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Old Jul 17, 2002, 10:19 AM
Registered User
Cincinnati, Ohio
Joined May 2002
67 Posts
Reverse turn motor pusher prop?

Hey guys, I know I've read this information on this very bright forum before, but I have confused myself. I have a 400x with an astro cobalt 20. The master airscrew prop that comes with it has the letters facing towards the front of the plane. So I guess what I am asking is is this correct? The motor is the 803Z, which is reverse turning. I guess it would depend if the prop is a tractor or pusher prop, which I do not know. I'm guessing its a tractor prop, hence the reversing. Has anyone ran this setup with 10 cells? Thanks in advance!
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Old Jul 17, 2002, 10:53 AM
SKINNI MINI flyer
Barrett's Avatar
Pearl River, LA, USA
Joined Sep 2001
645 Posts
If the motor is timed for reverse rotation, then a normal (tractor) prop will work. The prop needs to be placed on the motor with the lettering facing forward (toward the front of the plane.) I was confused about this as well when I first started flying my Zagi.
Then one day i realized that no matter where the prop is located on plane it still has to move air in the same direction, towards the back of the plane. So its not the prop that you have to worry about its the direction that the motor is rotating.

Hope this helps. I know that its not the best explanation but if you dont understand ill go in to morer detail.
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Old Jul 17, 2002, 10:54 AM
Ascended Master
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Palmdale, CA
Joined Oct 2000
13,466 Posts
Letters on the front of the prop.. front faces forward... a tractor prop mounts with the letters forward as a pusher prop.. a pusher prop does the same...
Direction of rotation of the -motor- is important..
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Old Jul 17, 2002, 11:32 AM
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Neil Morse's Avatar
San Francisco, CA, USA
Joined Jul 1999
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This issue is very confusing to newbies, and the discussion comes up periodically. I'm only chiming in here to clarify one thing: be aware that the Paul Gunther prop commonly used on Wingos and Zagis actually has the lettering on the back. This makes an already confusing situation even more confusing to a lot of folks. Therefore, in the case of the Gunther prop, the lettering should be facing toward the rear of the plane whether the prop is being used in a tractor or pusher (with reversed motor) configuration. In the case all other props which have the letter on the front in the conventional way, the lettering should be facing towards the front of the plane. Whew ... that's probably about as clear as mud, but that's the best I can do.

Neil
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Old Jul 17, 2002, 03:23 PM
SKINNI MINI flyer
Barrett's Avatar
Pearl River, LA, USA
Joined Sep 2001
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Good point Neil, forgot about that....
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Old Jul 17, 2002, 04:44 PM
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Kamloops
Joined Dec 2001
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And if you are still confused. Put it on turn on the motor if you do not have a whole bunch of air pushing out back switch the prop around and try agian. It will become very obvious as to which way the prop has to face.

Mal
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Old Jul 17, 2002, 04:52 PM
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Cincinnati, Ohio
Joined May 2002
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cool, thanks guys
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Old Jul 17, 2002, 04:58 PM
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Joined Mar 2001
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Easy way to remember:

Portion of prop facing forward during flight should be convex; portion of prop facing backward should be concave.

Now someone will come along with an exception.

Tony Turley
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Old Jan 06, 2003, 01:09 PM
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Ohio Wapak
Joined Feb 2002
3,710 Posts
quick question

I have an astro 020..not reversed timmed....my buddy(knows a lot about motors) said all I have to do so I can use it on my zagi is put a pusher prop on it..is that true???
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Old Jan 06, 2003, 06:07 PM
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Kamloops
Joined Dec 2001
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It all depends does your astro 020 have the ESC conectedDirectly tothe back of the motor OR isthe ESC aways away from the motor.In other words is it sensorless or sensord motor? Now if it is a Sensord motor(Board directly solderd to motor)Then YES you need a pusher Prop. If it isa sensorless motor Disconect TWo of the wiresand SWITCH them one for the other AND fip your Prop around soit is facing the other way. what you have done there is made the motor run the other way. and the Prop will now Push Air instead of Pulling it.

Kush
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Old Jan 06, 2003, 06:30 PM
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William A's Avatar
Tacoma,WA USA
Joined Jun 2001
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To add more wood to the fire.......

Most props are built like a wing/airfoil, that is, they have a thicker, more rounded leading edge and a thinner, more sharper trailing edge. Most even have a flat 'back side'.
If you were to cut your prop in half, between the hub and tip, like in a cross section, it is quite easy to see.

That being said, the correct rotation is when the thicker, leading edge, is the one to 'bite or cut into' the air first.
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