Here is a quick question: When sealing control surface hinge gaps (ail or elevator) where do you put the tape? On the top of the wing / stab, on the bottom, or both? And why?
Thanks,
Tom

On the bottom. The lower surfaces produce the higher air pressure so you seal that surface.

Huh???

Regardless of where the pressure is, you only need to seal one side to seal it, right? (If one side is sealed, then the gap is sealed and air can't slip through it)

Put it on the bottom so it's hidden.

I suspect that he is suggesting that the integrity of the seal will be protected by applying it to the high-pressure side -- the higher pressure tries to force the seal into the joint, rather than trying to balloon it out. Either way, it will work if it is properly sealed.

Thanks for the info! I had kind of logically worked it out already, just wanted some affirmation.
Tom

But the "high pressure" side changes as the control is deflected one way or the other. So there is never one high pressure side

Now you're applying logic -- that's not fun

How do you keep dirt and grime from sticking to the small exposed area of tape?

Khlash

Don't use tape, seal it with covering. I think most covering manufacturers still offer the clear.
When you do this it's very important to fully deflect the control surface in the opposing direction of the side you are sealing.
If you are still concerned about dirt, or subsequent build up in the gap, you can seal both top and bottom, or in the case of the rudder, both left and right.
For hinges, some modelers use two 1/2 to 3/4 inch strips,
seal it on the centerline on their bench (non sticky sides opposing), then apply it to the surface with the sealed centerline in the hinge gap.
Usually done on smaller than 40 size A/C.
This accomplishes both the sealing and hinge installation in one step.
Happy Flying!


Tom