gyro/heli autorotation question

[skyguynca]

Now if our blades on our gyros are always in autorotation, it enables us to takeoff, climb as long as the engine is providing thrust enough to overcome drag. We can desend and land even with no power.

Now the discussions have been on here before but my question is that if you have a fixed pitch helicopter, set at the same 3 to 5 degrees as you have on your gyro rotor system, you can overspin them and fly (we saw that happen on the peroxide prerotor system even though the flight was totally by accident) so as long as you have a sprag clutch in theory you should be ok with a fixed pitch system as long as the keep foward speed during a engine out, you should be able to land ok, right?

The reason I ask is that it seems to becoming popular with the coaxial ultralight heli to have a fixed pitch system for flight. I orginally was thinking this is terrible but if you have enough altitude and airspeed if the engine does quit you could still land safely.

Ok, now lets here some comments....

 

[C. Beaty]

The Nolan Brothers’ fixed pitch, tilt head, co-axial helicopter worked pretty well but I doubt if it was ever flown by anyone other than Jack Nolan; a self-taught pilot of exceptional skill.

It worked only because the rotor system had extremely low inertia which made lift control with throttle possible and torque balance of the co-axial rotor eliminated feedback into the control system.

The Nolan helicopter would not autorotate because of the tiny rotor and resultant high disc loading.

Bensen messed around with several co-axial tilt head helicopters but control was extremely sluggish due to rotor inertia.

The Cierva Company built a throttle controlled, tilt head, single main rotor/tail rotor helicopter shortly after WW II. It was also plagued by sluggish response and required hydraulic servos to tilt the rotorhead because of torque reaction through the gimbal pivots.

 

[Ga6riel]

the airscooter is likewise fixed pitch coaxial

 

[C. Beaty]

I thought something looked familiar about the AirScooter. The following is from their web site:

https://www.airscooter.com/pages/aboutus_personnel.htm

Jack and Herb Nolan serve as technical, test flight and training consultants to AirScooter. They used their racing background to develop small helicopter designs in the 1980s and have valuable practical flight experience.

The Nolan Brothers sold out a number of years ago.

 

[skyguynca]

Thanks Chuck, that was what I was wondering

 

[Rotor Rooter]

Patent

Patent

Airscooter Corporation

'Helicopter propulsion and control system' patent

For those that are interested, go to; https://patft.uspto.gov/netahtml/srchnum.htm

and enter; 6,460,802

also 6,886,777

 

[skyguynca]

One more little question for ya chuck, if you had full cyclic control but no collective so the pitch stick neutral was say 3 degrees, you would beat the sluggish controls but still only have cyclic and throttle, would that be better?

 

[C. Beaty]

It is the flywheel inertia of the rotor skyG., that makes control by throttle sluggish.

To increase rotor lift, the engine must accelerate the rotor to a higher rpm; to decrease lift, the throttle must be backed off and lift decreases as the rotor slows.

Because a normal rotor is a giant flywheel, the time delay between squeezing the throttle and the machine responding is simply too long for precise control.

I’ve watched Bensen hovering one of his throttle controlled helicopters and he bobbled around over an acre or so. Sort of like a DingBat ball in slow motion.

The Nolan Brothers throttle controlled helicopter had very light 14’ rotors so inertia wasn’t as great a problem.

However, Jack Nolan, the pilot, never held a stationary hover. He always kept the machine in motion so as to disguise any vertical bobble.

I have the promotional videotape of the Nolan machine. If you’d like a CD copy, stick $2 in an envelope to cover my out of pocket cost along with a self-addressed gummed mailing label and send to:

CA Beaty
4311 Turkey Creek Rd.
Plant City, FL 33567

 

[skyguynca]

WILL DO!!! Thanks