Maybe this?
No. Imagine an early helicopter with a vertical 6 cyl.
Rotor blade above the engine. Propeller below. the prop and engine are shrouded in a bell shaped funnel that is wide at the top and the rotor is above it.
I’m constantly amazed at the aircraft I never knew existed.
I’m sure there are much better pictures of this but I got a kick out of the source for this one.
Sikorsky CH-37 Mojave in Popular Mechanics.
You will have to scroll down to page 93. Can’t link to the exact spot.
I love looking at old Popular Mechanics magazines so that’s why I used that link. This helicopter is the grand daddy of the modern twin turbine helicopter.
and while you’re there go to page 117 and see the de Havilland Sea Vixen under development. Keep scrolling down and look at vertical lift planes and then you come to an article on wind turbines.
Next time you renew your driver license:
Here in Bozeman MT I saw a coaxial (counter-rotating dual rotor) helicopter fly overhead the other day. Any idea what it could be? Wiki says there are very few models, most of them Russian, although there are a couple of Sikorskys. It looked pretty new and modern.
I think a KAMAN K-Max (US, with intermeshing contra-rotating rotors) might be more common than the various KAMOV (Russian, contra-rotating coaxial rotors) in that neck of the woods… Just a guess.
An interesting helicopter. it looks like it uses ailerons to change the angle of the rotor blades.
That looks like it! Thanks!
Fascinating idea for a helicopter.
The original designer of the concept, Anton Flettner, was brought to the US as part of Operation Paperclip - same as another, probably more well known, German engineer/scientist - Wernher von Braun.
@Tride - I just love that paint job 
Actually, I take it back. That ship crashed a year ago, killing the pilot. They must have a 2nd one.
Good job spotting it and figuring out which kind it was!
Here’s a note on terminology.
A “co-axial” helicopter has the two rotors stacked on a common axis, although with separate concentric drive shafts. Like this:
The Kamov or US license-built K-Max that you saw has “enmeshed rotors” where the shaft axes are not parallel and the two rotors pass through each other’s rotor disk. This wikipic pretty well shows the K-Max arrangement. Here’s an much earlier US helo with a similar design, also designed & built by Kaman:
.jpg){kind=link}
Scroll down in the article for better pix of the rotor system; the headline picture hides more than it reveals.
Continuing the taxonomy …
Two-rotor helos where the two rotor disks don’t interact can be set up as a “tandem rotor” configuration, like (among several others) the famous and still in production:
or the rarely seen “transverse rotor” configuration like this Soviet beast:
For any of these wiki articles, scrolling down to the Specifications section gives a nice 3-view drawing that highlights how the various rotor systems fit onto the fuselage and interact or don’t with each other.
It uses the same aileron style rotors that the HH-43B Huskie used. I’ve seen that in the AF Museum and didn’t realize kaman built it. They even use the same wood spar design as the Huskie which they say is more durable.
I’m guessing they steer with exhaust thrust and rotor wash over the rudder.
Not quite ailerons, but yes, the tabs on the trailing edge of each rotor “fly” them up and down to achieve both collective and cyclic control.
Pretty wild to think about how the pilot’s control inputs of collective & cyclic stick position get translated into moving each of those four flaps differentially between each other and as they whirl around the circle ~5x/second. Correctly accounting for the delay & angular rotation between when the tab deflects and the blade itself responds by moving. Pure mechanical engineering magic. A Russian specialty even nowadays.
Servo tabs like this were / are common means of control boosting on late WWII and early jet age aircraft. And some not so early.
The elevators and ailerons on the 707 and the DC-9 / MD-80 / MD-90 / B-717 are controlled that way. The backup control system for the 727 & 737 ailerons & elevators are similar although they’re normally hydraulically powered.
In the case of the DC9 / MD80 / etc. elevator it’s even crazier: The pilot’s yoke is connected to small tab which in turn is connected to a larger tab which is in turn connected to the elevator. So for say aircraft nose up motion the pilot moves the yoke aft which moves the baby tab up via mechanical cables which pushes the medium tab down via airloads which pushes the elevator up via airloads which pushes the whole tail down via airloads which pushes the nose up because the fuselage is rigid. It’s a 2-stage mechanical power amplifier using the passing airflow as a power source.
Assuming you’re talking about yaw-axis control …
I don’t know for sure about the Kamov / K-Max or the Huskie but any dual-rotor helo can generate yaw forces by what amounts to differential thrust on the two main rotors. In response to yaw pedal input by the pilot the various blades tilt to produce no net pitch force, no net roll force, but some unbalanced yaw or torque force on the fuselage. Heading change AKA yaw is the resulting output.
So that’s another layer of mechanical magic in the control mixers that make the 4 (or sometimes 6) rotor blades do all the work of all the control surfaces of a conventional airplane plus all the lifting of the wings plus all the stabilization effects of the fixed stab & vertical fin.
Are you indicating that the K-Max is licensed from Kamov?
That’s totally what I wrote. But upon further research, it’s totally wrong. Thanks for calling that out.
I’m not sure exactly what wiring in my memory got crossed there. Kamov’s are usually co-axial rotor, not enmeshed rotors. See
But the Russians (/ Soviets?) did make a couple enmeshed models and I’m somehow recalling something about some design collaboration or licensing between them and the West.
Clearly I’m full of stuff on that one. Thanks.
I thought it sounded wrong. I checked, and couldn’t find anything so I thought I’d ask.
I’d thought the Soviets had a helicopter with intermeshing rotors, that looked like the Kaman Huskie. I thought it was the Kamov Ka-31, but it does indeed have coaxial rotors.