Effect of moving thrustline outboard?

[Terry Caron]

Hi all -

My Cardinal ARF has thin inner and thick outer alum strips to clamp the engine lugs.
Tightening the bolts to minimize vibration (which doesn't seem to do a great job anyhoo) warps the inner strips badly (which means I'm compressing the bearer wood) and is beginning to pull the installed nuts out of the nose.
What would be the effect of using thicker strips under the lugs, thereby moving the thrustline farther outboard?

Or another fix?
Inletting metal strips between the nuts?
(May just make it easier to crush the remaining hardwood tho').
Something (glue, tape, sandpaper?) between the engine lugs/alum strips to "stick" them together so not so much bolt tension is required?

Any help appreciated.
Thanks.

Terry

[Brett Buck]

Hi all -

My Cardinal ARF has thin inner and thick outer alum strips to clamp the engine lugs.
Tightening the bolts to minimize vibration (which doesn't seem to do a great job anyhoo) warps the inner strips badly (which means I'm compressing the bearer wood) and is beginning to pull the installed nuts out of the nose.
What would be the effect of using thicker strips under the lugs, thereby moving the thrustline farther outboard?

Or another fix?
Inletting metal strips between the nuts?
Something (glue, tape, sandpaper?) between the engine lugs/alum strips to "stick" them together so not so much bolt tension is required?

   Probably making it 1/16" thicker will be unnoticeable. If not, then add a tiny bit of engine offset to put the thrust line back where it was WRT the CG.

   Brett

[Terry Caron]

Trying to "imagine it out", seems it would statically move the center of roll out, like added tip weight, and also tend to dynamically pull the plane out due to added drag.
Or do I have the mechanics/physics all wrong?

Terry

edit - or possibly pull it in like an "engine-out twin" effect?
Guess I don't have a clue to the physics involved!      

[Brett Buck]

Trying to "imagine it out", seems it would statically move the center of roll out, like added tip weight, and also tend to dynamically pull the plane out due to added drag.
Or do I have the mechanics/physics all wrong?

Terry

edit - or possibly pull it in like an "engine-out twin" effect?
Guess I don't have a clue to the physics involved!      

   There are several things going on. One, moving it laterally does change the lateral CG slightly, so you might have to take out a tiny amount of tip weight. You could even figure it out, the delta-CG is about, say, 1/16" with 10 ounces of motor, for a balance moment of out .6 in-ounces, divide that by 24" where the tipweight box is, so maybe you need to remove .025 ounces of tip weight. So, negligible.

   What you are doing that is more important is moving the thrust line further outboard of the CG, causing a slight nose-in yaw torque. So, if you put a tiny bit of engine offset, it will come closer to passing through the CG as you want to create no yaw torque.

    Brett

[Terry Caron]

Well good then - now I at least know what to look for.
With the .46 LA it has plenty of line tension, so probably won't be a prob.

Thanks Brett! 

Terry