That's very interesting.
From what I'm seeing, this is a tension actuated VP, instead of our current torsion actuated VPs.
It looks like, at high tension the coil spring compresses and the actuator arms push in the direction of the arrows to open the prop to high pitch.
At low tension, the coil spring pushes out, and the actuator arms pull opposite the arrows to reduce pitch.
I think torsion would be a lot more consistent across motors than tension, though.
--- In Indoor_Construction_at_yahoogroups.com, "John Barker" <john.barker783@...> wrote:
>
> Gary
>
> I have not seen any response to your request for a photocopy from Zaic’s 1937 Year Book. I have a copy of the Model Aeronautic Encyclopedia vol1 which includes stuff from earlier YBs and on p81 there is a sketch of R. Hammer’s VP arrangement. The drawing of the working part is not much more than half an inch high so I did not think it would scan very well. I peered at it for a while through my loupe and made a larger sketch which I hope may be of some use. I have stayed with Frank’s drawing as closely as possible although I have given the wires some thickness to suit the larger size (in the original the wires were all drawn as single lines). I don’t understand what the arrows indicate and I certainly don’t understand the little circles on the pitch changing arms! The wire hinges (which I have drawn in blue) are just a single thin line in the original. Whether they are torsion wires or whether they pivot in some tubes I do not know.
>
> Operation would seem to be straightforward. One would expect the propeller blades to have a high angle near the root such that, looking at the top blade in the sketch, the trailing edge would be nearer than the leading edge. If the motor was wound tightly the spring would compress, the ‘U’ shaped wire would move backwards pushing the trailing edge of the blade further in and increasing the pitch. However I have never seen much correlation between the tension and the torque in a motor so I would not expect the device to have many followers.
>
> You also asked about Louis Garami’s ‘Torque Burner’. There is a short wire fixed to the motor stick, about 35% back and pointing downwards. The motor is made in two parts, a short front part and a long rear part joined by a wire ring. After the motor is wound the wire ring is slid onto the wire on the motor stick. The model flies on the front part of the motor until the tensions and torques in the two parts of the motor equalize, at which point the ring drops off the wire and the rear part of the motor comes into play.
>
> John
>
Received on Tue Dec 13 2011 - 10:21:45 CET
This archive was generated by Yannick on Sat Dec 14 2019 - 19:13:46 CET