Sukhoi T-50 PAK FA manouverability versus F-22

[EricChase88]

I asked a few questions over at f-16.net, and some of the posters brought up that the T-50 may have a higher bleed rate than the F-22 in tight turns because apparently, greater wing sweep typically means more AOA needed for a given amount of lift and thus more drag.

Also, T-50 has advanced features like LEVCONs and leading edge root extensions to improve lift, while the F-22 has nothing of the sort. I don't see how F-22 can match the T-50 in maneuvering performance.

 

[Kryptid]

The LEVCONS will probably reduce drag during maneuvering, helping the bleed rate issue.

The F-22 has LERX of a sort, but they are rather small. Nonetheless, they should still generate vortices that aid in preventing stall (it can operate up to 60 degrees alpha without using TVC). I believe each type (the T-50 and F-22) will have their own respective advantages in agility, as maneuverability is not a single "thing". For example, WWII fighters had much tighter turn radii than their modern descendants, but could never match the rate of climb possessed by current fighters.

 

[quellish]

So I'd say it is a hack that doesn't substitute for true 3D thrust vectoring.

Maybe, but their FCS and threat management system may be able to take advantage of the nozzles to limit control surface deflection when presented with certain threats. Other aircraft do similar things.

 

[chuck4]

Wouldn't the triangular missile bay under the so called "leading edge extension" on the T-50 act as a sort of tip winglet and inhibit to some degree the formation of tip vortices ? So instead of being true Leading edge extensions optimized to give strong vortices, they would only secondarily generate vortices, sort of like the hard chine on F-22?

Also, I am not entirely sure exactly what LEVCON could do. Has anyone see them deflect upwards? I've only seen them deflect downwards. If they only deflect downwards, then they look to me like an extension of the leading edge flaps on the main wing. If this is true, then when the LEVCON deflect downwards, they permit higher angle of attack without airflow separation over the parts of fuselage above the air intakes. This permit the plane to achieve higher AOA without entering the post stall regime.

 

[chuck4]

Another observation:

Front view of F-22 shows the wings have a noticeable twist, with outer part of the wing having a lower AOA than wing root when the plane pitches up.

Front view of T-50 suggest the wing has very little twist, if any at all.

This suggest that at high angle of attack, the inner portion F-22's wings would stall first, with wing tip remaining unstalled because of lower AOA. This would shift the center of lift backwards, and thus tend to pitch the plane downwards and prevent departure into unintended stall.

The T-50's wings might not do this. Instead the whole wing has essentially the same AOA and would nearly stall together. So if parts of the wing stalls, the whole wing would stall, and the plane would depart into stalled regime, unless there is control input to recover.

I wonder if the different approach to handling near stall flight might also account for the LEVCONs.

Just a observation.

 

[lantinian]

I don't see how F-22 can match the T-50 in maneuvering performance.

I cannot disagree more.


Just look at a video of the T-50 maneuvering and tell me it does not remind you of an F-14 in terms of movement. The F-22 on the other hand moves very much with F-16 nimbleness.


The reason for that is simple: inertia. The T-50 configuration places a lot more weight away from the center of the aircraft gravity and center axis, creating a of of inertia both in pitch and especially in roll with those engines that far apart. The F-22 is very compact in that regard.


Compare the general configuration of the T-50 to the F-2 and you will see a lot more weight past the trailing edge of the wing. The F-22 is basically a tailless design with only the elevators mounted on two booms.


The majority of the T-50 fuel seams to be behind the cockpit too, whereas the F-22 has its in the wing and near the center of gravity. This leads me to believe that the placement and movement of the T-50 LERX maybe because the center of gravity moves so much backwards in flight, not to achieve some spectacular turning performance.


It will be wrong to assume that just because the T-50 has larger and more control surfaces that it will have a better maneuvering performance. The distribution of mass implies the oposite in terms of instantaneous turn rate and agility.


Given similar weights to the F-22 and lower performance engines (on the prototype) I don't expect it to have a better sustained turn rate right now either.

 

[lantinian]

Another observation:

Front view of F-22 shows the wings have a noticeable twist, with outer part of the wing having a lower AOA than wing root when the plane pitches up.

