Helicopter CG

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Old 02-29-2008, 01:00 AM
  #1
RappyPilot
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Default Helicopter CG

HI guys.

Where abouts should a helicopters CG be? I replaced a 1100mah battery pack with a 2400mah bettery pack and obvioulsly its heavier so I had to trim it out a bit. Was just curious where it should be or how you test it.

Marcel
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Old 02-29-2008, 06:42 AM
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rcjon
 
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Default RE: Helicopter CG

RP,


It should be under the head. Turn the flybar perpendicular to the nose to tail axis and pick it up by the flybar.
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Old 02-29-2008, 08:07 AM
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jsenicka
 
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Default RE: Helicopter CG

I like mine just a tiny bit in front of the main shaft. As rcjon said, you can put the flybar out side to side and carefully lift by the flybar as close to the head as you can. The nose of the heli should drop just a touch
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Old 02-29-2008, 12:59 PM
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Default RE: Helicopter CG

Quote:
ORIGINAL: RappyPilot
Where abouts should a helicopters CG be? ... Was just curious where it should be or how you test it...
You were given two options and both are quite correct. it all depends on the type of flying you intend to do. A "neutral CG" will be best for aerobatics and 3D flight. A "slightly forward CG" will be best for flying around and scale-like maneuvers.

Rafael
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Old 03-01-2008, 10:27 PM
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Default RE: Helicopter CG

To expand on Rafael's answer, if you are interested in flying inverted its best to have the CG under the main shaft. Any trim you have in upright in the elevator will be reversed when inverted and is a nusance to smooth aerobatics.
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Old 03-02-2008, 10:20 PM
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Default RE: Helicopter CG

About picking up the heli - I wouldn't use the flybar.

Instead - pick it up by the blade grips and roll the heli onto its side so the main shaft is parallel to the ground.

Reasons,
1) The blade grips are designed to lift the weight of the heli - the flybar is not.
2) With the heli rolled on its side, you will get a far more accurate reading of the balance.
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Old 04-18-2008, 11:55 PM
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evilhorse
 
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Default RE: Helicopter CG

and remember to fill it with 1/2 a tank of fuel, and put the canopy on.
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Old 04-19-2008, 08:53 PM
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Default RE: Helicopter CG


Quote:
ORIGINAL: BarracudaHockey

To expand on Rafael's answer, if you are interested in flying inverted its best to have the CG under the main shaft. Any trim you have in upright in the elevator will be reversed when inverted and is a nusance to smooth aerobatics.

BH,

Been doing inverted hovers with my "beater" Raptor 50. It's the one with stock head and tail rotor parts. The other day I felt brave enough to go inverted with my 1, the one with metal head, bird cage, and upgraded tail section. When I half rolled to inverted, the nose pitched down (up? Toward the ground.) dramatically and very quickly. Caught me totally off guard and I nearly wrecked. I've found that I go inverted with it but I have to anticipate this unexpected plung.

Maybe I need to look at the CG?
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Old 04-20-2008, 05:40 AM
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Default RE: Helicopter CG

Check you swash is level fore/aft on the ground, if you have a lot of trim to keep it still in a hover then yes, thats probably your problem.
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