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Author Topic: Pusher  (Read 964 times)

Offline Larry Wong

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Pusher
« on: July 11, 2008, 05:02:23 PM »
Any body know what is the best way to use a pusher prop?
Which wires do I exchange? (on motor)
do I have to change  ESC to reverse?
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Larry

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Offline John Cralley

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Re: Pusher
« Reply #1 on: July 11, 2008, 06:10:14 PM »
Larry,

Swap any two wires between the ESC and a brushless outrunner motor and that will reverse the rotation. I have no experience with other motors.
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John Cralley
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Alan Hahn

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Re: Pusher
« Reply #2 on: July 11, 2008, 06:15:10 PM »
Larry,
John is right, you don't have to change anything in the ESC--just switch any 2 of the three wires between the ESC an brushless motor.
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Offline Robert McHam

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Re: Pusher
« Reply #3 on: July 11, 2008, 06:18:54 PM »
John is correct. On a brush less motor it makes no difference which two that are switched.
As for the ESC you don't have to make any change at all.

The propeller itself needs to be mounted backwards on the motor (writing towards the motor).

Robert
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Offline Larry Wong

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Re: Pusher
« Reply #4 on: July 11, 2008, 06:29:05 PM »
Robert
I'm using a 12x6 EP Pusher prop. do I still have to turn prop around!!!!!!
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Larry

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Alan Hahn

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Re: Pusher
« Reply #5 on: July 11, 2008, 07:19:21 PM »
Basically the part of the prop that has the numbers on it should face in the forward direction.

Remember that some people run "pusher" props as "tractor" props with motors that rotate CW (as viewed from front of plane) to counteract torque on takeoff.

The more I try to explain it, the more confused I'm getting! HB~>
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Offline Larry Wong

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Re: Pusher
« Reply #6 on: July 11, 2008, 08:00:37 PM »
Yep I though so tractor ( John Deer) turn conter clock wise.  Pusher turns clock wise to (advance time)  n~ n~ y1 y1
 LL~ LL~ LL~ LL~ LL~ LL~ LL~
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Offline Larry Wong

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Re: Pusher
« Reply #7 on: July 13, 2008, 09:05:13 PM »
Result  today with pusher prop, was it works great kept the plane out on lines in the whole pattern even overheads, but my plane never had any trouble with staying out on over heads , so it was hard to till if it work better or not. n~
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Offline Robert McHam

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Re: Pusher
« Reply #8 on: July 13, 2008, 09:34:30 PM »
How about a look at this thing!

Robert
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Offline jim gilmore

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Re: Pusher
« Reply #9 on: July 13, 2008, 10:06:42 PM »
Uhm, ok now I've thought too much about this and i'm confused.
Larry,which is it a pusher prop in front ,running the motor in reverse  so its a Tractor again or is it reallt pusher?


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Offline Larry Wong

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Re: Pusher
« Reply #10 on: July 13, 2008, 10:15:20 PM »
Ok the prop I used is a clock wise foreward tractor, and the normal forward prop turnes conter clock wise.( simple)  <= <= <= n~ n~ HB~> HB~> LL~ LL~ n~ n~
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Alan Hahn

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Re: Pusher
« Reply #11 on: July 14, 2008, 07:56:04 AM »
Quote from: Larry Wong on July 13, 2008, 09:05:13 PM
Result  today with pusher prop, was it works great kept the plane out on lines in the whole pattern even overheads, but my plane never had any trouble with staying out on over heads , so it was hard to till if it work better or not. n~

Larry,
Since in PA we fly just about as many maneuvers outside as inside, it isn't obvious there is any advantage of the pusher prop turning clockwise (from the front of plane) as a normal tractor prop turning counter-clockwise. The major advantage is at takeoff or low airspeeds where the torque tends to turn the plane in towards you. Speed and Carrier guys like the pusher for this reason--but they are always flying upright --at least on purpose!
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Offline Larry Wong

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Re: Pusher
« Reply #12 on: July 14, 2008, 09:15:26 AM »
Alan on the C/C esc new firmware can I lower the RPM on my motor for flight speed? if so how? my timer is as low as I can go.
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Larry

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Alan Hahn

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Re: Pusher
« Reply #13 on: July 14, 2008, 12:06:47 PM »
I am guessing that in RPM mode, you can put in any value you want---consistent with the battery voltage and motor kV of course. What rpm are you currently running?
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Offline Dean Pappas

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Re: Pusher
« Reply #14 on: July 14, 2008, 07:15:06 PM »
Quote from: Alan Hahn on July 14, 2008, 07:56:04 AM
Larry,
Since in PA we fly just about as many maneuvers outside as inside, it isn't obvious there is any advantage of the pusher prop turning clockwise (from the front of plane) as a normal tractor prop turning counter-clockwise. The major advantage is at takeoff or low airspeeds where the torque tends to turn the plane in towards you. Speed and Carrier guys like the pusher for this reason--but they are always flying upright --at least on purpose!

Hi Alan,
I hate to be contrary, but nothing could be further from the truth! Inverted and upright have almost nothing to do with it ... it isn't a rolling issue, it's a yawing thing. The spiral airflow gets worse at low airspeeds, and straightens out at higher airspeeds. Soooooo every time the nose is pulled up and the plane looses a bit of airspeed, the spiral airflow angles get worse. The spiral airflow pushes the tail right and the nose left. That means that with a normal prop, every time the plane slows, it yaws inboard. Put a pusher prop on the plane, reverse the rotation, and now every time you slow, the plane yaws outward. It's amazing how the "above 45" line tension improves especially as compared with the level lap line tension.

This really is an advantage for E-Stunt.
Dean

P.S. Happy Bastille Day, Y'all! Go overthrow something!
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Dean Pappas

Alan Hahn

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Re: Pusher
« Reply #15 on: July 15, 2008, 08:15:32 AM »
Dean,
I guess you are right! I was tending to think of the gyro precession in a sharp corner where insides and outsides behave oppositely---the reason for the Rabe Rudder.

But the propwash, I guess, is also the reason for the little bit of right thrust that we sometimes build into the motor.

The biggest problem with pushers is prop availability, but as I replied to someone else in another thread, APC seems to be producing more pusher E props too. Need to take a look to see if they have a 12-6 version.
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Offline Dean Pappas

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Re: Pusher
« Reply #16 on: July 16, 2008, 11:13:53 AM »
Hi Alan,
Yes, there is an APC 12-6 E pusher #^
Dean
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Dean Pappas

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