Front view of T-50 suggest the wing has very little twist, if any at all.

This suggest that at high angle of attack, the inner portion F-22's wings would stall first, with wing tip remaining unstalled because of lower AOA.

I am sorry but your logic is based on the assumption that stall happens uniformally across a diamond wing which is not the case at all.



The reason for the F-22 wing twist (a feature also found in the F-15) is to keep the airflow attached at the trailing edge of the wing tip so the ailerons can keep working up until 70 deg AoA. Separation of the airflow in the aileron section is a known disadvantage of the diamond wing.


So this

The T-50's wings might not do this. Instead the whole wing has essentially the same AOA and would nearly stall together. [/size]

is a completely incorrect assumption.

 

[lantinian]

Wouldn't the triangular missile bay under the so called "leading edge extension" on the T-50 act as a sort of tip winglet and inhibit to some degree the formation of tip vortices ? So instead of being true Leading edge extensions optimized to give strong vortices, they would only secondarily generate vortices, sort of like the hard chine on F-22?

There is some crude logic here (especially when you know that F-16 with AMRAAM on he wingtips has more range that with a Sidewinder), but I seriously doubt that:
1: T-50 designers placed the missiles bays intentionally there to limit the vortices created by the moving LERX
2: The side missile bays are any efficient as winglets.
3. There is a benefit of the effect you describe in the first place.

Also, I am not entirely sure exactly what LEVCON could do. Has anyone see them deflect upwards? I've only seen them deflect downwards. If they only deflect downwards, then they look to me like an extension of the leading edge flaps on the main wing. If this is true, then when the LEVCON deflect downwards, they permit higher angle of attack without airflow separation over the parts of fuselage above the air intakes. This permit the plane to achieve higher AOA without entering the post stall regime.

Or maybe this plane has so much fuselage area that produces lift that losing the lift early there (before the wing stalls) will have a huge impact on the total lift, so controlling it becomes a concequence of the design.

 

[Sundog]

The reason for the F-22 wing twist (a feature also found in the F-15) is to keep the airflow attached at the trailing edge of the wing tip so the ailerons can keep working up until 70 deg AoA. Separation of the airflow in the aileron section is a known disadvantage of the diamond wing.

While wing twist does have that effect, what you see in the wing of the F-22 isn't really twist. It's a conical wing shape, similar to the F-106's, to minimize wave drag at supersonic speeds. The F-15 has it to a limited degree as well, but more so in the F-22 since it's more optimized for super-cruising.

 

[Sundog]

Wouldn't the triangular missile bay under the so called "leading edge extension" on the T-50 act as a sort of tip winglet and inhibit to some degree the formation of tip vortices ? So instead of being true Leading edge extensions optimized to give strong vortices, they would only secondarily generate vortices, sort of like the hard chine on F-22?

Also, I am not entirely sure exactly what LEVCON could do. Has anyone see them deflect upwards? I've only seen them deflect downwards. If they only deflect downwards, then they look to me like an extension of the leading edge flaps on the main wing. If this is true, then when the LEVCON deflect downwards, they permit higher angle of attack without airflow separation over the parts of fuselage above the air intakes. This permit the plane to achieve higher AOA without entering the post stall regime.

Watch video of the T-50 rolling. You will see one of the Levcons deflected up and the other down.

 

[EricChase88]

I don't see how F-22 can match the T-50 in maneuvering performance.

I cannot disagree more.


Just look at a video of the T-50 maneuvering and tell me it does not remind you of an F-14 in terms of movement. The F-22 on the other hand moves very much with F-16 nimbleness.


The reason for that is simple: inertia. The T-50 configuration places a lot more weight away from the center of the aircraft gravity and center axis, creating a of of inertia both in pitch and especially in roll with those engines that far apart. The F-22 is very compact in that regard.


Compare the general configuration of the T-50 to the F-2 and you will see a lot more weight past the trailing edge of the wing. The F-22 is basically a tailless design with only the elevators mounted on two booms.


The majority of the T-50 fuel seams to be behind the cockpit too, whereas the F-22 has its in the wing and near the center of gravity. This leads me to believe that the placement and movement of the T-50 LERX maybe because the center of gravity moves so much backwards in flight, not to achieve some spectacular turning performance.


