Coaxial Helicopters

Started by Logi, August 27, 2010, 03:47:42 PM

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Logi

Coaxial Helicopters, like the Kamov helicopter series, basically use two rotors contra-rotating to eliminate each others torque to eliminate the need for another torque canceling engine and propeller.

It is known to be less mechanically reliable than conventional helicopters and prone to failures due to complexity, but it doesn't seem like a big departure from the helicopters of the later 1920s (ie 1929 and so on).

Why was such aircraft not pursued until the Kamovs of the 1947s and on? If you look at the pictures, those aircrafts look remarkably similar to the experimental helicopters of the 1920s. Is there some technological gap that I am missing?

Carthaginian

Yeah... the tech gap is actually pretty tremendous.
You stated the blatantly obvious reason in your OP: 'less mechanically reliable.'

Helicopters are not likely to play much of a role in N-verse, given that the reliability of any such machine was far below acceptable standards until the mid-late 40's... which will probably work out to about 1935-1940 in our world.
So 'ere's to you, Fuzzy-Wuzzy, at your 'ome in old Baghdad;
You're a pore benighted 'eathen but a first-class fightin' man;
We gives you your certificate, an' if you want it signed
We'll come an' 'ave a romp with you whenever you're inclined.

Logi

But less mechanical reliably does not mean; Does not work.

I asked why there were developed so much later than conventional helicopters. Not whether they work in N-Verse or not. Forty years later for experimentation is not easy to overlook.

They didn't even test the concept till something like the 1947s, meaning they didn't know really how unreliable it could be.

Guinness

I suspect there are two possible reasons the coaxial arrangement didn't appear until 1947:

1. No one had thought of it
2. It was too hard to engineer

It does offer several advantages: all power generated goes to lift, and the rotor diameter is smaller compared to the conventional single rotor arrangement.

As to why helicopters weren't practical until the end of WW2: I believe that was all about engine power. It wasn't until the late 30s that lightweight aero engines were developed that had sufficient power/weight ratios to make lifting practical payloads worth it. I can't imagine that would be much different in the Nverse.

Carthaginian

Quote from: Logi on August 27, 2010, 03:57:31 PM
But less mechanical reliably does not mean; Does not work.

I asked why there were developed so much later than conventional helicopters. Not whether they work in N-Verse or not. Forty years later for experimentation is not easy to overlook.

They didn't even test the concept till something like the 1947s, meaning they didn't know really how unreliable it could be.

No, they DID test the concept of rotary winged flight... it was measured, weighed, and found wanting. You DO realize that the Bell H-13 could only RELIABLY carry a pilot and spotter, or a pilot and a couple of patients (who were usually a few pounds lighter than they should have been)! Hell, a pair of M60's could actually provide enough weight and recoil force to strain the engine!

Sorry, no true helicopter is going to be serviceable in our time frame.

And in spite of DF's impassioned pleas, the gyrocopter isn't really much better.
A decent spotter, but not too damn much else.
So 'ere's to you, Fuzzy-Wuzzy, at your 'ome in old Baghdad;
You're a pore benighted 'eathen but a first-class fightin' man;
We gives you your certificate, an' if you want it signed
We'll come an' 'ave a romp with you whenever you're inclined.

Logi

#5
I think you are misunderstanding something. If a helicopter is developed by the RRC, they would NEVER be used offensively. As you said, it can't carry anything useful for attacking and fighting.

But you did say it could carry a pilot, spotter, or a pilot and a couple of patients. Those people are weight. If the RRC attempts an helicopter, it is a cargo helicopter. Remove the spotter or couple of patients and carry cargo instead.

There is no point in developing the helicopter as an offensive weapon because, as you stated, it doesn't work and is very unreliable.

Carthaginian

Quote from: Logi on August 27, 2010, 04:30:16 PM
There is no point in developing the helicopter as an offensive weapon because, as you stated, it doesn't work and is very unreliable.

No, Logi... I did not.
I said a KOREAN WAR HELICOPTER wasn't able to be used offensively, and was barely able to be used successfully as a medevac and spotter bird.

YOU are trying to say that the experimental birds of the 20's (which barely got off the ground) would be useful in a far larger capacity than they actually were.

