hebertjj

Hey,

The other day I dorked my Kaos 40 in on a landing - lotta sink, low approach, and dumb thumbs; instead of just letting it plop down in the tall grass, I tried to "save" it and ended up with a tumble that knocked the tail loose and broke one of the plywood hold down threaded plates that had a 1/4-20 nylon bolt in it.

I've got the tail and hold down plate fixed now, but I was wondering if a 1/4-20 bolt is overkill and would a smaller bolt have sheared instead of breaking the threaded plate. Is this desireable? Or is it a trade off between crash damage and ripping the wing off in some high G manuever? I would think that flight loads would mainly be tension loads and crash loads would be mainly shear loads on the bolts.

Anyone ever done a study on what size nylon bolts to use on a given model size?

Thanks,
Joel

rvd

Just reinstall the same style bolts that came with it..
1/4 20 nylon are fine.

Scorpionjack

1/4 X 20's are just fine. In fact out of 54 Aircraft currently in the stable 40 of them have 1/4 X 20's

As for G'Forces on a Kaos hmmmm That is such a good flying aircraft wing loading is light enough. I can't see you ever exceeding the limits of that aircraft. Except finding out the Ground Sucks. As you've seen already. : )

As for style of aircraft with what Nylon bolts?
Landing gear on a Q-500 I use 8 or 10 X 32 nylons. Wings are 1/4 X20's, and if I have a Bolt on V-tail they are on with 10 X 32 or 1/4 X 20's.
Wing hold down's on sports are all 1/4 X 20's other people I've seen use 10 X 32's but to me more is better, You just can't fly a missle in other words a Plane without a wing make a nice dent in the ground.

I never like steel bolts just a preference thing so I have always used Nylon. I love them on Landing gear as if a hard landing they shear and don't tear the LG Blocks out and can usually be removed without to much problems.

Hope this answers your questions.

Rodney

The 1/4-20 are fine if all you want is removable wings. If you want them to sheer in side loads, 8-32 are more than strong enough; in fact, 6-32 will do the job. I have several 1/4 scale jobs that are in excess of 17 lbs. and I use 10-32 on them. Never a failure under normal use.

hebertjj

Thanks guys! Some useful info here. I did assume the 1/4-20s were more than enough, and yes, I learned that the ground sucks! The Kaos is faily light, but tight turns make for high Gs even if it's light. I don't do a lot of neg G stuff (yet) though, which is what loads the bolts.

S-Jack, your example of 1/4-20 on the LG is what I was thinking of and you get nearly all shear on a landing foul up and I'm sure the AL gear slices the nylon nicely and makes for a much easier repair, but the consequences of a wing separation versus the LG coming off could be quite different ( a "missile" I think you called it; yikes!)

Rodney, you say 10-32 is more than enough? OK, I'll probably go that way on my next model.

Thanks again,
Joel

Scorpionjack

Herbert;
Your on the right track, As I said 1/4 X 20 I use for wings. 10 x 32 if thats what your thinking for landing gear is excellent also on the Kaos especially. Wing hold downs 1/4 x 20 since it's a bottom wing tight inverted turns and loops will pull against the mount bolts. Regular Knife Edge turns and standard loops will put pressure against the fuse. You won't have any problems either you decided will be fine.

bear750

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If you really want the bolts to shear on contact, CAREFULLY drill a 1/16" hole through the center of the bolt (not through the head. I've been doing this for over a year and never had one break unless the ground caused it...