Purpose of the Thrust Angle?

[clipper453]

What exactly is the purpose of the thrust angle that's designed into the Super Cub?

I've been considering converting my SC over to a brushless configuration, and I noticed "NoFlyZone" over on the RCGroups website had detailed conversion instructions that included keeping the original thrust angle. (Ref: www.rcgroups.com/forums/member.php?u=106813 )

Is it necessary to keep the thrust angle the same when converting to a brushless motor? Is there any reason why the thrust angle should be changed? What would happen if there was no thrust angle, and the axis of the motor was in parallel to the axis of the fuselage?

Thanks in advance.

[mrmugen]

The thrust angle keeps the plane from rolling on it's own when throttle is applied. If it were straight inline with fuse this would happen a lot. Kevin

[clipper453]

So does that mean the thrust angle should be changed when upgrading to a higher output motor to account for the additional torque? If so, how do you calculate the optimum thrust angle?

[mrmugen]

Well I have been using the stock thrust angle with my BL cubs and it works fine. I would say that once an angle works withthe airframe then it sould work no matter the power source....I may be wrong. I have used several planes with big and small motors and used the same thrust angle on all of them.....no issues. Kevin

[cjg]

Theoretically it should change with power/rpms. However, the power band that motors run maybe narrow enough that an "average" setting like the stock angle works for a range of power.

[spar]

Presumably real airplanes have a thrust angle on their motors (engines?). Is the need for a thrust angle canceled if one has two motors? They'd probably have to spin opposite directions though.