Im finishing off a scratch built Stik, and was wondering about wing hold downs. Im going with bolts, but was wondering what everyone considers the best way to go about it. 4 bolts (2 in front, 2 in rear), OR using a dowel or two as locating/locking points for the front, with 2 bolts in the rear?

Any of your prefered methods to install the front bolts / dowels would also be appreciated. I basically have the wing to the point where I need to add the supporting plywood for the bolts or dowels, and would just like some insite on these methods.

Thanks!

Clay

If you go to www.bestrc.com and download the manual for the Great Planes PT-60 kit, they show pretty good photos of how to do it using a front dowel.

+GLH:

If you tend to have "Active" arrivals you might want to use rubber bands. Beyond that, I have planes using dowel/screw retention in the mid sizes, but over 1.0cid total engine size I generally use four screws.

Bill.

Ive actually thought about incorporating both wing hold downs on this plane so I can see which I like better.

As for the dowel method, is there any advantage to using two dowels vs. one? This is actually an Ugly Stick from Phil Kraft plans. Its a little bigger than a 40 sized Big Stick, and a little smaller than the 60 sized Big Stick. So Im probably going to go with a .60 sized engine.

Clay

Clay:

Up to 0.25 I'll use a single dowel, but larger I prefer using two. Not only is it stronger than a single of the same size, but the greater advantage is spreading the load and being more rigid.

Bill.

I would go with the two dowl system as stated above, helps to spread the wing loading.

FYI I would consider using aluminum pins in lieu of dowls. I have an Ultrastick 40 with a Saito 61 on the nose. Noticed a puff of smoke coming from the front of the wing at the fuselage on shutdown. Dowls had burn marks and had "worn" 1/3 way through. Saw on another post that this is not uncommon in aerobatic a/c. Removed the wood dowls and replaced with solid aluminum, also beefed up the front hold down former.


Jim

Clat:

Jim's post brought another thing to mind - slop in the mounting. If there is no slop, the dowels can't rub, and they do not wear or burn.

Using rubber band mounting, or four screw mounting, there is no relative movement between the wing and the fuselage.

If there is no clearance in the dowel mounting it's too tight to assemble the plane, slop is necessary.

The cure is make everything as tight as you can, and then put foam tape on the wing seat. Multiple advantages. It seals the joint and keeps fuel residue out, it prevents wearing of the wing and seat from vibration, and it holds the dowels firmly in their holes so they cannot move and get worn.

Ideally, the wing will sit with the trailing edge about 1/2" off the seat, having to be forced the rest of the way with medium finger pressure, then the screws keep it in place.

Bill.

Can anyone point to directions on how to make a wing a bolt down, instead of a rubber band type? I haven't started on the wing yet, figured now would be a good time to ask.

thanks

Jason

In case you're wondering I'm building a stick 40 plus with no dihedral in the wing.

Check out www.greatplanes.com and go to their manuals. (like listed in the 2nd post of this thread). The PT-40 manual shows very well how to install a front dowel and rear bolts.

Clay