Hi

Just a quickie, are Air retracts any stronger than Mechanical retracts ? i dont need scale appereance or anything like that i just want them to hold up, but ive heard good and bad things about both............. (i would rather go with Mechanical as thier cheap and if they muck up can just by another set) and Air retracts over in the uk are pricey.............

What do u guys think ???????????

I've put Dave Brown retracts in a couple of planes. They're mechanical. You have to have a very straight route from the servo to the retract (you can get by with a bend if you have to) but when they're locked up and locked down they're very solid. Air retracts (I've put one set in) are bigger because of the cylinder, more expensive (as you said) but the air supply can be anywhere in the plane, including in either the wing or the fuse. Quick disconnects work ok. They lock by putting continual pressure against the retract toggle so they probably hold "harder".

A lot has to do more with the weight of the plane, the weight of the gears and tires, and how much you're willing to cobble up the wing to put them in.

Flying off grass? Makes a big difference with retracts.

I have used retracts only on one plane. I fly off grass. .40 size mechanical retracts. The takeoffs and landings (even when "gentle"), are often enough to bend the gear struts by more than 1/4 inch. On my plane that means the wheels fo not retract the whole way, and the retract servo binds, and the battery (potentially) drains. I have to check and often bend the gear after every flight. They are a PITA. Next time around I would buy more sturdy retracts, or go with fixed gear.

The bonus of air retracts is as follows: The gear struts are normally stronger (bend less). There is no battery drain if the gear does not retract fully.

gus

I won't get into the air vs mechanical debate.

How "strong" a set of retracts are basically depend on 2 things.
1. How well are they secured in the wing or fuselage.
2. What size is the strut ?

If they are secured PROPERLY and REENFORCED properly, both are strong. The strut size is another matter. The MAJORITY of 40 - 60 size retracts have a 5/32" strut. My experience has indicated that this size strut can bend fairly easy, especially if flying off of grass.

I strongly suggest using 3/16" diameter struts. They rarely bend when flying off of grass. Some manufacturers now offer retracts with this size strut, and others can be modified to accept this size strut simply by drilling. Robart has both mechanical and air retracts with 3/16" struts. Spring Air has air retracts with the 3/16" strut.

A couple of suggestions/hints:

Instead of bending the strut to make the axle, pick up a set of DuBro "EZ-Axles". You cut the strut off at the length you want, file a flat spot, and put these on. Make sure you use some locktite on the screws. This eliminates one leg being longer than the other and the aggrevation of retempering the bend you heated up.

For mechanical retracts you want to have as straight a connection from the servo to the retract as possible. MAKE SURE THERE IS NO BINDING. With air retracts make sure to use quick disconnects (makes life MUCH easier ) and route the lines so there are no kinks and wear/abrasion areas are padded.

For attaching the gear doors to the struts SIG has landing gear hold downs. They are nylon preformed straps that come in various wire sizes. I use a piece of 1/4" square basswood between the door and the strut to attach the gear hold downs so I have adequate space/holding for the attaching screws.

Hope this is of some help to you.