stevegauth30

Hey guys, I don't know where I should ask this, so I figured one of the war bird guys might know. I have a TF Corsair 60 with robart 615's installed. I'm not too sure what the problem might be, but they rarely retract. Some times one side will go, but never both. They drop down just fine, but not retract. As far as I can see there are no kinks in the lines, unless its inside the wing. I hope not. I've tried opening the valve screws, I even removed them completly. No luck. I've only pumped it as high as 100 psi. I thought I read not to go above that. Is that right? Ill try any thing so any thoughts would help. Thanks for your input, Steve.

Flyin Hwn

Check for leaks. I assume none as they retract. Check your servo throw on the downside. Maybe not enough throw.
Good luck

dasintex

My Feedback: (10)

Not sure if you have tried this: Place the Plane Upside down on a stand; operate the retracts and see what happens, if the retracts have a hard time extending or deploying; but retract or rotate and fall back into the wheel well without any problems, then its possible the Wheels are too Heavy? an air leak would be a possibility; are they new retracts, or used and been sitting around awhile, if so the air cylinders need some retract lube to help seal them, same goes with the valve; just a few thoughts to share, others may chime in with other plausable causes.

Chad Veich

My Feedback: (60)

Make sure that you have not inadvertently twisted the retract frames when you screwed them to your mounting rails. It is best to actually bolt the gear to the rails first and then glue the rails into the wing but obviously that is not always possible. The 615's are VERY susceptable to distortion caused by mounting rails that are not perfectly parallel and it results in binding. Loosen up the mounting screws a bit and if they function normally then you know what the problem is.

BarracudaHockey

My Feedback: (11)

What Chad said!

Its very easy to distort the frames.

Also, leak check with dish soap mixed with water and applied around the valve etc.

stevegauth30

I really do think there leaking, it's been at 80 psi for over an hour now. I'll bet the frames are twisted. I'll chech. BTW, there brand new, but were on the bench during part of the build, so can there be sawdust an crap got inside? How can I clean it out? What about oil? Someone said something about luring the valves?i unhooked the servo arm and manually cycled them still no luck. What's the highest psi I can pump it to?

da Rock

Want to know if the frames are twisting them? Loosen all but one of the mounting screws.

You might do that when you try the excellent suggestion of trying to retract with the plane inverted.

Advice is valuable only if you try it.

stevegauth30

ok, so they are twisting. should i remove the rails and install them on the retracts first? i cant really thi.k of another solution. ill probably have to do that. thanks. i knew someone would know. i love rcu. Steve

invertmast

My Feedback: (23)

If the retract frames are twisting when you tighten their mounting bolts, you can remove the retracts and put a coat of non-stick cooking spray on the frames. Then mix up some 30 minute epoxy and microballona to a peanut butter consistency. Put this mixture of goo on the retract mount rails where the retracts sit. Reinstall the retracts tightening one screw completely, and the other three just enough to squeeze out some of the goo. You should also test the gear to make sure they arent tightened up so much that they have twisted again., while the goo is still wet

stevegauth30

That would be strong enough?would I be better off to pull the rails out? I don't care to cut corners, not to say that your way isn't good, I just don't want problems later. If epoxy and micro balloons are strong enough I might give it a try. Thanks. Btw, I know you know what your talking about, I've followed along your build threads.thanks.

da Rock

That would be more than adequately strong. When the epoxy cures, it's harder than wood rails usually are. Epoxy with micro balloons is usually as strong as the wood used in most rails. Don't overdo the amount of micro balloons. Or just leave them out of the mix.

As for strong enough.... the filler isn't really structural. It only has to stand up to the compression. It won't be so thick it will feel much else. It'll be strong enough.

Edwin

My Feedback: (2)

What darock says. As an alternative, I've used JB weld for bedding retract rails. Make sure they line up before it cures.
Edwin

wingspar

My Feedback: (3)

If you really want to do it right and with all do respect to the moderator you don't want to use a low density filler such as microballons. For max strength you want to use a HIGH Density filler/additive to your epoxy such as West System 404. This can be obtained at any marine store. Also use a good quality epoxy.

Dave N

invertmast

My Feedback: (23)

The microballoons arent providing any strength to the wood mounting rails, they are just providing a subtrate to provide a level mounting surface so as to not bind up the retracts.

If done properly and the rails are fairly close to parallel when originally installed, there should be no more than 1/16" of microballoons on the rails.

WWIIP38

My Feedback: (43)

I had nothing but problems with Robart 615's in my TF P-40. They functioned and didn't leak, but ground handling was atrocious! Tried two new pairs of 615's. Tried toe-in, toe-out, no-toe, shortening the gear legs, etc. The problem seemed to be that they were sloppy loose when down. Finally replaced them with Sierra gear and PRESTO!, problem solved.
(Note; I have used many other varieties of Robart retracts in 30 years of flying scale R/C with very good success.)

wingspar

My Feedback: (3)

It has nothing to do with providing strenght to the wood.

Microballons are great for non structuaral use such as wing fairing that make them light and easier to sand.
A high density filler such as West System 404 is a specially made to handle high compression loads without failing.

This doesn't mean that Microballon wouldn't work for the posters application, however it would not be the proper use of that product.

Dave

stevegauth30

What is the 404? I use west system all the time for glassing. I have the 105 and 206but that's just the epoxy.

stevegauth30

I think I will just take the road less traveled. I will pull out the original rails and remount them to the gear first. These do seem a bit flimsy. I have spring airs in my TF Mustang and the body's are much more rigid. I don't remember what models they are, but way better. And it's not like the 615's were any cheaper. I still paid out the arss for em. Oh we'll. thanks for all the input.BTW, what works as a debonder for epoxy? Anything?

wingspar

My Feedback: (3)

From their website. "404 High-Density filler is a thickening additive developed for maximum physical properties in hardware bonding where high-cyclic loads are anticipated."

It's available at just about any good marine store or supplier or ordered from the internet.

Just mix up your epoxy first, then keep adding the 404 until the epoxy has the consistancy of peanut butter.

BarracudaHockey

My Feedback: (11)

Or just go get some EpoGrip

invertmast

My Feedback: (23)

A saw

Edwin

My Feedback: (2)

A dremel grinding head works. Just a suggestion, I'd spend the money and go with sierra's. I've used the 615's before, way too much trouble and flemsy.
Edwin

stevegauth30

im considering it. i havent even maidened the plane yet, and already i dont like em. arrrgggghhhh. kind of frustrating. thanks

iflircaircraft

You could elongate the holes in the retract flanges to relieve the binding I've done it and it worked out just fine.

iflircaircraft

If this is the ARF TF Corsair the rails for mounting the retracts are not level. If you look close you will see the rails towards the leading edge of the wing follow the contour of the wing's sheeting, especially the inboard rail.
A shim under the flange is needed to keep the rail from binding.
Been there did that.


Tom