Jan 26, 2007, 01:31 PM
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Joined Jan 2005
1,286 Posts
Something Curious

Some 45 years ago there was a plan for a free flying gyro in a german magazine. It was a small gyro with something like a 1/2A engine and not much of a fuse.

What I disticly remember was the rotor construction because I never quite understood how it was supposed to function. The blades had axles glued into them and these axles could rotate in their holders. Out of the front edge of the blades came a piece of piano wire which pointed some 30° to 40° downwards and had a liitle weight at the end. The blades with the weight were prevented from just turning downwards by a little stopper. I hope the attachment is able to lift the fog of my description.

Has anybody an idea how this could work?

Jochen

# Images

 Jan 26, 2007, 02:00 PM This is my other autogyro! Live in Inverness, Scotland, work away. Joined May 2006 2,125 Posts Hi Jochen, First thoughts, looks like the old constant speed propellor theory I was supposed to learn in ' 74, where the ATM (aerodynamic turning moments) are in opposition to the CTM (centrifugal turning moments), but that was for a powerdriven rotary aerofoil/airfoil , I need to think on this in the Autorotative sense. I'm sure some one will have the answer, may be if you get the designers name you can trace it. Yes very curious indeed. regards Al(T)
 Jan 26, 2007, 02:19 PM iPhly R/C with iPhone Silicon Valley, Calif Joined Jan 2005 1,712 Posts Did the article say how well the design flew? Ari.
Jan 26, 2007, 02:41 PM
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Joined Nov 2004
2,752 Posts
An idea that's still around.
http://www.coxmodels.com/prodinfo.asp?number=004421

It works by virtue of the fact the objects try to spin flat due to centrifugal force. In the diagram R1 is smaller than R2, hence the weight which is free to twirl on what I would call the feathering axis, will turn to be at the largest radius.
The higher the rpm the more the weight tries to pull flat and pull pitch into the blades. As the blade pitch increases the rpm slows and gravity acting on the weight pulls the pitch out, somewhat like an automatic pitch regulator.
On the cox helicopter it pulls the blades to positive pitch when the motor is running so the blades help the climb. When the engine quits and the rotor slows the blades automatically de-pitch to the autorotation setting. I assume the stop is there to set the lowest pitch allowed and prevent a fully feathered position that won't start spinning by itself.
ain't physics fun?
mickey