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Old Sep 04, 2004, 07:15 AM
high tech redneck
Greenville, SC
Joined Feb 2004
69 Posts
which way does a motor pul

I think I mounted this motor wrong I gave it down and right....isnt it that the motor will natually pull up and right???
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Old Sep 04, 2004, 08:03 AM
Registered User
Staffs, UK
Joined Nov 2003
10,559 Posts
Mounting with a little down thrust and right thrust is perfectly normal (assuming it's not a pusher). Not all models need either down or right but I don't think I've ever met one that needs left .

Steve
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Old Sep 04, 2004, 08:23 AM
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Dr Kiwi's Avatar
Chattanooga, Tennessee, United States
Joined May 2003
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Under power there will be a tendency for the aircraft to climb - hence the need for ~3 degrees downthrust.

Now to the "right thrust":

Look at your aircraft head on - the prop will be turning counterclockwise won't it. Every action has an equal and opposite reaction - thus the aircraft will have a tendency to roll clockwise, as an opposite reaction to the centripetal force exerted by the counterclockwise turning prop. Rolling clockwise will drop the left wing, thus instigating a left turning action - giving the motor ~3 degrees right thrust will balance out this left-turn tendency.

Physics 101 - I hope you can understand this ill-expressed explanation!

Cheers, Phil
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Old Sep 04, 2004, 08:42 AM
high tech redneck
Greenville, SC
Joined Feb 2004
69 Posts
Thanks guys. I got it now.
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Old Sep 04, 2004, 01:21 PM
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Bill Mixon's Avatar
Georgia
Joined Mar 2002
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Quote:
Originally Posted by crudpuppy
I think I mounted this motor wrong I gave it down and right....isnt it that the motor will natually pull up and right???
A motor only pulls in the direction it's pointed. (With the exception of gyroscopic procession) Other pitch yaw issues are airframe related.

Quote:
Look at your aircraft head on - the prop will be turning counterclockwise won't it. Every action has an equal and opposite reaction - thus the aircraft will have a tendency to roll clockwise, as an opposite reaction to the centripetal force exerted by the counterclockwise turning prop. Rolling clockwise will drop the left wing, thus instigating a left turning action - giving the motor ~3 degrees right thrust will balance out this left-turn tendency.
This is dependent on the aircraft, but a right offset is only used to counter slipstream spiral, and P-factor.
If the aircraft is setup with 0 right thrust, and is flying relatively straight adding 3 degrees of right will only cause the aircraft to yaw to the right with power.
At flying speeds the wings provide such a stabilizing force that torque is a minor factor to consider. A slight right aileron trim may be needed though.
I must stress that the type of model makes a huge difference in how you look at offset.
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