F-22 Aelerons act as elevators also??

[mikoriad]

Has anyone one noticed in the many F-22 videos, that when the aircraft is in a hard climb or turn the aelerons look like they are also acting as elevators, or stabilators??? Can any one give definite answers... make me think the main wing is far enough back to perform similar to a delta wing.

 

There are many examples, but you can observe in this video a round 2:37..

 

http://www.metacafe.com/watch/1061601/f_22_raptor_extreme_moves/

[nellen_mellen]

AFAIK,

 

they probably do deflect in strange ways in some photos, although whether or not they are bening used as elevators is another question. They're doing that probably as a result of the 'adaptive' FCS, i.e., the pilot puts control inputs through the stick, and the aircraft figures out the best combination of control surface deflections to yield his request. If this means lowering both aelerons, so be it.

 

If you watch closely on some of the better videos out there of it in its post-stall area (when its recovering from a powerloop or doing the "helicopter" yaw-turn) you can see the control surfaces wiggling all over the place.

[mikoriad]

well yeah, I understand the whole adaptive flight control stuff. This is just something that I haven't seen out of anything else. Even the Superbug which also sports adaptive FC technology. I'm thinking this is more of an aircraft design side effect... main wing being set soo far to the rear.

[mvsgas]

Sorry guys, I don't see what the ailerons are doing. What exactly are they doing? Do they go up when the aircraft pitches up? Sorry I don't see what you are talking about on the video you posted. Could it be that when the flaperons or flaps (wish ever you call them in a F-22) go down they make the ailerons look like they are deflecting up?

[mikoriad]

I'll find another movie clip and post it. I was thinking the same thing, as far as the flaperons, but the more I looked at vid, it seemed other wise...

[Teknetinium]

Dont know the answer for this one but I must admit that F-22s engines are truly amazing.

[mvsgas]

With all the computers on moderns aircraft that makes a lot of sense. Remember , a lot of this FBW aircraft , the pilot has not physical link to flight control surfaces, the pilot tells the computer what he wants and the computers decides what surface to move to achieve the desire aircraft movement. Maybe that is the reason.

[Force_Feedback]

On the Sukhoi S-37 the canards alternate between a destabilisator (like on the Su-30MKI/33/34) and in slow speed flight as a flapleron with roll inducing movement. Also judging from high res videos.

[Trident]

Could be to lower bending loads on the wing structure during high-speed, high-g turns by reducing lift near the tips. It is hard to tell whether they are actually deflected in the same direction or differentially in this video, though.

[Groove]

The F-22 FCS works full automatic in its own regime. There is a video interview with the main test pilot who describes it. You cant overstress the frame because of that but also the FCS will always allow you to get the max out of the plane at that particular moment if you for example would pull the stick to the max.

 

The FCS was actually the highest development costs on the F-22.

[mikoriad]

...reduce wing flexing, that would be interesting...

 

http://www.airliners.net/open.file?id=1296424&size=L&width=1200&height=811&sok=&photo_nr=65

 

Not to rehash this again but aside from this just being an AWESOME picture:thumbup: it's very clear and visible here what I'm talking about. Sure would be interesting to know exactly what's going on.

[mvsgas]

I see now what you are referring to. I have no idea ,but I still think it could be just the way the ailerons seem. For all I know he might have the speed brakes on to stay below a certain speed with AB light up. AFSIK the speed brake on the F-22 is just all the flight control surfaces moving in unison to slow down the aircraft. I'm very ignorant about aerodynamics, even more on the F-22 but it does not seem he would need that much pitch control for a low fast pass like in the photo ( Is that what he is doing? A low fast pas over the crowd)

[mikoriad]

I guess the speed break is possible, though usually the rudders will be deflected outwards also... But who knows what the FLCS decided to do at that speed.

[Pilotasso]

On the Sukhoi S-37 the canards alternate between a destabilisator (like on the Su-30MKI/33/34) and in slow speed flight as a flapleron with roll inducing movement. Also judging from high res videos.

 

I think its the opposite. I think I read in serveral publications that due to the Russians analogue FBW (wich doesnt do the exact same thing as it does on western fighters), the cannards are there merely to increase manueverability at the same time minimizing any resulting loss of precision in controlability (like nose wobbling). It works as a stabilizer in snap manuevers, not a destabilizer.

 

So much so that the current Su-35 has completely eleminated the cannards with the adoption of a more powerfull and broad digital FBW. The Su-35 with thrust vectoring is probbaly a more agile airframe than even the MKI. Its simpler and lighter.

[Force_Feedback]

^S-37.... S-37.... not Su-something.

[Pilotasso]

well you forgot what you added in parentisis :)

[Rhino104]

On the F-18, there is a setting for auto-flaps, which makes the flaps usable to the FCS. My thought is that there is something similar built in with the Raptor. If you ever notice a pic of the Blues in a tight left turn in the diamond, their flaps look to be down a bit, and its due to the FCS controlling them.

[S77th-konkussion]

I think the rudders deflect inward as part of the speedbrakes. This may have been taken just as he was inputting to come out of his left roll? (transitioning back to level flight) Hard to tdetermine the position of the port aileron from that angle.. The starboard aileron certainly looks as though he is putting in right roll.... :unsure::dunno: