Single Bladed Torqueless Helicopter Design

kolibri282

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title: Single Bladed Torqueless Helicopter Design
author: Klijn, Martinus M.
comment: Klijn proposes an interesting type of strap on helicopter. The very detailed presentation of his design decisions and step by step calculations make this an interesting report for everybody who wants to dive a bit deeper into the nitty gritty of helicopter design. Have fun!
https://ia801909.us.archive.org/8/items/DTIC_ADA045375/DTIC_ADA045375.pdf
 

C. Beaty

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I’ve been that route before only to learn that counterweighted single blade rotors don’t work.

Apply cyclic and the single blade responds normally but the counterweight holds its position, slowly following the single blade. In the meantime, the vertical vibration becomes a violent vertical hop.

This is easily proven by making up a scale model and running in front of a large fan. I was just too dumb to think of that before cutting metal.
 
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Jean Claude

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I piloted gliders C800, Bijave, C 310, airplanes Piper J3 , PA 28, Jodel D117, DR 220, Cessna 150, C
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About 500 h (FW + ultra light)
Without aerodynamic lift the counterweight wants to keep its rotation plan. It will change its plan like the blade only if it is cyclically pushed by a lever taking support vertically on the rotor head.
 

kolibri282

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The mechanism in the invention below was conceived, from what I understand, to alleviate the problem described by Chuck and Jean-Claude. The counterweight remains in the plane of rotation while the blade flaps. It seems though that the lateral shift in center of gravity is not taken care of. I am not sure, whether this is significant.

https://www.google.com/patents/US6619585
 

C. Beaty

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Things with a single blade don’t work very well; first there were the TIDD propeller patents of 1939:

https://www.google.com/patents/US2297815

And the Boelkow helicopter of the 1960s:

http://www.aviastar.org/helicopters_eng/bo-103.php

A single blade aircraft propeller seems to be a clever idea at first glance; skew the teeter hinge and you have a constant speed propeller without the complications of feathering bearings and necessary control mechanism; but the vibration can’t be eliminated.

The Boelkow BO-103 used a Hiller type servo rotor to slow down the rate of application of cyclic input but driving a rotor with an unbalanced torque moment produces a different kind of shake that is impossible to eliminate.
 

Jean Claude

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Joined
Jan 2, 2009
Messages
2,018
Location
Centre FRANCE
Aircraft
I piloted gliders C800, Bijave, C 310, airplanes Piper J3 , PA 28, Jodel D117, DR 220, Cessna 150, C
Total Flight Time
About 500 h (FW + ultra light)
In add, the author of this project seems forget that with such a low load the VRS can appear from a very slow descent rate: Around -500 ft / min
 
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