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  1. #1
    jmess73's Avatar
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    Twin head Autogyro help

    I recently acquired a twin head autogyro, I'll give some specs before I ask my question. It's a 5lb model with two rotor heads mounted on a "wing" there are no ailerons on this wing and it has a 5 in. cord, I don't think it would provide any lift. Each 30" rotor has 4-2 "wide blades, which are flat on both sides. They are set in a fixed head set with 10 deg. pitch(?) they are not adjustable or removable. They are set on the wing with an angle of attack into the wind but I'm not sure it looks like 10 deg. also. I have flown this Autogyro, and it does fly pretty well, to me anyway, its the only one I have ever seen, and nobody around here flys them. It flys allot like a plane, I can do loops and it lands pretty predictably. Now for the questions, I got it from a club member who wrecked it and lost interest. I'm not crazy about the rotor head because if I break a blade its a real chore to replace. Everything I've read on this site and others have allot of terms I'm not familiar with ex. flap, teeter, etc... and why are the blades hinged? Do I need this? I was pretty excited after flying today, I figured I would read up on some Autogyro info tonight, and now I'm more confused than ever :-( can anybody dumb this down for me, and maybe give me a diagram for a new rotor head, I could build easily?

    Thanks,
    Jeremy

  2. #2

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    RE: Twin head Autogyro help

    Jeremy,
    I am fairly dumb about Auto Gyros also. First lets see if we can ID this Bird.
    Jim

    Does it look like this.. A Gyrace x 2 and a Giant Whistler
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  3. #3
    Icanifixthat's Avatar
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    RE: Twin head Autogyro help

    I am thrashing together an electric twin rotor. When I started I had a vague idea of how the things worked so I did some research.

    The best site, although it's currently not being maintained, for model autogyro stuff is: http://www.autogyro.com/ Read everything at the site, follow the links there, and you'll go forward with a lot more practical knowledge.

    For a very good article on how 'Gyros work try: http://www.jefflewis.net/autogyros.html

    For ready-made rotor blades: http://aerobalsa.com/

    Basically, teeter and flapping are both ways of dealing with the retreating blade problem that affects all rotorcraft. A blade advancing into the airstream develops more lift than a blade retreating with the airstream. So one side (retreating) of your rotor disk is developing less lift than the other causing the 'Gyro to roll toward the retreating blade side. Visualize an airplane with one long wing and one short one. By allowing the blades to teeter or flap the effect on roll is minimized.

    Teetering is where the rotors on a two-blade head are coupled together and actually teeter up and down on a pivot point at the rotor head. Flapping is the use (In models) of a flexible plastic mount for the rotors. They both do the same thing but flapping allows the use of three or four blade rotors.

    The good news for you is that twin rotor designs don't suffer from this handling problem because the roll tendencies are cancelled out by the oppositely rotating rotor heads.

    Hope this helps.

  4. #4
    jmess73's Avatar
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    RE: Twin head Autogyro help

    I'll try to upload some pics if it doesn't work it looks kind of like the small one on the bottom of the pic you have

    Jeremy
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  5. #5
    Icanifixthat's Avatar
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    RE: Twin head Autogyro help

    Nice, clear pix. And a nice-looking gyro!

  6. #6
    jmess73's Avatar
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    RE: Twin head Autogyro help

    Any ideas on the make? How about my rotor heads? Everything I have read on this forum would lead me to believe that this setup should not fly, yet is does,hmmmm. One thing I would like to do is make a head that I could replace blades on easily, this one is really tough to fix up.

    Jeremy

  7. #7
    Icanifixthat's Avatar
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    RE: Twin head Autogyro help

    Can't pin the design yet - but then I don't yet have all of the plans I ordered either. As for the heads, I'd fab new ones with the same size blades, angle of incidence on the blade, etc. as your current setup and use two 4-40 nylon screws through each blade to hold it in place. You can find the screws by Googling on "nylon screw." Why nylon? It will likely shear in the event of a blade strike which will minimize damage to the aircraft. I'd love to take the credit for this one but I believe that it's a feature of Autogyro of Arizona ( http://www.autogyro-rc.com/default.asp ) kits.

    As far as not flying, I'm guessing that you mean the flat plate blades. Another peculiarity of twin heads is that they work with flat blades.
    - Just don't forget to balance each of your new rotor assemblies.

  8. #8

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    RE: Twin head Autogyro help

    could you confirm which way your rotas go round
    do you have them spining in towards the center
    its just that they look wrong to many other photos
    as in the leading edge on your rotas if turning in towards center is high and trailing is low
    dose this work better or do you have your blades turning out
    i have one and can not workout which way to have them
    many thanks
    crispin

  9. #9

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    RE: Twin head Autogyro help

    His rotors are spinning forward in the center and back at the tips of the wings. I think either way works well, but I prefer to have them spinning inward towards the center, because the prop wash gets the blades spinning faster. The best thing to do is try one way and see if it works.


    The problem with this design is it doesn't have a flapping head and everyone that works with autogyros know that the flapping head fixed a lot of problems in the autogyro world.
    Autogyro Crazy

  10. #10

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    RE: Twin head Autogyro help

    thanks for reply
    i have mine turning inwards as looking from front
    but its the angle of the blade i think is wrong /or \ if you see what i mean
    ie on left hand as in from behind the model is


    . looking at end of blade slooping which way
    .
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    many thanks


  11. #11

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    RE: Twin head Autogyro help

    fter 3 more flights yes turning into center is best
    mine is still very rocky in flight but apart from that great upto 20mph winds
    now looking at spare fuses i have to convert to single head autogyro :-)


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