved turns (on the side of the canopy) and not outside of the curve for the very same reason why big turns on roller coasters have the roller coaster car on the interior of the curve and not the exterior; G-force and drag is greater on the exterior of curves than it is on the interior of curves. While fighter pilots are trained to make interior curve evasive maneuvers, the g-force/drag is still exerted heavily on the intakes that are on the exterior of the curves. Intakes on the exterior of curves getting pulled by excessive g-force would cause more mechanical erosion and expedite wear and tear on the airframe, and shortening a fighter aircraft's service life. The drag caused by intakes on exterior curves would also affect AoA negatively. 3D-TVC from 2 engines almost completely rectifies issues of air flow for post-stall maneuvers, as the Su-57 has demonstrated the ability to even maintain lift even at nearly complete stops mid-flight.

I'm arguing specifically for jet engine intakes to be blended on the top of the fuselage, which dramatically reduces chances of FOD, reduces drag, mechanical erosion on airframes and RCS and increases speed, lift and fuel efficiency. The times that fighter aircraft have to urgently use their dogfighting ability is infinitesimally smaller than when have to fly in a standard flight pattern.

I respect your opinion, while I personally don't agree, I'll even give you the benefit of the doubt and argue from your POV but also argue in Reductio ad Absurdem. 4th and 5th gen aircraft already resemble flying sharks, why can't some intakes resemble shark gills? If airflow to engine intakes are disrupted by the silhouette of the fuselage, then they could install variably retractable thin staggered intakes on the bottom of the fuselage resembling shark gills. They could be 5 thin retractable intakes staggered like shark gills, that open up by 20% of that of a standard intake during dog fights, and retract and close shut during standard flights to reduce drag and RCS.

"The shadow of the fuselage would deprive them of the airflow" Let's also argue from that statement and say that's true, we would also need to acknowledge that making sharp turns at low subsonic speeds (like during dogfighting) would significantly reduce air flow to the intakes anyway compared to flying a straight flight-path at high-subsonic speed.

Just imagine yourself driving a car on a street, you take a exit turn on to the highway, except the exit turn requires a major curve to merge on to the highway. You can exert the same force on the pedal as you would on the highway, but because of the major turn you would be traveling as fast. If you turned down the volume on your radio, you'll notice the sound of airflow around the car chassis is much quieter than you would if you were just driving a straight path. By the time you fully merged to the highway, and your still exerting the same force on the pedal, you'll notice by going in a straight line the speed of airflow significantly picks up. At the same time the sound of airflow picks up and gets louder by the very nature of the vehicle higher speed leads to the higher speed of air flow around the vehicle. What I'm arguing is by the very nature of taking sharp turns in vehicles, the speed of airflow dramatically reduced compared to going in straight line. 3D-TVC for 2 engine aircraft will maintain lift/flight no matter if the intakes are places below or above the fuselage.  

Also If I had it my way 5th gen weapon bay doors would be replaced with modular revolving bomb bay doors, which should reduce RCS, drag and complexity.

That sounds interesting, do you have some example?

The concept is not really different than a revolving door turnstile in a office building. The outside portion is flat and uniformly conforms with the bottom of the fuselage, while the interior portion curves to hold the munition. Ideally it would be modular in length and width to accommodate different weapon loads. When the munition is launched, it turns to drop the munition, and quickly turns back to the flat conformed side. This would reduce drag and RCS while launching munitions compared to standard internal bomb bay doors. They could even take it another step by have internal veins in the munition compartment that lead to small tanks of of electromagnetic opaque aerosol (with a chemical composition of microscopic aluminum-silica spheres) that's inject aerosol during the launching of munitions to further reduce interior bomb bay RCS.

magnumcromagnon wrote:You argued that, but you also argued for single engined aircraft which would eliminate 3D-TVC

Not necessarily. With the current Saturn nozzle, the plane would have 2D TVC, but with Klimov or Salut technology it could be true 3D. Roll authority would be lost, but a single engine airframe would partially compensate that by being more agile (due to less angular inertia) around the longitudinal axis.

which would weakened AoA ability far more so than the above fuselage intakes.

The evidence contradicts that and shows that there are indeed fighters without TVC, but none with intakes above the fuselage. TVC helps in many conditions, mainly at low speeds where control surfaces have little authority. In any case a single engine fighter would not loose that contribution, even when limited to 2D TVC.

I have some issues fully getting your point in the next paragraph:

Also you notice something about dogfighting is that fighter pilots are trained to make turns inwardly on curved turns (on the side of the canopy) and not outside of the curve

A pilot can withstand 9 positive g, but only 3 negative units, because blood rushes into the brain an can easily kill them. Besides, the turning in the sense of positive g is done based on the lift generated by the airframe for normal flight, which is for obvious reasons the way the aerodynamics of the plane are optimized.

G-force and drag is greater on the exterior of curves than it is on the interior of curves.

I think I don't understand this.

While fighter pilots are trained to make interior curve evasive maneuvers, the g-force/drag is still exerted heavily on the intakes that are on the exterior of the curves. Intakes on the exterior of curves getting pulled by excessive g-force would cause more mechanical erosion and expedite wear and tear on the airframe, and shortening a fighter aircraft's service life.

Intakes in the exterior of the curve? Like those on a MiG-29 at high AoA? This is not a conditional proposition, it is the way fighters are currently designed, so it works.

3D-TVC from 2 engines almost completely rectifies issues of air flow for post-stall maneuvers,

TVC creates a torque arm after the CoG of the plane, it has essentially nothing to do with air flow in the engines, and also cannot provide for lift at the CoG, which is what you need for sustained turning.

