RE: Tam Jets Gear Fail Safe
I thought of putting a gear fail safe on my Skygate Hawk but wanted a better system, here's the idea based on the Jet Provost (and F4) system.
The servo which drives the gear valve can contact an air micro switch when it over travels slightly from the gear down position, the over travel being created by mixing gear to gear on the radio. No servo or channel required. The air supply to the micro switch is either the brake tank or a separate air tank. When the micro switch opens the air from this tank is fed to the valve via a T connector In the supply line but is prevented from returning to the main tank via a NRV inserted in the supply line upstream of the T. It's that simple.
So if your gear doesn't extend when selected down operate the mixer switch and feed alternate air to the valve at the pressure in the reserve tank. Down comes the gear, simple. !
If you have an electronic gear valve use a micro servo Y,d into the channel to operate the micro switch.
If you have air driven doors, supply this valve too with alternate air, if you wish.
If desired, instead of using the brake tank, use a separate air tank.
The advantage of this system is that YOU choose when to extend the gear, even after the original leak which is almost certainly in the UP system.
You also extend the gear with full pressure in contrast with a lower, depleted pressure.
It is tested by retracting the gear, then clamping the main supply hose and then trying the ALT system, simple.
I believe this is a more controllable and potentially more reliable system than an electronic faisafe, less than half the price, too.
Regards,
David.