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Propeller going in the wrong direction?

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  • Propeller going in the wrong direction?

    All RC props must rotate <i>counterclockwise</i>. You've hooked up your motor to the electronic speed control (esc) and the prop is rotating in the wrong direction, what do you do? The solution is simple. There are three bullet plug connections from your motor to the esc. Just switch out any TWO of those plugs and the engine will rotate counterclockwise.

  • #2
    Re: Propeller going in the wrong direction?

    I forgot to mention this in the posting above. On some models it can be a pain in the butt to get to the electronic speed control, (esc). If you see the prop is spinning in the wrong direction you might have to take off the prop and spinner and then remove the cowling and then get to the esc connectors and reconnect and rescrew the other parts back into place. One thing that I do before I put on any prop, spinner or cowling is the take a piece of duct or masking tape and attach it to the motor's prop shaft and then I turn on the motor. I can easily see the tape's rotating direction and make changes then if needed. That saves a lot of screwing around.<smiley image="smiley_grin.gif"/>

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    • #3
      Re: Propeller going in the wrong direction?

      These are good tips Baron. Thanks!

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      • #4
        Re: Propeller going in the wrong direction?

        Quick question on your comment about which direction a propeller "must" go...

        I purchased a used brushless motor, esc, and prop for an airplane that I scratch built. The prop that came with the motor is a reverse prop (maybe for use as a counter-rotating prop previously) I ended up just reversing the motor so it spins the opposite direction now to pull the plane - is there any reason you would recommend against that rotation setup? The torque rolling effect would be opposite a normal plane - but it is going to be a hand launch only plane anyway because I don't have rudder - just aileron and elevator.

        I know props are cheap, but I have it all mounted, soldered up, and heat shrinked now - didn't notice the direction of the prop until after doing all of that work. So I'd just as soon leave it the way it is if there aren't any major reasons to change it back.

        First time I break a prop, I'll probably switch it back

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        • #5
          Re: Propeller going in the wrong direction?

          Most ESCs are programmable for rotation as well. You can do the programing with a radio, but it is nicer if the ESC has a programmer or a card to set it up.

          Only problem I can think of with running a reverse rotation on a single engine plane would be getting used to countering the torque in an opposite direction. Hand launching shouldn't show it that much, but I think it could be a problem with ground take offs because one would be trained to react opposite of what "normal" is.

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          • #6
            Re: Propeller going in the wrong direction?

            The motor is probably mounted with an offset to the right, to help offset the torque of a prop rotating in the correct direction, and a reverse prop will apply torque in the opposite direction. That means you have to fight both the prop torque and the thrust offset to make it take off in a straight line.

            BTW, the prop turns CCW when observed from the front of the aircraft, looking aft. It would be CW from the pilot's point of view, so it's important to mention which way you are looking at it.

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            • #7
              Re: Propeller going in the wrong direction?

              While prop torque has some effect on takeoff, prop wash has a great effect. The rotating prop wash pushes on the left side of the vertical stab, moving the tail to the right, therefore, making the plane tend to go left. Of course when flying speed is reached, the air flow makes the plane go straight. Don't take my word for it. Read up on some fundamental aerodynamics. Rotating prop wash, for the most part, is the culprit. Piper Cubs, which I have many hours in, are notorious for this. The Doctor

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              • #8
                Re: Propeller going in the wrong direction?

                There's some debate on the true source of this force, but there's no debate that it is there. Of course, your example is for a prop turning in the correct direction; this force would be reversed for a reversed prop, so the thrust angle meant for the correct forces would add to it. The bottom line is, you have to dismount the motor to correct the offset, correct the rotation of the motor, or put up with a plane that is really difficult to trim.

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