Bending wing tip bows.

[Steve Pierce]

Aside from installing other types of tips (droop etc.) what method do ya'll use to get your wing tip bows to fall in place?

 

[J5Ron]

I have only had to do this once...but I took some 3 or 4" fire hose...cut to length about 2 feet longer than bow...sealed off the ends put bow inside...filled with warm water...came back an hour latter...done...nice and flexable...

 

[Speedo]

Clyde Smith covers this in his rebuilding seminar. You could try calling him at his hanger in Lock Haven.

 

[RMREBOB]

I tried PVC pipe and steem once but the pipe melted.

 

[Marty57]

I do my bending in a piece of PVC pipe. Same idea, cap and glue one end, fill with hot water, insert wood and cap other end (no glue). About an hour will do fine. Next, bend and clamp wood to a jig (2x4"s) with a slightly tighter radius than needed. After it dries overnight unclamp. The bow should spring back some, giving you a good fit.

Marty

 

[bob turner]

Or you can buy them pre-bent from aircraft spruce. Shipping is a problem, but Fed Ex gave us a good deal last time we bought a pair.

 

[Steve Pierce]

I saw them in the Spruce catalog but figured they were just getting them from Univair. Did they fir well? I have three cracked from Univair. They sent me some more but it is a pain. I have a fixture made to put them in to make the shape but have been breaking them trying to put them in. I thought about putting them in the pool but I don't know. PVC or Spruce sounds like a good idea. I'll try the PVC trick first. How big is the box from Spruce?

 

[planenut]

wing tip bows

You could try what i did on a Piper replica i built! I made laminated bows! I cut hard maple into strips 1/8' by 1" and glued 8pcs of them together with recorcinol glue in a jig i had built to the shape of pipers wing tip bows.
After drying and putting the radius on with 1/2" round over bit in a router table, what you get is an extremely tough bow! Almost all of the certified and homebuilt pipers at my home field are using these.

 

[Gordon Misch]

Steve, I bought a pair from Dakota, and was able to just bend them right onto the wing. They were too large a radius as-shipped, but bent without cracking. Dakota has a written installation procedure on their website that worked for me - - -

 

[Clay Hammond]

I made laminated bows! I cut hard maple into strips 1/8' by 1" and glued 8pcs of them together with recorcinol glue in a jig i had built to the shape of pipers wing tip bows.

We did this very same thing on a New Standard D-25 my dad is building/restoring and it made for an extremely strong piece. We were able to do the glue up and screw it onto the wingtip to let it dry in place. Working with a jig would work just fine as well.

 

[SuperCub MD]

Stick them in a flex dryer duct and splice the duct into your dryer duct system, then have the old lady dry a bunch of towels or jeans on high heat.

 

[JP]

Mine came from Univair. I just started at one end and worked my way around to the other. They went on beautifully.

 

[CubCouper]

Jim (at Univair) and Clyde told me years ago that their source for the bows was the Amish community back in Pennsylvania that has been making them since the original J3 was introduced. I suspect that anyone selling a "certified" part is getting them from the same source. Lead times were horrible, so I would suspect that various suppliers tend to purchase stock in annual or more batches, and that stock probably sits in the corner of a warehouse, gradually drying out and straightening itself until it is sold. I've had to replace one. I soaked it overnight, then tied a string to each end, long bow fashion, and tightened the string to slightly smaller than the needed size. Worked great. Capped firehose or flexible PVC sounds like a great idea.

My -12 project has metal bows. They look heavy, and Clyde suggested that I remove them-- said wood bends and breaks, metal bows transmit the shock of impact further into the wing. But there was a caveat (which I don't remember) about seaplanes, which is the targeted use of this project. Oh well.

 

[bobnall]

This year I replaced both wingtip bows. The first one went on out of the box by securing it a one end and working it to the other. Went well. The 2nd one broke using the same method. Univair said the 2nd one could have been older and thus dried out.

I got another one, tied the ends like a longbow, threw it out on the lawn, wetted it down and left it sit out over nite. Put it on the wing like the first and it went on just fine. Finished with 2 coats of spar varnish.

-Bob

 

[RON NORMARK]

Do not use spar varnish on bows if you are using Polyfiber system. The solvents will dissolve the varnish. Polyfiber has an excellent two-part expoxy varnish that resists solvents.

Ron

 

[Cimarron]

I had the same problem with univairs bows and they are good at replacing the broken ones. I just use hot water in the tube they send them on with plastic bag taped over down side end. Lasts long enough and is easy to dispose of afterwards.

 

[6 short]

Boz, I like your idea, had not heard of the method before.

Steam will typically give more flexibility to wood but it sometimes takes more time to get into the wood. A teakettle with a piece of radiator hose going to a device to hold the wood along with the steam works. Slant the tube holding the wood and put a small vent in it on the high end to allow a little flow. Don't pressurize the container, just restrict the flow to keep the part saturated with steam.

Pat