SBarber

I'm building a 3 meter sailplane that has a thin glass covered balsa wing with flaps and ailerons. The wings have servo access holes but nothing to mount the servos except a reinforced glass surface. I have hitec digital wing servos for the wings that come with peel and stick mounting tape. The question I have is do I need to glue wood into the wing to help secure the servos or will the tape be sufficient to hold the servos?

Thanks for any help.

Steve

forrest adams

you never want a permanent installation (servo gears and arms can be damaged and need to be replaced - this of course requires that you remove the servo - i've had to replace both).
i usually shim (on the sides using thin plywood or hard balsa) then tape over the servo and outside skin (that works fine). the peel and stick tape sounds ok, however, i've never tried it. just remember, someday, you'll want to remove that servo and you don't want it to damage the upper skin of the wing. the shim/tape method is very comman among sailplane pilots and works very well - i still use it,like it, and have never had that method fail.

isoar

My Feedback: (1)

I would not use the double sticky tape on a bet. First thing you do is cut off all the mounting lugs on the servo. Second make a light balsa shim the size of the servo but just thick enough that it allows the servo to be flush with the bottom surface of the wing (the side with the hole you are working in). CA the balsa shim in place and then CA the servo to that. Just 4 drops of CA in each step. You'll be able to break this bond or split the balsa if you ever need to get the servo out.

Now for the most important part. The servo now needs to be glued to the bottom wing skin as well or else the top skin will flex and buckle under load. You should have positioned the servo in such a way that with a little epoxy with micro balloon thickener you can make this bond. The servo is flush with the bottom wing surface so this process is just shoving the glue in the butt joint crack between the lower wing skin and the servo. An exacto knife can get through this bond if you have to in the future.

There are a zillion ways to mount wing servos, but this works for me. I've also used silicon and goop and it works fine as well. Key point with any method is the servo must be firmly attached to both top AND bottom wing skin. The problem I see with the double back tape is after a few years (and we hope your plane will be around still) the stickiness may give up. Also, there may be some movement (which makes control slop) with a tape installation. There are nifty commercial mounts you can buy too, but I'm too cheap for that.