I'm arguing specifically for jet engine intakes to be blended on the top of the fuselage, which dramatically reduces chances of FOD, reduces drag, mechanical erosion on airframes and RCS and increases speed, lift and fuel efficiency. The times that fighter aircraft have to urgently use their dogfighting ability is infinitesimally smaller than when have to fly in a standard flight pattern.

Well, I have nothing against the advantages of such configuration, but until now nobody is using it for a fighter and that must be for a reason, don't you think? If the role of the fighter changes so much they dont need to operate at high AoAs, it may happen as you propose. Until now what we see is a trend to increase the overload characteristics of each new aircraft generation and even proposals to eliminate the pilot altogether in order not to restrain the ultimate capabilities of the airframe in this regard. And t makes sense, since this AoA capability is what determines its agility, not only for manoeuvring air combat, but also in BVR (see discussion about defeating AAMs in air missiles' thread for some reasoning about it). MiG-29 had intakes above the fuselage precisely because of FOD and it got them removed on last versions, in exchange for more internal fuel.

I respect your opinion, while I personally don't agree, I'll even give you the benefit of the doubt and argue from your POV but also argue in Reductio ad Absurdem. 4th and 5th gen aircraft already resemble flying sharks, why can't some intakes resemble shark gills? If airflow to engine intakes are disrupted by the silhouette of the fuselage, then they could install variably retractable thin staggered intakes on the bottom of the fuselage resembling shark gills. They could be 5 thin retractable intakes staggered like shark gills, that open up by 20% of that of a standard intake during dog fights, and retract and close shut during standard flights to reduce drag and RCS.

And I respect yours too, of course. What you propose is a possibility indeed, it would mean weight, complexity and reliability issues. Dynamic pressures on intakes at high speeds are really big, so the structures involved need to be very resistant, but why not? My point is that aero engineers already know what make sense and I just try to make sense of it  

"The shadow of the fuselage would deprive them of the airflow" Let's also argue from that statement and say that's true, we would also need to acknowledge that making sharp turns at low subsonic speeds (like during dogfighting) would significantly reduce air flow to the intakes anyway compared to flying a straight flight-path at high-subsonic speed.

You can check this for yourself, there are CFD simulations of fighters at high AoA to see the low pressures formed above the fuselage and high pressures below it, where intakes are placed. This is what allows to feed the engines during turning.

The concept is not really different than a revolving door turnstile in a office building. The outside portion is flat and uniformly conforms with the bottom of the fuselage, while the interior portion curves to hold the munition. Ideally it would be modular in length and width to accommodate different weapon loads. When the munition is launched, it turns to drop the munition, and quickly turns back to the flat conformed side. This would reduce drag and RCS while launching munitions compared to standard internal bomb bay doors. They could even take it another step by have internal veins in the munition compartment that lead to small tanks of of electromagnetic opaque aerosol (with a chemical composition of microscopic aluminum-silica spheres) that's inject aerosol during the launching of munitions to further reduce interior bomb bay RCS.

OK I see

MiG-29 had intakes above the fuselage precisely because of FOD and it got them removed on last versions, in exchange for more internal fuel.

The MiG-29 needed the upper surface louvers to let air in because their intake doors that stopped FOD intake were solid and completely blocked the airflow.

Later they used grid type doors as used on the Flanker series so the upper louvers became redundant.

Regarding airflow during tight turning suction relief doors along the engine trunk should suffice for the periods when the aircraft is pulling hard turns... or just an ability to greatly increase the air intake area for short periods... perhaps half intakes above and below the wing area with the ability to use one or the other or both depending on the conditions...

The suggestion that 'Roll authority would be lost, but a single engine airframe would partially compensate that by being more agile (due to less angular inertia) around the longitudinal axis.' ...really?

The ability to follow a target with your nose is critical because where your nose points is also where your sensors and weapons point too... being able to launch missiles directly at targets means the difference between a hit and a miss with most missiles... and the faster you kill the other guy the less chance they have to launch a weapon to kill you... because with modern weapons something he launches before you kill him can still kill you even after he is dead or hanging from a parachute.

A twin engined airframe generally has more engine power than a single engined one... it is simply easier to make a twin engined aircraft more powerful, and when you are using TVC more engine power and widely spaced twin engines means ability to point where you need to point...

It also means more internal volume for internal missile carriage.

GarryB wrote:The MiG-29 needed the upper surface louvers to let air in because their intake doors that stopped FOD intake were solid and completely blocked the airflow.

Later they used grid type doors as used on the Flanker series so the upper louvers became redundant.

Do you know if the Flankers are also rated for unprepared airfields? Even when the mesh screens avoid ingestion of bigger objects, I doubt the sand and dust do any good to the engines. I also wonder if the newer generation of the MiG-29 (M/M2/K/Mig-35) can still be operated from rough airfields the same way as they were before.

The Flanker:



The MiG-35:

Regarding airflow during tight turning suction relief doors along the engine trunk should suffice for the periods when the aircraft is pulling hard turns... or just an ability to greatly increase the air intake area for short periods... perhaps half intakes above and below the wing area with the ability to use one or the other or both depending on the conditions...

This is more or less what magnumcromagnon said, if I understood him properly. I can only say that intakes as of now are simpler than that, but maybe this is doable. That wind tunnel model above has some interesting intakes which do not protrude from the fuselage, maybe one could install doors above and below the fuselage and open them according to the situation, I don't know.

The suggestion that 'Roll authority would be lost, but a single engine airframe would partially compensate that by being more agile (due to less angular inertia) around the longitudinal axis.' ...really?

