Does any one have a pattern for a 3 bladed balsa rotor head?

Maybe someone will write and say thay have a plan for a balsa rotor head but it seems to me that balsa is not a suitable material for such an item. Loads/strains on the rotor hub are considerable, not just aerodynamic but if the plane tips over on landing and the rotors smack the ground. I find the rotors survive OK (being held with a single bolt so they swing back) but the hub itself takes a bump, often breaking a hinge.
I use a simple design head/hub. made from 1/8th plywood - a sandwich of two layers with code 5 plastic `filling` hinge - this sometimes obtained from the bottom of an icecream container. More details if required.

Picture of the hub type I use is included on my webpages http://www.geocities.com/tintrax/page6.html (copy & paste if necessary)
Note also the nuts & bolts that clamp things together. Contact cement used too. In the event of a hinge breakage after a bad landing the hub can be prised apart and a new polypropylene hinge installed. Fifteen degrees delta angle, blades at zero incidence relative to each other, the delta angle takes care of incidence alterations automatically in flight.
I am not saying this is the best hub, just the simple cheap design I have settled on.

Tintrax,

Thanks for the idea I never thought of using some ice cream bucket plastic for a hing. i just wanted an inexpincive way to make a good one so i didn't have to buy one.
I have never flown an autogyro before and i decided to convert a Right Flyer trainer that I had laying around to a gyrocopter.

Any advice would by greatly appreciated, thanks again.

Tye

Here are a few pictures of my plane (soon to be gyro).

Tye - What size motor is that? What length of rotor blade do you have room for? I mean how far from where the centre of rotor hub will it be to the fin? (Centre of rotor disc will presumably be just behind the front of the cabin, and of course several inches above). Will you be retaining elevators and rudder, or are you intending full direct control? (all control by tilting the rotors & use of throttle).
I suggest side tilt on the rotors and retain the elevator & rudder control.
Colin

Tintrax,
I intend to use a 46 size Meco for power. I have room for a 50 inch rotor, and I think I'll need every bit of that.
The plane was origanly tricicle gear but converted it to a tail dragger so i plan to use DC and use the previous elevater pushrod as tail wheel control.

I am hoping someone else will come in with some advice for Tye. I do not claim to be the great fund of all knowledge on the subject of autogyros! Working alone here I must admit I have never seen any other autogyros in flight - only my own! However here are some of my thoughts, but I will say the we all have differing approaches to the subject and my thoughts may not fit in with everybody.
Anyway - 50 inch diameter rotors, in my experience a .46 motor is on the `hot` side.
One of my planes is powered by an O.S. 40FP and has a 56.5 inch rotor disc. I consider it to be rather overpowered. Autogyros are great for slow flight, they are not speedy racers.
My smallest is .15 powered with 35 inch diameter rotor disc, and handles stiff breezes fine.
Weight is important, 5 ounces per square foot is maximum (I reckon), my .40 plane has only 3.5 oz loading. Try to keep your plane light. Are you going to have no moving surfaces on the tailplane? Dc is OK, but is requires a more complicated rotor head. Load on servo is cconsiderable too.
Colin

Correction - In my letter above I stated my .15 powered plane has 35 inch disc, clumsy typing - it has 45 inch disc.
Colin

Is it posible to have the rotor head to high?
I could either raise the rotor head or make the virtical fin shorter.
50 inches is as much as the rudder would would allow.

Tye

If you are going to have the rotors extending over the top of the fin I suggest that even a low fin is likely to suffer `rotor strike` at some stage. A very low fin may be OK, together with an underfin and also tip fins on the stabiliser - but even they need to be mainly below the stabiliser and very little above it. See my modified Gyrace (now a single rotor autogyro on my webpages mentioned the other day). I found I had to cut down both fin and tip stabiliser fins and extend them `down under` to compensate. I have also had rotors hit the fuselage on aircraft that have rotors that don`t extend over the fin.
Autogyros have their challenges, but it is great to achieve success.

Tintrax,
Thanks for the advice.
I'll keep you posted on my progress.

Tye

I have finished the pylon. Now I'm ready to recover the nose. I ordered a set of four 36 inch Aerobalsa blades that should be arriving shortly. I hope to get it in the air in the next couple of weeks.