pinnedup

My son’s World Models Sky Raider Mach I augered in over the weekend, hitting on the wing tip first, then the nose. The wing broke off, ripping the wing bolt support and hold down nuts off the fuselage. The wing remained intact although damaged but the fuselage cracked in two at the point of the wing bolt connection, the wing bolts were the original 4x35 mm steel. I imagine nylon bolts might have reduced the damage to the fuselage and want to replace the 4x35 mm steel bolts with nylon bolts. The Sky Raider Mach I is a high wing trainer.

Do I need to increase the diameter of the wing bolts when I replace them with nylon bolts? What size of nylon wing bolt should I use? Where do I find 4x35 mm nylon bolts?

ArCeeFlyer

My Feedback: (1)

I assume this is a .40 size plane. 1/4" x 20 nylon wing bolts are the most commonly used. Should work great and will more likely snap the bolts in a crash reducing damage.

parrthd

first off, what size plane is this?

next most all my .60 size planes have 1/4-20 nylons bolts in them, two on the trailing edge of the wing, my current project has one at the fore end and one at the aft end of the wing chord. i fly pretty hard most of the time and i've not had any problems with the 1/4 bolts being weak. i figure if they hold through a dive and climb maneuver they'll hold anything i'll be doing.

now as far as 4X35 mm, if you're going to have to rebuild it anyway you can make the holes whatever size you want.

if you do change sizes i use this procedure. use basswood blocks for the wing hold-downs at least 3/4 to 1" thick. drill for whatever size bolt you plan on using, (if you're not sure, ask and i'll be glad to tell you.) AFTER you've tapped the holes flow several drops of thin ca into the hole to harden the threads. i would wait a minimum of fifteen minutes (i usually wait overnight making this the last thing i do before bed, tv, shower, etc.) run the tap back through the hole to just "clean up" the treads and make sure no "globs" of ca are in there.

now you've got wing bolt blocks that will probably outlast the plane!!!

hope this helps.

pinnedup

The Sky Raider Mach I is a .40 size plane with a wing span of approximately 66". What size nylon wing bolt would you recommend?

In your procedure using basswood blocks for the wing hold-downs there is no metal blind nut? The boly is tthreaded through the CA hardened basswood alone?

Thanks,

ArCeeFlyer

My Feedback: (1)

The 1/4-20's will work fine for that. The hardwood threaded blocks that parrthd mentioned work great. I have used maple myself. Be sure to glue the blocks in before drilling and tapping. Get the wing in place and use those holes as guides to drill the blocks so it matches up. Tap them, thin CA them, tap again to clean out. The blocks are deeper than a blind nut and hold much more surface area on the threads for a much better hold and less wear on the bolts.

Richard L.

My Feedback: (24)

I use 10-32 nylon bolts on my 40 size planes and 1/4-20 nylon bolts on my larger planes.

MinnFlyer

My Feedback: (4)

What Richard said holds true if you're looking for the bolts to snap.

1/4 - 20 nylon bolts will not shear as easily as you might think - you will most likely snap your fuselage with 1/4" nylon bolts (Regardless of plane size)

When nylon bolts were first introduced for holding wings on, that was the popular theory, however, many broken fuses have proven that theory wrong. But they are still used for mainly two reasons:

1 It's easy to drill a single hole through the wing and block and then tap it

and

2 A nylon-on-wood connection will not allow the bolts to vibrate loose (which can happen with a steel-on-steel connection)

Rodney

Actually, you could even get by with 6-32 Nylon. I only use 10-32 on my quarter scale (12 to 17 pound) planes.Average tensile strength for 6-32 is 30 lbs., 8-32 is 85 lbs., 10-32 85 lbs. Average sheer strenth is 15 lbs for 6-32, 40 lbs for 8-32 and 150 lbs for 10-32. Since you will be in tension, you could pull 10 Gs on a 3 pound model with a single 6-32 holding the wing on, 20 G's if you had two bolts. The weaker sheer strength are good as, in ground loop or crash, the wing will sheer of with minimal damage to the structure it is tied to. 1/4 20's are much to large for anything if you want minimal structure damage as a result of a misshap. If all you want is a removeable wing, then anything will work, just expect lots of structural damage in a crash.

ArCeeFlyer

My Feedback: (1)

I also agree that the 1/4-20 nylons can be strong enough to tear out wing hold down plates, blocks and such. I've seen it go both ways and I guess it depends a lot on the plane's structure. I like the 10-32 idea for better fuse damage prevention.

Bax

My Feedback: (11)

The original Top Flite Contender used one 1/4" dowel at the leading edge and two 8-32 nylon bolts at the trailing edge. This provided plenty of strength to hold the wing on the model through all of the flight stresses it would encounter. They would, though, shear if you had a good blow to the wing. I know, because I sheared a few sets of bolts in my first Contender.