Bensen B8M-H, Hover-gyro, 1976.

[quadrirotor]

Are gyro men interested in this kind of rotorcraft?

A propulsed gyro with a double rotor, coaxial rotors!

Take this one with a bigger pusher engine, may be a smaller rotor engine.
Or one engine with two PTO!?!

The Bensen B8M-H, hover gyro, 1976!!!

 

[enewbold]

Very interesting.

http://www.aviastar.org/helicopters_eng/bensen_hovergyro.php says this about it:

"Demonstrated in public for the first time in 1976, this is described as a 'Hovering Gyro-Copter'. It is powered by a 70-110hp modified water-cooled outboard engine driving the lower of the two rotors; the upper rotor autorotates. One 14 hp modified air-cooled go-kart engine drives the pusher propeller mounted at rear."

 

[DennisFetters]

Are gyro men interested in this kind of rotorcraft?

A propulsed gyro with a double rotor, coaxial rotors!

Take this one with a bigger pusher engine, may be a smaller rotor engine.
Or one engine with two PTO!?!

The Bensen B8M-H, hover gyro, 1976!!!

It's a helicopter. I got to tinker with it when I was at the Bensen factory working on Rotax approval on his Gyrocopter gyroplane.

The rotor hubs would automatically pitch depending on power, and the small prop on the back was only to blow across the rudder for yaw control, nothing more.

It was only an experimental concept machine, never really flew but a few times, ended up being way too complicated, and Bensen abandoned the concept.

 

[quadrirotor]

Yes Dennis, the design of the hover-gyro (or Zipster?) is somewhat complex...But a Nolan type with bigger autorotativeable blades + an efficient pusher prop (blowing also on a rudder)? This could be an inexpensive compound helico...Almost a gyro with a big prerotator without the reaction torque? yes? no? with hover capabilities...
One engine (Subaru?), two PTO, one for the rotorsystem + one for a variable pitch (Ivo-) prop...
Is it sexy enough for you?

 

[Hognose]

Is this the Bensen helo that's in the museum at Mentone, or is that a different one of his experiments?

cheers

-=K=-

 

[Bruno]

I don't quite get it. What did the upper rotor do? Did the two rotor discs have the same AoA, or did one have a positive angle and the other negative? To me, it looks like the upper rotor just generated drag, without doing anything useful.

 

[DennisFetters]

Yes Dennis, the design of the hover-gyro (or Zipster?) is somewhat complex...But a Nolan type with bigger autorotativeable blades + an efficient pusher prop (blowing also on a rudder)? This could be an inexpensive compound helico...Almost a gyro with a big prerotator without the reaction torque? yes? no? with hover capabilities...
One engine (Subaru?), two PTO, one for the rotorsystem + one for a variable pitch (Ivo-) prop...
Is it sexy enough for you?

There is no such thing as an inexpensive compound helicopter, nor can it ever cost less using twice the amount rotorblades and rotorheads.

There is no such thing as a "big prerotator" to push 60 or 80 horse power through a rotor system, that is a full-blown transmission system, costing a lot of money and weight.

Dreaming is one thing, doing is another. Sure, you got to dream to conceive new ideas, but it's not like we haven't been doing this for a while now, so realism has to play a part in what we are able to do.

 

[quadrirotor]

Bruno, the upper rotor is set at an autorotative fixe pitch (ex: 4 degrees aerodynamic), the lower rotor has an automatic variable pitch, the pitch is higher with rrpm...The gears incorporate a differential to accomodate the difference of RRPM of the two rotors. In case of the engine failure, the autorotation is enabled...I wonder of the problem of vibrations!?

Kevin, the "little zipster" alike helicopter in the Mentone museum is this one:

 

[quadrirotor]

Dennis, you are right, from a manufacturer point of view, if you want to make this coumpound helo to sell it: it's too expensive! But for a good tinkerer, by using out of the shelf elements from the auto industry, this set up represents the easiest and the least machining!!! I have already a realistic idea of how to make it!!!

(Four smaller blades are cheaper (and same weight, and more efficient) than two big ones!!!, NO SWASHPLATE, etc...)

 

[DennisFetters]

Dennis, you are right, from a manufacturer point of view, if you want to make this coumpound helo to sell it: it's too expensive! But for a good tinkerer, by using out of the shelf elements from the auto industry, this set up represents the easiest and the least machining!!! I have already a realistic idea of how to make it!!!

(Four smaller blades are cheaper (and same weight, and more efficient) than two big ones!!!, NO SWASHPLATE, etc...)

Good luck!! I'll be the first to congratulate you if you succeed.

Even a helicopter built that fly's using the junk-yard dog approach is admirable in it's own way.

Let us know how it goes.