Pretty sure this has been posted on many times in here. But it is kind of mind boggling that a two seater heavy Su-27UB/30 could easily beat a Hawk in BFM..
The flattened exhaust nozzle installed at an angle is planned to reduce the signature of advanced versions of the Su-57. The novel flattened exhaust nozzle is planned to reduce the radar signature of advanced versions of the Su-57 Felon fighter.
In the Su-57 and the Su-35, the AL-41F-1 features a thrust-vectoring nozzle of axisymmetric type. This is also known as three-dimensional thrust vectoring and provides pitch, yaw, and roll control.
The round nozzle was 2D canted to provide yaw movement; not full 3D like the nozzle used on the mig-29 demonstrator from years ago. The new nozzle seems to work just like the circular one
Your Cl_max is completely wrong and way off for the F-15, it's not 1.1, it's actually much higher at 1.6 based on flight testing. Where did you get 1.1 from? So much for Soviets "overestimating". You should not accuse me of making things up when your own information is so wrong.
First of all, that is not my information; it is coming from people who have claimed to possess all the necessary data from the F-15C flight manual. Years ago, I didn't bother to verify it, which doesn't necessarily mean they were wrong when you place the data into real context.
Second, Soviets did overestimated F-15C performance, just look at their STR prediction of 22 deg/s, when in reality F-15C has around 20,5 deg/s at sea level.
Third, there is a difference between maximal usable Cl and Clmax, and I'll explain why.
And while Su-27 has higher Cl_max of 1.85, also has higher wing loading of 322kg/sqm at 20,000kg while F-15C at 36,000lb weight which has similar AB duration has wing loading of 59.2lb/sqft or about 289kg/sqm, which is proportionally similar to the difference in Cl_max, so the ITR (proportional to product of wing loading and Cl_max) at these weights is not substantially different for F-15C.
It doesn't work like that.
When we look at the Cl chart for the F-15 you have posted, we can see that the Clmax 1,6 is achieved at 40 deg. AoA.
Su-27 Clmax 1,85 is achieved at 24 deg. AoA.
At 24 deg. AoA F-15 has around 1,21 Cl which means that for the same AoA Su-27 has substantially higher Cl which translates to superior L/D ratio and faster turn rates.
Now, to be able to exploit the Clmax for the fastest ITR, F-15 would need to pull the highest permissible G at that AoA. That means that the F-15 would need to pull around 9G in a horizontal turn, at the bank angle between 70-80 deg. and 40 deg. AoA.
Is that condition permissible for the F-15C?
Don't take my word for it because I don't have the data at my disposal, but I think that the F-15 operational AoA limit is around 30 deg. AoA +- few degrees.
Su-27 operational AoA limit is around 25 deg. AoA, and both planes (unlike some hard limited planes like F-16) can override that limit, but when you override the 25 deg. AoA in Su-27, your ITR starts to drop in exchange for the pitch rate and nose pointing capability.
Even if we assume that the the F-15C can exploit the Clmax at 40 deg. AoA, the amount of drag the plane would generate at that AoA would be preposterously high, and the plane would still have considerably worse ITR than Su-27 with stupendously higher energy loss.
The earliest point where Su-27 can pull its highest G load (9G with 50% of normal fuel) is at around 600 km/h sea level, and that is the point where the plane is AoA (25 deg.) and G limited, and that is the point where it has the fastest ITR, slightly over 30 deg/s.
So, we can clearly see that the Flanker can exploit its Clmax to the fullest, which is not the case with the F-15, and that is the reason Clmax 1,6 is not used as the max usable Cl for the fastest ITR.
The 9g sustained turnrate chart for Su-27 is for 2xR-27, 2xR-73, and 2,600kg fuel. And at 37,000lbs or about 16,800kg the F-15C with 4xAIM-7 would actually carry a bit more fuel. For similar AB duration, F-15C with 4xAIM-7 will have just under 36,000lb weight. And keep in mind, at that weight Su-27 requires g-override while F-15 has no limitations at that weight.
Note: per the manual in the station loading section the F-15C with F100-PW-100 weighs 28,500lbs and -220 engines each weigh about 200 lbs more.
If we assume that both planes are left with 2,600 kg of fuel, the Su-27 will have more range and more fuel to burn; the same is true if we assume that the F-15C is left with 2,700 kg of fuel. The main reason for this is the Su-27's better lift-to-drag ratio and very fuel efficient engines. You cannot calculate fuel consumption in afterburner without knowing dynamic thrust numbers for every flight condition for both fighters.
If we take these weights without missiles (20 tons for the Su-27 and 16.75 tons for the F-15C) and add only the fuel for simplification, the Su-27 is left with around 3,700 kg of fuel, while the F-15C is left with about 3,851 kg of fuel.
With that fuel load, the Su-27 can cover approximately 1,414 km, whereas the F-15C can cover roughly 1,333 km. Therefore, it is absolutely fair and objective to compare these two fighters at those weights. At those weights, the Su-27 can sustain 9G at about Mach 0.86, while the F-15C can sustain 8.5G at Mach 0.93 at 10,000 ft, which translates to superior STR for the Flanker.