Normally yes. The twin-engine podded layout, especially with widely separated engines, increases the roll moment of the plane. If the mass of the fuselage is concentrated along the longitudinal axis of the plane, its roll moment will be lower. And unless the airspeed is extremely low, ailerons have way more authority than the differential deflection of the nozzles.

A twin engined airframe generally has more engine power than a single engined one... it is simply easier to make a twin engined aircraft more powerful, and when you are using TVC more engine power and widely spaced twin engines means ability to point where you need to point...

It also means more internal volume for internal missile carriage.

It is difficult to settle this discussion since there is no 'wrong' or 'right', just different ways of understanding the priorities for a light fighter. I am as convinced about the single engine layout as others are about the twin engine, it is ok, these are just opinions. In the end MiG seems to be using the MiG-29 as a base for a 5th gen fighter:

Early talks about MiG-29 as a foundation for a stealth plane:
http://www.flightglobal.com/news/articles/rac-mig-boss-eyes-fifth-generation-fighter-400087/
http://www.icas.org/ICAS_ARCHIVE/ICAS2000/PAPERS/ICA0753.PDF

- Agreement with UAE:
https://www.ainonline.com/aviation-news/defense/2017-02-23/abu-dhabi-idex-show-highlights-key-uae-developments

- Contract to analyse the aero for a twin engine fighter:
https://twitter.com/i/web/status/1250692021704065024

BTW, this is the last article from Butowsky from which the latest drawings come.

https://radar.rp.pl/technologie/17212-mig-kontynuuje-projekt-lekkiego-mysliwca/amp

He explains that the model as conceived now is a delta-canard, but with surface controls in the tail. In that sense, it could correspond to a layout like that of the Su-30, but then it would rather not have a delta wing. Alternatively it could have the elevators between the keels, like the MiG 1.44. This makes more sense than delta wing and tails and is BTW the layout I chose because provides best possibilities for redundancy and synergy of control surfaces, wing-body blending and wing area. They talk about similar size to MiG-29 but 15.5 m long is quite smaller.

Delta-canard is a configuration for manoeuvrability, so that should be the defining characteristic of the plane compared to other 5th gen projects of conventional layout:

Do you know if the Flankers are also rated for unprepared airfields?

Looks like a very fine mesh to me so I would expect they intend to operate from all sorts of airfields and in all sorts of conditions.

Wasn't one of the issues with the Su-35 in Syria a problem with sand ingestion rather that stones or grid...

Even when the mesh screens avoid ingestion of bigger objects, I doubt the sand and dust do any good to the engines.

I would expect the design of the engine takes that in to account and directs heavier matter away from the delicate and very hot parts.

My understanding is that one of the features of the new generation engines is blisk disks instead of individual blades they have disks with blades... which makes them stronger and more resistant to bird strikes...

I also wonder if the newer generation of the MiG-29 (M/M2/K/Mig-35) can still be operated from rough airfields the same way as they were before.

It will likely be an operational requirement... if not dirt runways then stretches of high way tarmac...

Normally yes. The twin-engine podded layout, especially with widely separated engines, increases the roll moment of the plane. If the mass of the fuselage is concentrated along the longitudinal axis of the plane, its roll moment will be lower. And unless the airspeed is extremely low, ailerons have way more authority than the differential deflection of the nozzles.

Are you sure... I would think 11 tons of thrust angled down at 20 degrees and 11 tons of thrust a few metres away directed upwards at about 20 degrees would have a hell of a lot of roll effect... isn't the location of mass in the middle or even just around and between the engines much more conducive to roll rate that weight out at the wing tips that resists the roll?

When an ice skater does a spin... they usually speed up when they bring their hands in closer to their centre of gravity and slow down when they spread them out...

In a post stall environment without proper airflow over the wing and tail surfaces... the difference would be that the twin engined aircraft can roll and the single engined aircraft can't... and when manouvering hard being able to pull out of controlled flight to point your nose at the target and launch a missile and not have to worry about stalling makes dogfighting much easier and much less stressful.

I have read about pilots flying the Mig-29 finding the control system to be their liking because there are soft limits and feedback on the control when you are going to depart from controlled flight and you can still pull through that if you need to.... like to avoid hitting the ground or another aircraft...

On the F-16 there is a hard limit the software wont let you go through.

With TVC you don't need to keep an eye on your speed and altitude and angle of attack... and you can focus on getting the target in your crosshairs and firing.

It would be the best thing in the world if America had it on all its planes...

It is difficult to settle this discussion since there is no 'wrong' or 'right', just different ways of understanding the priorities for a light fighter. I am as convinced about the single engine layout as others are about the twin engine, it is ok, these are just opinions. In the end MiG seems to be using the MiG-29 as a base for a 5th gen fighter:

I agree, there is a lot of opinion involved, but if we look at history... the MiG-21 was good because it was cheap and simple... but to keep it competitive you need new AESA radars and new self defence avionics and lots of other new stuff that is going to add weight and take up space and it needed more fuel anyway...

F-16s sell for 100 million a pop on the export market and are not particularly cheap to operate and Gripen is neither cheap to buy nor to operate either.

In my honest opinion the only two successful cheap single engined fighters are the F-5 and the A-4 Skyhawk... and both are obsolete now for most missions.

There is no cheap radar, there are no cheap engines and normally mission creep means they end up trying to make it better than the bigger planes which makes it more expensive than bigger planes and that ruins the whole concept.

Lead In Fighter Trainers used as light fighters suffer all the same problems... adding the necessary stuff to make them a fighter plane makes them much more expensive and also more complex and less useful for training. Ironically it is often the most expensive ones that try to justify the high price by suggesting it could also be used for COIN or CAS or light fighter duties... which means you are starting with an aircraft that is too expensive anyway...