It will be wrong to assume that just because the T-50 has larger and more control surfaces that it will have a better maneuvering performance. The distribution of mass implies the oposite in terms of instantaneous turn rate and agility.


Given similar weights to the F-22 and lower performance engines (on the prototype) I don't expect it to have a better sustained turn rate right now either.

I don't think the T-50 would have more inertia than the F-22. In any case, the T-50's differential thrust vectoring should compensate for the bigger roll inertia. As for the length axis, the mass seem to be pretty concentrated just like the F-22, so I don't know why you would think that the F-22 might have better pitch performance. Also, sustained turn has more to do with lift, and in that regard, the T-50 has a huge lifting surface, particularly in the fuselage. It's far lift more than F-22, so better sustained turning.

The T-50's bigger sweep may require more AOA for lift, but if that's really the case, shouldn't the LEVCONs more than compensate for that?

And true, the current T-50 engines are not as powerful compared to the F-119. Perhaps the second stage engine will allow it to outperform the F-22.

 

[overscan (PaulMM)]

Sustained turn is thrust limited. High lift means high instantaneous turn, but high sustained turn rates need high thrust to overcome the high drag of high lift.

 

[EricChase88]

Sustained turn is thrust limited. High lift means high instantaneous turn, but high sustained turn rates need high thrust to overcome the high drag of high lift.

Okay, but shouldn't the T-50's aerodynamic features like LEVCONs, tandem missile bays and smaller vertical tails give it lower drag than the F-22 when turning? That when combined to the T-50's superior lift compared to the F-22 would make the T-50 a better sustained turner as well.

Also, lantinian compared the T-50 to the F-14 in the movement of its control surfaces while comparing the F-22 to the F-16. So what point are you making with that comparison?

 

[kcran567]

I don't see how F-22 can match the T-50 in maneuvering performance.

I cannot disagree more.


Just look at a video of the T-50 maneuvering and tell me it does not remind you of an F-14 in terms of movement. The F-22 on the other hand moves very much with F-16 nimbleness.


The reason for that is simple: inertia. The T-50 configuration places a lot more weight away from the center of the aircraft gravity and center axis, creating a of of inertia both in pitch and especially in roll with those engines that far apart. The F-22 is very compact in that regard.


Compare the general configuration of the T-50 to the F-2 and you will see a lot more weight past the trailing edge of the wing. The F-22 is basically a tailless design with only the elevators mounted on two booms.


The majority of the T-50 fuel seams to be behind the cockpit too, whereas the F-22 has its in the wing and near the center of gravity. This leads me to believe that the placement and movement of the T-50 LERX maybe because the center of gravity moves so much backwards in flight, not to achieve some spectacular turning performance.


It will be wrong to assume that just because the T-50 has larger and more control surfaces that it will have a better maneuvering performance. The distribution of mass implies the oposite in terms of instantaneous turn rate and agility.


Given similar weights to the F-22 and lower performance engines (on the prototype) I don't expect it to have a better sustained turn rate right now either.

I don't think the T-50 would have more inertia than the F-22. In any case, the T-50's differential thrust vectoring should compensate for the bigger roll inertia. As for the length axis, the mass seem to be pretty concentrated just like the F-22, so I don't know why you would think that the F-22 might have better pitch performance. Also, sustained turn has more to do with lift, and in that regard, the T-50 has a huge lifting surface, particularly in the fuselage. It's far lift more than F-22, so better sustained turning.

The T-50's bigger sweep may require more AOA for lift, but if that's really the case, shouldn't the LEVCONs more than compensate for that?

And true, the current T-50 engines are not as powerful compared to the F-119. Perhaps the second stage engine will allow it to outperform the F-22.

