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G400 autogyro

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Old 03-03-2007, 05:21 PM
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Lizard
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Default G400 autogyro

Hello folks,

I have been off the autogyros for some years. I have been building other type of flying machines as well
Now I have built and flown succesfully a new electric autogyro G400. It took 2years to build this one I needed to give a name. I think there is no other autogyro named G400? G comes from gyro and 400 from its size (speed 400 size). It flew today two times. G400 was designed by me.

I took basic parameters from [link=http://www.autogyro.com/technic/specs.htm]www.autogyro.com[/link]. The fuselage took inspiration from from MH400 electric glider but later on it had very little same with the glider - especially the wing Earlier this summer it tried to fly it, but it crashed on the takeoff. It had direct control and no elevator control. I believe it was due to bad hand launch but now it has also elevator control. The nose was rebuilt and is now rectangular shape (and more ugly) because I wanted to fix it fast. Blades have clark-y profile because it is easy to make.

G400 has now two flights. It is a bit unstable sideways. I think the problem is flimsy pushrods. The problem could also be the plastic tube that it use to hinge the mast. I believe the first reason is the real problem. It flies very slow and it was able to hover still easily at 2m/s light winds. The landing gear is too thin and bends too easily. It will be changed later to 4mm CF tube. More comments on flight behaviour will be later after more flights.

A video from first flight is online at [link=http://picasaweb.google.fi/jussika/Misc/photo#5037824035359238642]my picasaweb page[/link]
Main specs:
flying weight 600g
rotor diameter ~ 110cm
motor GWS brushless (180W)
battery 4s etec1250 mAh
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Old 03-03-2007, 07:27 PM
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Default RE: G400 autogyro

Congratulations!!! It looks like you did the right thing and followed the advice of other gyro nuts but it still takes and lot of trial and error to get one of these things to fly like they are suppose to.

Thank you for posting the video. It's always good to see what others are doing. By looking at the pictures, I suspect that you don't have a problem with the motor and speed controller over heating.

Keep us informed on your gyro project.

Phil
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Old 03-04-2007, 01:17 PM
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Default RE: G400 autogyro

It is interesting to see others having problems with autogyros as well and how they have solved the problems. I solved my problems by using better pushrods to the mast and redusing the rotor angle close to zero. This worked well, and now it is pleasure to fly. I think autogyro.com's design specs are good point to start designing but often you have to make your own changes. Now I will start redusing the elevator movement and start gradually fly by direct control only. It is a thing that interests me. There could be more down thurst on my autogyro. All the autogyros like down thurst

I ripped the flimsy landing gears off and put a carbon fiber stick to bottom of the fuselage. You can see two paper balls attached to stick's ends from second [link=http://picasaweb.google.fi/jussika/Misc/photo#5038130511340579330]video[/link]. Landing speeds are low and anyway it wouldn't roll on the snow without skies. Later I will put a real landing gear to G400.

Phil, you are right about the motor cooling with this weather However it gives some additional problems to the LiPo battery that doesn't like cold.
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Old 03-04-2007, 04:17 PM
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Default RE: G400 autogyro

Hi,
Nice video! Looks like you've got it flying pretty good. That's a great success story. I'm not a mechanical engineer, but I think you would have better control if your servos were in that back pulling down. It looks like you are pushing up on in front of the pivot point which would cause the severo rods to flex. However, I guess you solved that problem anyway.

I have no experience with lipo batteries in the cold. I'm in Florida and usually the problem is keeping stuff cool.

Phil
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Old 03-06-2007, 11:33 AM
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Default RE: G400 autogyro

Hi, Phil. Your idea about moving servos behind the pivot point is great idea. I will try that one on next version I will build. I am too lazy to move servos now, when everything is working fine. The metal pushrods I use are enough strong.I have been told not to fix something that is working ok.

Do you think my central of gravity is too behind, because this one flies with aft rotor tilt being only few degrees? It flies very stable now. The autogyro.com recommends 6 to 14 degrees aft tilt to the rotor ( B in the picture). This seems much to me. Any comments? How much you have aft tilt on your tractor autogyro designs?


The picture is linked from [link=http://www.autogyro.com/technic/specs.htm]http://www.autogyro.com/technic/specs.htm[/link]
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Old 03-06-2007, 12:26 PM
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Default RE: G400 autogyro

I agree, if ain't broke, don't fix it.

I usually set the mast till back at about 10 to 12 degrees. We also use what is called the hang angle instead of CG. Hold the gyro by the rotor shaft and the fuselage should till down about 10 degrees. Also, if the motor quits the nose will drop and you still have control. If it's tail heavy and the motor quits it will just float to the ground, but you have no control. I also use at least 5 degrees downthrust on the motor.

Phil
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