In my personal opinion... there are two concepts that would be best for cheap light fighter... an armed drone, and a medium fighter with most of the stuff dialed back with cheaper simpler versions of it.

GarryB wrote:Looks like a very fine mesh to me so I would expect they intend to operate from all sorts of airfields and in all sorts of conditions.

Wasn't one of the issues with the Su-35 in Syria a problem with sand ingestion rather that stones or grid...

Yeah, I remember the issue with the sand, and that was operating from a perfectly fine runway. I will try to find out more about the kind of airfields they need, but I don't think I have ever seen a Flanker on a dirt strip, and with its range and mission it would not make much sense, to be honest. The MiG-29 was a point defence fighter and it made sense at that time to have it operating from unprepared airfields, but now it is turned into a multi-role fighter with increased range and capabilities, so that specialisation may not be relevant anymore.

It will likely be an operational requirement... if not dirt runways then stretches of high way tarmac...

Sure, that makes sense and the reinforced undercarriage in almost all Russian planes allows it.

Are you sure... I would think 11 tons of thrust angled down at 20 degrees and 11 tons of thrust a few metres away directed upwards at about 20 degrees would have a hell of a lot of roll effect...

You can see this for yourself in any airshow, Flankers do not roll any faster than F-16s or even twin engine aircraft with a compact airframe like the Rafale, rather the opposite is true. The main issue here is torque arm. The engines are close to the centerline of the plane, while ailerons are at the far end of the wings, that multiplies its contribution, because their torque arm is several times bigger. With modern FCS, other aerodynamic surfaces contribute to roll too (elevators, canards, flaps), which further decreases the contribution of the TVC to the total amount of torque. And of course, being the Flanker's TVCs actually angled 2D, when they deflect differentially in the vertical plane they create a yaw moment too, which needs to be compensated by the keels.

isn't the location of mass in the middle or even just around and between the engines much more conducive to roll rate that weight out at the wing tips that resists the roll?

When an  ice skater does a spin... they usually speed up when they bring their hands in closer to their centre of gravity and slow down when they spread them out...

Exactly, the single-engine fighter resembles the skater with their arms close to the body, the podded type the skater with their arms open.

In a post stall environment without proper airflow over the wing and tail surfaces... the difference would be that the twin engined aircraft can roll and the single engined aircraft can't... and when manouvering hard being able to pull out of controlled flight to point your nose at the target and launch a missile and not have to worry about stalling makes dogfighting much easier and much less stressful.

Rolling will not make you point your nose better at zero airspeed, rather yaw and pitch inputs are important for that matter. And airspeed is normally not zero, after that either you kill the enemy or you are killed. But of course "carefree" handling is a must today and a single engine fighter could have it too. Even F-35 is way ahead of F-16 in this regard, without TVC.

It would be the best thing in the world if America had it on all its planes...

For sure  

They are so proud because the nozzle in the F-22 deflects 5º more than in Russian planes... regardless that the torque arm is much shorter both in pitch and roll, and no yaw moment is possible.

I agree, there is a lot of opinion involved, but if we look at history... the MiG-21 was good because it was cheap and simple...

That's it, replacing MiG-21 and F-16 is where export money is. There are many places where MiG-21 are still operating, Vietnam complains that there is nothing in the market to replace them. They will not buy the JF-17, but many other countries will, if nothing more is available.

but to keep it competitive you need new AESA radars and new self defence avionics and lots of other new stuff that is going to add weight and take up space and it needed more fuel anyway...

For an air force with heavy and light fighters, the light may be networked to the sensors of the heavier ones and act as a reinforcement, so the avionics could be simpler. In air forces with little money, you need something as cheap and simple as possible, with grow options for the future. Operational costs play a big role, and single engine, light fighters are way cheaper. Such countries face the unsolvable dilemma of needing a capacity that they cannot really pay, so they frequently play fooling themselves buying cheap but having constant modernization needs. To be successful there you need small fixed costs for the procurement and operation of the planes and a range of improvement packages where they can put their money, when they get it. Of course, a light, single engine plane is much better than a medium, twin engine in that regard.

F-16s sell for 100 million a pop on the export market and are not particularly cheap to operate and Gripen is neither cheap to buy nor to operate either.

US can extort money from anyone not having real chances of buying somewhere else. While Gripen is actually very cheap to operate, probably the cheapest Western plane by far.

There is no cheap radar,

Half the modules is half the money, and they are a big part of the cost of an AESA radar. Besides, if the plane is cheaper you can have more of them and numbers will help reducing the need for installing the absolute best equipment. Contrary to Western air forces that buy F-35 and as a result they can have way less planes and less capability.

there are no cheap engines

No, and twin engine is twice as many, and twice the spares.

and normally mission creep means they end up trying to make it better than the bigger planes which makes it more expensive than bigger planes and that ruins the whole concept.

See above. This is not a problem for Russia, because they can sell the planes and then offer to pimp them up, it is a matter of political games between the government and the air forces of their customers and will only work in their benefit as supplier. For their own, they should focus on keeping them simple, under the command of the Su-57, and actually buy most of them in unmanned variant

Lead In Fighter Trainers used as light fighters suffer all the same problems... adding the necessary stuff to make them a fighter plane makes them much more expensive and also more complex and less useful for training. Ironically it is often the most expensive ones that try to justify the high price by suggesting it could also be used for COIN or CAS or light fighter duties... which means you are starting with an aircraft that is too expensive anyway...

Trainers can be decent attack planes, but not fighters. And I agree, this cost and mission creep is what happens when you want something but refuse to admit you can't buy it.

In my personal opinion... there are two concepts that would be best for cheap light fighter... an armed drone, and a medium fighter with most of the stuff dialed back with cheaper simpler versions of it.

