ORIGINAL: CGRetired

Thanks.

What I have is a Seagull Super Star. This plane has an arrangement with one rudder servo and two elevator servo's under the horizontal stab. I opted to make the rudder system as pull-pull which eliminates one servo back there. On the elevator, the holes in the fuselage that were already there, have the servo arms on the same horizontal plane. That makes the choice to have differential or use a Y with a reverser, which is what I did.

The reason I brought this up was that I was somewhat concerned about the potential differential (confirmed by Bruce) that will occur with the up-down setup without a Y Reverser. I was looking to see if the DX7 had some sort of mixing scheme to put the elevator servo's on a separate channel then have them operate that way, but thought that it would be much simpler for the elevators to be connected via the Y Reverser.

And, as I said, in another posting, there is the mention of this up-down setup and I was thinking of the differential posed by such an arrangement.. as of course could be corrected as Da-Rock suggests. But, that means that different cutouts must be made in the fuselage to accomodate such an arrangement.

So, it seems that the simplest design would be to use the Y Reverser.

A third choice, of course, would be to put the servo's in the wing saddle area (there is certainly plenty of room in the Super Star for this) and use either rods or pull-pull. My Excelleron 90 has pull-pull elevators AND rudder. That's a lot of cables going back to the tail.

Dick.