I agree with latinian in defense of the f-22. The f-22 is an older design, yes, but those designers really knew what they were doing. The T-50 has a huge lifting surface as you said. The F-22 can generate a lot of lift too, but the f-22 is a more compact design and the trade off being that the Sukhoi is going to need the levcons etc to help control all the lift generated, and there are design trade offs to generating a huge amount of lift-the T-50 is going to have to trade and lose in other areas, cant have it all.
One of the surprises of the f-16 program for example, was that the unstable design allowed tail lift to augment the lift of the main wing. As a result, the main wing was able to be made smaller and lighter and the tail worked with the wing to provide lift. This also greatly lowered drag and increased range while allowing very high levels of agility without a huge wing.
As latinian mentioned, the outboard masses of the T-50 present a design challenge/trade off as well. As far as wing twist, the t-50 has it too. Many modern fighters have wing twist the f-16, f-15, the f-35 and f-22 very noticeable, the j-20, can even be seen on the F-5 family.

 

[TaiidanTomcat]

Also, T-50 has advanced features like LEVCONs and leading edge root extensions to improve lift, while the F-22 has nothing of the sort. I don't see how F-22 can match the T-50 in maneuvering performance.

A pessimist could say it needs those features just to catch up to the F-22. the pak fa could be heavier as well, for example

Remember there is more to performance than just that and It was pointed out earlier in the thread that the Pak Fa needs new engines that are being designed as we speak, so the Pak fa we see now is not going to be near its potential.

Simply put its way too early to tell in my opinion, and the F-22 is the king of the mountain until its knocked off. A pak fa is not going to do that in its current state. The F-22 is the ideal, and although its not in the numbers hoped its still 180 in service vs Pak Fa prototypes. This is the equivalent of telling a pro athlete that a new born baby will outperform him someday. the most obvious statement would be "give it 15 years, then we'll see" I want to see where the Pak Fa is in 10-15 years.

 

[flanker]

A pessimist could say it needs those features just to catch up to the F-22.

Have you ever seen Su-35S? That manages just fine to eh, "catch up to the F-22" without "cheating" like canards.

 

[lantinian]

While wing twist does have that effect, what you see in the wing of the F-22 isn't really twist. It's a conical wing shape, similar to the F-106's, to minimize wave drag at supersonic speeds. The F-15 has it to a limited degree as well, but more so in the F-22 since it's more optimized for super-cruising.

Thanks Sundog. I was not familiar with that, although I am quite positive as to the stall characteristics of a diamond and that maintaining some roll control up to the maximum operational AOA via the ailerons was a design requirement in the F-22 design.

Also, lantinian compared the T-50 to the F-14 in the movement of its control surfaces while comparing the F-22 to the F-16. So what point are you making with that comparison?

I don't think the T-50 would have more inertia than the F-22.

Well, it does. Same overal mass spread to a larger volume in plan view.

That's why when you watch its demo flights, its like watching a F-14 from those TopGun videos.

Actually if you look at a picture of the T-50 overal engine & weapons configuration it does look a lot like an F-14 one, which is probably why there two aircraft look to maneuver so similarly.

This configurations of spacing the engines appart does have payload caring advantages but in also does produce aircraft which do not roll or turn as quickly as closely coupled engine configurations.

Watch video of the T-50 rolling. You will see one of the Levcons deflected up and the other down.

That probably proves my earlier point for the bad roll performance of a diamond/delta wings at high AoA. You really need another aerodynamic surface to help with the roll.

In any case, the T-50's differential thrust vectoring should compensate for the bigger roll inertia.

True. The real advantage of TVC is in changing direction in cruise without loosing lift and in very low speeds and high AoA where aerodynamic controls loose authority. The rate of deflection of the F-22 tails/ailerons is 60 & 70 deg per second. The rate of defection of its 2D nozzles is 20 deg per second. So in most flight regimes, aerodynamic controls still offer superior performance.

The bottom line is that while the T-50 does look to be able to make tight turns thanks to its advanced aerodynamic layout, but it does not yet look to be able to change its direction of flight very quickly thanks to its long range/high payload/two engine configuration.

It's a highly maneuverable but not a very agile plane.

 

[Sundog]

It should be noted, that widely spaced engines in and of themselves do not mean a lower sustained roll rate or initial roll rate. It just means you will need more control power to match the roll rate of an aircraft that has most of it's mass closer to the c.m. It seems to me that the T-50 is not lacking in control power, especially given the fact that it's vectored thrust will be more powerful in roll given the spacing of the engines.

