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Some design questions about new gyrocopter - 7/23/2006 10:56 AM   
jt99


 

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From: , GERMANY
Status: offline 		Hi all,

I am new to gyrocopters and would like to build one on my own. So far I have made some decisions which might be checked for usefullness :-)
Please yell to me if you find mistakes or have concerns.

* keep it simple construction using carbon, some aluminium and some wooden parts (tail)
* Saito 6,5ccm four stroke engine (~300g), 200ccm fuel tank, mounted to push the aircraft
* thrust will be about 1000g to 1200g
* rotor with only two blades, I know, I know....
* diameter of about 1,1m
* flight weight not more than 1200g
* rotor controlled only left and right
* big elevator and vertical tail, both controlled
* 3 wheels, most likely 2 in the front

What do you say about these assumptions?

Some things produce headaches:

* should the rotor blades really be mounted with some degrees play (flapping hinge) to enable them to move up and down because of different air speed of rotating blades (on the right more than on the left side)?
* How much play does one need? About +- 8 degrees?
* What angle of attack do the rotor blades need? Photos showed none to very little angle of attack of maybe one degree....
* Is a somewhat simplified Clark-Y sufficient for my needs?
* How many degrees should the rotor be controllable to the left and the right?
* Is it the best to join the movement of the rotor (left/right) with the vertical tail?

Please forgive my bumpy technical terms.



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RE: Some design questions about new gyrocopter - 7/23/2006 11:32 AM   
rcflyerfl



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From: Lakeland, FL, USA
Status: offline 		jt99,
Some of the questions I would ask you is how many Autogyro's have you built from others plans or kits and how sucessful were your flights.
I do know there is some that think well these are just airplane fuselages with some rotors on top, not diffacutt at all.

You might read www.autogyro.com and do some studying there.
Good luck you may be right on the button with your ideas..

RcFlyerfl

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RE: Some design questions about new gyrocopter - 7/23/2006 11:49 AM   
jt99


 

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Status: offline 		I have never build autogyros before, that's why I feel it is a good idea to ask these questions. My experiences are just about normal 3 axe airplanes up to 12ccm.
www.autogyro.com is awesome! Already read lots of stuff from that site but I am still missing some important details.

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RE: Some design questions about new gyrocopter - 7/23/2006 9:48 PM   
jt99


 

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Status: offline 		Here is an early draft of the dimensions. But I am sure some things will change...



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RE: Some design questions about new gyrocopter - 7/24/2006 11:22 AM   
rcflyerfl



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From: Lakeland, FL, USA
Status: offline 		jt99

You might do a search on Mickey's "BEGI" which is an electric Autogyro that is a pusher looking somewhat like yours. He is on vacation now but can give you some thoughts as to what you doing. The begi is a twin blade.. There should be some info on your search that willgive you the angles that you can use.

RCFLYERFL

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RE: Some design questions about new gyrocopter - 7/25/2006 7:56 AM   
jt99


 

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Status: offline 		Thanks. I will have a look at BEGI.

To repeat the both most important questions here is a small sketch. Is that right?




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RE: Some design questions about new gyrocopter - 7/25/2006 3:29 PM   
mnowell129


 

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Status: offline 		There is not a universal answer to this question. Flapping hinges are needed if
you have a wing and intend to control the roll and pitch with ailerons and elevator.
Flapping hinges would also be needed if you intend to tilt the rotor head for control,
but for a different reason, that is to relieve the servo stresses.
How do you intend to control the roll and pitch of this model?
mickey


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RE: Some design questions about new gyrocopter - 7/25/2006 3:48 PM   
jt99


 

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Status: offline 		The gyro will have an elevator and vertical tail like a normal plane both radio controlled. To simplify things I thought it is best to just controll rotors angle of attack to the feft and right with a midsize servo.

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RE: Some design questions about new gyrocopter - 7/26/2006 2:07 PM   
mnowell129


 

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From: longwood, FL, USA
Status: offline 		I urge you to read all the threads here and on rcgroups.com (http://www.rcgroups.com/forums/forumdisplay.php?f=224)
from those who tried to design their own gyrocopter with no previous experience. It may be insightful.
I want to encourage you with gyrocopters, so I suggest you build a known good design and learn the
flight characteristics first. Then you are more prepared to design your own.
Your basic design has been attempted many times and the likely result is a model that will be uncontrollable
in roll. I suggest a more stable 3 bladed head with relatively stiff flapping hinges or a flybar stabilized head.
The single rotor gyrocopter is fairly difficult to design.
regarding some other dimensions:
1,1 meter diameter is 10.2 square feet of disk area, 1.2 kg is about 42 ounces, yielding a disk loading
of 4 ounces/sq foot of disk area. This is probably high. A two bladed system should probably be in
the 2.5 ounce/sq foot disk loading range. At 42 ounces the disk area should be around 16 square feet,
or 1,4 m diameter.
mickey

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RE: Some design questions about new gyrocopter - 7/27/2006 7:50 AM   
jt99


 

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From: , GERMANY
Status: offline 		Thank mnowell129 - these are very helpful informations!

The diameter has to the expanded to about 1,3m if I really want to use only two blades, which is subject to reconsider...

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