E-conversion thrust line question...

[Metalhead]

Hi everyone,

I have a question....

I am building a Great Planes Ultimate and the firewall is marked for a gas or glow engine. As such, the centerline for the engine mount is offset to the left looking down from above and looking forward. I know this is done to counteract torque.

However, i am building this with an electric motor, so, the question is:

Do i use the same centerline as the gas engine or should i mount the motor in the center of the firewall?


Thanks,

Brian

[CF Av8or]

Brian,

The engine is offset to the left so that the prop shaft exits the cowling in the middle of the opening when right side-thrust is incorporated (for the purpose of counter-acting torque). You will need to do the exact same thing with an electric motor. The only difference will be in the amount of offset required to centre the prop shaft in the cowling opening. This will, of course, depend on the length of the motor and the side-thrust angle required.

The right side-thrust angle will be the same for the electric motor as for the gas/glow motor only if they produce the same amounts of torque. Some experimentation may be required to determine the side-thrust required for an different motor/propellor combination.

Similarly, engine installations typically incorporate some down-thrust angle to compensate for the extra lift produced as engine/propellor rpms are increased. This would require the motor mount to be offset upwards.

Cheers,
Vic

[Metalhead]

Thanks Vic,

That makes sense! I never though of it that way...

See, it's great to have this resource!!

Now i have to go plug some holes....lol

Brian