When building in right thrust.... when facing the plane, prop spins left and as I was told (I think) add 2-3 washers under the front motor mounts... this is on a Profile with a 55 AX on its side... but, doing this pushes the nose left (when facing the plane) so the nose it seems is facing toward the prop spin? Isn't that backwards to counter balancing the prop inertia? here is a overhead and a front view.... thanks for any help...

A profile shouldn't have any built in right thrust. The engine should run just as straight as the fuse.
...But if you're wanting to add right thrust, one washer should be sufficient under the front mounting holes.

Avalanche,

The direction of engine thrust line offset is always referenced from the pilot's seat. So, what you have is right thrust. The reason for the right thrust has to do with P-factor, torque, spiral slip stream over the vertical tail, etc. Remember, right thrust is only a good thing when the airplane is right side up. If it's in a vertical climb or inverted, right thrust can actually compound the effect you're trying to minimize. That's why most acro planes have a zero thrust line.

Paul

To get the right thrust on your profile, add the washers to the front of the motor. I ran a little right thrust on my OMP Edge-540. What does your manual say to do? You can also experiment. Add a little right thrust and fly it. Then take it out and fly it again. See what works best for your particular plane.

The right side of the plane is the side where the right turn signal would be, if it had one. If you wanted to add right thrust, that's what you've done.
Eh? Right thrust counterracts the P-factor.

You'll know if you need the P-factor correction when you make a vertical climb. If yaws to the left, you need more right thrust. If it yaws to the right, you have too much.

Good luck,
Dave Olson

Avalanche2, You have already received a lot of good information, however here is a bit of background info. that may help you analyze whatever you might need.
Look at your head-on pic. Your engine is NOT mounted on the centerline of the fuse but just a bit off center. So every time you make a throttle change the model either receives (fast T) or loses (low T) a tendancy to turn left its left as seen from the pilot's station as 'pmw' so stated. The prop turns CCW as we look at it for starting but it's CW when sitting behind it.

Many new 1:1 scale pilots really get a shock when they start multi-engine training and find what happens when they lose an engine on one side and just how much rudder can make a difference. Ailerons with resulting induced drag only complicate the problem. Engines way out are truly a handful while even those with so called Center-Line thrust (engines close to fuse. or mounted on fuse) will require almost full rudder application against the dead engine to maintain heading when an engine fails on take-off at or just prior to T.O. speed. During landing, engine-out, you are constantly adjusting the rudder trim as you change power on the good engine.s and/or airspeeds during the approach phase.

Now since you with your RC model have no need to constantly adjust rudder trim every time you adjust throttle, the thrust-line adjustment will do it for you. Power back, no pull, Power up, the added power pulls right counteracting the left turn-in to assist you to maintain heading. When you learned RC maybe you had a trainer with engine downthrust. That is what downthrust does: counteracts the high-throttle acceleration which creates lift that requires something, elevator or downthrust, to counteract the effect of lift which increases by the square of increasing speed. If you just trim the elevator down, then when you pull the power back, hey it's dive time. [X(]

Yes that very small off C-L will make a difference. When combined with all those things the elites love to argue about, the machine, she is a-gonna turn left. [sm=50_50.gif] Engine offset is the answer. Shaved hard plastic beats washers because washers creep into the wood loosening your engine and mussing your fine paint job.

Edited to add: RC pilots have problems with multi-engine-out because they cannot quickly see which way the aircraft yaws, only a wing drop and generally apply significant aileron complecating the problem even more.

Go get 'em and keep it straight.

Thanks Hossfly and all for the input. It just seemed that as the prop is spinning CW it would be throwing its weight that way (CW) and with the right thrust built in it would only add to the effect.... but, from all the information this obviously isnt so... must be a physics thing... Thanks again all for the help in understanding "right thrust". P.S. Hossfly I have the shaved blocks maybe Ill make that switch out with the washers... thanks again...