Well, I tend to agree on the UCAV part, the advantage for the light fighter is that it can be directly applied, only by removing the cockpit and adding fuel and avionics. An unmanned medium fighter would be less advantageous due to its size and cost.

Yeah, I remember the issue with the sand, and that was operating from a perfectly fine runway. I will try to find out more about the kind of airfields they need, but I don't think I have ever seen a Flanker on a dirt strip, and with its range and mission it would not make much sense, to be honest.

Yeah but from a design perspective you have to design for reality... an airfield is not going to be spotless, no matter how many airfield runs a day where you have all the personel on the airfield walking side by side picking up stones and bits of metal and rubbish to keep the airfield runway and apron clean... and that is during peace time... it makes much more sense to design the aircraft so it doesn't need that sort of cotton wool treatment because in war time you can be sure your enemy wont attack your nice clear airfields... but you know they can't make holes every 150 metres along the entire length of all your motor ways...

The MiG-31 has offset main wheels... one in front of the other but not running across the same track of ground just for the purpose of operating on soft ground if it needs to. They don't run it from dirt runways but they probably could in an emergency....

The MiG-29 was a point defence fighter and it made sense at that time to have it operating from unprepared airfields, but now it is turned into a multi-role fighter with increased range and capabilities, so that specialisation may not be relevant anymore.

It needs to be able to operate in places where the runways are not so good... whether that is somewhere in the third world or in Russia on the flat ground beside an otherwise perfectly good runway that now has large craters in it...

You can see this for yourself in any airshow, Flankers do not roll any faster than F-16s or even twin engine aircraft with a compact airframe like the Rafale, rather the opposite is true.

The difference is much bigger if you can't do it in a stall...

Also the widely spaced engines are part of the body lift mechanism that greatly improves flight performance....

With modern FCS, other aerodynamic surfaces contribute to roll too (elevators, canards, flaps), which further decreases the contribution of the TVC to the total amount of torque.

Only in a normal flight regime and also in that normal flight regime a Flanker has both the torque of the control surfaces and the engines so it should be much better having wider wings too.

And of course, being the Flanker's TVCs actually angled 2D, when they deflect differentially in the vertical plane they create a yaw moment too, which needs to be compensated by the keels.

Why are you talking about Flankers? The MiG-29/35 will have full 3D thrust vectoring engines and control surfaces on their wings giving the same torque or better than a single engined plane...

Exactly, the single-engine fighter resembles the skater with their arms close to the body, the podded type the skater with their arms open.

But a roll wont take you away from where you are, it just allows you to rotate your axis of best turn speed to a different angle... so instead of pushing down at -3 g you can do a quick flick roll of 180 degrees and then make the same turn with a 9 g pull back on the stick...

Rolling will not make you point your nose better at zero airspeed,

Rolling allows you to align the enemy target so you are pulling positive gs to follow them... having to pitch and yaw down and to your right respectively is not an ideal flight manouver...

That's it, replacing MiG-21 and F-16 is where export money is. There are many places where MiG-21 are still operating, Vietnam complains that there is nothing in the market to replace them. They will not buy the JF-17, but many other countries will, if nothing more is available.

The problem is cheap and simple is OK for CAS, but not for fighter aircraft these days. Russia is not afraid of cheap, but it has to be able to win... I think the best possibility would be for Russia to build a UCAV in the 15-20 ton class that is supposed to be a light fighter class aircraft... for Russia it can be a drone to operate with the light MiG fighter that MiG are going to develop, and for export there can be a manned version that is cheap and light and manouverable and you can fit what you like to it from very basic to rather quite capable...

For an air force with heavy and light fighters, the light may be networked to the sensors of the heavier ones and act as a reinforcement, so the avionics could be simpler.

I think Russia will have heavy and medium fighters and the light fighter role will be UCAV support drones... the S-70 for Su-57 and something based on MiG parts to operate with the new MiG.

Operational costs play a big role, and single engine, light fighters are way cheaper.

I disagree... AFAIK the MiG-29 is much cheaper to operate than the F-16 or F-35 or Gripen... The MiG-21 was cheap to operate because it was simple... that didn't mean it took 1 hour of maintenance per hour of flight time... it meant guys who went to high school could maintain it essentially car mechanics would pick up how to keep it flying fairly quickly... and you didn't need university educated geeks to keep it going.

The idea was to make planes where during a 500 hour period in war time needed next to no serious work on them... but after 1,000 hours of flight essentially went for an almost complete overhaul... parts were cheap and time was cheap... and during a conflict you didn't have to worry about things wearing out.

Of course, a light, single engine plane is much better than a medium, twin engine in that regard.

I disagree. That is the theory, but it has never happened in the real world. And likely wont happen again.

While Gripen is actually very cheap to operate, probably the cheapest Western plane by far.

Not what the countries who did buy it said... the when offering Gripens to Finland they didn't even say it was cheap to operate when they were trying to sell it to them because they knew it wasn't.

No, and twin engine is twice as many, and twice the spares.

Compare F-16 with MiG-29... an 11 ton thrust engine is more expensive that two 8 ton thrust engines, but provides 5 tons more thrust...

Or being more fair... comparing apples with apples... the F-5 with two small engines is much cheaper than the F-20 with a single bigger engine... the former was successful and the latter wasn't because the latter stopped being cheap to operate and maintain.

For their own, they should focus on keeping them simple, under the command of the Su-57, and actually buy most of them in unmanned variant

Russia already has S-70 drones to operate with the Su-57.... creating a cheap light single engined 5th gen plane to fly around with Su-57s will just limit the range and potential of the Su-57s... if the cheap light 5th gen fighter has the same flight radius as the bigger plane then you have the fuel fraction or payload fraction wrong.

