Okay, I have to preface this question by admitting a very guilty pleasure. I’ve recently been reliving my childhood and bought the first three seasons of Airwolf on DVD (the fourth season includes a cast change, network change, and the loss of the Bell 222, so all flight scenes used recycled footage - season four is godawful.)
Anyway, the show has Airwolf equipped with “turbos” that are essentially dual jet engines mounted on the wing stubs to allow it to go supersonic. Whenever the pilot wants to engage them, it shows a closeup of his hand on the cyclic control, and he presses a little red button. It looks like they used the stock Bell stick, without re-labeling anything, because the “turbo” button actually says “Force Trim.”
I’ve googled the term and found some references to the Huey and other Bell whirlybirds, but nothing that explains it in terms that I can grasp. One website makes it sound as if force trim simply adds a little (magnetic) resistance to the cyclic, which is usually very ‘loose’ (to the point of just flopping over if one takes his hand off it.)
The other, which sounds more plausible to me as a fixed-wing pilot, is that force trim allows the pilot to “trim” the helicopter by essentially zeroing the cyclic in a certain place - for example, in forward flight, he could push the “force trim” button and then bring the cyclic back to a neutral position, but the bird would be “set” as if he was continually pushing the stick forward. Seems that would be more comfortable, but I’m not a rotary wing pilot, so I have no idea.
So, dopers, anybody care to clear up the mystery of force trim?