some european company......kinda cool, plus they are using the flathead D-motor...
http://www.edm-aerotec.de/index.php?id=2
https://www.youtube.com/watch?v=CntuCF-0nXQ

Can it autorotate if the motor goes quiet?

Or do you just die?

I don't know, Can coax's autorotate? that is not my area of expertise.

I am not sure if coax's have collective to get the pitch down to an autorotatible AofA? ..... I am not at all sure?

It appears they might... and maybe even better than a single rotor Who knew??

http://www.airliners.net/forum/viewtopic.php?t=740591

Speaking of autos and single rotors.... if a heli has a decent size vertical stabilizer fin.... if a heli was flying at a good cruise speed and the tail rotor fell off.... could the heli maintain speed and if not maintain altitude, make a very shallow descent at high speed... so as to be able to continue some distance before having to initiate an auto and actually land? I ask because of this....

coaxil helicopters use more large sized and costly parts to do the same as a normal helicopter. they need a special control system mixing for collective and yaw. not a 'simple' arrangement at all. and the real ones can do autorotations.

Evidently the real benefit of coax is they can lift more without the possibility of running out of anti torque from the tail rotor.... I read that they are a bit bumpy ride when not lifting much weight and slower... but great cranes...

My favorites are the Kmax type... the rotors have little ailerons that make drag on that rotor set, which makes them turn in hover..... pretty clever....

To me, coax are not in competition with other heli's.... they are simply another heli. No one can sat a single rotor heli is better than a coax, or a coax is better than a single.... neither can do everything, both can do something the other cant.... they are all great imo

no drag for yaw on the K Max, cyclic & collective, yaw in the servo flaps, no hydraulics simple through the mast controls.

that white one man coaX is an old Gyrodine RON 1, they claim it's new but it's over 60 years old,

It started life as bendix helicopters - then Papadocos of gyrodine out of New York that RON 1 was an Army brat, then the QH 50.

Project Snoopy used a cannon to blast things by remote control, Navy DASH helicopter program used to drop depth charges and torpedos

all controlled by destroyers

Some of the KMAX and Husky's have the little ailerons.... All of the ones I have video of anyway

those are servo flaps the are the controls, up down collective, yaw pitch roll. and you can adjust blade track in flight

Kaman also has servo flaps on the Sea Sprite H-2 ASW helicopter

Yeah. I was always wondering how they achieved yaw control.... whether they had some sort of cyclic. With things like rc coaxial helicopters, there is a motor for each direction, so I was wondering on a flettner, with the rotors geared together/intermeshing one side blades cant slow down or speed up individually.... so I looked into it and saw a video where a fire helicopter pilot was showing the controls.... and how those little aileron flap things can create more drag on one side causing yaw. It is quite fascinating.

I first got interested when there was some bushfires/wildfires around Canberra and I saw a Hughes 500 with a bucket, then a jet ranger with a bucket.... then this red open top funny looking helicopter with 2 sets of weird rotors..... with a bucket the size of an Olympic swimming pool (and changing rooms) I was stunned.... you could see the pilot sitting up front like he was sitting in a canoe.... (no roof) he just had a helmet on and was looking over the side of the fuselage.... the rotors didn't look like they were even going fast enough?? Compared to the 500 and the ranger, when they lifted their little bucket, the motors roared and you could see them struggle a little.... the intermeshing heli just ambled over to the pond they were getting water out of, dip in the bucket, then lift it like there was no effort what so ever.... no change in engine note.... no apparent struggle..... yet the bucket was 10 times bigger than the other heli's had....

I think I sat there for a couple of hours wondering what the heck I was looking at

I have never seen another open top/convertible flettner like that one.... it looked like a cartoon helicopter, like something gyro gearloose would fly 2 mains and tail dragger

There is a big difference between Coax (counter rotating) and inter meshing rotors.
Counter rotating ones don't lift heavy at all and complex as Don said it so eloquently.
Inter meshing rotors have a larger disc area and an advancing blade coming every 90* to help a very even and stable hovering.
I love the Kamans.

Kaman and Flettner yaw is done with cyclic feathering one set of blades go fwd cyclic the other set go aft cyclic (think of a retarded chinook) same yaw action instead of a set of fore and aft rotor systems on the ends of a pencil go side by side on a stubby eraser.

Kamov coax uses collective mixing

Gyrodine drag tip flaps

Here ya go, you can download the K max calendar..

http://www.kaman.com/sites/default/file ... 017web.pdf

Cool! an open cockpit heli!

Imagine an intermeshing heli open top like that.. that is like that fire fighting one I saw. I was so fascinated with the slow rotors, too many rotors

And seeing the pilot looking over the side.... I had never seen one before and it just looked so wrong

Very KuuuuuL tho

I wish I could find a pic of one....

I stopped and took some video of it, but don't know what ever became of that tape (VHS)

They just changed the radar antenna on the control tower the other day here at ATL.

I know some of you will enjoy this:

I do not claim to be an expert on intermeshing or coaxial rotor helicopters, but:

* Single rotor helicopters have long, skinny, fragile driveshafts going back and the T/R consumes about 5% of the engine at low power and as much as 15-20% in max perf. maneuvers (when you really NEED it). This is not the best.

* Coax machines can use 98% of the engine to make lift and go up. Even when yawing, a little bit of engine is "democrat-ted" from one rotor and given free to the other one to turn the helicopter. Net change in lift ...practically zero. Engine power used...practically zero. Yes they autorotate just like a single rotor machine. The head`s a little more intense design but the absence of TRGB, Blades, Driveshaft, Boom, and all that...makes it pretty much equal. They are much taller. I would assume both rotors can be significantly smaller and I would guess they fly like a sports car because rotor MASS (not mast) is close to the overall CG. They probably spin at a much higher RPM, and maneuvering force or authority is created by TWO rotors. Roll rates are probably FAST. I would also speculate that autorotations are done with blades at higher pitch so descent rates would be lower?

* Intermeshing machines also benefit from most of this too. When yawed (as hillberg said) one rotor`s disk or tip-path-plane is cyclically tilted forward and the other is tilted aft to yaw the helicopter. Tilting BOTH disks changes a small amount of the lift into a horizontal component which eats up some horsepower. Because of that, yawing requires adding a little throttle. The fuel-controller does that so the pilot doesn`t have to. A K-Max or Sprite doesn`t have cyclic feathering of the big, heavy blades. The little aileron-like thingys are manually controlled cyclically with a long Teleflex cable (like ultralights use) and their defection exerts an up or down force at the trailing edge of the big blades. The trailing edge gives the aileron flap the most mechanical advantage to pitch/feather the big blades. No hydraulics. No complex systems. Not very smooth. Very simple and reliable.

My personal choice is Coaxial. It`s best. These little $10 RC coaxials that are very stable and controllable amaze me.

Very true Bryan. There is an advantage of the Coaxial (not the intermeshing) rotors in autorotation due to A PHENOMENA called biplane cell effect.
They act as the wings of a biplane and actually makes autorotation slower and safer than the single rotor system.
I also don't claim to know anything. I am just here to act smart.... with not much success....