We also can't know from videos which would be better unless we're assuming the videos we've seen are of the aircraft performing at their maximum level of performance. I don't think we can make that assumption.

Now if you want to post how each aircraft's FCS architecture operates, the actual flight control laws and response derivatives, then we can start talking about which is "better" in terms of basic flight performance parameters. But if you really want to tell me which is better, get me the actual specifications written for both aircraft, the mission parameters, and how well they meet them.

At this point, I'm of the opinion that the F-22 mostly meets the USAF requirements, we know it fell short of the supercruise requirements, and I'm not talking about missing mission equipment. What I've seen of the T-50 so far seems like it will meet Russia's requirements, on a basic competency level, but I'll have to wait and see how their engine tech turns out. I don't mean in terms of power, they've never had problems in that regard, but more in terms of engine life and reliability.

 

[sferrin]

At this point, I'm of the opinion that the F-22 mostly meets the USAF requirements, we know it fell short of the supercruise requirements,

In what way? Range?

 

[TaiidanTomcat]

A pessimist could say it needs those features just to catch up to the F-22.

Have you ever seen Su-35S? That manages just fine to eh, "catch up to the F-22" without "cheating" like canards.

Of course it does Thats why they are working on the Pak Fa because the 35S is that good.

 

[flanker]

Superb counterargument right there.

 

[TaiidanTomcat]

Superb counterargument right there.

Come on Berkut

 

[kcran567]

While wing twist does have that effect, what you see in the wing of the F-22 isn't really twist. It's a conical wing shape, similar to the F-106's, to minimize wave drag at supersonic speeds. The F-15 has it to a limited degree as well, but more so in the F-22 since it's more optimized for super-cruising.

Thanks Sundog. I was not familiar with that, although I am quite positive as to the stall characteristics of a diamond and that maintaining some roll control up to the maximum operational AOA via the ailerons was a design requirement in the F-22 design.

Also, lantinian compared the T-50 to the F-14 in the movement of its control surfaces while comparing the F-22 to the F-16. So what point are you making with that comparison?

I don't think the T-50 would have more inertia than the F-22.

Well, it does. Same overal mass spread to a larger volume in plan view.

That's why when you watch its demo flights, its like watching a F-14 from those TopGun videos.

Actually if you look at a picture of the T-50 overal engine & weapons configuration it does look a lot like an F-14 one, which is probably why there two aircraft look to maneuver so similarly.

This configurations of spacing the engines appart does have payload caring advantages but in also does produce aircraft which do not roll or turn as quickly as closely coupled engine configurations.

Watch video of the T-50 rolling. You will see one of the Levcons deflected up and the other down.

That probably proves my earlier point for the bad roll performance of a diamond/delta wings at high AoA. You really need another aerodynamic surface to help with the roll.

In any case, the T-50's differential thrust vectoring should compensate for the bigger roll inertia.

True. The real advantage of TVC is in changing direction in cruise without loosing lift and in very low speeds and high AoA where aerodynamic controls loose authority. The rate of deflection of the F-22 tails/ailerons is 60 & 70 deg per second. The rate of defection of its 2D nozzles is 20 deg per second. So in most flight regimes, aerodynamic controls still offer superior performance.

The bottom line is that while the T-50 does look to be able to make tight turns thanks to its advanced aerodynamic layout, but it does not yet look to be able to change its direction of flight very quickly thanks to its long range/high payload/two engine configuration.

It's a highly maneuverable but not a very agile plane.

Take that picture of the bottom plan view of the F-14, wings swept, add levcons, move the horizontal tails back slightly on booms, the vertical tails further apart...looks a lot like the T-50 aerodynamic/missile carrying layout from below. Just an observation.

 

[Kryptid]

It's a highly maneuverable but not a very agile plane

Care to explain the difference?

 

[lantinian]

It's a highly maneuverable but not a very agile plane

Care to explain the difference?

Yes, high maneuverability is how much you can turn.
High agility is how quickly you can change the turn.
B)

See the attached diagram of the F-22 flight controls.
You can say the amount of flight control surface deflection determines the aircraft maneuverability and the rate by which they turn the aircraft's agility.

