rotor blades-autogiro type

[jplot]

I have been working for some years in an effort to develop a flyable and controllable rotorkite. That is, a unit with a rotor spun by the normal wind that will create lift and thus fly. I have met with much success and many problems as most probably any engineer can envision.
What I need to solve at this time is the weird way that my larger rotors (I have been making wooden rotors of from 29 to 130 inches in length) will spin just great in one outing and then simply not perform nearly as well the next time out. I am very careful to consistently check on blade balance as I have come to find that just the humidity overnight can change the balance of a wooden rotor quite drastically.
I have experimented with all different amounts of teeter and do not believe that is the problem. What I am wondering about at this time is the possibility that the relationship of the negative pitch angle of the blade on one side of the rotor to the other blade may be of more importance then I have envisioned. I usually set all of my rotors between –2 to –5 degree pitch and assumed that if I just get a reasonably close match that the teeter will take care of the dissymmetry of lift. But I am now wondering if I must find a better and closer tolerance way to set my pitch angles.
Any comments would be appreciated.

 

[wilarytopia]

Sealing the wood completely after first drying to about 10-15% moisture content (air drying in the U.K.lowers the MC to around 20-25% during the summer, storing in a centrally heated house for 4-6 weeks typically reduces MC to 10-15%)should stabilise the timber.
Adding a dihedral angle to the tips of the rotors should give added stability.
Good luck.

Wil

 

I made a nice chinook roter kite had 3' rotors total length 5 foot ,used venitian blinds with a spar (wood rod) flew real neat.

 

try 0 or positiv pitch up to 3 degree's.it could be you need to give a little push to give initial speed.I build a rotor (1.5 meter) with colectif pitch on a broomstick and it spun like hell giving a lot of thrust.look for Benson Gyrocopter on the web for simple rotorhead construction.even simpeler can be found at moddel airplane sites.some more profesional invo can be found at:

http://naca.larc.nasa.gov/reports/1937/naca-report-552/