Dear All,

This is a bit silly, but I can search for it and install it only if I know what it is called: I just received a US40+ kit a close friend built for me. However, he built it such that the nylon bolts that hold the wing to the fuse screw direct into some wood instead of putting in a nylon bolt nut (See picture). In many of my ARFs, the same arrangement has either a SCHS nut in the fuse side or a nylon nut there. I am worried that after assembling and dis-assembling the plane a few times, the screw will shear straight out of the wood and I will have a crash. So please tell me what the nylon nut is called

Ameyam

The setup you have there is very good and used in many airplane kits. You'll wear out the plane before you wear out the holes.

If you are at all concerned, wick some THIN CA into each hole to harden the threads but make sure it is fully cured before putting a screw back in it!

I wicked some ca in once, but I did not wait long enough, had to redo the whole hole again.

I should think you are referring to a blind nut. (?)

The 'nut' in the photo is just a hole with threads tapped in the wood. It is a perfectly fine setup for bolting on a wing. Like Minn and Minn said, after tapping the threads, drip in thin CA and wait until it is completely cured. Do not spray it with accelerator. After it cures, i like to run the tap through it again to clean up the threads.

Blind nuts are another option, but I don't like them as much.

I have a question. Can this part be replaced with hardware that is not nylon, say aluminum?

They are metal, and are called blind nuts. See below.

http://www3.towerhobbies.com/cgi-bin...?&I=LXD966&P=7

CGr.

^ Does it come with blind screws too?

Did some research:

I am told this is birch wood (or something like that, sorry if I am using the wrong terminology). Am told (like Minnflyer said) that it good enough. I will harden with CA however (there is only one type available in my country) purely to put my mind at rest, lest I keep worrying about it.

The metal screw and blind nut (SCHS, again correct me if I am wrong) is what the kit recommended and supplied, but he didn't use it. I have one ARF with the SCHS and the other with nylon nuts in the wood as described above, but never had one with this arrangement.

Right now I have started to worry about other things: the Oracover monocote that my friend used is old stock and has started to delaminate. He should have stopped and informed me so could get something else. Now I will have to tape it all over.

This plane was 60% built by me and then I ran out of free weekends so he completed it. I messed the rudder in a way that the plane is going to keep turning left. Hope the large control surface helps me trim this out

Anyway, I am posting pictures"naked" plane (sorry for the language but I am still to apply decals and it is past midnight here) for comments

Ameyam

You can always use the birch (or any hardwood) for now and if it loosens up, you can then install a blind nut.

Looks good so far.

If you don't like it drill it our and epoxy a 1/4 - 20 blind nut. With 5 min epoxy this is a 7 min job.

You MN guys always in a hurry[sm=thumbs_down.gif]

hi,

some places/stores will call them T-nuts for some reason..... not sure why but when i asked for blind nuts they had no idea what i meant then i showed them the one i had and the said Oh a T- nut sure there right over here.... LOL

so but as minnflyer said what you have will work very well.



bass

This only works if the CL of the new nut is on the exact CL of the wood screw holes now. Those screws don't always go in perpenduclar to the wood, but perpenduclar to the surface of the wing directly under the head of the screw. Putting in a blind or T nut is asking for trouble because it will try to straighten so the T part is flush to the wood.

Personally, If I get a kit or arf with the blind nuts, I remove them and drill and tap wood.

ShaneLittle, you don't want' a metal screw in there. Especially on a trainer. You want the nylon screw to break off if the wing whacks a tip. A steel or aluminum screw is a sure recipe for a totaled wing.

While we are talking about the nylon screws, as some of you guys on this thread don't have much experience with them, so a bit of advise. it is very easy to tighten up a nylon screw to the poiint of failure. It is strongest at the point it is tight. Make sure the screw screws in with little drag. screw it in finger tight then maybe 1/2 to 3/4 turn more. It won't feel very tight, but it is at it's strongest there. If you tighten it more, you are stretching it and it will take less stess to break it. There is no danger of it viberating loose either, which a metal screw in a metal nut will do if not tighten very tight. Hardware store 1/4-20 nylon screws are the best. I use them on any plane that has a screw on wing. I'm up to a 92" span now with them and have yet to have one break or fail other in an all out crash.

Don

<font size="4">i have an UltraSport 60 that has the same setup.  Nothing wrong with that.  Nylon  into wood is the same way mine is held on. The way that it is held on once you tighten the screws snug, it will knock the wing off, rather than bust the wing when it touches the ground, etc.    I assure you that whatever you can dish out in the air, that the setup you have will NOT fail.  My plane has done violent snap rolls, level to straight up, and everything else, and has not loosened a bit.   The plane is built simular to mine, I believe.  (someone correct me if I'm wrong)  You will like the plane.  </font>

I have seen kevlar reinforced 100" glider wings fold and the nylon screws were intact. They work great.

use a 1/4-20 blind nut if your worried. should be fine if that hard ply had a tap run through it for threading then you wouldnt need a thing just tsp the hole and fly.

I would just add a few drops of thin CA glue and let it cure. The glue and the wood fibers will become very strong, almost like some sort of composite material. There will also be some friction against the screw threads that help prevent loosening from vibration.

I would only add one thing and that is after adding the thin super glue...... let it soak in for a few minutes....
I then wick up any excess glue with a paper towel then hit it with accelerator.
Then I run the appropriate tap back through the hole. Usually 1/4-20. When I re-tap it , I do it with the wing in place so all the angles are jiving together. Make sense?

I also have a GP Super Sporster .20 and it has the same set up using smaller 10-32 nylon bolts.

No worries!

Looking at your post, yes indeed, what you want is called a 'blind nut'. Is is metal, and the most common size in the States is 1/4 - 20.

As has already been noted though, those wood threads can be just as strong if hardened with CA. This system has been used for wing attachment for decades. Very simple, very reliable.

Please note, avoid getting CA on those wing bolts. It makes the nylon brittle, and subject to cracking.

You are refering to blind nuts. Don't use them, the tapped wood holes work fine. In fact better than blind nuts. Metal blind nuts will eventually wear the threads off the nylon bolt, in fact it will strip them off if you cross thread them. The wood hole is not as likely to do this.

As a carpenter by trade, with all due respect, I can't say I agree with this statement. I see nothing wrong with blind nuts, and cross threading causes damage no matter how you look at it. In the case of a blind nut, the damage would be to the softer bolt. Easy to replace. In the wood, it would be to the softer wood. Not repairable ( in a practical sense) and a blind nut or metal insert would be the solution anyway.

As far as wear goes, I have never, in over 40 years, worn out the threads on a nylon bolt, talking them in and out a few times a month, even over several seasons. I loose them before that ever happens.

That being said, IMO, either way of mounting a wing is perfectly fine. I use both wood (for 60 size and smaller) and metal blind nuts (for over 60 size to giant scale, and for the latter I use metal bolts as well). Never lost a wing yet. (from wings bolts failing, that is).

OK, OK, I get the point. Wood with CA is the way for me... and I will not hurry the job. Wish someone cud do the same for the covering as well, but any way. How's the plane? Its my first kit...

Ameya

It looks fine for your 1st build..... be proud.
I always like to Put a pilot in the cockpit and an instrument panel and paint a frame on the canopy.
I even have one plane where the pilots head turns with the rudder! The kids love that kind of stuff....

I'm a big fan of monocote..... maybe in the off season you could try to recover it....... Maybe just fly the thing till its usefulness is gone and hope you have another project lined up to take its place.

Good luck to you

Ditto[sm=thumbs_up.gif]