 

[EricChase88]

lantinian, are you sure the scale on that overlay is correct? The T-50 isn't that much bigger than the F-22. It's 19.8 meters against F-22's 18.9. I believe the T-50 has less inertia than you think. Also, I don't see why you would think the T-50's control surface will move any slower than the F-22's, so I don't believe the T-50 would be any less agile. Given the advanced aerodynamic layout and features (more than what's seen on F-22) the T-50 should also outturn and outmaneuver the F-22.

 

[Kryptid]

Yes, high maneuverability is how much you can turn.
High agility is how quickly you can change the turn.

Are those "official" definitions? I've never heard of such a distinction before.

All of these comparisons with the Tomcat really don't make much sense to me. I would argue that the Flanker types are closer to the F-14 in design than the T-50 is, and I never see their maneuverability called into question. One must be very careful when using videos of flight as evidence for an aircraft's performance: (1) it isn't apparent how fully the aircraft is pushing the limits of what it can do, (2) human eyes are not precise instruments of measurement, and (3) videos taken from the ground obviously don't demonstrate how an aircraft flies and maneuvers at high speeds and high altitudes.

The T-50 will, without a doubt, far exceed an F-14 in maneuverability. It has more powerful engines in an airframe of similar weight, relaxed static stability, thrust vectoring and a modern flight control system. As current measurements place it smaller than Flankers, it will probably exceed them as well. Unless one runs good computer simulations to compare with the F-22 with the T-50, we can probably not say categorically whether one or the other is superior in all ways. The main issue limiting the T-50, in my mind, is the thrust. The F-22 probably has an kinematic advantage currently with its F119s.

 

[lantinian]

lantinian, are you sure the scale on that overlay is correct? The T-50 isn't that much bigger than the F-22. It's 19.8 meters against F-22's 18.9. I believe the T-50 has less inertia than you think. Also, I don't see why you would think the T-50's control surface will move any slower than the F-22's, so I don't believe the T-50 would be any less agile. Given the advanced aerodynamic layout and features (more than what's seen on F-22) the T-50 should also outturn and outmaneuver the F-22.

Well, you need to spend more time analyzing the two aircraft weight distribution around its longitudinal and pitch axis. Belief won't help you reach the correct conclusion.

I never said the T-50 control surfaces more any slower that the F-22 ones . What I said implied that they have to move a lot faster to compensate for the difference in weight distribution to achieve F-22 like agility.

The T-50 videos to date do not show that. They show a maneuverable but somewhat sluggish aircraft. I watched quite a few today looking for signs of agility but could not find it. I actually found clips showing F-16, F-18, F-14, Eurofighter and SU-35 all making the minimum radius turn faster than the PAKFA.

 

[EricChase88]

On a side note from all the maneuverability/agility talk, the way the weapon bays are arranged on the T-50 offers lower drag than on the F-22. The main bays are in tandem and so they show less front area, and they are also in line with the front fuselage which further minimizes drag. The small missile bays under the ways are also much more efficient in using volume than the F-22. The result is that the T-50 is not as bulky and chubby as the F-22. Also, the T-50's layout of having three main volumes (forward fuselage, engines) like the YF-23 instead of one big volume like the F-22 indicates that the T-50 likely has better area ruling as well. The T-50 should thus have lower drag than the F-22 and the second stage engine will allow the T-50 to be the superior supercruiser.

 

[EricChase88]

lantinian, are you sure the scale on that overlay is correct? The T-50 isn't that much bigger than the F-22. It's 19.8 meters against F-22's 18.9. I believe the T-50 has less inertia than you think. Also, I don't see why you would think the T-50's control surface will move any slower than the F-22's, so I don't believe the T-50 would be any less agile. Given the advanced aerodynamic layout and features (more than what's seen on F-22) the T-50 should also outturn and outmaneuver the F-22.

Well, you need to spend more time analyzing the two aircraft weight distribution around its longitudinal and pitch axis. Belief won't help you reach the correct conclusion.

I never said the T-50 control surfaces more any slower that the F-22 ones . What I said implied that they have to move a lot faster to compensate for the difference in weight distribution to achieve F-22 like agility.

