Sean,

If you go to the Skymaster F-4 section at www.detail4scale.com, you will find the installation instructions for the SM F-4. It shows the step by step for the entire system. The F-4 chute system uses a special servo holder that holds both the trigger servo and a micro push button valve; when the valve is depressed by the servo, the plunger fires ejecting the chute. The rear chute door is hinged as on the rear F-4 and held in place by a pair of rare earth magnets. The plunger at 70-80psi has more than enough force to overcome the pull of the magnets when fired, thus opening the door and ejecting the chute. There is a great video on the SM F-4 page of our site that shows the actual ejection on landing. The large SM F-4 is roughly 1/8th scale and the 16" bellowed slotted chute is sized for the aircraft. The chutes are effective enough that most landing require no brakes to slow the aircraft as you'll see on the video. The AUtochute II is a chute deployment system with 5 built in safetys and the best part is that the system doesn't require the use of ANY additional channels from the radio. It uses 4 inputs, brake, flaps and throttle for the first safety set and then a wheel sensor to insure the aircraft is on the ground before firing the chute. Once programmed, the Autochute II does everything automatically for you. You just land the plane; no buttons or switched to press so you can keep your eyes and mind on the landing. If all the safety parameters are met, the chute fires at touchdown wheel spin-up. I hope this will answer most of your questions.

Dan