I've installed the Robart air system and the infamous #615 retracts into my TF Corsair. Unfortunately I glued the retract rails more than half a year ago, before I read that they should be glued with the retracts screwed on. To no surprise, the retracts are binding. They need a lot of air pressure to build up to get past the binding, then they slam up to the wheel well. Fortunately, the notch in the main spar stops the strut before the wheel goes through the top wing skin.

I half heartedly tried tweaking it to try to stop the binding. Should I put in new rails using the proper method? The existing rails are epoxied in pretty good. It would take quite a bit of effort to remove them.

Juice

You should be able to put shim washers between the rails and the retracts to keep them from twisting. I've done that myself.

Juice.... sounds like from your observations the rails might not be straight and true.....might need to "shim" the rails to make them true........you could try removing the gear and lay each one on the rails and look to see if they are flush...if not shimming might work to correct the problem....Bill.....

Thanks guys... I think I've made a little progress here, but it's still not perfect.

My original retract rails were a little too deep inside the wing and they made the strut point perpendicular to the wing when extended. The "shims" I added were wedge shaped pieces of hardwood. The wedges are placed between the original rails and the retracts so that the struts will be angled forward and the wheel axle is directly underneath the LE when the tail is up. The wedges are not glued in yet, but the retracts are screwed in tight while I make sure that nothing is going to bind. I'll epoxy them in later.

My lack of experience leads me to my next question... When the struts are down and locked, how long should it take the air pressure to unlock them when they are to be retracted?

I've managed to get rid of most of binding, except at the instant when the retracts need to unlock to retract. It takes about a second for them to unlock and when they are finally released the strut will SLAM into the notch in the spar. Should the wheels be retracted gently into the wheel well? Is that my next goal?

I have video evidence of this on my web site. Click on my WWW button below. Tell me if there is anything else that I need to be concerned about.

Thanks,
Juice.

I use washers for my shims. No problems. Except when its my own fault. Mine lock instantly, they come down pretty quick. They also slam up into the wheel wells. Doesnt bother me anymore. I only require that they work. I also used a TINY amount of 3in1 oil that helped a lot.

Is something wrong with you if you're imagining you are in the cockpit doing a carrier landing in your corsair? Got to stop trying to catch that wire.
Edwin

Juice, this is part of a post on a similar question.

Remove the gear from the plane completly and verify that it works correctly. Once confident that they are working correctly continue.

Now reinstall the gear tight, recheck the bind. If it is still there loosen each screw by one turn. Does it work like it was free of the plane now? If so remove each screw and count the turns. Remove the retract unite and mix up some filled epoxy, this can be regular epoxy with microballoons, or sig epoxilite, or any one of a dozen. Amply cover the mounting rails with the stuff leaving the mounting holes open (free of the stuff). Then take two small peice of platic rap and place it over this mess so that it completly covers it and drapes down into the cavity where the retract mechanisum will be. Replace the retract mechanisum and tighten down the screws the number of turns you counted as you removed them. The screws may give some dificulty going through the plastic rap so dont be afaid to use a sharpened, or heated pushrod wire to punture the plastic. Once everything is buttoned up set it aside for 24hr.

The next day remove the retracts one last time, trim all the extra gobs off. I like to leive the plastic rap between the epoxy and the mounting ears but remove it every were else (having the plastic rap as a barier garentees I'll be able to remove the thing in ten years). Tighten the gear back down tight and it sould not bind now.

Good luck!

Juice, are you using a Robart speed control valve? Mine operates more like scale than what you are describing.

Devo,

I'm using "Robart Variable Rate Control Valve", #167VR (http://www.robart.com/pages/airsys.html).

If the retracts weren't binding I'd be able to restrict the exhaust air a little more to slow down the motion and the wheel would gently retract into the wheel well. That would be the most ideal and scale-like operation.

I'm going to try Paladin's trick to try to remove the binding. Thanks for the tip.

Juice.

You should be able to slow your gear more than is shown in your video. The gear does react more slowly at first because the postion it starts in is where it has its least amount of leverage. My gear reacts the same as yours, but more slowly. It takes a very small turn from closed on the "Varable Rate Control Valve". I'd keep working the wood shims until you get the gear to lay flat on your rails. Using epoxy as shim material sounds heavy and messy to me.