Help with thrust angle

[lakedude]

I like the way my xb29 flys stock except for the battery life. A bigger pack will fix that easy. The problem I have is with the EDFs being lower then the fuse and getting torn up. I plan to modify one of my xb29s by putting the engines on TOP of the wings to solve that problem. When the engines are below the wing they are below the vertical center of the pane so they would tend to make the plane nose up when switched on. Puttin em on top the wing is gonna make em push the nose down when they kick on. Clearly if the engines are gonna be on top the thrust angle needs to change so the engines will have the same affect as when they were on the bottom. How do I figure out the proper angle? The plane is not tuff enough to use the old trial and error method.

Notice EDFs sit below fuse in pic:

[BMatthews]

I doubt if it will make much difference. With the thrust coming at the mid point of the model thrust angles won't have much effect. I'd just move them up on the same angle as they are.

It's sure gonna look odd though. What about a couple of music wire skids instead?

[Ollie]

Why not mount adjustable vanes horizontally in the out flow of the EDF's so that the vanes can redirect the flow a bit? If you pivot the vanes at 25% of their chord, the stress on the mounting and adjustment mechanism will be minimized.

[Sparky Paul]

I'd put in some upthrust... for the illustrated reason.
If the plane flew OK with the c.g./thrust below, it will pitch down with the motors raised...