Forum: F-35 versus XYZ

Been wondering because these 2 planes look like a good fight, the F-35's engine can actually do supercruise, but the plane wasn't built to "handle" it but the Eurofighter can do a sustained supercruise just over mach 1. Both aircraft do not have TV and the F-35 A varient is said that it can perform 9.9 g manuvers. While I am not sure what the Eurofighter can perform up to. Also it is all obvious to us that the F-35 is a 5th generation stealth fighter and carries it's weapons internally. While the Eurofighter is 4.5 gen and carries weapons externally. Finally, the F-35 A varient is piloted by Airforce while the Eurofighter is piloted by the RAF

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Most of the stuff in the original post is largely irrelevant to determining the quality of aircraft in the 21st century.

TV's only real use is for supersonic maneuvers. F-22 has it, Typhoon uses other means to get good supersonic maneverability.

Supercruise appears to be more of a 6th gen thing. The F-22 is the only real supercruiser and even then it shortens the range a lot.

9.9G maneuvers kill energy.

Who sees whom and with whose sensors? Who has the best sensors and who has the best sig management? Who can share data better?

There's nothing like the F-35. It's looking more and more like a paradigm shift like when naval warfare went from BBs to CVs or A2A went from WVR to BVR.

Im only pasting what i heard, i just waned the truth so i came to f-16 net

raptorpilotwannabe wrote:

Im only pasting what i heard, i just waned the truth so i came to f-16 net

Good place to go. Def Talk bans vs threads but you could try WAB. Strategy Page is dead.

Edit: Added this:

http://www.sldinfo.com/shaping-an-econo ... the-f-35b/

Watch that video and imagine someone started a thread F-18 vs F-35.

shingen wrote:

TV's only real use is for supersonic maneuvers. F-22 has it, Typhoon uses other means to get good supersonic maneverability.

No, it is the other way around, TV is near to useless for supersonic maneuvers.

pseudonymous wrote:

shingen wrote:

TV's only real use is for supersonic maneuvers. F-22 has it, Typhoon uses other means to get good supersonic maneverability.

No, it is the other way around, TV is near to useless for supersonic maneuvers.

Apparently, the effectiveness of aerodynamic control surfaces goes down as a plane goes supersonic, particularly at high altitude. The F-22 uses TV to make up for this (the YF-23 just used really huge control surfaces).
As I am not a aerospace physicist, I don't fully understand the whys.

Supersonic effectiveness of some control surfaces, primarily rudders and ailerons, is reduced. These are both trailing edge surfaces, and when they are deflected the airfoil on which they are mounted will twist in the opposite direction. For example, an upward deflected aileron will cause the wing to twist leading edge up, resulting in an upward acting force on the wing. That reduces the effectiveness of the downward acting force on the aileron.

This reduced effectiveness is more pronounced at supersonic speeds. Thus roll power through the ailerons and yaw power through the rudder are often reduced at such speeds. However, horizontal tails are affected very little because they are all-moving, so pitch control power is easily maintained.

TV is used at supersonic conditions, but primarily for pitch trim. As speeds pass transonic, the center of lift for the wing and fuselage moves aft significantly, so some means must be provided to keep the airplane balanced in pitch. Without TV, horizontal tails, primarily, and sometimes flaperons are deflected trailing edge up to generate a down force aft of the CG to provide the necessary balance. But since lift must be maintained, that down force must be overcome with more lift, requiring more AoA and more drag. Plus the deflected tail or flaperon also causes added drag.

If TV is available, pitch balance can be maintained by deflecting the thrust angle, with little added drag and only a very small loss in effective thrust.

To summarize, TV is used at low speed for maneuvering and at high speed for pitch balance and trim drag reduction. If 3D TV is available, Yaw thrust may be used to assist in yaw control and if differential TV is available, it can help with roll control.

Interesting. The F-22 has large leading edge flaps -- are they used for pitch trim?

@johnwill,

Thank you so much for explaining why control surfaces "lose effectiveness" at supersonic speeds. I guess it does add a lot more weight to the importance of research being conducted on Active Aeroelastic wing technologies after all.

If TV takes over form the horizontal stab for pitch can the horizontal stab be better used for roll control compared to if there were no TV?

That's what I meant about TV helping supersonic maneuvers. If I'm wrong I stand corrected.

count_to_10 wrote:

Interesting. The F-22 has large leading edge flaps -- are they used for pitch trim?

I don't know about the F-22, but the F-16 does use LEF for pitch trim. I mentioned the flaperons may be raised for pitch trim on some airplanes - F-16 to be precise, possibly others, as the F/A-18 has a scheduled TEF also. I should have mentioned the F-16 uses LEF the same way. On that airplane, between 0.95 and 1.05 mach, both surfaces are moved up two degrees. An up load is generated on the LEF and a down load on the flaperon. The resulting nose up pitch moment helps to balance the airplane and greatly reduce the down load on the horizontal tail required to completely balance the airplane.

The LEF is less effective than the flaperon since it is swept and is much closer to the CG, so has less moment arm.

shingen wrote:

If TV takes over form the horizontal stab for pitch can the horizontal stab be better used for roll control compared to if there were no TV?

That's what I meant about TV helping supersonic maneuvers. If I'm wrong I stand corrected.

You are quite right, but I'm inclined to think the TV is used for trim balance rather than hard maneuvering in pitch at high speeds. So whatever trim load can be handed off to TV, results in more available to the tail for pitch and roll. The most severe tail load condition is high g rolling, where both roll and pitch loads are imposed on the tail. Any off-loading to TV will help reduce the maximum tail load and fuselage tail attachment load (and weight).

But TV is no free lunch either, as the engine structure and the fuselage structure must be heavier to withstand the added TV load.

tacf-x wrote:

@johnwill,

Thank you so much for explaining why control surfaces "lose effectiveness" at supersonic speeds. I guess it does add a lot more weight to the importance of research being conducted on Active Aeroelastic wing technologies after all.

Right. Leading edge ailerons, for example, could use the elasctic properties of a wing to increase aileron effectiveness at high speeds. Oh, wait, the F/A-18 already does that to improve roll performance at low altitude, high speed conditions. That function was added to the airplane LEF when early flight test showed inadequate roll performance above 0.7 mach at low altitude.

The F-16, when confronted with the same problem earlier, chose to add more roll control deflection to the horizontal tail at higher mach numbers.

And did you realize the Wright Brothers used Active Aeroelastic wing technology on the 1903 Wright Flyer? Roll control was provided by twisted wings.

JW-

What's the reason the F-22 deflects the ailerons up during high G maneuvers? Reduce span loading and or twist and bending loads on the tips?

Forum: F-35 versus XYZ

F-35 vs Eurofighter?