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Thread: Scales used for Pull test

  1. #1

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    Scales used for Pull test

    What type and brand of scales are used when testing the pulling power of our airplanes? Where to buy?

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    Aviator's Avatar
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    http://www.mcmaster.com
    search "fish scales"
    They have them up to 5000lbs.

    Cheers

  3. #3

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    I was hoping there was something less expensive in the range we needed. I"l keep looking.

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    I have seen several different varieties, one was a very fancy electronic gadget used to test the pull on my 180, another was a very ingenious one made by Brian Sutton to test the pull on their props - it was hydraulic with a remote readout, and I have seen the simple spring scale type - probably the hardest to read since it does not record the maximum it continuously fluctuates.

    sj
    "Often Mistaken, but Never in Doubt"
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  5. #5
    85Mike's Avatar
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    My partner in our 12 took a load cell out of his Peerless Roadrunner scales that he weighs airplanes on and fabricated a set-up to attach shackles to. It's a remote reading and they are certified scales but they don't record the max. You have to watch it. It's been very interesting to pull various props etc. on Cubs, 180's (0-470s and 520's) & 185 2 and 3 blades. I gained 100 lbs static going from an 82" to an 86" 2 blade on my 185. His 180 with an 0-470-50 Pponk matched an IO 520 Black Mac 86" 3 blade @ 1100 lbs static thrust.
    Mike

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    Quote Originally Posted by Fortysix12
    I was hoping there was something less expensive in the range we needed. I"l keep looking.
    If you scroll to the bottom of the page, they have 2000 and 5000lbs scales for under $300. At that price, they're probably not very precise, though.

    When I once built a retractable-gear replica fighter, I used stuff you find in a hangar to rig up a simple 90 degree cable-pulley-weight scale to measure gear extension force. Might work for you too.

  7. #7
    gdafoe's Avatar
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    http://stores.ebay.com/Transducer-Technologies

    Seems like these would be ideal. Never used one but looks like it would be a good solution. Just get the one in the correct range.
    Gerald

  8. #8
    SJ's Avatar
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    Gerald, that is what the super accurate one they used to do the 180 was. We used to use that technology in postal and counting scales also. Very accurate stuff.

    sj
    "Often Mistaken, but Never in Doubt"
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    Dave Calkins's Avatar
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    Quote Originally Posted by 85Mike
    His 180 with an 0-470-50 Pponk matched an IO 520 Black Mac 86" 3 blade @ 1100 lbs static thrust.
    Mike
    Mike, what prop on the Pponk 180? Thanks. DAVE

  10. #10
    Dave Calkins's Avatar
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    Mike? prop?

    Thanks. DAVE

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    I have a dial type load cell with a second arm that the weight indicator moves and records the max weight. very simple design.

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    85Mike's Avatar
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    Dave
    I was mistaken!!! 1st time in 62 years!!!! LOL The 0-470-50 pulled the same as my IO520-D. 1000 lbs. Both are with an 86" prop. I thought he'd pulled with his 88" SP prop from his 0-470. The 86 Black Mac did pull 1100 while our 86's pulled 1000.
    Sorry for the confusion.
    Mike

  13. #13
    Dave Calkins's Avatar
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    Thanks Mike.

    One of my customers went to an 88 inch prop on a 180 with only an A model, and it pulls great.

    That A seems to go fine. I suppose if they're operated well and looked after and fed enough fuel and have good cooling they'll run ok. Still, there is a better 470 model in this a/c's future.

    D

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