Hi there,
I am looking for the formula that calculates the amount of engine thrust offset. I use to have a simple one in Excel ... but it is anyones guess where it went to. Thanks!!!

I am using 3 deg right thrust for everything because people who are interested in such stuff find that something about like that works pretty well for many set ups. The tangent of 3 deg is 0.05. So if you have an engine with the mounting holes 1" apart in the direction parallel to the shaft, offset the front holes 0.05" to the right of the rear holes.
If you have a phd in math I didn't mean explain the obvious. If you need to calculate how many deg right thrust is optimum for a given prop pitch, dia, rpm, plane geometry, and all else that factors in , I dunno.

The short answer is that there is no such formula. Offset thrust is used to compensate for the asymmetrical thrust produced by a turning propeller. The amount of unwanted yaw varies depending on the size and pitch of the propeller, the power being developed, and the speed of the airplane, way too many variables to be solved in a single formula. It also changes for every flight condition. For R/C airplanes it is usually enough to simply trim out any unwanted yaw with the rudder trim control. If the unwanted yaw is significant, the amount of offset thrust is best determined by trial and error, and as Jack Hyde says, somewhere in the vicinity or two or three degrees usually works about right.

For free flight models offset thrust is an essential part of trimming the flight profile of the model. A typical trim setup has the model climbing in a right hand turn, then gliding in a left-hand turn. This uses a combination of left rudder trim with right thrust. A lot of trial and error is involved in precisely tuning a free flight.

Thanks for your responses. One of the guys has sent me a message and because of his help I have the formula I seek. It makes it much easier to design properly. Once again ... thanks to all who responded

The one time famous Perigee has noted on the plan a 1/8 inch offset to the left side, and a 1/4 inch offset down, PLUS the two degrees of twist as already noted.

Wm.

Too many variables, including airfoil, and intended useage of the plane.

Perhaps we misunderstood the question. How about sharing the formula you received.