just a few lines on my experiences with air retracts.
they are more flexible in mounting because you can route the air lines easily.
If you have trouble getting air tubing, I have used 1/16th id plastic tubing
used by upholsterers to make piping - the round edging material on chairs,
stools etc $19 for 500 metres! the only servo work to do is to set up the valve
operating one so it is not loaded at either end of its travel. I have made my own air bottles out of hair and deodorant bottles with small bore copper/brass
tubes epoxied in the ends. solder a piece of small bore tube into the end of
a car tube valve for pressurizing - use a foot operated tyre pump to fill - I
usually get 80-100psi in quite quickly. some people like rhom etc make connector
s to go from pressure bottle in fuse to lines in wing. the trick with making the
cylinders leak proof is to use proper hydraulic cups or rings to seal them, not
just 'O' rings. with big heavy birds, it can pay to mount the retract softly, ie
on a fibre-glass and/or carbon fibre on a fibre-glass and/or carbon fibre
expoxied plate, screwed down at its corners, but able to flex with big loads
instead of ripping the retract screws out, or pulling the wood out of the foam!
