Hi All,
In my building instructions for SIG Kadet Senior I have two options for engine mounting - zero or right side thrust. I don't know what is better.

10x.

If you build it as a taildragger, right thrust. With trike gear it won't matter much but a little right never hurts.

I just built that plane and chose to go with the right thrust. It flies just great, of course it is one plane on a short list of planes I have constructed so my opinion probably shouldn't carry too much weight. But it seemed that when I asked that question the general consensus was that it is better to have it. I found the instuction manual only omitted it for sake of ease. It's really not any more complicated than the steps outlined without it.
I had to play with the shim a little bit to get the angle just right. You may want to purchase a one-piece engine mount of the same size in order to simplify the process. I found that the engine got pinched between the two mounts (because one was at an ange and the other is not) and this put a lot of undo stress on the blind not that you epoxy to the firewall. Mine almost became stripped. It all worked out though. How is the plane going? I had a great time building mine.

right thrust

Hi vinnie, why is there a diff between a taildragger and a trike ? Any technical explanation for it ? Thx......

You will benefit from some right thrust regardless of whether it is a tail dragger or not. You may also require some downthrust, especially if using the larger size engine, to keep from having to continually adjust elevator trim as you change throttle settings.

Rajul,
the reason for right thrust is to counter the effect of prop torque pulling the aircraft left on the ground. A nose gear tends to lessen that effect somewhat. A taildragger's ground handling benefits significantly with a couple of degrees right thrust. But as I said, a degree or two won't hurt in either case with the airplane in question.

Rodney and Vinnie said it all.

You also need right thrust to keep the plane from veering to the left when going vertical. That's a good way to see if you have enough. As for downthrust with a pattern plane and everything else being right down thrust will make it fly level inverted. To little down thrust and you will have to feed in some elavator

Thanks folks. Why does the engine torque create the tendency to veer left or upward ? Is there an explanation from a physics or engineering standpoint ? Thanks again........

The downstroke on the prop is more effective thus the tendancy to pull left.

P factor is cause by the angle of attack on the blades of a prop.In level flight the ascending and descending blades have equal angles of attack,producing uniform lift. As the plane enters a climb,the descending meets the air at a greater angle of attack than the ascending blade and as a result produces more thrust.This increase in thrust produces a left turning tendency,which can be countered by right rudder,engine side thrust or a combination of both.

Hi John, what if the plane is descending ? The higher AOA of the ascending blade will then cause the plane to veer right. If there is a right engine thrust angle, the tendency to veer right will be aggravated during a descend ?

Rajul you are testing my small mind now,but here goes.When going to a negative-G maneuver,the force is applied to the top of the prop as it spins,causing the effect to be felt on the right side and can be countered the same as P- factor.This is called the gyroscopic precession.All of this is if the prop is spinning to the right,if spinning left then the corrective action will be opposite.

Hi John, I've printed your post and I'll mull over it later. Now where did I keep that college physics book ? Good to go back to basics once in a while. Thanks again...........Mike