Hi All..
Am planning my build of the KMP Adam A500, my first twin. Am setting it up w/ electric motors, and have a couple questions I can't seen to find answers for via forum search.

This is a push-pull configuration. I'm assuming that no thrust needs to be set, just use whatever is given on the firewall?
Now to the part that confuses me 2 motors out of the box, typically rotate clockwise, as seen from behind the prop, according to how the leads are plugged on a typical single setup. This is fine, since one in front and rear, that would seem to offset torque. A pusher prop would seem to push the air out in this case, as IF the motor was ran reversed? Is that correct? If you ran one motor reversed, that would put all the torque to one side, correct? It would seem easy to want to reverse the rear motor and run a standard prop, but am thinking that again, both motors would therefore turn the same direction hence too much torque?

If someone can set me straight on push-pull, it would be appreciated!

I think props are very ineficient when turning in the backwards direction from which they were designed but if motors are mounted fore and aft I think the torque will cancel out

Keep the motors turning the same way and put a pusher prop on the rear..

I have flown a Cessna 337 twin that had two OS46 engines, the rear one modified to run in the reverse direction and using a tractor type propeller. Torque was not an issue at all. Tractor propellers are easier to find, available in more sizes and are usually less expensive than pusher-type propellers.

Hi Radical Departure
I designed and built a SPAD pusher/puller using two standard .28 Magnum engines and 9 X 6 props. The rear was a pusher prop. My plane could not do a crisp snap roll. Since I do snap rolls with all of my planes, I decided that the reason was the props going in opposite directions. As I recall, it could also not do a good Hammerhead stall. What Red B is suggesting may be the way to go. Since it is electric you can experiment with both. Let us know.

I had a similar problem for pusher props for a scale model. I just run the motors in reverse & use tractor props fitted backwards on the shafts, that is the CURVED face of the prop MUST face forwards.

As for the torque of the two motors together in the same direction? , just the same as the torque of one bigger motor if you ask me. - John.

BTW, sharp looking plane!

One of the primary reasons of having a pushme pullyou configuration is that the torque from each motor cancels out the torque from the other making for much better handling qualities. If the rear motor is reversed (and a tractor prop used) the torque will be additive resulting in an increased yaw tendancy to the left. Since you don't have a rudder in the slipstream, it may cause handling problems at low speeds. Pusher props are very much available from Zinger, Master airscrew, APC and Graupner. Pusher props for electrics, thought, are pretty rare..... but there is law saying that yoiu have to use electric props...FWIW.

Hey Guys.. thanks for the info. From what I'm reading, since there are several pusher props available for electric, it shouldn't be too difficult to finish with a setup that cancels torque and pushes it throught the air as designed.
Boomerang1, the pic does very little justice to the kit. A far better representation can be seen in the June Model Airplane News. It would have been the cats meow to have been able to get one unpainted. Since its my first scale project, I'm in the process of taking it down to the primer, for a final pearl white paintjob that will reflect Adams N501AX, #C0002. Man.. you talk about some work.. it'll take me 3 months or better just to get that much done! But.. may as well take time and do it right... we'll see just how sturdy the Black and Decker Mouse sander is!

I have a question for all you PUSHERPROP guys and or gals out here. My friend has built a "PUSHYCAT" from RCM plans. This plane has been built for some years and this year he is wanting to get it in the air. Here's the problem. He or I have never run a PUSHER type aircraft "EVER"... Now we have run tractor props but never pusher props. When we put the prop on we put it on with the lettering out toward the prop nut. Then when starting the engine, the air blast came forward toward the front of the plane not back? The props are "PUSHER" props with the (P) designation so we know we got the right props, however, trying to run the engine in reverse keeps blasting the prop off and will not run. It will however, run clock wise but the prop blast goes to the front not the back. Now, again I have done this RC stuff for many years but NEVER in my life have I ever messed with this. I am "TOTALLY" confused and in need of some expert "PUSHERPROP" advice. The motor we are running is a S.T. .051. Upon looking at the way the prop is designed it looks like the engine would need to run counter clock wise, NOT clock wise. But the engine will NOT runbackwards? So I am looking for ANY help toresolveour little issue. It's probably something so very simple I willbe red faced after I get help from someone, I'll want to crawl into a hole and bury myself. But Iam not sure what to do, Iam stumpted stumpy....

(1). What do we need to do to get this to "PUSH"

(2). What are we doing wrong?

(3). Everything we did or tried did not work?


Thank you in advance

Bill

G'day Bill,

If I am reading your post correctly, it sounds like you may have the propellor on backwards!

The convex curved face of the prop blades must face forward, i.e. away from the prop nut in a pusher installation.

I suspect your prop has the lettering on the curved face in which case the lettering should be towards the front of the plane and away from the prop nut.

You have got a normal rotation engine haven't you? Sometimes an engine intended for a pusher installation may have been modified for reverse rotation, in which case you would use a normal propellor (again with the curved face of the blade facing the direction of flight).

Hope this helps.

Dave H.