pusher props

[fly boy3]

As a newbie to electrics, can i ask what direction should an electric motor turn, when using a pusher type prop, and what are the consequences of motor turning the wrong way, or putting prop on wrong way. cheers Fb3

[Tim Mackey]

Viewing the prop from the front of the 'plane, then the prop should face forward toward you with the lettering forward, and rotate anticlockwise - same for tractor or pusher.

[Tim Mackey]

Consequences of either of your other scenarios is a serious lack of thrust

[Bob Cotsford]

motor turning the wrong way - not neccessarily a lack of thrust, just that it will not be in the direction you would like it!

[Tim Mackey]

True

[fly boy3]

Thanks all, just a quickie, would I be able to differentiate a pusher from a tractor prop by just looking at it. Cheers

[Ernie]

Hi Flyboy, Of course, if you have the prop on backwards, your aircraft will fly backwards very well

 

ernie

[fly boy3]

Cheers Ernie, onour site on a ww2 disused airfield, it is often so windy that some models will fly backwards with the prop on correctly. LoL. Cheers

[Steve Houghton]

Please shoot me down in flames if necessary , but...

 

Surely the purpose of a pusher prop is to reverse the thrust of a motor that always turns the same way. Hence, a tractor prop turns anticlockwise, viewed from the front of the plane; a pusher prop also turns anticlockwise, from the front of the motor (usually the rear of the plane), or clockwise viewed from the front of the plane.

 

If a rear-mounted motor is pointing forwards (with a suitable prop slot cut in the fus), then it will use a tractor prop and turn anti-clockwise, viewed from the front of the plane.

 

Surely the issue is whether a pusher prop is required with an electric motor, when the direction can easily be reversed and a tractor prop still be used, but presumably fitted backwards so that it is running most efficiently.

 

I'm sure there's a simpler way of saying this!

 

I've never used a pusher prop, so I shall willingly bow to those who have.

 

 

 

[fly boy3]

Hi Steve, as I indicated earlier I am a newbie,and have a lot to learn, but now I am confused. LoL Cheers

[Steve Houghton]

A little more simply..

 

If the motor turns anticlockwise viewed from the front of the plane you need a tractor prop. If it turns clockwise viewed from the front of the plane you need a pusher prop. This would be the case with a non-reversible IC motor.

 

Hence, if you reverse the direction of an electric motor you should be able to use a tractor prop, turning anti-clockwise viewed from the front of the plane. However, props work best when mounted with the front (lettered side) pointing into the oncoming air. So, a tractor prop on a reversed electric motor should be mounted with lettering towards the front of the plane.

 

I was just unsure if there were any technical reason why this could not be done - someone else may be able to answer.

 

 

 

[fly boy3]

Thanks Steve, that I understand , but cannot give a reason. Someone on this forum will though. Cheers FB3

[Tim Mackey]

Pushers are not necessary with electric - if its a pusher model then fit a standard prop, and refer to my first post.

Simply reverse the motor direction as required by swopping wires over to obtain the correct direction.

[Bob Cotsford]

The only reason for a pusher prop would be to counter torque on a multi engine model - tractor prop(s) on one wing, pusher on the other. Same thing for a quadrocopter I think.

[Seamus O'Leprosy]

Can I try and help here.. Flyboy what are you trying to achieve?

[fly boy3]

Hi Seamus, I am trying to get some info for an electric flier who accidentally put his pusher prop (his words) on backwardsand experienced lack of thrust because of it, Needless to say I am an ic man who uses engines that go anti clock from the front and cannot be reversed intentionally. It looks as if Tim has the answer, but I think Steve needs to know why. Thanks FB3

[John Privett]

FB3 - If the motor spins the "wrong" way, then the thrust from the prop will be in the wrong direction. The plane will then (try to) fly backwards. This is rarely successful...

If the prop is put on the wrong way round then the thrust is in the correct direction, but the prop works less efficiently so the thrust will be less than it should be. Some people used to do this deliberately when test flying free-flight models. The idea seemed to be that if the model was not properly trimmed, with less thrust it would at least arrive at the scene of the accident more slowly!

[Tom Wright 2]

John.

[fly boy3]

Thanks all, for the info. Even I now can understand. Cheers