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I've got to do something with it.. can't just leave it hanging

Discussion in 'Off-Topic Members Lounge' started by flippineck, Jul 7, 2014.

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  1. flippineck

    flippineck

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    Sep 8, 2013
    I just bought a nifty model helicopter from Toys R Us. It works on 27MHz and has aerials roughly 60cm long, one on the transmitter, and a loose wire one hanging from the helicopter itself.

    Flies great! Big fun & my 5 YO lad loves dad's heli, constantly wants control ;-)

    Only trouble is, this long dangly antenna on the heli... it doesn't half get caught up in the works sometimes.

    Caused a major crash in next door's sycamore tree yesterday. Luckily next door = 2 old ladies who are very forgiving and don't mind random crazy dudes turning up demanding to climb their trees

    Anyway.. quick solution, wrap the antenna pretty randomly round and round the skids. This sorts out the 'antenna gets caught in the gearwheels' nonsense but, seriously cuts down the range.

    What should I do to get the best of a bad deal.. coil it like a tight spring round the tail boom? tape it back and forth on the boom with a specific repeating length?

    The instructions insist the antenna should be left dangling free full length beneath the heli but this ain't workin', joe :lol:

    I figure 60cm is something like a 1/18th wave whip at 27MHz? Smallest I've seen commonly documented is 1/4 wave..
     
  2. (*steve*)

    (*steve*) ¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd Moderator

    25,491
    2,833
    Jan 21, 2010
    How about something like this:

    hele.jpg

    A stiff antenna (coat hanger) that hangs down to something a bit less than vertical but can swing up against the fuselage in a way that doesn't foul either rotor.

    You can probably shorten it more by loading the antenna (in essence placing an inductor part way along the antenna)
     
  3. shrtrnd

    shrtrnd

    3,816
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    Jan 15, 2010
    I like *steve*s idea, but if that doesn't work, is there a possibility of hanging a small weight on the end of the antenna, so is stays down, and doesn't get caught-up in the helicopter when it makes a rapid (hopefully under control) descent?
     
  4. (*steve*)

    (*steve*) ¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd Moderator

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    Jan 21, 2010
    That was my first thought, but I considered that the risk of a weight at the end of a wire getting caught up in the rotor to be potentially more damaging.

    But that doesn't mean it's not worth carefully investigating. If it works it will be easier to implement.

    How aggressively is the model helicopter maneuvered?
     
  5. shrtrnd

    shrtrnd

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    Jan 15, 2010
    I think *steve*s idea is the best bet. I believe flippineck wants NO antenna hanging down. I think the hanging antenna is what snagged his chopper in the first place. I can't think of a way to just get the antenna out of the
    way (by wrapping it around the tail section or something else he considered) without losing transmission/receiving range. I'm guessing there might be a reception boost electronic circuit somewhere that he might be able to
    integrate into the helicopter receiver, that might allow a shorter antenna. Not knowing much about R/C helicopter controls, maybe the manufacturer, or even a hobby website for R/C controllers might have good ideas,.
    This was a good place to check,but it doesn't look like we've got very many users here who work R/C control devices like the helicopter. *steve*s idea is the best way I can think of to keep the present antenna length, while
    shortening the actual 90 degree down length of the antenna so it's less likely to snag trees.
     
  6. Arouse1973

    Arouse1973 Adam

    5,165
    1,087
    Dec 18, 2013
    I used to use antenna tubes for my helicopters. Feed the wire through the tube and use the rubber end stop to secure the end and the tape any left over to the tube. Cable tie this to one of the skids. Depends how big the heli is also and if you have room.
    Adam
    FAST103.jpg
     
  7. flippineck

    flippineck

    292
    9
    Sep 8, 2013
    Did the swingy thing using a big tie-wrap combined with, coiling up the wire in the middle like a spring. there's a handy transverse bar underneath the fuselage between the skids, could have been made for the purpose. Seems to work well.

    It's maneuvered as violently as a tired 4 year old full of sugar can manage, and more violently than that if it's windy lol

    Crashed it loads now & it's survived so far
     
  8. shrtrnd

    shrtrnd

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    518
    Jan 15, 2010
    Avoid the trees.
     
  9. (*steve*)

    (*steve*) ¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd Moderator

    25,491
    2,833
    Jan 21, 2010
    Excellent o Prince of Insufficient Light!

    I proactively leverage my synergies.
    I proactively leverage my synergies.
    I proactively leverage my synergies.
    I proactively leverage my synergies.
    ...
     
    Supercap2F likes this.
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