F-22 Aileron Deflection

Unread postPosted: 02 Jan 2020, 22:58
by f119doctor
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In the attached photos, you see the F-22 in a moderate AOA (see vortices & deflected AB exhaust) rolling turn. The horizontal stabilizers are deflected for a left roll, while the aileron are deflected for a right roll. Is this aileron positioning to generate a proverse yawing moment? There is no visible rudder deflection.

We often see both ailerons deflected up and the flaperons deflected down during a symmetrical pull, which increases the aerodynamic twist to reduce the bending load at the tip of the wing. But I have never noticed this opposing roll deflection of the ailerons and horizontal stabs.

Re: F-22 Aileron Deflection

Unread postPosted: 02 Jan 2020, 23:13
by sprstdlyscottsmn
That does indeed look bizarre. I agree that proverse yaw seems to be the only benefit. Great pictures though!

Re: F-22 Aileron Deflection

Unread postPosted: 03 Jan 2020, 22:21
by vilters
Seeing the LEF deflection;
The AOA must be high (or the speed very low) but the twist of the fuselage seems strange at first.

Re: F-22 Aileron Deflection

Unread postPosted: 05 Jan 2020, 19:54
by n3sk
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I noticed this before as well. Here is a screen shot from this video. https://youtu.be/-MbXpwKlbVk . The still shot was taken around 1:26 into the video during extreme Aoa.

So i would guess it helps control Yaw when the vertical stabilizer are not able to. As extreme Aoa disrupts airflow over the vertical but not the horizontal stabs.

In the video above that motion initiates a high degree of left hand turn rate.

In the picture posted by the OP it would keep the nose from dropping in the steep bank.

Re: F-22 Aileron Deflection

Unread postPosted: 06 Jan 2020, 07:03
by johnwill
Remember, a proverse yaw around the airplane yaw axis is added roll around the flight path roll axis. The flight controll system, with a constant g command, rolls the airplane around the flight path roll axis. The difference between airplane and flight path axes is AoA, so at high AoA, opposite aileron can contribute to roll performance.