Contra-rotating Main Rotors
Thread Starter
Joined: Aug 2000
Posts: 2,681
Likes: 10
From: Just South of the last ice sheet
Contrarotating rotors
I'm working in Kazakhstan and saw a Kamov heli buzzing around yesterday. Funny looking thing with the twin rotors on the same axis. . .. .I understand how a conventional and a NOTAR heli works but how do they turn a machine with no tail rotor. It did have large vertical fins and thus I assume rudders which would work in forward flight but what happens when you want to turn in the hover?. .. .As an aside, I've always it funny that the US machine with a different (read strange) rotor system also begins with a K (Kamen)
Joined: Nov 2000
Posts: 467
Likes: 0
From: Sunrise, Fl. U.S.A.
Kamen aircraft have intermeshing rotor systems.. .. .Not specifically like a H-46, but where you have two masts, angled out laterally somewhat, and independant rotors on each.. .. .Torque management is the same though I believe for turning the craft.. .. .Kamen also makes the H-2 Seasprite for USN, and while only having one rotor, it has a uniqueness in having an actual controlling flap on the rotor blade itself. Anyone know of others that have that feature?. . . . <small>[ 28 March 2002, 15:31: Message edited by: RW-1 ]</small>
Joined: Jun 2001
Posts: 27
Likes: 0
I don't exactly know how the Kamov yaw system works but would assume that because the rotor systems are in line with each other the only way would be differential pitch which in turn causes differential torque and causes a yawing force on the fuselage.. .. .The Kaman helicopter use differential pitch as well as tipping one disk forward and the other aft during yawing turns. It helps pedal authority a little.. .. .It would be interesting to fly the Kamov rotor system or talk to someone that has. I wonder if it has the same "dwell zone" in the middle of the collective where there is very little if any pedal authority.
Joined: Aug 2000
Posts: 3,670
Likes: 1
From: UK
Low'n slow: with a signing off slogan like that, some might regard your nick name as appropriate, and would most probably deem your residence appropriate too...however, i could not possibly comment.. <img border="0" title="" alt="[Embarrassed]" src="redface.gif" />
Joined: Nov 2000
Posts: 452
Likes: 0
From: Vancouver, BC, Canada
LowNslow,. .. .Some or all of the Kamov coaxials mechanically switch the pedals when the craft enters autorotation.. ._____________. .. .RW-1,. .. ."In 1930, Corradino d'Ascanio of Italy built a relatively successful coaxial helicopter, which flew under good control. His relatively large machine had two, two-bladed, counterrotating rotors. Following the work of de la Cierva, the blades had hinges that allowed for flapping and a feathering capability to change blade pitch. Control was achieved by using auxiliary wings or servo-tabs on the trailing edges of the blades, a concept that was later adopted by others, including Bleeker and Kaman in the United States." ~ from an <a href="http://www.flight100.org/history/helicopter.html" target="_blank">article</a> by Professor Gordon Leishman.. .. .Professor Celi, who is also at the University of Maryland, is working on advanced blade control, which I believe uses tabs.. .____________. .. .H-43,. .. .The are a couple of Kamovs in Western Canada, which are used for logging. One was/is based in Victoria. That's not too far from you.. . . . <small>[ 28 March 2002, 19:48: Message edited by: Dave Jackson ]</small>
Joined: Dec 2001
Posts: 192
Likes: 0
From: Sandbox
From what I heard, the kamov has a great big brake unit which slows one of the main rotor systems creating the differential for turning in the hover, could be?????. .. .edited for spelling gremlins. . . . <small>[ 29 March 2002, 03:33: Message edited by: C4 ]</small>
Thread Starter
Joined: Aug 2000
Posts: 2,681
Likes: 10
From: Just South of the last ice sheet
Thanks for the info people. I would imagine the system has more disadvantages than advantages or every heli would have two main rotors <img border="0" title="" alt="[Big Grin]" src="biggrin.gif" />
Joined: Nov 2000
Posts: 452
Likes: 0
From: Vancouver, BC, Canada
LowNSlow,. .. .Not necessarily so. <img border="0" title="" alt="[Big Grin]" src="biggrin.gif" /> . .. .The latest and greatest has two rotors. [V-22] <img border="0" title="" alt="[Eek!]" src="eek.gif" /> . .. .___________. .. .Edited to add the following propaganda. <a href="http://www.unicopter.com/B280.html" target="_blank"> Good copter -?- Bad copter</a>. . . . <small>[ 30 March 2002, 00:03: Message edited by: Dave Jackson ]</small>
Joined: Aug 2000
Posts: 716
Likes: 7
From: London
Opposing Main Rotors
[questions from a f/w flyer...]
