Forum: General F-22A Raptor forum

I was just thinking about stuff, and this came up. Every generation of fighter has seen some significant change in aerodynamic philosophy which led to increased performance in general.

2 - swept wing
3 - area ruling
4 - blended wing/vortex generation
5 - TVC? chines (vortex with less drag)? internal weapons (F-102)?

What is the 5th generation's aerodynamic leap? TVC control that reduced drag at supersonic speed is fairly significant, but not strictly an aerodynamic feature, even if it can influence aero such as the PAK-FA's small stabilizers.

Chines seem to provide the same benefit as blended wing body/LERX's with less area, so I would think less drag, however this is a guess of mine (but something has to contribute to clean F-16's getting out maneuvered by F-35's loaded with bombs and more than twice the fuel load).

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There's not much room for improvement after relaxed stability, chines, and blending. You can go canard delta and take the hit in signature but that's about it. The sixth generation will probably be tailless. They'll just have to eat the losses from engine out and loss of control.

shingen wrote:

... The sixth generation will probably be tailless. They'll just have to eat the losses from engine out and loss of control.

With both the F-15 and F-16 flying without one wing, is the "loss of control" for the tailless really going to be an issue? Stealth and tailless will surely define sixth generation along with advances in Mission Systems and possibly early directed energy or unmanned (either mission duration or "G loading" or both) Shocked

exorcet wrote:

2 - swept wing
3 - area ruling
4 - blended wing/vortex generation
5 - TVC? chines (vortex with less drag)? internal weapons (F-102)?

What is the 5th generation's aerodynamic leap?

Well, combining modern aerodynamics with stealth technology without sacrifacing performance and maneuverability.

Regards

6Gen - Morphing wing

Well, and here I thought bringing up 6th gen would not provide much discussion. How wrong I was.

I am at least correct in thinking that chines produce the same amount of high AoA lift (and I mean quantitatively, not qualitatively) as LERX's with less drag? If that's true, what was the logic behind making the Super Hornet's LERX's huge?

On tailess aircraft, most fighters have some limited back up power to keep things running after the engine goes out correct? I'd assume it would be enough to run the FBW and some limited aerodynamic surfaces (they'll need airbrakes and flaps right? Slats would probably help too).

The point is, a tailless aircraft with no rudder(s) will not be controllable without TVC. No engine, no TVC.

When does a chine become a LERX and vice versa? Chines add lift at supersonic speeds, something the designers of the Honet didn't seem to be worried about.

I'm not at all sure where the line between LERX and chine is. All I know is, I see chine more often when people talk about the F-22 and I see LERX attached to the F-18. Generally, I go by size. The Hornet and Flanker have a lot more area than the F-22 infront of the wings.

Don't chines also generate vortices in low speed high AoA flight? They're basically delta wings to the extreme (at least on the F-22 and F-35).

Chines are an extension of the body and LERX are an extension of the wing. To tell the two apart look at the body shape at the point of "attachment".

I'm surprised twist-bodies or warping wings aren't in the works for 6th gen. We had somewhat both in the first generation of planes, but the technology just wasn't there to match the engineering ideas.

madrat wrote:

I'm surprised twist-bodies or warping wings aren't in the works for 6th gen. We had somewhat both in the first generation of planes, but the technology just wasn't there to match the engineering ideas.

Actuator technology has advanced to allow electro/ hydraulic actuators on the F-35. This eliminates the need (and the fire risk) for the hydraulic fluid distribution system. With this advance the warping now can be implemented in the design regimen. Smile

Back in the in the late 80s, an early development F-111 was fitted (by NASA and Boeing) with something called the Mission Adaptive Wing. The leading and trailing edges could be "warped" into shapes optimized for takeoff, landing, subsonic, transonic, and supersonic flight. There were no separate leading and trailing edge surfaces, just smooth shape transitions to vary the camber. It worked as planned, but was never put into production. The leading edge was one surface root to tip, while the trailing edge had three spanwise segments which were actuated separately for roll control.

Here is a good link for more information.

http://spaceflightgtm.nasa.gov.speedera ... H-1748.pdf

"What is the 5th generation's aerodynamic leap?"

6) internal weapons storage on a light fighter
7) thrust

6th gen.. no pilots..

Forum: General F-22A Raptor forum

Signature of 5th generation areodynamics