I am wondering how it is integrated with flight controls. Is it in a dynamic mode during flight like a fixed-wing elevator or is it “set” for certain parameters?
IANA Black Hawk pilot, but a friend of mine flew one in Gulf War 1. I’ll have to ask her.
Helicopters have horizontal stabs to trim the aircraft in cruise flight. That is, they keep the deck angle reasonable when the rotor is tilted forward. I fly Robinson R-22s and Schweizer 300CBs, both of which have fixed stabilizers; the former has a horizontal and a vertical one, and the latter has a diagonal one and a vertical skeg. As you’ve noticed, the one on the Black Hawk moves. I don’t know if it’s integrated into the flight control system (i.e., the cyclic, collective and throttles), or if it’s manually set (like using the trim on a fixed-wing aircraft, or, in a slightly different way, the trim on the Schweizer). I’ll try to call my friend later and ask her.
The horizontal stabilizer on the UH-60 is scheduled according to airspeed. That is, the flight control system (air data system) knows what the ship’s airspeed is, then sets the stabilizer incidence to a predetermined position. It is not hooked into the cyclic, meaning that if the pilot pulls aft cyclic, the stabilizer doesn’t move until the airspeed changes. There is a switch on the instrument panel that allows the pilot to override this system, and put it wherever he wants.
The main idea is to put the stabilizer at a kind of ‘optimal’ setting with regard to where the rotor wake is. In hover the stabilator is full down (trailiing edge down) to get it out of the way of the rotor wake. In forward flight, it’s up to a more horizontal position, as the wake is not impinging on it. The settings in between have been determined (flight test & so forth) to provide a smooth transition.
The AH-64 works about the same way.
Before Johnny comes back and nit picks, I just checked the operator’s manual. In addition to the airspeed sensitivitiy I mentioned, the stabilator is electronically coupled to the collective, to minimize pitch attitude excursions. There is also some pitch rate feedback, and some sideslip coupling, all to improve handling qualities.
But if I catch the gist of the OP, the stabiliator is not directly controlled like a fixed wing elevator.
:smack: I meant to post that it’s probably automatically controlled. I was thinking it. But as you can see by the time, I had only just gotten out of bed.
In any case, I talked to my friend the ex-Black Hawk pilot, and she says what Race Bannon says.