Well, I tend to agree on the UCAV part, the advantage for the light fighter is that it can be directly applied, only by removing the cockpit and adding fuel and avionics. An unmanned medium fighter would be less advantageous due to its size and cost.

Again.... what is your definition of a light drone... the S-70 is a 20 ton drone which makes its NTOW 2 tons heavier than the MiG-35 and only 4 tons lighter than the Su-57s NTOW...

GarryB wrote:Yeah but from a design perspective you have to design for reality... an airfield is not going to be spotless, no matter how many airfield runs a day where you have all the personel on the airfield walking side by side picking up stones and bits of metal and rubbish to keep the airfield runway and apron clean

The mesh screens solve that FOD problem, so that Russian planes are not so reliant on someone constantly cleaning the runway to perfection. That pretty much shows how little afraid the West is of a Russian attack, BTW, because otherwise they would design their planes the same way. But using a dirt strip demands to avoid ingestion of sand and dust in the engines, and I suspect that is not solved in the Flankers or in the new MiGs, because the mesh cannot filter small particles. If I get the proof I will share it, but by now I have no evidence that such type of operation is intended for those planes.

Why are you talking about Flankers? The MiG-29/35 will have full 3D thrust vectoring engines and control surfaces on their wings giving the same torque or better than a single engined plane...

As far as I know, the MiGs had this OVT prototype (with awesome manoeuvrability), but the technology was not implemented in the series, while the Saturn design is indeed operational. BTW, this video is very nice and apart from it we have the test pilot of MiG explaining what the TVC is for. In summary, for safe recoveries and the very end of a dogfight, where speed is very low.

https://www.youtube.com/watch?v=BdVJPZAKAQE

Rolling allows you to align the enemy target so you are pulling positive gs to follow them... having to pitch and yaw down and to your right respectively is not an ideal flight manouver...

Sure, the reason I said this is because we were talking about very low speed manoeuvring where aerodynamic surfaces have no authority, so no positive or negative overloads are involved. Otherwise rolling by aero surface deflection is normally available.

I think the best possibility would be for Russia to build a UCAV in the 15-20 ton class that is supposed to be a light fighter class aircraft... for Russia it can be a drone to operate with the light MiG fighter that MiG are going to develop, and for export there can be a manned version that is cheap and light and manouverable and you can fit what you like to it from very basic to rather quite capable...

I think we are basically on the same page here, only I don't see the need for the additional medium fighter, since there is already a top-tier plane (Su-57) that has both the legs, the weapons and the speed to cover a big area, while potentially many subordinate UCAV fulfil lesser tactical missions, so an additional fighter to cover that same supervisory role of the Su-57 would be wasteful to me. It is easier to increase the number of planes controlled by one Su-57 than to create another plane for that very mission, with a marginally smaller price that is going to be more than offset by the development costs.

BTW and that is a good point you made: the UCAV or "light" fighter as I conceive it would be ca. 10 t empty, 16-17 t NTOW, 20-22 t MTOW. If you want it to have a minimum weapon carrying capacity and range, smaller than this seems difficult. I know "light" is normally considered well below that weight, but now that has changed, there is no 5G fighter project below this size that I know, even the follower of the Gripen was expected to grow because otherwise weapon bays for normally sized armament are not feasible.

I think Russia will have heavy and medium fighters and the light fighter role will be UCAV support drones... the S-70 for Su-57 and something based on MiG parts to operate with the new MiG.

The Okhotnik is a ground attack plane. Do you see no need or place for a A2A UCAV to go with the Su-57?

I disagree... AFAIK the MiG-29 is much cheaper to operate than the F-16 or F-35 or Gripen...

We would need to check that then, and to make it more difficult, numbers need to come from the same operator. MiG says the -35 is 2.5 times cheaper to operate than the -29, that implies a big maintenance cost for the older model, because fuel-wise you are only going to have very minor savings, if any. With the short operating life of older soviet engines I don't think the -29 can be cheaper to operate than a Gripen. Considering engine maintenance, two engines are twice the labour and twice the pieces to be exchanged, it is an unavoidable fact  

Not what the countries who did buy it said... the when offering Gripens to Finland they didn't even say it was cheap to operate when they were trying to sell it to them because they knew it wasn't.

Do you have the sources?

an 11 ton thrust engine is more expensive that two 8 ton thrust engines

I will come back to this with hard data if I find them, but for the same technological level this is very difficult.

, but provides 5 tons more thrust...

In terms of size, the F-16 could use the F119 and have a TWR of almost 2... I see no clear advantage of the twin engine layout in that regard. You can say that two engines take proportionally less space along the plane's axis for the same engine frontal section, so you free some space for fuel or weapons. The catch is that this increased cross section is a mayor driver of drag. And drag + weight are the main enemies of a fighter.

Russia already has S-70 drones to operate with the Su-57.... creating a cheap light single engined 5th gen plane to fly around with Su-57s will just limit the range and potential of the Su-57s... if the cheap light 5th gen fighter has the same flight radius as the bigger plane then you have the fuel fraction or payload fraction wrong.

The Su-57 would fly high in the rear in order to control a sector of the air space, while the lighter fighters / UCAV fulfill their missions. They don't need the same ranges, to operate from the same bases or to fly together by any means, just to be coordinated at a tactical level via data links. The Su-57 could use its persistence to ensure air superiority over an area for an extended period, while smaller fighters and land attack UCAVs engage in combat with the enemy air force or penetrate enemy territory. The speed and flight altitude, plus big weapon bays of the Su-57 allows it to attack other planes from safe distances in most cases. This is the tactical setup that makes sense to me, it creates a series of very interesting synergies between the different resources of the air force and allows to use cheaper assets in numbers while keeping the overall upper hand in the battle by means of a reduced number of high capacity ones.