The T-50 videos to date do not show that. They show a maneuverable but somewhat sluggish aircraft. I watched quite a few today looking for signs of agility but could not find it. I actually found clips showing F-16, F-18, F-14, Eurofighter and SU-35 all making the minimum radius turn faster than the PAKFA.

Well, the T-50's flight control systems are clearly not matured, so the flight control surfaces may move much faster when they are done with testing the flight envelope.

While it's agility is unknown, the T-50 is likely more maneuverable than the F-22 (and certainly so when the T-50 gets the second stage engine), because of the T-50's advanced aerodynamic layout and features like less drag, comparable thrust with second stage engines, LEVCONs, greater lift. When it comes to instantaneous and sustained turning performance (not responsiveness), I think the T-50 has a clear advantage over the F-22.

 

[lantinian]

On a side note from all the maneuverability/agility talk, the way the weapon bays are arranged on the T-50 offers lower drag than on the F-22. The main bays are in tandem and so they show less front area, and they are also in line with the front fuselage which further minimizes drag. The small missile bays under the ways are also much more efficient in using volume than the F-22. The result is that the T-50 is not as bulky and chubby as the F-22. Also, the T-50's layout of having three main volumes (forward fuselage, engines) like the YF-23 instead of one big volume like the F-22 indicates that the T-50 likely has better area ruling as well. The T-50 should thus have lower drag than the F-22.

I agree here completely. The T-50 is aerodynamically superior. That's one of the disadvantages of the F-22 design approach, which if why I favor the YF-23 a lot more. T-50 can however only effectively exploit this advantage supersonically. Right now, it is probably lost due to the F-22 more powerful engine.

I don't think that optimizing the F-22 so much for a dog fight was the correct choice especially given how its used operationally at Red Flag, and the lack of helmet mounted targeting system. for the AIM-9X.

The T-50 PAK FA is optimized for range, speed and efficient carriage of payload as well as high AoA maneuvers, but its not agile.

 

[EricChase88]

Turning performance has more to do with lift and drag, so the T-50 should have an advantage here once it gets the second stage engine. Compared to the F-22, the T-50's greater lift, particularly in its large flat fuselage, would give it superior instantaneous turn and lower drag will also give it superior sustained turn. T-50 might be less agile than F-22, but the T-50 is better at turning.

 

[kcran567]

Well, you need to spend more time analyzing the two aircraft weight distribution around its longitudinal and pitch axis. Belief won't help you reach the correct conclusion.

I never said the T-50 control surfaces more any slower that the F-22 ones . What I said implied that they have to move a lot faster to compensate for the difference in weight distribution to achieve F-22 like agility.

The T-50 videos to date do not show that. They show a maneuverable but somewhat sluggish aircraft. I watched quite a few today looking for signs of agility but could not find it. I actually found clips showing F-16, F-18, F-14, Eurofighter and SU-35 all making the minimum radius turn faster than the PAKFA.

Lantinian, I agree. The clips I've seen of the Pakfa seem to show a fairly maneuverable aircraft that can turn well but is restricted in some ways and executes directional changes fairly sluggishly as you suggested. I'm keeping in mind the availability of newer engines but the sluggishness in directional changes looks more from layout and weight distribution of the aircraft. The f-22 looks much sharper, crisper in rapid transition directional changes, and also looks much more high energy at low level altitudes, observing the energy of the vortexes, etc.

 

[chuck4]

I think the contention that T-50's tendom weapon bay offers a superior solution, presumably due to smaller frontal area, is overly simplistic. F-22's wide main weapon bay and larger side bays are nestled inside the curves of the plane's serpentine ducts. In effects, they added no additional frontal area to the f-22 beyond what is otherwise required to achieve its stealth specification.

 

[chuck4]

There has been a lot of praise from T-50 fans about the lifting nature of the tunnel between engine pods. I would like to see some actual data on the lifting characteristics of this layout, as compared to lifting characteristics of more conventional twin engine fighter fuselage, such as those on the F-15 or F-22.

