Setupfrom Addendum to 3-D Helicopter Simulator documentation, version 1.0, 8/28/87.
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.
On some non-IBM memory upgrades you will not be able to return to DOS upon exiting the program. You will have to power off your computer and re-boot.
Out Of Memory Problems
3-D Helicopter Simulator is obviously an extremely complex program and barely fits into a 256K machine. If you have 256K you will not be able to run the Helicopter Simulator while memory resident applications (such as Sidekick) are active or on a later version of DOS than 2.11
... an extremely complex program and barely fits into a 256K machine...