FunK

I'm currently at the point on my Creek Hobbies Sukhoi where it's time to mount the wing hold downs.

Basically the kit uses 2 blind nuts and some (what looks like pretty cheap) bolts to hold the wing down.

The question is, would I be better off beefing these bolts up to a much thicker bolt and blind nut or do you think that nylon bolts would be the way to go? This is a 1.20 size plane and I just think that the bolts look a little cheezy for a plane this size...

So, Larger bolts (with appropriate blind nuts) or Nylon (through wood only) or with blind nuts as well?

The other question is in reference to the fiberglass cowl. I'd hate to mess up cutting all the needed holes for the engine and such. Is there a simple way to make a copy of the cowl (disposable). That I could use as a template?

I was thinking of perhaps wrapping the cowl in saran wrap and then spraying it with some form of adhesive to harden it. I just want something fairly strong to use after mounting the engine that I can hack up as a template... Anyone done this or have a bettter method? My idea seems like it would work, but I don't know how effecive it would be. I really don't want to have to use epoxy to make a copy if that's possible. It doesn't have to be pretty, just get the job done.

Thanks!

Vince

My Feedback: (1)

What size are the wing bolts? Typically ARF manufactures use 6-32, or 8-32 nylon bolts. I would upgrade the wing bolts to 1/4" nylon.

I know of no easy way to cut a cowling for engine clearance, it's always been a cut and fit operation for me.


Vince

FunK

They are perhaps 4-40 METAL. I'm not 100% on their size, but they don't look any bigger than that.

I'm thinking the same thing you are (1/4' Nylon). I've used larger nylon bolts on .60 size planes and had no problems. I'm just not sure that the older planes have seen the G's that this one might. Do you think I would need blind nuts to go with them (or just tap the wood hold-downs?). The holddowns are about 1/2" to 3/4" deep.

I'm still looking for the cowl answer. I've found a few tips and tricks in that forum. Some guys use pins to locate the needle valve / glow plugs. That might be one way to go. Aparently there is an ARF manufacturer that sells their kits with a clear plastic cowl (dummy) for just this purpose. I'd like to make my own dummy with the existing cowl.


Thanks!

Kevlar

My Feedback: (47)

For the bolt's, I'd recommend 1/4 nylon through the balsa make sure the receiving end is at least 1 ½ inches thick. Build the back side if you can. Then get a tap and thread the holes after you’ve predrilled them with 3/16” bit. Run the tap all the way through, and then add drops of thin CA down the holes. Let dry, run tap again, let dry and CA. (Remember to clean off the tap after each step, or the crud will be hard to get off) Do this at least 3-4 times to build some solid threads in the balsa. I did this with my Sig 4*60 and 120. Works Great!

As for the cowl, remember paper machete, flour and water mixed to soak newspaper and place over balloons? Do the same thing with your cowl, COVER with saran wrap first. And cover the plane where it might meet. I’d use about two layers of paper strips, squeezing as much gunk out as possible. REMEMBER to cover the plane with saran wrap as well. Don’t want the flour and water mixture all over the front end. Don’t worry about neatness yet, you can trim the paper cowl to fit and then start cutting your access/engine/muffler holes.

FunK

Both sound like excellent ideas. Thanks!

I had forgotten about using the CA on the threads. Makes perfect sense. I think the hold downs are ply blocks and not Balsa. I'm sure the same steps apply.

I'll probably go that route with the wings and beef up the blocks with at least balsa (behind the ply).

Paper Machete sound like it would work. I'd really like to keep it see through but that's not a necessity. I can hack up the paper version and still get everything accomplished by just doing it one time so that sounds good. I'll let you aknow how it goes.

Thanks again.