A new tractor design

Supermotive

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Jean Claude, Thank you very much for the dialogue. You are keeping me on my toes and causing me to think a whole lot. Maybe some others can learn from our conversation also .
 

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
Total Flight Time
About 500 h (FW + ultra light)
I am just comparing here the change of stability due to the position of the propellers, all things being equal.
Do not think I denigrate the tractors: I'm finishing mine.
 

Kevin_Richey

Yamaha gyro...Oregon, USA
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Sport Copter gyroplane
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Here you can see Jean Claude in person as well as a couple of photos of his wooden tractor gyroplane out of his workshop:


There used to be more photos on the French Autogire site, cannot locate them now...
 

Alan_Cheatham

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I agree with this if the center of gravity never moved. Center of drag may be another issue. The pusher will also be pushing against the cg and the center of drag which will always be dynamically moving and not in the center of thrust.
Can you elaborate on your theory that the CG is dynamically moving?
 

Supermotive

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Here you can see Jean Claude in person as well as a couple of photos of his wooden tractor gyroplane out of his workshop:


There used to be more photos on the French Autogire site, cannot locate them now...
Thank you. Pretty cool!
 

Jean Claude

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Centre FRANCE
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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)

XXavier

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Also, few pictures here
Also, few pictures here
A novel, and very interesting peculiarity of JC's gyro design is the articulated, three-side truncated pyramid that replaces the mast. If I'm not mistaken, the rotor head is controlled, both in pitch as in roll, directly with the hanging stick, that tilts the smaller base of the pyramid in the desired direction...

Or so I think it works... Is that right, JC...?


Captura de pantalla 2019-10-08 a las 10.19.38.png
 

Brian Jackson

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It appears from looking at the 2 photos that the rear leg of the pylon has pitch/roll freedom provided by it's spherical rod end, with a clevis attachment to the rotorhead assembly. Pushing the stick forward tilts the rotor backward. Roll looks to be provided by the freedom of the rod ends of the two forward pylon legs that changes the side-to-side angle of the head. It looks like the head will move location sideways but the centerlines of the forward legs appear to converge near the rotor's "teeter" point. By my novice eye it achieves the same control motion as a conventional head. I'm curious about its mimicry of the offset gimbal effect. It really is a nice looking design, though I am unsure of my interpretation.
 

Jean Claude

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Centre FRANCE
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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)
I imagined this articulation so that the vibratory forces in the plane of rotation are not transmitted in the pilot's hand
With the usual Cardan's joint, rolling shocks on the hub during the run cause stick movements. And also true for vibration caused by rotor unbalance. This new articulation will make them disappear.
But it will now produces a return force to neutral which did not exist in the past. To test.
 

Jean Claude

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Jan 2, 2009
Messages
1,882
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)
Designing a 2-seater tractor side by side is difficult, because the pitching balance needs to be kept with two heavy passengers as well as with light one
This means that the seats must be on the rotor thrust line.
In these conditions the rear airframe must be heavy enough to balance the weight of the engine. It's unfortunate for rise performance.
You can arrange the different masses in a spreadsheet to monitor the hanging angle during your design. As here:
Sans titre.png
 

Supermotive

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Designing a 2-seater tractor side by side is difficult, because the pitching balance needs to be kept with two heavy passengers as well as with light one
This means that the seats must be on the rotor thrust line.
In these conditions the rear airframe must be heavy enough to balance the weight of the engine. It's unfortunate for rise performance.
You can arrange the different masses in a spreadsheet to monitor the hanging angle during your design. As here:
View attachment 1145465
Jean Claude, I agree with you. Thank you for your input. You are very helpful. Are you able to share the spreadsheet? my email is [email protected]. Again, I appreciate you and respect your great knowledge.
 

Supermotive

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Here is a rough sketch of one concept I am working on. It is by no means finished. For an idea of scale, the length of the tube structure in the drawing is 12 feet.

E4F3CE21-BB9D-4F1C-86CA-066F19B838A2.jpeg
 

wolfy

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western australia
Here is a rough sketch of one concept I am working on. It is by no means finished. For an idea of scale, the length of the tube structure in the drawing is 12 feet.

View attachment 1145483
It looks like you will have easy entry and exit to the cockpit but I think you need to triangulate more somehow between station 4 and 2.
The way you have your rear shock geometry the shock motion ratio is digressive, if you were to have the top of the shock mounted back on (or towards) the same station as the trailing arm pivot the motion ratio will be progressive. With progressive damping you can achieve a soft ride at ride height and bottom out control also.

jim
 

Supermotive

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It looks like you will have easy entry and exit to the cockpit but I think you need to triangulate more somehow between station 4 and 2.
The way you have your rear shock geometry the shock motion ratio is digressive, if you were to have the top of the shock mounted back on (or towards) the same station as the trailing arm pivot the motion ratio will be progressive. With progressive damping you can achieve a soft ride at ride height and bottom out control also.

jim
Jim, thanks for the input. Yes. I fully agree about the lack of support between 2 and 4. I actually redrew the fuse (see attached) with a little more length for stability, but I still haven’t addressed the 2-4 structure yet. I need to really study that part. I agree about the rear shock as well. I am hoping to never need the shock. It’s there for plopping down out of the sky during an engine out with poor landing options.
 

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Alan_Cheatham

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Here are a couple of links that may be of interest:

A CAD comparison I did of a Littlewing LW5 at the normal width of 26" vs someones proposed 42". Flow separation becomes an issue with the wider width unless the fuselage is made much longer.

Back in '05 a friend and myself built a LW5 till it was a rolling airframe before he canceled and sold the project. I did much of the fuselage fabrication and TIG welding myself which was not easy given the LW5's smaller frame, very difficult to squeeze ones body through the frame openings with welding hood to be able to see the joint while welding. One word of advise, no matter how long it takes drill vent holes linking all the tubes internally together, this will prevent pressure from building up while welding which can "boil" the weld.

Here is our LW5 build thread:
 
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