gyrocopter rotor pivot position

Owly

Newbie
Joined
Aug 30, 2010
Messages
18
Location
Melville, Montana
I've wondered for some time what the rationale behind the pivot point on a rotor is above the blade bar. Is this related to cone angle and reducing the resistance to rotor rocking by approaching the center of the disk which in flight is actually a cone? Interestingly the result is a side shift as the rotor rocks...... Is that slight shift an asset or a liability? I'm curious to hear thoughts on this.

Howard
 

Not Yet

Member
Joined
Nov 3, 2004
Messages
456
Location
Haines City Fl
Total Flight Time
5
I think you are referring to the teeter pivot. It is there to compensate for the difference in lift between the advancing blade and the retarding blade. Without this central flapping hinge the gyro would tip over before it attained flying speed. It allows the advancing blade to raise whale the retarding blade falls, so the gyro won’t tip over.
 

robo_nipsy

Member
Joined
Dec 9, 2008
Messages
318
Location
Mankato, MN
Aircraft
Gyro Technic
Howard,
Yes, your are correct that has to do with the coning of the blades.
When the blades are coned to their in-flight configuration, the CG of the blade assembly (Blades and hub bar) should be located very near the axis of the teeter bolt.

If it is not, it will result in a 2/rev shake as you say because it is shifting back and forth as it turns....

If the CG of the blades is aligned with this point, then, even though the hub bar seems to be shifting back and forth, the CG of the blade assembly as a whole is not, and remains centered on the teeter bolt allowing the blades to spin smoothly.
 
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