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Securing the Wing Tube - 3/12/2003 2:43 PM   
3DwanaB


 

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From: San Diego, CA, USA
Status: offline 		Is there a better way to secure the wing tube in the phenolic tube other than the hose clamp method. This is for a 33% AW Edge 540T. Any suggestions are appreciated.

Thanks

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Securing the Wing Tube - 3/12/2003 8:27 PM   
CAP232CM



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Status: offline 		Why would you want to do that? I would want the tube to pull out for easy transport. It's not going anywhere once the wings are on an screwed down.

On my Somethin Extra since the wing tube was so small I just left it in. I secured it with a machine screw. I just drilled a hole in the center of the tube and put the screw in.

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Securing the Wing Tube - 3/12/2003 10:04 PM   
tkilwein



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Status: offline 		I use some tape wrapped around the metal tube at the point it slides into the fuse section. This is a tight fit and holds the tube
when I slide the wings on. I have a miss san bernadino 12ft wing
10ft fuse I use this trick on. Like the earlier post when the wings are on the tube will not go anywhere. The tape just holds the tube so you can put the wings on.
Hope this helps.
Tony

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Securing the Wing Tube - 3/13/2003 11:27 AM   
3DwanaB


 

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Status: offline 		CAP232M: The pilot and builder of the Edge used the hose clamp method to keep the wing tube from moving off center. You gently tighten the clamp on the phenolic tube to keep the wing tube in place and when finished flying, you release the pressure and remove the wing tube. The wings have no stops in them and supposedly, vibration forces can cause the wing tube to rotate and move away from center and out of the wing. Using a machine screw sounds like a good idea. I don't see why I can't just drill a smalll hole through the phenolic and wing tube and use a nylon bolt to hold it in place. Thanks

tkilwein: The tape method is also a good idea. I'll have to try it although the wing tube is already pretty tight going into the phenolic tube. Thanks

I appreciate the responses, what other ideas are out there for securing the wing tube, any pictures???

Take Care,

Gary

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There is a different way - 3/13/2003 11:40 AM   
JRozman-delete



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Status: offline 		3DwanaB,

You can shape and glue a 1/4 thick ply pad on the phenolic tube. Then tap the ply pad for a 1/4 nylon bolt. DO NOT DRILL AND TAP THE WING TUBE. Then you can slide the tube in, and then tighten the nylon bolt against the tube.

Jess

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keeping the wing tube from moving - 3/13/2003 11:59 AM   
shill



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Status: offline 		Well I am going to assume you have stops at the end of the phenolic tubes in the wing.
the phenolic tube used for wing tube socket is the same tube they use for some high power rockets and you can go and get a body tube coupler from a hobby shop that sell the more advanced rockets. Or check online at Greatlakeshobbies.com The coupler is a snug fit in the wing tube you will center your wing tube in the fuse measuring the tube sticking outside on both sides. Then measure into each wing with a yardstick not a tape measure it is not as accurate. Take the measurement of the tube in the wing and subtract the measurement of the tube sticking out of the fuse and subtract 1/8 of an inch for any variance and cut a piece of the coupler and slide it in the wing tube and push it down with the wing tube repeat for the other side and you are done no bolts no clamps no nothing simply put the wings on and off. The coupler tubes keep the tube from sliding side to side it might move 1/8 to a 1/4 of an inch but no problems here.


Steve Hill

< Message edited by shill -- Mar 13 2003 4:06AM >

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Maybe this will work for you? - 3/13/2003 12:26 PM   
bdphil



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Status: offline 		I just bent up a custom cotter pin and use it to hold my wing tube in the correct place. Keeps everything centered and real easy to remove if you want (a little tricky to get it lined back up if you remove it). Hopefully the pic shows up OK.

Ben

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Securing the Wing Tube - 3/14/2003 2:05 AM   
mulligan



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Status: offline 		Yikes!

I don't know about drilling holes in wing tubes- seems like a small hole, but...

- George

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Securing the Wing Tube - 3/14/2003 2:46 AM   
CAP232CM



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Status: offline 		I have a question. Why is it not ok to drill holes in the wing tube? I have 3 airplanes with plug in wings and stabs and I've drilled and taped them all. I can't see a hole for a 4 40 screw doing any harm to the tube. Can someone elaborate a little more why this is not ok. Thanks!

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Securing the Wing Tube - 3/14/2003 3:05 AM   
mulligan



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Status: offline 		Forgive me.

I'm not very experienced with wing tubes or their strength/safety factor.