The mesh screens solve that FOD problem, so that Russian planes are not so reliant on someone constantly cleaning the runway to perfection. That pretty much shows how little afraid the West is of a Russian attack, BTW, because otherwise they would design their planes the same way. But using a dirt strip demands to avoid ingestion of sand and dust in the engines, and I suspect that is not solved in the Flankers or in the new MiGs, because the mesh cannot filter small particles. If I get the proof I will share it, but by now I have no evidence that such type of operation is intended for those planes.

I guess the key here is that their airfields are not in deserts in Russia so it really wont be as much of a problem most of the time.

Sure, the reason I said this is because we were talking about very low speed manoeuvring where aerodynamic surfaces have no authority, so no positive or negative overloads are involved. Otherwise rolling by aero surface deflection is normally available.

Not just low speeds... when the airflow is not moving over the control surfaces includes at very high angles of attack where a plane without TVC engines can stall or super stall...

I think we are basically on the same page here, only I don't see the need for the additional medium fighter, since there is already a top-tier plane (Su-57) that has both the legs, the weapons and the speed to cover a big area, while potentially many subordinate UCAV fulfil lesser tactical missions, so an additional fighter to cover that same supervisory role of the Su-57 would be wasteful to me.

That is funny, because I would say a light fighter is next to useless because to be light and to be cheap you end up with what is effectively a drone that carries extra missiles to support the missions of larger aircraft. Why not make it a medium sized aircraft so it has the capacity to be actually useful.

A small single engined cheap fighter might as well be a drone...

It is easier to increase the number of planes controlled by one Su-57 than to create another plane for that very mission, with a marginally smaller price that is going to be more than offset by the development costs.

Lets be realistic even a very small manned stealth fighter is not going to be actually cheap... MiG managed to make the MiG-35 smaller and cheaper with 90% of the capabilities of the bigger Flankers, but it has not won them any prizes... the only relatively cheap item would be a drone that flys with and supports fighters.... the Su-57 has the S-70, which at 20 tons should be rather expensive by your measure if the 18 ton normal TOW MiG-35 is too heavy to be considered a light fighter...

BTW and that is a good point you made: the UCAV or "light" fighter as I conceive it would be ca. 10 t empty, 16-17 t NTOW, 20-22 t MTOW. If you want it to have a minimum weapon carrying capacity and range, smaller than this seems difficult.

Would have to be lighter than that... at 24 tons MTOW and 18 tons NTOW the MiG-35 is too heavy remember...

I know "light" is normally considered well below that weight, but now that has changed, there is no 5G fighter project below this size that I know, even the follower of the Gripen was expected to grow because otherwise weapon bays for normally sized armament are not feasible.

Internal weapons is going to make the new aircraft draggier and bigger and heavier, which means an even bigger engine will be needed... more expense...

The Okhotnik is a ground attack plane. Do you see no need or place for a A2A UCAV to go with the Su-57?

It is intended to use ARMs for SEAD missions and will also carry long range AAMs too... why do you think it is only A2G?

They are not going to make a separate type for air to air...

MiG says the -35 is 2.5 times cheaper to operate than the -29, that implies a big maintenance cost for the older model, because fuel-wise you are only going to have very minor savings, if any.

Fuel really does not come in to it... Russia has plenty of oil... no problem there...

With the short operating life of older soviet engines I don't think the -29 can be cheaper to operate than a Gripen. Considering engine maintenance, two engines are twice the labour and twice the pieces to be exchanged, it is an unavoidable fact

Funny you say that... the old D-30 engines in the Il-76 burned a bit more fuel than the new PS-90A engines and had less thrust, but they were 800K each to buy and spare parts were easily available and cheap. The new PS-90A engines cost $6 million dollars each and the new parts included all sorts of expensive titanium parts that were seriously not cheap. Spend 24 million to reduce fuel costs and make the engines less noisy and make maintenance more expensive... they probably wouldn't break even on fuel costs alone for a decade and that ignores the more expensive spare parts...

Do you have the sources?

our discussion was on this thread:

https://www.russiadefence.net/t4804p750-su-35s-news

from post 753 onwards...

So i looked through myself and in post number 767 Lsos says this:

There was a swiss leaked report about the testing of Rafale, Eurofighter and Gripen to choose their new fighter. They find out Saab lied completly avout the prices and tge Gripen is just as expensive as the other two whike being single engibe and lighter.

Btw they concluded that Rafale was the best in almost any field including EW. Both Saab and Eurofighter brag about how they are the best in EW anf it proved they suck compared to Spectra.

In terms of size, the F-16 could use the F119 and have a TWR of almost 2... I see no clear advantage of the twin engine layout in that regard. You can say that two engines take proportionally less space along the plane's axis for the same engine frontal section, so you free some space for fuel or weapons. The catch is that this increased cross section is a mayor driver of drag. And drag + weight are the main enemies of a fighter.

No, you can't just stick any old engine into an aircraft... get the power and size wrong and you end up with a very short range aircraft.

Two engines increases the internal space which increases drag but modern stealth aircraft need more internal volume for internal weapons anyway.

The Su-57 would fly high in the rear in order to control a sector of the air space, while the lighter fighters / UCAV fulfill their missions

One of the roles a UCAV could perform is a zoom climb to altitude and speed to launch long range AAMs at targets deep inside enemy held airspace... any extra height and speed will boost performance of any AAM...