Anyway, if you want to argue that the F-15C can match/exceed the Su-27 ITR/STR performance, you are probably going to be the first one, because the numbers and direct real world comparison between the two planes says otherwise.
Here is the nice example of the Flankers exceptional ITR:
What I specifically said is that fuselage lift, being a very low aspect ratio surface, can cause greater induced drag when turning. Of course this depends on condition and not meant to be a broad sweeping statement claiming it's necessarily better or worse.
The F-22 is not a continuation of the F-15, any more than Su-57 is a continuation of Su-27. In fact F-22 is made by completely different company from F-15. You also make comparison using data that is flat out incorrect as shown above. If you want to talk about data, then present the correct data.
As shown above, you don't know what you are talking about, since it is more than obvious that the Su-27 blended wing-body layout is aerodynamically more efficient even if the plane in question has inferior T/W ratio and wing loading compared to the F-15C.
The Su-57 is a clear example of the blended wing-body design (just as the Su-27 is with its widely spaced engines), and the F-22 also has a similar layout to the F-15, with closely coupled engines. I have given you the Su-27 and F-15 examples since you claimed that a wide fuselage and LERX would cause greater induced drag when turning, and we can see that, in the overall picture, this was a moot point.
F-22 does have a LERX, the sharp edges between the intake lip and the wing generates vortices, which is the whole point of a LERX. The way a blunt shape like the F-15 wing root fairings do not. What's funnier, the NASA paper that you got the image from literally calls the F-22 having a LERX (the paper calls it LEX, "leading edge extension") which is what Lockheed calls it too.
They can call it whatever they want; that is not a true LERX by standard definition. Technically, it is attached to the wing root, but that is just a pronounced, sharp edge or lip of the air intake that generates vortices. They were constrained by stealth requirements on that layout, so the real, full-sized LERX could not be employed. Like I said, the F-15's sharp inlet edges, as well as the blunt root extension, also generate vortices, which can be seen in the examples I have provided. That text actually confirms that.:
"Smoke was injected into the flow ahead of the model for visualizing the vortex pattern along the leading edge of the wing and engine inlets. The trajectory of the vortices observed over the F-22 are similar to the trajectories shown in Figure 2 for the F- 15"
Here is the comparison between true LERX and F-22 "LEX".
The effective lifting surface of the F-22 "LEX" is dramatically smaller compared to the true LERX!
Here is the look from another perspective:
Just the LEVCON surface alone dwarfs the F-22 sharp inlet edge surface wise, let alone the whole LERX. The same thing is if you compare it with the Su-35S, F-16, F-18SH etc. F-22 doesn't have convectional LERX, that is more than obvious to anyone!
And yet the F-22 was specifically designed to recover without TVC or malfunctioned TVC.
I'm pretty sure Lockheed engineers know more than you about this subject too. Sukhoi describes design rationale as it applies to their own T-50/Su-57 design, but when it comes to characteristics about F-22, pretty sure Lockheed has a better idea of what it can do.
Oh, I'm pretty sure they know much more than I do, but as I mentioned, Sukhoi engineers probably made that claim based on their requirements for the Su-57. Taking into account the plane's instability margin (unlike the F-22, the Su-57 is also directionally unstable) and its significantly extended flight envelope, the F-22's aerodynamic surfaces would be inadequate.
Based on the data you have provided (thanks for that), and the data I already have, it is pretty safe to say that 60 deg. AoA is essentially critical AoA for the F-22 for relatively more complex maneuvers in horizontal plane, since at that AoA F-22 can still retain some directional controllability. For example, YF-22 can maintain full 360 deg. roll capability at 30 deg AoA, 180 deg. roll capability till 45 deg. AoA, and 30 deg. roll capability till 60 deg. AoA with relatively slow rate.
J-turn depicts that very nicely.
On the other hand Su-57 can execute full 360 deg. roll at any AoA few times faster, and can change the nose position during roll at any time:
Even with the TVC, F-22 would depart from controlled flight if tried to execute the same maneuvers Su-57 is doing.
It is also interesting to look at the Su-57 version of the J-turn:
I have already addressed that issue, and they might be suitable for the F-22 flight envelope, but not for the Su-57 extended envelope. The Su-57 can actually do more with less.
You don't understand the difference between "holes" and structural holes. A "hole" that is a closed structural. . . . . .
This situation is becoming really tiresome, and I completely understand what you are trying to say. However, what you don't understand or don't want to accept is the fact that two planes do not share the same type of airframe, load distribution, and pressure points.
I have presented information coming directly from the Sukhoi designers regarding the structural composition of the Su-27 and Su-57. In both cases, they emphasized that such designs provide necessary structural rigidity with a decrease in weight or minimal weight gain (in the case of the Su-57), while at the same time, they assert that the F-22 weapons bay layout with large S intakes increases the weight and the plane's cross-section.
If you want to argue that, you should talk to them, as I have no intention of wasting my time on this. You have stated that the Su-57 requires more strengthening than the F-22. However, the F-22, having similar dimensions to the F-15, has an empty weight equivalent to that of the F-15A and F-16A combined! Conversely, the Su-57 is a larger plane than the F-22 but weighs less?! That doesn't align with your claims, but it corresponds very well with the Sukhoi claims.
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