Adding a horizontal motor/prop to drive a quad

Posted by Dan Jacob on February 2, 2016 at 10:48pm

When you command a quad to go forward, it tilts forward, and that creates a forward "thrust".
What would happen if I attached a horizontal motor/prop onto the quad, and provided a horizontal thrust that way? Would the quad maintain level?

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Replies

    • Flying Buddha > james sowell February 4, 2016 at 4:45am
      I fly one of these for work, without the turbine of course. Its a Riegl RiCOPTER and it is made to carry a Lidar sustem. Just scale those are 30" props.
    • Dan Jacob > james sowell February 3, 2016 at 1:10am

      That's an encouraging video, James. Thanks.

  • Developer
    Randy February 3, 2016 at 12:44am

    There are a few videos of this kind of thing on YouTube including this one.

    This idea has come up a few times and there was even a pull request to add support into Copter.  It wasn't accepted because we're not ready to break the assumption that the thrust is always vertical (i.e. it made the position control code extremely messy).  Also the general consensus on the dev team was that although it's kinda fun and cool, it doesn't actually add much value (at least in the scenarios that we could think of).  If someone is looking for a faster copter, it's better just to increase the power of the existing motors rather than add a new one.

  • iskess February 3, 2016 at 12:07am
    What you are describing is very similar to what was just introduced by Tridge as "quadplane". Look it up in the wiki. Perhaps you could set the min speed so high that the aircraft never achieves it, then the quad motors would always be active.
    • Dan Jacob > iskess February 3, 2016 at 12:25am

      @Azobe: What do you mean by "spaz out"?

      Suppose I pulled the quad with a string 10m away from its GPS position, would it be at a constant tilt trying to get back to its original position?

      Actually what I'm thinking of doing is using a quad to launch a fixed wing plane that would be carried on top of the quad. The quad would hover at a GPS position and the plane would gradually provide horizontal thrust. When the plane's speed is near flying speed, it would separate from the quad and the quad would return to home.

      Is that feasible?

      @iskess: How does the quad measure speed, with a Pitot tube?

    • Developer
      Randy > Dan Jacob February 3, 2016 at 12:49am

      Sorry, my other reply was before I read all the other comments here.  Insitu did something similar to what you're talking abuot here.  My understanding is that the test was using ardupilot (aka Copter, aka APM:Copter, aka ArduCopter) on the multicopter that was doing the lifting.

    • Dan Jacob February 3, 2016 at 12:48am

      A lot of planes won't be controllable without any forward speed. Dropping the plane might work if it started with a nose down attitude. Some planes might just spiral down due to control surfaces not having enough air across them.

      I want to treat the quad like it was an airborne carriage. It would be like the plane was on a runway in the air.

    • Dan Jacob February 3, 2016 at 10:55am

      I'm thinking about launching planes up to about 1kg.

      The quad would be a hacked CX-20 (or similar). I'd use only the control systems of the CX-20 and provide a much larger frame with a more powerful drive system.

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