Hi,
I'm rebuilding my P51 PTS after a crash,and am getting different answers from a couple of guys at our club about positioning the motor.
One is advising me to put the motor dead straight on the mount and the other is telling me to put it pointing approx 2mm to the right looking from the rear.
Which is correct,I really don't want to crash it again after rebuilding it straight away
Cheers

It depends on how much trouble you had with it pulling to the left on takeoff.
Mine did but I had no trouble controlling it with some right rudder. I mounted my engine dead straight.
If I was to add right thrust I wouldn't do it at the engine. I would add shims between the engine mount and firewall.
Keep in mind that any adjustment will make your engine sit differently in the front of the cowl.

The motor mount has the correct down thrust and right thrust angles for the PTS P-51.

You really do not want to change the thrust angles unless you have done something like screwing up a motor mount, so that the engine is slightly angled, etc.

Since most mounts are resin-plastic, I normally sand them down using a planar or band sander, to get any changes to the thrust I desire.

This works pretty well as the base of the mount is still entirely in contact with the firewall. It's also very easy and quick to do.

go with it dead straight and see how you get on with it, if it pulls to the right apply a few shims to the mount like missile said, ditto if it pulls left

sorry i cant be of more help bud, i dont have a P-51 PTS... []

IMO the right thrust will help in tracking straight during take off. Once in the air, however, I don't think the right thrust will make much of a difference. So, I would say if you are having difficulty taking off, add the right thrust, if not, no worries mate.

DaveB

Thanks for all your advise
I only had a bit of trouble at take off with the plane going left so that wasn't a hassle
My problem was that it actually winged over to the left on it's maiden flight but had very little damage
Later on when I was flying I had to keep using a lot of right controls to keep it straight
Finally had a major crash after getting caught in a side gust of wind while landing
BUMMER[:'(]
So I've been rebuilding the fuselage and the local guys have been advising me about the motor postion.
I think I'll just put it back straight first and see how I go
Again Thanks
Cheers[8D]

Nearly all models benefit by having a degree or more of right thrust built in. This is often done when the plane is built as the firewall will have the built in offsets on the better designs. You can experiment a bit by simply putting some washers or spacers between the back of the motor mount and firewall to change the thrust line and find out what works best for your model.

The firewall already has the proper thrust angles set, although you are free to experiment.

Sounds to me like your airplane was not trimmed properly?

Thanks again for the advise[8D]