An Israeli F-15 flew home and land safely after losing almost the entire right wing to a mid-air collision. This means the F-15 fuselage and intake can generate enough lift to compensate for both the lift from the lost wing, and also to compensate for the asymmetric nature of the lift from the remaining wing. To do this, it seems to me the magnitude of the fuselage lift would have to considerably surpass the lift of the lost wing to overcome fuselage lift's much shorter moment arm, and prevent the plane from departing into a uncontrolled spin due to asymmetric lift from remaining wing.


This shows at least the F-15 fuselage can generate prodigious lift, equal to a substantial fraction of the total lift, greater than the lift from at least one of the two wings, without the tunnel between engine pods. Wouldn't F-22 fuselage have the same capability?

 

[totoro]

That idea goes down to theory of lift and in what ways is lift created, what are major components of lift, etc. Some people will surely disagree but this is my stance of the two layouts:


f22/f15/mig31 fuselage layout is good for lift at supersonic speeds and drag at supersonic speed. f14/mig29/su27/pakfa layout is good for lift at subsonic speeds.

 

[kcran567]

That idea goes down to theory of lift and in what ways is lift created, what are major components of lift, etc. Some people will surely disagree but this is my stance of the two layouts:


f22/f15/mig31 fuselage layout is good for lift at supersonic speeds and drag at supersonic speed. f14/mig29/su27/pakfa layout is good for lift at subsonic speeds.

Yeah, but the Israeli F-15 flew many miles then landed at subsonic speeds without a right wing. That's a lot of subsonic body lift don't you think? ???

I wonder if an SU-35 or 27 could fly and then land with only one wing? This was a testament to the lift generated by the f=15's flat body and internal tunnels as well as its flight control redundancy and engine power.

I sense that the "Pakfa tunnel is better as a lifting body then f-22 shape" argument is getting weaker, and I for one am tired of hearing that be repeated endlessly here.

 

[bobbymike]

That idea goes down to theory of lift and in what ways is lift created, what are major components of lift, etc. Some people will surely disagree but this is my stance of the two layouts:


f22/f15/mig31 fuselage layout is good for lift at supersonic speeds and drag at supersonic speed. f14/mig29/su27/pakfa layout is good for lift at subsonic speeds.

Yeah, but the Israeli F-15 flew many miles then landed at subsonic speeds without a right wing. That's a lot of subsonic body lift don't you think? ???

I wonder if an SU-35 or 27 could fly and then land with only one wing? This was a testament to the lift generated by the f=15's flat body and internal tunnels as well as its flight control redundancy and engine power.

I sense that the "Pakfa tunnel is better as a lifting body then f-22 shape" argument is getting weaker, and I for one am tired of hearing that be repeated endlessly here.

What I don't understand is when someone posts about a early development aircraft vs an in service 5th Gen fighter something like "Well the Pak-fa has such and such a feature therefore it is OBVIOUSLY better than an F-22"

Most of the knowledgable members here offer great informed speculation while others seem to want to troll for a argument. Just my humble opinion.

 

[EricChase88]

chuck4, okay, I see that weapons on F-22 are tucked behind the intakes. Still, the fact that the T-50 splits the fuselage into 3 volumes unlike F-22 which has one large volume indicates better area ruling and thus lower drag. Naturally, this should allow the T-50 to outperform the F-22 aerodynamically (supercruise, sustained turning) when the T-50 gets the second stage engine.

As for lift, what is certainly clear is that the T-50 have a much bigger lifting surface than F-22. Also, the F-14 which has widely spaced engine and tunnel like the T-50 can fly with one wing fully swept and one wing fully extended and even land on a carrier like that, so its fuselage must also produce a lot of lift like F-15.

 

[Trident]

Does it really bear mentioning that the T-50 almost certainly used nowhere near its full potential during the displays flown so far? Its first public display was some 18 months after it first flew for crying out loud! How far do you think the envelope was cleared by then, bearing in mind that for 12 of those 18 months there was only one airframe available and even that one was grounded for some time during the 2010 wild fires. I seem to recall displays up to now did not exceed 5g, representing less than 60% of the aircraft's full turning potential.
And if it comes to that, what if one were to judge the F-35 on its only air show performance so far, fully 5 years after its first flight - a flyby at what, 1g? Compared to THAT, the T-50 is doing shockingly well.
Come on, you cannot be serious.