[fixer]

I have a Hobby King 1250 mm ws Tiger Moth ARF which I'm re-building because it did not fly at scale speeds very well. I found the motor mount had been re-attached at some point and had been placed almost concentric to the fuse. (no thrust angle, just some offset) I'm assuming that this is not a recommended mod, and would like to reestablish the correct/recommended thrust angles. Can anyone advise. I have the instructions for the (arf) kit, but no thrust angle is given.

[kip51035]

2.5 deg. down and right are standard. On an aircraft that size move the back of the motor a little over 1/8" to the left then angle it to the right until the prop is back in the center. to check for the proper right thrust: Fly your aircraft straight away from you in level flight then pull it straight up. After a short distance idle the motor and observe which way the nose goes and correct accordingly. You might have to set the rudder trim to get it to go straight up first.

[fixer]

Thanks for the quick reply kip51035. I should have mentioned I'm a neub pilot. If I read this right, I get in level flight running away from me (I'm looking at the tail) with whatever throttle (1/2-3/4 ?) to keep it straight and level, then I pull it up to run vertical, (I'm looking at the top view of the plane). After establishing vertical flight (adjust rudder trim as required) I cut the throttle to idle (prop still spinning) and observe which way the nose moves. Once again I'm assuming, but the plane will start to fall back, like a hammerhead. The part I'm not sure about is if the nose were to move to the right, would I be correcting the thrust angle back somewhat to "0" or just compensating with trim? Thanks, Fixer...

[kip51035]

Yes you got the idea, when traveling up under power, use rudder trim to get it to go straight up. Probably not very far with that aircraft. While traveling straight up you chop the throttle to idle if the nose continues to go the same way every time, adjust the thrust line to suit usually using washers under the mount. Washers come in various thicknesses.

[fixer]

Got it. Thanks for your help. One less hurdle.