Down/Side thrust & pushers

[Hurra912]

Could someone, in lay terms, give a primer on down & side thrust? I am also curious how these rules apply to pushers or even push/pulls like the Do 335 or Cessna 225.

Thank you,
Wayne

[Sparky Paul]

Could someone, in lay terms, give a primer on down & side thrust? I am also curious how these rules apply to pushers or even push/pulls like the Do 335 or Cessna 225.

Thank you,
Wayne
.
There are no rules for either. Both can be used, or one or the other. It depends on the configuration of the plane, and its use.
The two full scales referenced probably have no thrust offsets.
As models have quite different inertial characteristics compared to full-scales, and different purposes, there's usually a range of offsets that are -typical- but not required for any of these.

[bz1mcr]

Down and side thrust are typically applied to the motor thrust line, with the objective of getting the plane to only speed up when the engine power is increased. With neutral or centered thrust, most models will tend to nose up and bank to the left when throttle is added. Note, most models use a single prop. in tractor configuration, and the prop turns clockwise when viewed from the front of the plane. Thus, most planes have 1-3 degrees of down and right thrust applied.

[Murocflyer]

That's a good question.

Not sure if I understood the answer. Is a thrust mod "typically" required on a pusher?

Thanks!

[HELModels]

If the pushing is done from above the center of mass. Not sure if C.O.M. is the correct terminology, but when you put the prop up high and to the rear of the main wing, then you have to point the thrust down a little more than seems necessary. On my version, I use a crude adjustable mount. I have tried variations on the angle and it flies best with some down. I also get an easy right turn tendency which is contrary to needing right thrust. To put it more simply, the right thrust on a tractor is to counter torque, but on a pusher rotating in the opposite direction, the torque is to the right, so the side thrust should be left.

[bz1mcr]

I have only one pusher. It is a slow flying "Frog" with the motor mounted well behind the CG. It is being flown per Hippos plans with 0-0 thrust. It does have a mild tendency to nose up when power is applied, if it was easy I would add a small thrust correction. I think the thrust should be pointed slightly down in the back, but I have not tried it since my stick motor mount is not adjustable and the stick is pretty well built in to the power pod. It would be a very minor improvement anyway, the Frog just flys well anyway.


I don't fly wings, but as far as I know they are all pushers and all fly with 0-0 thrust.

Don