why is the trailing edge of the horizontal stabilator of the Ah64 Apache 1 side up and 1 side down?

Question

I understand that it is a whole piece structure. What I'm interested is the there is 2 90 degrees bent on the rear edge of the stabilator, 1 bending up and the other bending downwards. What's the rational behind it? Please e-mail me if pictures required as they wouldn't allow me to attach a picture.

Answer 1

They are called gurney flaps. They help with the difference of air flow going over the stabilator caused by the EFABS(enhanced forward avionics bays) If they weren't bent 90 deg on either side of the stabilator, the aircraft would experience some vibrations.

Answer 2

It must have been broken (LOL). The Apache has a one-piece horizontal stab. It is actuated by 1 ram underneath. There are no tabs on the trailing edge etc. If (huge if) there were such an asymmetrical horizontal stabilizer it would only serve to twist the tail and place undue stress on the airframe.

Here is a great shot of the tail and you can see there are no articulated parts beyond the whole.
http://www.airliners.net/open.file/0237137/L/

Answer 3

I've never walked up and touched an Apache but I have noticed that the Horizontals are not in the same position from picture to picture. The most recent pic I saw had them both level. Helicopters, especially fast ones have a tendency to twist in level flight due to the fact that one blade is rotating into the direction of flight while the other blade is rotating away from the direction of flight causing an imbalance.

Answer 4

I honestly don't know what you're talking about. AH-64 have a one-piece rear elevator and no trailing edges on it at all. The whole elevator rotates on a hinge, not separate.

I randomly check like 5 or so images where the tail is visible and none of them have anything close to what you described. Please cite a picture so we can evaluate it with you.

Answer 5

I haven't seen it, but I can imagine the reason:

To counteract engine torque at cruise.