from Addendum to 3-D Helicopter Simulator documentation, version 1.0, 8/28/87.
Page 21, last paragraph. Failure of your engine during flight will always result in your "death"
We have included a loadable helicopter modeled on the Apache AH-64 military attack helicopter. Although this will change your appearance, your helicopter will still fly as though it is a Robinson R-22.
The Edge of the World
When you fly off the "edge" of a scene, you will "wrap around" to the opposing side. For instance, if you fly East from town long enough you will eventually re-enter the same town from the West.
Controlling the Helicopter
We have attempted to accurately simulate the controls of a real helicopter by slightly delaying the keyboard response to match the delayed response of real helicopter controls. This produces an "inertia" effect which is a prevalent helicopter flight characteristic.
Page 31 of the documentation mentions that dual joysticks are required. If only one joystick is used, it will be presumed to be the cyclic stick.