Hey Chuck, and all you helicopter / gyronuats (spelling deficiency)

skyguynca

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OK yep it has been awhile since I flew a gyro, even longer for a helicopter. With all this time I have with the shut down/stay at home/workshop order I have been doing a bit of thinking and need some feed back from you experienced guys and gals.

Ok so as a example we have the common gyro, blades set at 1 to 3 or so degrees for auto rotation. For jump gyros you can over spin the rotor system and get lift i.e. the hydrogen peroxide pre rotor guy found out many years ago, video was posted here somewhere.

Now with the helicopter the base setting for the blade pitch is the auto rotation pitch and then collective is an additional range of 7 to 13 degrees (if my memory has not failed) depending on the airfoil used for the blades.

So some may remember I was looking at the Stork, a weight shift ultralight helicopter design that disappeared because the designer passed away of a heart attack. I believe Chuck had met him at Oshkosh and he was using a copy of Chuck's rotor drive system from his 3 blade helicopter.

So to keep complexity down along with the weight, would it be feasible to build a weight shift helicopter, but instead of a complex head that changes pitch to flight and auto rotation based on power, could you just set the blades to a auto rotational pitch that allows for a controllable descent, and over spin them for lift for normal flight? I understand that this will be a much higher than normal rotor rpm, so it will be a balance to put the blades at an rpm that will allow both modes of flight safely.

You would control your amount of lift by throttle and if you experience an engine failure or drive system failure the blades would slow but only down to the auto rotarional rpms provided you have enough forward speed in the descent.

I realize this is not optimal, but could it actually be done with a decent safety margin for a minimal ultralight weekend flier?

Thoughts and comments gladly accepted.

David
San Jose, CA
 
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C. Beaty

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Sure, it could be done if you don’t mind burning more power than would be required with collective pitch, David.

The person you’re speaking of with the weight shift helicopter was a well known rotorcraft engineer formerly employed by Kellett who had designed and obtained FAA certification for a standard helicopter. His name is at the tip of my tongue but won’t come out. He died at Sun and Fun of a heart attack during an unusual heat wave for that time of year, around April 1st.
 

skyguynca

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Scheutzow , yep a very interesting drive system on his certified helicopter. I have the videos of it somewhere around here. I was so interested in the Stork design but want to make it just a bit simpler both in construction and control.

I understand it will require more hp and fuel consumption having to spin the rotors about 30% higher. What I am hoping is to have a simple easy to construct UL helicopter that the average builder can use to get into the entry level of owning and flying a helicopter. Plus fewer controls since with weight shift for cyclic control, leaves one hand for tail rotor and one hand for throttle. Plus in the event of engine failure or drive system failure the rotor system will automatically enter into autorotation without pilot interventions.

This is just a thought for something for a weekender pilot to fly local. With design improvement and additions the basic model can evolve to a full standard control system. The cost for the end product paid for over time while flying the basic weight shift model.

David
San Jose, CA
 

skyguynca

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OK, so in doing some thinking, having experienced too many "DUH" and "DOH" moments I have a question. I have a couple of sets of blades from courtesy of Glenn B. In doing the calculations I should be good @ 60hp for my helicopter idea. I calculated at the tip I need 4 degrees of pitch to allow the blades to autorotate and overspin for flight. The amount of overspin (tip speed) that is the limit for the 269 blades I am not sure of, I can not find the OM for this helicopter to find out the factory limits.

I am also thinking of putting the cnc router table to work and possibly creating a set of wood blades a slight "spin off" of Bensen's blades. Bensen blades will handstart because the over balance weight at 75% span cause a slight nose down pitch, as the blades come up to speed the beveled trailing edge pitches the blade positive for flight. He used this design advantage for his Little Zipster powered coaxial helicopter. Bensen would spin the blades from 300 to 330 to provide lift for the Zipster to fly. However the Zipster would not autorotate.

I am sure you are familiar with this already with all this old information.

I am sure there must be a way to configure theses blades to allow this type of operation. Bensen did do it with the Zipster with his standard gyro blades. I think with the use/addition of fiberglass and a flexible resin matrix that you could torsionally make the blade a bit more rigid to allow the blades to be set at autorotational pitch so they will only twist to the driven/flight pitch and with power decrease the rotor rpm would slow and the blade twist would decrease to the autorotational rpm.

Input from all is greatly appreciated.

David
San Jose, CA
 

Smack

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That's a cool idea.
Just off the top, it would seem that it might be challenging to get the fiber weave/stiffness correct to get the suggested automatic 'twist'.
Perhaps, similar to Bensen, a 'flap' adjustment on the trailing edge to fine tune?
Would like to see your experiment tried !
Brian
 

C. Beaty

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It has been so long ago that I read about Bensen’s experiments that my memory is pretty foggy, David.

One that I sorta recall was a coaxial helicopter with the contra-rotating blades driven by a differential, providing equal torque regardless of speed differential to each rotor as RPM was run up and down, eliminating the need for a tail rotor.

One rotor had variable pitch that changed as a function of centrifugal force. Each blade was retained by a cable loop having a 90 degree twist and CF tried to untwist the loop and increase pitch as a function of RPM. More RPM = more pitch. Its pitch travel stop was set for autorotaional pitch and the cable was installed under tension.