Garry, I will try to research some actual values, so it is not a matter of opinions, but I still answer some points in advance.

GarryB wrote:I guess the key here is that their airfields are not in deserts in Russia so it really wont be as much of a problem most of the time.

If the front wheel is operating on a dirt trip it will create lots of dust, which low air intakes will ingest. That is BTW the reason why the Flanker has mud guards on the wheels, despite de mesh screens.

Not just low speeds... when the airflow is not moving over the control surfaces includes at very high angles of attack where a plane without TVC engines can stall or super stall...

Flankers could do >90º AoA already before the TVC was implemented, and that meant extremely low airspeeds, because a plane cannot fly flat against the wind for a long time... So in the end the problem with single engine TVC is just (IMHO) a small loss of roll authority at very small airspeeds, where yaw and pitch authority + plane's inertia can still be used and ensure noise pointing and recovery. Enemies have no TVC (F-35, Eurofighter, F-16, Rafale etc), while J-10C will have TVC on its only engine and only apparently J-20 will have TVC on two engines, which are very close to each other and hence may not have much roll authority. For this plane and for F-22 it is not even clear, whether differential deflection is programmed in the FCS.

Lets be realistic even a very small manned stealth fighter is not going to be actually cheap...

It is a relative issue. It needs to be x % cheaper than a medium or heavy fighter, so that more of them can be bought and operated.

MiG managed to make the MiG-35 smaller and cheaper with 90% of the capabilities of the bigger Flankers, but it has not won them any prizes...

Exactly. The market attractive of the Flanker is a direct consequence of its size. MiG on the other hand has no special sales arguments apart from price, and I am not sure whether this price difference is based on costs or rather on benefit margins... almost half the price in the market than a Flanker at the same margin would mean a MiG-29M costs like $10-12 million to produce, which I don't find likely

the only relatively cheap item would be a drone that flys with and supports fighters....

What kind of supporting drone are you imagining, in terms of layout and capabilities? They can be very basic, no stealth, no supersonic flight, no systems but just a dummy airframe with some missiles on it, but then their life is going to be short against any enemy with some capability to monitor airspace. I imagine actually a small plane that can do dogfight and fly supersonic, so it can actually oppose enemy fighters. It may be more expensive than the others, but still a huge advantage because it can be exposed to attrition, no pilots need to be trained and little if any flight hours are needed to keep them fit. Actually this is the reason why I think in the near future there is going to be a massive shift towards unmanned platforms under command of manned ones, which try to stay far from the fray.

the Su-57 has the S-70, which at 20 tons should be rather expensive by your measure if the 18 ton normal TOW MiG-35 is too heavy to be considered a light fighter...

The Okhotnik is quite ok for A2G and reconnaissance roles: very stealthy, huge persistence, economic to operate (single engine, no A/B in the final version) and with capability to carry big weapons, which are necessary for that role.

The MiG-35 is normally considered a medium fighter, but everything needs to be compared within the proper context. Su-27 is like 16 t, F-15 13 t, F-16 8 t. MiG-29 with 11 t, 17 m long and two engines is definitely not a light fighter. F-16 would be at the upper limit of what can be considered a light fighter, but as said 5G demands a certain size growth. The way I see it, if it can be powered by one engine of the type used in heavy fighters, then it is light and contributes further to the economies of scale of the air force.

Would have to be lighter than that... at 24 tons MTOW and 18 tons NTOW the MiG-35 is too heavy remember...

That is the lower limit I think... For the MiG on the other hand the problem is not those weights you mention, but the little fuel and load it carries and how heavy it is intrinsically. A F-16A has a MTOW 2.32 times its empty weight, the Rafale 2.48 times. The MiG probably does not even reach MTOW 2 times its empty weight. In the Flanker the big empty weight is more or less justified because it does not need EFTs, but that is not the case of the MiG.

Internal weapons is going to make the new aircraft draggier and bigger and heavier, which means an even bigger engine will be needed... more expense...

Let us see whether newer weapons can be carried conformally in new designs without compromising drag and RCS too much. The KFX was moving in that direction apparently, at least for the first variant.

It is intended to use ARMs for SEAD missions and will also carry long range AAMs too... why do you think it is only A2G?

Because it cannot manoeuvrer or accelerate. It can have self defence weapons o maybe even be used as a mobile SAM, but it is not your typical A2A asset, it cannot be.

One of the roles a UCAV could perform  is a zoom climb to altitude and speed to launch long range AAMs at targets deep inside enemy held airspace... any extra height and speed will boost performance of any AAM...

Not the Okhotnik I think, TWR is going to be terrible an max speed subsonic... the fight will be over by the time it can climb

They are not going to make a separate type for air to air...

They should  

they probably wouldn't break even on fuel costs alone for a decade and that ignores the more expensive spare parts...

Yeah well, that is a shame. But you need to introduce newer technology which has not been still paid for, or we would still use horses and swords. Once the production has been established the price differences need to be reduced. But it is an interesting topic to research.

our discussion was on this thread:

https://www.russiadefence.net/t4804p750-su-35s-news

Ok thanks, I will check it out.

No, you can't just stick any old engine into an aircraft... get the power and size wrong and you end up with a very short range aircraft.

C'mon, it was just a theorical argument against twin engine fighters having per se higher TWR    

Actually a F-16C has higher TWR empty than the MiG-29

Two engines increases the internal space which increases drag but modern stealth aircraft need more internal volume for internal weapons anyway.

If you do that you loose badly in kinematics. Su-57 has a smaller cross sectional area than a Flanker.

Just a quick modification of the proposal I made turned into UCAV, so that it is clearer what I mean. 15.5 m long, ca. 10 t empty: