CG of a Helicopter
01-04-2009 | 05:57 AM
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From: RIDGENew York
CG of a Helicopter
I just purchased my first real heli the AXE 400 3D and had a question regarding mine and all other helis for that matter.
1) Do you balance the CG on helis like you do with airplanes?
2) If so what effects does balance have on a Heli?
3) Also with planes having an aft Center of Gravity causes the model to be more pitch sensitive as well as helping it fly inverted a little more neutral. Having it set more nose heavy helps the plane to be more stable in forward flight and less pitch sensitive.
4)When I'm hovering and I trim the heli to fly somewhat hands off, and then go into forward flight the heli always wants to pitch up where as I need to constantly hold down pitch to track straight and level across the field. Is this normal and if not does CG have any thing to do with this?
1) Do you balance the CG on helis like you do with airplanes?
2) If so what effects does balance have on a Heli?
3) Also with planes having an aft Center of Gravity causes the model to be more pitch sensitive as well as helping it fly inverted a little more neutral. Having it set more nose heavy helps the plane to be more stable in forward flight and less pitch sensitive.
4)When I'm hovering and I trim the heli to fly somewhat hands off, and then go into forward flight the heli always wants to pitch up where as I need to constantly hold down pitch to track straight and level across the field. Is this normal and if not does CG have any thing to do with this?
01-04-2009 | 06:59 AM
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From: New South Wales, AUSTRALIA
RE: CG of a Helicopter
The CG of a helicopter is not as critical as on a plane.
Having said that, it does still have an influence.
Optimum CG is on the mainshaft or slightly forward. A slightly backwards CG does not have the dramatic effect as on a plane.
The usual cause for pitching up is too light a flybar, too light mainblades and CG of mainblades being too far back (chordwise).
Delta offset can also be the cause, but is usually not adjustable on small and cheaper helis.
To improve the situation:
Adjust CG to be on or slightly forward of mast
Increase weight of the flybar via flybar weights.
Purchase or move CG forward on the main blades
I don't know this specific model, but if it's delta offset in the head is specifically designed for beginners..ie stable, then I don't think that there is a lot that you can do about it.
Having said that, it does still have an influence.
Optimum CG is on the mainshaft or slightly forward. A slightly backwards CG does not have the dramatic effect as on a plane.
The usual cause for pitching up is too light a flybar, too light mainblades and CG of mainblades being too far back (chordwise).
Delta offset can also be the cause, but is usually not adjustable on small and cheaper helis.
To improve the situation:
Adjust CG to be on or slightly forward of mast
Increase weight of the flybar via flybar weights.
Purchase or move CG forward on the main blades
I don't know this specific model, but if it's delta offset in the head is specifically designed for beginners..ie stable, then I don't think that there is a lot that you can do about it.
