Installations like this DerJet F-35 require careful planning with locking cylinders and multiple gear doorsThree valves, one for gear and two for gear doors operating on separate sequences.
The brake valve is mounted on another plate.AUTHOR & PHOTOGRAPHER:DAVE WILSHERE
Starting with turbine jets
Basic advice for newcomers
Air retracts
Simple is best, could be the perfect phrase
when planning your retract installation. I
guess this is true for all retract operating
systems, but we are talking about pneumatic
systems. The majority of kits are still supplied
with air operated undercarriage systems.
History proves these can be incredibly relia-
ble. Adding joints to allow servicing is crazy, if
you need to remove something later in a
models life, then split the tubes and add joints
if really there is no chance of replacing the
whole line.
Air operated systems are simple when you
break them down. Most pneumatic systems
these days use air to push the cylinder rod
back and forth. In the early days Spring-air
systems, where a spring was fitted inside the
cylinder to drive the gear down were popular.
The idea of this was a ‘failsafe’, loss of pres-
sure would allow the spring to start the pro-Articolo Dave_Layout 1 07/03/18 15.36 Pagina 2