Shimming the motor mounts?

[muleyman78]

I talk to a fellow BH owner today. He told me that many builders including himself shimmed the motor mounts so the spinner is slightly down and to the right. He said it has helped a ton with the height of the nose at low power and full flaps as well as left turn tendencies. This builder is an engineering expert in aviation. Said it was a touchy subject on this forum many years ago. Has anyone else done this or even heard of it"

[Mark Goldberg]

I do not think "many" Bearhawk builders have done this. Just a few. I have never seen the need on my BH. Your plane/project. Do what you want assuming that how you do it does not cause a structural problem for your plane. Mark

[Battson]

Sounds like it might help for this few moments at T/O and landing. For the other 95% of the flight in cruise, would it be any help? Or would it hurt?

I see no need on my plane. I can't imagine it would help much at all with visibility over the nose, unless you are talking about some huge shims.

[whee]

I've head of it from one guy. He said it mainly helped during takeoff. He couldn't keep the plane on the center line during a max performance takeoff unless he started aligned ~30deg off the center line. He didn't like that so he added a couple washers on the left side. I think there is only a very few guys that have done it. I personally don't see the need but obviously others feel differently.

[Battson]

He couldn't keep the plane on the center line during a max performance takeoff unless he started aligned ~30deg off the center line.

I find that hard to believe. Something else must have been wrong?
The Bearhawk has a huge rudder and under power the pilot has massive control effectiveness, keeping a kit-built plane straight is very easy during all phases of flight. In fact, you can easily swing through a J-turn (left or right) into a take-off under power, although not full power until you are starting to point the right direction - wouldn't want to roll the plane into a ground loop.

[whee]

I agree about the nicely sized rudder; one of my favorite features. All I know is what I was told. I could see a 260hp engine swinging a big prop having significant p-factor and not being able to counter it till there is some airflow over the tail. Cobbing the throttle from a standstill could require some brake to keep things reasonable straight. That is what this kit builder was referring to. I think better pilot technique, throttle finesse, would be better than shims.

[Mark Goldberg]

No problem keeping my 250 HP Bearhawk on the centerline using a full power take off. Even goosing up the power while holding the brakes. No problem. Mark