OK- I'm using DuBro hinges in my 8' balsa B-2 bomber. #1-Should I install hinges before or after covering w/Monocoat. #2-If I closed up a space without putting extra balsa behind a 1/4" wall will pins be enough to hold the hinge securely? The a/c will probably be a slow flyer. Thanks for any help.

It's always easier to do the final install of any hinge after covering. I would put a little more meat than 1/4" where the hinges go and glue them in addition to the pins.

Hinge after and then seal.

How is this plane powered? How big are the control surfaces? How many hinges each? I like to put a hinge about every 3" or so. If you do that and pin them AND you don't put the plane in terminal velocity power dives, then you should be fine. But it wouldn't hurt to put another 1/4" piece of balse behind that trailing edge at the hinge locations. Why skimp if it can cost you the plane?

Thanks for the reply Cafeenman. It's an 8' span B-2 bomber with an OS70x4 stroke on the nose. All up weight should be 9lbs. The control surfaces are scale to the real thing and are pretty big. The plan shows hinge location but I think I will put in an extra hinge on each surface. I don't know if the plan conforms to you're 3" rule but it sounds good. I definitely plan on pinning using tooth pics. Considering that I closed everything up how can I add another 1/4"of balsa? If I pin through the 1/16" top and bottom sheeting just inside of the 1/4" hinge surface do you think it will be ok?

That should work. 3" is just a base starting point. If it's 2.75 or 3.75 or whatever. I just make sure that there are enough.

With that size engine you shouldn't have to worry about it if you pin them as you say.