Why didn't Kamov's rotors take off? (For want of a better pun).
Or didn't they really make it easier? With no torque effect, it just looks like one less complication in the horrendous stability madness that rotary flying appears to be
Oh, and whilst we're here, if the budget runaround Hiller had auto something-or-other, where it could hovver when flown by a couple of sandbags (see latest 'Pilot' mag), then why hasn't that kind of thing become common place, at least for basic trainers?
Why didn't Kamov's rotors take off? (For want of a better pun).
Or didn't they really make it easier? With no torque effect, it just looks like one less complication in the horrendous stability madness that rotary flying appears to be
Oh, and whilst we're here, if the budget runaround Hiller had auto something-or-other, where it could hovver when flown by a couple of sandbags (see latest 'Pilot' mag), then why hasn't that kind of thing become common place, at least for basic trainers?
Joined: Nov 2000
Posts: 452
Likes: 0
From: Vancouver, BC, Canada
paulo,
What nice questions.
The real reason why the single rotor helicopter became predominant is classified. This is it; but don't tell anyone else. The Russians (with their coaxials) and the Germans (with their intermeshing) fiscally lost WWII, where as the Americans (with their single rotor) won.
The intermeshing synchropter was used by the US to train pilots for a short while. They then stopped because the intermeshing was too easy to fly and the pilots were not getting the training required to fly single rotor helicopters.
Lu,
This might start a bigger controversy than gyroscopic precession.
What nice questions.
The real reason why the single rotor helicopter became predominant is classified. This is it; but don't tell anyone else. The Russians (with their coaxials) and the Germans (with their intermeshing) fiscally lost WWII, where as the Americans (with their single rotor) won.
The intermeshing synchropter was used by the US to train pilots for a short while. They then stopped because the intermeshing was too easy to fly and the pilots were not getting the training required to fly single rotor helicopters.
Lu,
This might start a bigger controversy than gyroscopic precession.
Last edited by Dave Jackson; 24th April 2002 at 19:53.
Avoid imitations
Joined: Nov 2000
Aviation Qualifications: ATPL
Posts: 15,110
Likes: 1,083
From: Wandering the FIR and cyberspace often at highly unsociable times
Dave,
Gyroscopic precession doesn't happen on this type of helicopter
Uh-oh, now we've gone and done it again!
Gyroscopic precession doesn't happen on this type of helicopter
Uh-oh, now we've gone and done it again!
Joined: Feb 2001
Posts: 103
Likes: 0
From: the other America
Yep you got it Robbo,
If both rotor systems are producing torque - 1 cancelling/opposing the other you will be able to effect yaw control by pedals either
1. Slight tilt of one disc fwd while the other back .
2. Slight pitch inc in one disc + dec in the other ....... therefore different/uneven torque, a/c will turn with the larger torque reaction.
or a mix of both.
mmmmmmm 1/2 bottle of very nice chardonnay followed by a "stonking" coffee. Luverly mix! I recommend it!!
Now I just need somewhere warm and soft to curl up.
G'night
If both rotor systems are producing torque - 1 cancelling/opposing the other you will be able to effect yaw control by pedals either
1. Slight tilt of one disc fwd while the other back .
2. Slight pitch inc in one disc + dec in the other ....... therefore different/uneven torque, a/c will turn with the larger torque reaction.
or a mix of both.
mmmmmmm 1/2 bottle of very nice chardonnay followed by a "stonking" coffee. Luverly mix! I recommend it!!
Now I just need somewhere warm and soft to curl up.
G'night