But basic engineering suggests that removing material at the highest stress point on a structure is not a good thing. On a wing tube (or any basic pass-through wing structure), the highest stress point is at the top and bottom of the center of the tube.

There may be sufficient strength in the tube to tolerate this, but it certainly weakens the highest loaded part of the airframe.

To get even more picky, not only is there a weakening of the structure to static stresses, but, especially in the case of tapping threads in the tube, a hole provides a crack initiation site. If you're lucky enough that the plane lasts awhile, fatigue cracking might begin.

If you had to put a hole in a tube, the best place would be at the 3 and 9 o'clock positions and as far outboard as possible.

- George

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Securing the Wing Tube - 3/14/2003 9:40 AM   
bdphil



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Status: offline 		mulligan,

I disagree (a little). If the wing tube were unsupported for the entire length then the highest stress would be in the center. Being that the tube is supported at the fuse sides by plywood, the weakest area should be just outside the fuse? I'm not a certified engineer, but the bent wing tubes I've seen (from crashes) were bent at the fuse sides. If my planes last long enough for the tube to develop cracks, I'll let you all know.

Ben

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Hole in wing tube-bad idea - 3/14/2003 12:07 PM   
EJB


 

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Status: offline 		I've seen an AW 31% Sukhoi fold it's wings after about 6 flights.Cause? That's right....hole in the wing tube.Guys around here use the method in post #5.

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Securing the Wing Tube - 3/14/2003 10:37 PM   
mulligan



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Status: offline 		[QUOTE]Originally posted by bdphil
mulligan,

I disagree (a little). If the wing tube were unsupported for the entire length then the highest stress would be in the center. Being that the tube is supported at the fuse sides by plywood, the weakest area should be just outside the fuse? I'm not a certified engineer, but the bent wing tubes I've seen (from crashes) were bent at the fuse sides. If my planes last long enough for the tube to develop cracks, I'll let you all know.

Ben [/QUOTE]


Your point is well taken. The highest stressed point could be just outside the fuse if the fuse wall thickness is sufficient to resist bending stresses. I don't think that is the case, though. In crashes, the high impact shear forces from the inertia of the wings might cause the tube to fail at the fuse wall.

Not sure about phenolic, but aluminum LCF can begin after just a couple hundred cycles if loading is high enough. If you pull a few hard maneuvers in each flight, fatigue cracking could begin in only 30-40 flights.

This is all qualitative of course- I have not done any kind of quantitative analysis, but it doesn't really matter, I'm sure you'll agree- the main point is that removing material will weaken the structure to some degree, so don't do it if you can avoid it.

- George

< Message edited by mulligan-RCU -- Mar 14 2003 2:46PM >

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Securing the Wing Tube - 3/14/2003 10:59 PM   
bdphil



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Status: offline 		[QUOTE]the main point is that removing material will weaken the structure to some degree, so don't do it if you can avoid it. [/QUOTE] - I do agree

I like that nylon bolt idea. I think I'll go that route on my new plane just to be safe.

Ben

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Securing the Wing Tube - 3/15/2003 12:53 AM   
3DwanaB


 

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From: San Diego, CA, USA
Status: offline 		Thanks for all the great ideas and comments guys, very informative and creative. If there is a picture out there of the suggestion in Post #5 (Thanks Jess), I would like to see it. I just received a CF tube from Troy Built and concerned about the wear and tear of any kind of bolt against the CF wing tube, aluminum would probably be no problem???

Also, the wing tube coupler idea in Post #6 (Thanks Steve) is a possible solution although the wing tube fit in the wing seems a little tight for a coupler, I'll have to check it out and if feasible, try to purchase the coupler material. There are no stops in the wings so would probably have to very carefully drop some CA on the coupler in place in the wing, yikes!!!

Hey, the high-tech description of wing tube stresses and crack intiation sites was great, very interesting info (Thanks George).

...and thanks to Ben for his comments, I hope your cotter pin method continues to hold up. If it's a small hole and sealed with CA, you would think no problem.

Thanks again to all contributors, any more ideas and/or pics out there

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Securing the Wing Tube - 3/15/2003 9:35 PM   
BAS



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_____________________________

Bruce A Swartfager

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Securing the Wing Tube - 3/15/2003 9:37 PM   
BAS



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Status: offline 		I am putting together a Radiocraft 33% extra 330, i just ended up putting expozy on one half of the wing tube slid it in left wing half and that will take care of the problem with wing tube moving inside the wing or fuse tube. Have used this method before with no problems

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