Since the differential insured torque balance, there was no torque applied to the airframe so cyclic pitch was possible with tilt head cyclic; gyrocopter style.


Sorry that I can’t remember more.
 
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okikuma

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Chuck,

I'm sure your memory about the B-9 Little Zipster is quite accurate. I found some drawings and photos to back up your memory.

Wayne
 

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C. Beaty

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Thanks, Wayne, that’s it. I think Bensen published those pictures in the PRA magazine while it was still a Bensen in-house publication, ~ 50 years ago.

Bensen was a compulsive tinkerer/inventor; some of his creations were brilliant, others were weird.
 

skyguynca

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You are both correct in all aspects. I have tons of pictures of the zipster, and the only drawings I know of that have been published. I also have all of the books by Bensen and books about Bensen I can find. Some of his work shows incredible foresight and almost all of it shows outside of the box thinking (like Chuck).

I think a modern zipsters possible, I've started post on here about that before. In the EU there's a company that has done small coaxial call the sch1 which was reported to be part 103 compliant, use the tilt cyclic control, but had Collective. The next model was the sch2 which had full standard cyclic and collective. I got one of their demo Manuel's from them for the SCH 2, they have videos on YouTube, but since I haven't heard from any of my email inquiries. They were only asking over $30,000 per unit. In Germany they have a much more elegant machine that makes standard certification requirements but can qualify as an ultra-light for the same price. If I was going to spend that money I would buy the RotoScheimde

David
 
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skyguynca

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That's a cool idea.
Just off the top, it would seem that it might be challenging to get the fiber weave/stiffness correct to get the suggested automatic 'twist'.
Perhaps, similar to Bensen, a 'flap' adjustment on the trailing edge to fine tune?
Would like to see your experiment tried !
Brian
I know, I was thinking since i would be using fiberglass which would also add strenght along with stiffness, I could use something like a movable trim tab connected to a spider linkage to give tacking and blade trim control. It would not be alot but it could be enough.

David
 

C. Beaty

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Bensen’s designs for hovering gadgets anticipated the current crop of RC drones using 4 or more electric motors with props.

One was a device he called his “Magic Carpet”; 4 or perhaps 6 chain saw engines with props producing vertical lift mounted on a frame resembling an old bed-spring with Bensen seated in the center with this thing hovering a couple of feet off the ground.

Another was a gadget resembling a saw horse with a Mac engine at each end producing vertical thrust; Bensen seated in the center and controlling with vanes in the propeller slipstreams. He was a lot braver than I’ve ever been.
 

skyguynca

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I remember the magic carpet, it had a lot of small chain saw engines I want to say I think it was 12. I remember the one about the sawhorse and a Mac on each end, it was the first Hover Cycle that everybody brags about inventing now. Is it just me or does it seem that all these quote new inventions that people are coming up with we're actually things guys did in the 50s? I don't know if everybody remembers but flying jeep was actually the first quadcopter that the Army experimented with also back in the 50s.

David
 

skyguynca

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Bensen B12 called the Skymat or Skyway

I have a picture in the book but it is a bad picture.I was wrong it is 10 engines for redundancy. 9hp Mac M75. Scarey

c0tbe5qlf8031.jpg.cf.jpg

The B-10 Propcopter, 2 Macs, 75hp each.

1588219987383.png

David
 
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C. Beaty

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Perhaps present day gyronauts aren’t aware of it but the feedback of a component of rotor thrust in the cyclic system is stabilizing and enhances angle of attack stability via Bensen’s offset gimbal rotorhead; i.e., an upward gust feeds a nosed-down force into the cyclic control system, tending to keep the machine headed into the relative wind.

Bensen had a related design for a conventional 3-blade helicopter rotor system where the tilt of the rotor tip plane relative to the rotorhead was summed up and used as a feedback force in the cyclic control system.

One of his licensees was a small company by the name of Orlando Helicopters. Several times, before or after a Bensen Days flyin, I’d drop him off at Orlando Helicopters and the next day or so, they would drop him off back at my place.

Cierva used an offset gimbal rotorhead to reduce stick force but the control force was so great due to offset flap hinges as to mask any stabilizing effect. About the only thing Cierve failed to patent.
 

skyguynca

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Oh, the coaxial using the CF twist via tensioned/twisted cable was his hover gyro. that is where he came up with the transmission and drive train for the Zipster coaxial helicopter. That B8MH was a crazy contraption, he used a smaller engine to provide thrust for forward flight and it blew air across the rudder for control in hover. You can see the much bigger hub on the lower rotor that could change pitch. It was too heavy for the Zipster coaxial and he wanted it easy to build for the average guy. This gyro is everything but simple.

1588122838217.png

the Zipster is pretty simple.

1588122995647.png

David
 

okikuma

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There was this version with a single rotor. The only picture of this type that I could find.

Wayne
 

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C. Beaty

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That must have been a handful; two engines, both controlled via throttle.. I wonder if it ever left the ground.

Bensen also had another one with engines mounted on the rotor, about half way out, driving props. I’ve no idea whether that one left the ground either.
 

wolfy

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That must have been a handful; two engines, both controlled via throttle.. I wonder if it ever left the ground.

Bensen also had another one with engines mounted on the rotor, about half way out, driving props. I’ve no idea whether that one left the ground either.
Love to see a picture of that one if anyone has one.

wolfy
 
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