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Thread: Pitch Change Rotorhead for Homebuilders?

  1. #1

    Pitch Change Rotorhead for Homebuilders?

    This thread is a child of the first one. I am a 20 year gyro wannabe who could never afford it. I have designed a pitch change rotorhead simple enough to be made by a homeuilder - hopefully to be me if the design is worth a few bucks - with the goal of jump starting, but the jump brings difficult problems and if you want to understand some of them you may want to read Jump Rotorhead Dynamics. I hope to get some excellent comments here as on that first thread.

    A few initial thoughts -
    1. Soon after starting this project I realized that pitch change gets you more than just jump. By reducing pitch at your top speed you reduce drag, control excessive rotor RPM, reduce the forward stick required improving safety and further reducing drag, with all of this producing more speed on the same power.
    2. The resulting design provides an easy way to add rubber shock absorbers at the teeter bolt to help with 2-per-rev shake.
    3. It is also possible to add a simple set screw adjuster to the head of the blade root anchor bolt to simplify balancing the pitch between the two blades, eliminating the tedious shims.
    4. Single bolt blade removal is easily added, which is really just a lead-lag pivot that’s not allowed to pivot. Or maybe it could be and we might discuss that along with potential ground resonance.
    5. Set screw stops can be used at the pivot which will provide an easy spanwise alignment adjuster.

    My patent application, which I hope may provide a few bucks toward flying, covers a teetering head with the mechanism to transfer pilot input from a vertical central actuating shaft to a turning rotor blade anchor bolt, plus item number 3 above. The parts cannot be physically added to any currently existing teetering head.

    Items 1,2,4 and 5 are not claimed and are freely available to anyone. Items 4 and 5 can be added to any teetering head.

    Note that these drawings are for illustration only, having been drawn for the heavy duty jump start version in which weight became a problem, so you must ignore all size references. It will take a little time to redraw for the lighter weight pitch change only version, and will have to change bearings on the rotor blade anchor bolt, but this will give an idea of function.

    Jim
    Last edited by James J. Judge 42935; 03-17-2015 at 08:53 PM. Reason: Put 2 together

  2. #2
    PRA Secretary JOHN ROUNTREE 41449's Avatar
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    Hi Jim

    The problem are special characters as it's limit is 200,000 characters so it would fit.
    I have the same problem. Solved it by clicking the 1st button of the left. The 'AA' button switches the editors mode to WYSIWYG = what you see is what you get.
    Click this button before you past and that solve the problem 95% of the time.

    Back on topic.
    It appears you are well on your way. Nice work.
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  3. #3
    Thanks John, I've put the two together
    Jim

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