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Contra-Rotating Prop project

Discussion in '* Scratch Built Section *' started by KX-5, May 23, 2010.

  1. KX-5

    KX-5 Member

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    Here are some pictures of a fun but challenging project. The goal was to use the PhlatPrinter to make the box to hold the components for a contra-rotating transmission. And, a little help from my mini lathe to make the shafts. I've only tested it to 2500 RPM as that is the fastest my drill will go. I'm thinking it will need a 500+ watt motor to power it. I don't have a plane to try this on yet. I will size up a saucer to match the power. You may notice the props are in a pusher configuration.







    Attached files [​IMG] [​IMG] [​IMG] [​IMG] [​IMG]
     
  2. Jnida63

    Jnida63 Member

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    Pretty sweet :D :D :D
     
  3. navionflyer

    navionflyer New Member

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    Mark needs one of those for the ATOM. ;)
     
  4. KX-5

    KX-5 Member

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    It's been a long time since any news on the ATOM. What's its status?
     
  5. frankrcfc

    frankrcfc New Member

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    Now that's intense. Be curious how the project works out.
     
  6. kram242

    kram242 Administrator Staff Member

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    This is amazing! Great job LaVerne!
    You guys are right it would be perfect for the atom! :)
    Really nice job this is an awesome project
    Mark and Trish
     
  7. Tweakie

    Tweakie Member

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    That is remarkable indeed - excellent work.
    I like the incorporation of the thrust bearing, thus the pusher configuration. ;)

    Tweakie.
     
  8. 3DMON

    3DMON Moderator Staff Member

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    Nice work Laverne!
    Those gears look like they are from a Trex torque tube transmission.
    I like the idea of using one motor instead of two.
     
  9. KX-5

    KX-5 Member

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    Hey guys, the forum comments are always great to hear! And what a treat to hit the front page. :D The gears came from SDP and are from a project I worked with 20 years ago. No, I don't throw many things away. In addition to the thrust bearing, there are nine 1/4" bearings holding the shafts. The next step is to match up a right sized motor. Not sure what that should be. Any suggestions? At the moment, it has a pair of APC 8x6 props.
     
  10. tvcasualty

    tvcasualty New Member

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    Wow!!! Coolness!!!
     
  11. KX-5

    KX-5 Member

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    To me, a project like this has 2 levels of POC. 1. Proof of Construction or can it be built successfully. 2. Proof of Concept or will it acually work on an airframe? I've made it thru step one. Now, it needs to be proven that a motor can successfully drive the transmission. I need to find a motor for the next step.
     
  12. cncmachineguy

    cncmachineguy Member

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    It seems to me the next step would be to see if the to props make enough extra thrust over 1 to make up for the added weight. Don't get me wrong, it is WAY cool!! I am just thinking about the weight of it.
     
  13. KX-5

    KX-5 Member

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    Yep, there are a number of tests to do yet. This project came out of another experimental airframe I built where I was using a dual in-line motor assembly (counter rotating) that turned two props. Which helped null out each others torque affect. The interesting observation was even though the ESCs where the same, fed by a single battery, the RPMs would vary between the two motors causing the frame to roll one way or the other. And, I just love a challenge like this. The goal was not thrust related, it is the torque related to using dual motors/props.
     
  14. cncmachineguy

    cncmachineguy Member

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    Well its way cool!
     
  15. rcav8r

    rcav8r Moderator Staff Member

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    Neat stuff for sure... I remember reading WAY back on counter rotating props, and I believe the guy found he needed 2 different sized props. I forget if the larger one went in the back or front though.
     
  16. KX-5

    KX-5 Member

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    I have seen where HiMax dual motors use a bigger outer prop than the rear one. Usually about 1" bigger in size.
     
  17. janbjorn

    janbjorn Member

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    is it really different diameter that's used? I think the rearmost prop usually has higher pitch due to that the first prop has already accelerated the airflow when it hits the rear prop.
     
  18. KX-5

    KX-5 Member

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    I don't have personal experience with the prop sizes yet. But, Maxxprod.com website says that the CR3516 series motor has Suggested Props: For 3-cell operation APC 12x6P front prop, APC 11x8E rear prop. The same holds true for their other dual motor setups.
     

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