Props4ever

Im looking for guidance how to make fibreglass sleeves or sockets for present CF and aluminum wing tubes on hand. I have on hand 1/2" x 24" CF and 3/4"x 16-3/4" aluminum wing tubes on which I need sleeves made. I know bit about the process and in past I tried to make my test sleeves but failed when tube couldn't break loose from the socket. I also had wax paper and also waxed the main tube b4 laying up the test tube yet it failed to come out of the sleeve. What should I do to make sleeves prevent from sticking to the tubes at the resin curing time....

sensei

What I do is acquire a .125" wall thickness tube of aluminum the diameter of the tube I am going to sleeve; next I cut a .060" slot through and lengthwise the tube on a mill. Now I cut a piece of .063 sheet aluminum 1.00" longer then the tube and .375" wide, I then slightly taper one edge of the aluminum strip so it can be easily inserted into the slot of my tube expanding it by .003". In most cases I have had to sand the strip just so slightly for the desired fit. Now I seal all the aluminum tooling with Freekote FMS, and apply Freekote 700 NC mold release. I then place the strip in the slot flushing it to the OML (outer mold line) of the tube and layup my fiberglass sleeve/tube. After the cure cycle is complete I remove the strip of aluminum by the 1.00" extra of length I previously spoke of allowing the tube to spring in just a little while self de-molding the tube. Here are a couple of pictures of an untrimmed 5" diameter tube, and with mounting flanges manufactured with this process, I have also manufactured up to 8' long tubes molded this way and in smaller diameters as well. Note: Aluminum tubes spring in when cut through span wise, steel spring outwards making it a non suitable choice for this application.

Bob

crashlander

My Feedback: (10)

I take the alum tube or carbon fiber tube and wrap a portion with wax paper making sure it is neatly wrapped around the tube and tape the it down at the ends where I know the FG will not be.
I then wrpa several layers of 1-1/2 ounce cloth wetting each wrap thoroughly. Let it cure and remove the the new FG sleeve.
Hope this helps out.

Orlando

speedracerntrixie

My Feedback: (29)

Bob, that is a real trick process there bud. I usually wax up an aluminum tube really well then glass it and cure at 180 degrees or so. This cures it with the tube slightly expanded. When its time to remove the tube I put it in the freezer to contract the aluminum tube. Even with all that it's a fight to get the two separated.

sensei

Hey buddy,

The reason I adapted to this method was twofold, first it allowed us to engineer the component ID to exacting tolerances when utilizing room temperature cure cycle systems as well as the elevated pre-preg cure cycle systems along with (CTE) considerations of course. Now that I think about it we have been predominantly utilizing pre-pregs on just about all component manufacturing for around 20 years or so now. The second reason was if one of my technicians happened to place the smallest of unnoticed nicks in the tube/mandrel then component removal became at times an impossibility and a complete source of irritation if you know what I mean.

Bob

MTK

I've tried several ways to make the release simple and effective but have not been happy with the results. I like Bob's method though especially if you're gonna make bunches of them...

I've decided to make sockets from balsa instead. First I glass the inside of the balsa sheet, letting that cure well. 1-1.5 oz glass is fine. Once cured, the sheet is wetted and wrapped around the carbon tube, glass in. After a few passes with the heat gun to dry, the seam is carefully cut for a butt seam and ca'd. The socket must release of course. Maybe a butt seam isn't necessary if you use 1/32" sheet; a small overlap seam is probably just fine. But I have always butt seamed mine so far. I then re-insert the carbon tube into the socket and bias wrap the outside with 3K carbon or kevlar tow and dope it down (nitrate); doesn't need much to hold the shape yet be snug on the carbon tube. The release has already been established so there are no issues. This works well for up to 12 pound models. Probably would work fine for large models too but I have not done it.

It's a fairly simple, cheap and lightweight way to go, (lighter than several layers of glass). The trick for lightweight strength is how one supports the socket inside a wing or stab.