Sorry, that tech simply doesn't exist.
Helicopters aren't workable at this time, and are BARELY workable in the 40's!
So 'ere's to you, Fuzzy-Wuzzy, at your 'ome in old Baghdad;
You're a pore benighted 'eathen but a first-class fightin' man;
We gives you your certificate, an' if you want it signed
We'll come an' 'ave a romp with you whenever you're inclined.

Logi

QuoteI said a KOREAN WAR HELICOPTER wasn't able to be used offensively, and was barely able to be used successfully as a medevac and spotter bird.

Ok, and so what?

QuoteYOU are trying to say that the experimental birds of the 20's (which barely got off the ground) would be useful in a far larger capacity than they actually were.

What? You've been jumping to conclusions and putting words in my mouth.

QuoteSorry, that tech simply doesn't exist.
Helicopters aren't workable at this time, and are BARELY workable in the 40's!

Right... still don't see what you are talking about.

I'm talking about one thing and you're on something totally different.

Guinness

At the risk of stepping into the line of fire:

I've been IM'ing with Logi about this. I don't see this question as being anything more than curiosity. I don't belive Logi is planning on the Chinese magically hatching functional helicopters any time soon. What he is doing (as I undestand it) is researching the very early origins of helicopter technology as a foundation for a possible storyline. Nothing much more? Right Logi?

Logi

Indeed. If things go like I think, it's going to be an interesting story, but won't produce anything useful.

Helicopters seem to hold great potential, but would take many years of refining to get it to work for operational status. In other words, it's going to be a dead end.

TexanCowboy

Best you could do at this point is that Austrian Helicopter built in 1916, that was tethered to the ground...

Carthaginian

Quote from: Logi on August 27, 2010, 04:30:16 PMBut you did say it could carry a pilot, spotter, or a pilot and a couple of patients. Those people are weight. If the RRC attempts an helicopter, it is a cargo helicopter. Remove the spotter or couple of patients and carry cargo instead

Logi,

RIGHT HERE you were using my analysis of a helicopter THIRTY YEARS REMOVED from the current N-verse time period as saying 'a helicopter can't be used offensively, but maybe as a spotter.' What you are not 'following' is the fact that none of the helicopters of the 20's or 30's could reach anything close to even that simple and utilitarian duty!

Were you to start 'developing' an 'experimental' chopper now, it would still be well into the 40's before you'd be able to get any kind of useful service out of them even as spotters. PERIOD.
So 'ere's to you, Fuzzy-Wuzzy, at your 'ome in old Baghdad;
You're a pore benighted 'eathen but a first-class fightin' man;
We gives you your certificate, an' if you want it signed
We'll come an' 'ave a romp with you whenever you're inclined.

Logi

And I never said I had a problem with that. ;)

Nobody

#13
Quote from: Logi on August 27, 2010, 03:47:42 PM
Coaxial Helicopters, like the Kamov helicopter series, basically use two rotors contra-rotating to eliminate each others torque to eliminate the need for another torque canceling engine and propeller.

It is known to be less mechanically reliable than conventional helicopters and prone to failures due to complexity, but it doesn't seem like a big departure from the helicopters of the later 1920s (ie 1929 and so on).

Why was such aircraft not pursued until the Kamovs of the 1947s and on? If you look at the pictures, those aircrafts look remarkably similar to the experimental helicopters of the 1920s. Is there some technological gap that I am missing?
I'm not sure whether this is what you mean, but the first two series build helicopters had two counter rotating rotors (http://en.wikipedia.org/wiki/Flettner_Fl_282 and http://en.wikipedia.org/wiki/Focke-Achgelis_Fa_223)

ctwaterman

Yes the first functional use of helicopters was by the Germans with their 2 Counter Rotating props to lift conservatively very light loads say pilot and under 250 Kg of other weight basically a spotter and a radio or 2 litter patients.  I think the Larger German one could carry up to 4 people but not all their equipment.

The US also had some success using Its helicopters in 1944/45 in Burma and such to rescue downed pilots and evac wounded Chindits and Marauders from behind enemy lines.

To say that a single small arms hit would have been dangerous to any of these rotors is being kind.

The Break through in helicopters comes not with smaller lighter gasoline engines but the use of Jet Turbine engines to give them a reall weight to lift ratio.

But there is alot of research to do their and alot of reading to do about the history of rotary aircraft of which Igor Sikorsky plaid a very intimate role.  Even some of his best aircraft were latter built for the United States.

Charles
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