Pitch Control Benefits of Elevators for Autogyros in Low-Speed Forward Flight

Doug Riley

Platinum Member
Kolibri 282 and Arco are both correct.

From the cyclic-pitch viewpoint, a tilt-spindle system produces exactly the same effect on the blades as a swashplate system. Some naiive gyro pilots incorrectly believe that we physically push the rotor disc about with our arm muscles. We couldn't, and we don't. The tilting spindle makes cyclic-pitch changes and the rotor responds by flying itself to its new plane of rotation.

The outboard-flap-hinge arrangement cannot work with a tilting spindle, though. When the pilot tries to tilt the spindle, the centrifugal effect of the blades produces such a powerful centering reaction that the controls can't move with ordinary human muscle force. It's the same centering effect that can provide stability and control in zero G events.

Yes, Cierva encountered this problem, and moved his flap hinges axes very close to the spindle's rotational axis. There were still complaints about high control pressures.

Horizontal tail surfaces (controllable or not) are a simple solution to zero-G pitch stability for those who want to retain the simple, reliable tilting spindle and (consequently) centered flap hinges.

More complex gyros than the typical sport aircraft often have powerful prerotators and/or large, heavy rotor blades. These features tend to eliminate the option of the tilting spindle. So we see the Groen Hawk, LFINO, Air & Space 18A, and McCulloch J-2, all with swashplate controls. More cost, more moving parts to jam or fail, but a necessary tradeoff.

Also lost in this tradeoff is the excellent control-pressure feedback generated by the offset-gimbal version of the tilt-spindle head.

Those who insist on a tilting spindle can, I suppose, use hydraulics to force the spindle around, but that's hardly a simple solution.
 

C. Beaty

Gold Supporter
Thanks, Smack; I will write a book if you can interest a publisher. But I doubt there’s a rational publisher interested in publishing a book with a sales potential of a few hundred copies. Gyrocoptering isn’t exactly like golfing or fishing with millions of participants.
 

All_In

Gold Supporter
PRA will publish anything you write Chuck!!! You are a superstar with your own PRA "Chuck Beady Engineering" award with a $1,000 cash prize available to any aspiring Chuck Beady's in our future.
 

Smack

Re-member?
Chuck,
Let me start the chapter outline (you fill in the details !):
1. Early history of the gyroplane (maybe done before, but with your insight)
2. The Bensen revolution (he resurrects the gyroplane, provide some good/bad opinion) and it divergence from helicopters
3. How does the Gyroplane create lift through 'autorotation'
4. Rotors (aerodynamic profiles, old vs. new, reasons to choose this one or that); 2 blades vs 3 blades vs 1 blade
4a. Rotor construction: alum extrusion, composite, tip-weights, chord,
5. Rotorhead (slider, teetering vs. other, swashplates, Cierva aerodynamic control)
6. Tractor vs Pusher thrust configurations
7. Vibration, harmonics, dampening. Methods, considerations. The importance of the 'mast'.
8. Pre-rotators (pneumatic, hydraulic, mechanical, chemical, combustion, electric)
9. Thrustlines (high, low, centerline) and countermeasures for non-optimal alignment
10. Fuselage (open vs 'cabin'); aerodynamic stability considerations
11. Partially-powered rotor
12. Landing gear and ground harmonics
13. Weight and balance, the 'hang test'.
14. Control systems: pushrod vs cable vs hydraulic
15. Safety, simplicity
16. Material considerations (steel, aluminum, welded vs bolted, composites)
17. The 'Eurotub' revolution
18. The future of the gyroplane

Okay, Chuck, fill in the blanks !
Everyone else: add to the chapter titles or improve mine

Brian
 
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