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Micro Chopper

Discussion in 'Electronic Repair' started by Nelson, Dec 26, 2008.

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  1. Nelson

    Nelson Guest

    So I got my kid (well, OK, I wanted to try it out too) one of these for
    Christmas. As far as I can tell there are only two motors, one for the
    main rotor and one for the tail rotor. Yet there are controls for
    throttle, right and left rotate, and right and left directionality.
    How can you get that many degrees of freedom from speed controlling
    only two motors? I get that the throttle controls the main rotor and
    makes it go up and down and am guessing that the rotate control is some
    kind of stepper that modulates the speed of the tail rotor. But right
    and left turns have me stumped.

    Any one else have one of these?
     
  2. Which one have you got. As you say it has a seperate motor for the tail
    then it's a reasonably advanced one. - the real simpl ones have no tail
    rotor but have two contra-rotating main rotors instead.

    So guessing, I'm assuming it is fixed pitch so will have the following
    controls

    1 - Main Rotor speed - on a collective pitch hello this will also do the
    rotor pitch
    2 - Cyclic (Elevator) - tips main rotor back and forward
    3 - Cyclic (Aileron) - tips main rotor left and right
    4 - Tail Rotor Speed - moves tail left and right

    There will also be a gyroscope which is driving the tail.

    Cheers,

    Nigel
     
  3. f825_633

    f825_633 Guest

    My son has one of these type too (I wont let him near my
    Nitro Heli )

    The pitch of the blades are fixed so the higher the speed of
    the motor the higher it goes which also provides forward
    motion. The tail rotor stabilises as in the real thing and
    bigger heli's and provides turn. Ingenious....
     
  4. jakdedert

    jakdedert Guest

    The left/right turns requires the understanding that, without the tail
    rotor, the entire craft would spin because of the rotation of the main
    rotor. The tail rotor counters that. The speed of the tail rotor
    either over-corrects, resulting in a turn in one direction; or
    under-corrects, resulting in a turn in the other.

    When the speed of the tail rotor exactly balances the craft's natural
    tendency to spin, the result is straight-ahead flight.

    jak
     
  5. krw

    krw Guest

    Ever hear of "Google" or "Wikipedia" (or for that matter
    configuring your newsreader properly), dummy? Helicopters have two
    main controls (each with two axis of control) the "collective" and
    "cyclic". The "collective" controls the overall pitch of the main
    rotor for the complete blade rotation (thus the up/down movement of
    the chopper) and the pitch of the tail rotor (the rotational
    velocity of the chopper). The "cyclic" controls the pitch of the
    main rotor during the rotation (or cycle), thus the thrust produced
    by the main rotor during the rotation. Increase the pitch of the
    blade when it's behind the CoG and the nose pitches down, to the
    left and the bird pitches right,.... It's really very simple,
    until some damn fool starts the engine.
     
  6. Nelson

    Nelson Guest

    Thanks for your friendly help. However if you look into this a little
    less superficially you will find that the flight controls and rotor
    configurations on many, if not most, RC model helicopters differ
    substantially from those of actual helicopters.
     
  7. Nelson

    Nelson Guest

    Well, the Chinglish instructions that came with it are not that clear
    :) What do you expect for $25 :)

    The "trim" buttons control right and left rotate about the main rotor
    axis and are used to stop it from spinning out of control. At least
    that's their intent. There is a separate joystick which is labeled "L
    and R". I can't get the thing to fly well enough or long enough to
    determine exactly what that button actually does but my impression is
    that it causes the helicopter to fly in a circle clockwise or counter
    clockwise. So you set a fixed tail rotor speed with the "trim" buttons
    and then vary it slightly with the joystick to get the left or right
    circling motion as someone else stated above.

    There are only two motors. The main rotor motor and the small one that
    spins the tail rotor. The only degree of freedom there is speed of
    rotation. The pitch of the main rotor is not under direct user control
    and appears to be controlled by a mechanical linkage that is attached
    to a rotating inertial dumbell "blade" above the main rotor.

    I have since looked at many RC Model Helicopter sites (eg
    http://www.rchelicopters.net/) and can see that the more you pay, the
    more controls you get and the more the model behaves like the real
    thing.

    In the case of the little one, the marvel is not how well it flies but
    that it flies at all :)
     
  8. krw

    krw Guest

    It seems that many were getting the two confused. You can't have
    4-axis control with only two controls.
     
  9. Nelson

    Nelson Guest

    Mine comes with a downward pointing "fin" that slides along the rear
    boom. It allows you to change the center of gravity resulting in
    forward or backward motion... or, more usually, out of control crashing
    :)
     
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