Does anyone have a simple method for determining the offset ( how far off center to the left) the engine should be mounted to give a certain thrust offset, eg, 3 degrees and still have the prop located on the thrust line??

Appreciate any input.
Thanks
Bruce

Mount the engine on its mount, then measure the distance from the back of the engine mount to the back of the propeller. That distance is "y".

The thrust angle is "theta".

Then, the offset that will center the propeller is:

x = y * TAN(theta)

The distance along the fuselage center line from the back of the propeller to the center of the firewall will be, call it "z" :

z = y / COS(theta)

I would measure y, calculate the other, then make up a small triangle template and hold it up to fire wall just to double check that everything looks right.

I have a little diagram here that may or may not make it clearer... but I haven't had any luck getting it scanned and attached to this message (it's only 39K, but exceeds RCU's 700x700 limit). If you want it, I can attach it to an email. PM your email address and I'll send it. No problem.

JBruce: Go to the giant scale web site www.gsal.org they have a calculator for that very thing, just put in the numbers and it will calculate it for you. from the menu on the left of the screen click on tools and then motor offset. this is a very valuable tool for any offset. Rick

Convenient tool. It calculates this:

x = y * TAN(theta)

I'm glad you guys had the formula. I know I had it in one of my old text books, and I ALMOST started digging through those dusty boxes. (Momma told me math would come in handy some day!)

Pilgrim