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Why are Helicopters with the Flettner-System so slow?

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Why are Helicopters with the Flettner-System so slow?

Old 20th Dec 2006, 03:26
  #41 (permalink)  
 
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Post A picture is worth a thousand words

Re Speed:

Here's a picture of an enclosed Flettner FL-282. This picture was taken 1941, a year before Sikorsky came out with the 'boxy' R-4.






Sometimes misconceptions are born out of misrepresentations (politely called marketing).

From 'IGOR I. SIKORSKY-THE MAN - His Aviation Firsts'
  • 1943 ~ R-4 First helicopter to land on a ship - Bunker Hill
. . . . . . September 1942 ~ The FL-282 landed on the M.S. Greif.
  • 1943 ~ R-4 First mass produced helicopter
  • 1945 ~ R-4 is the only helicopter to serve in World War II
' ' ' ' ' ' ' "The Kolibri "Humming Bird" was the first helicopter put into mass production" [10 BEFORE 1943; plus 14 during 1943 and 1944] "and the only helicopter to make any significant contributions in World War II." In addition, the Focke Achgelis FL-223 was also mass produced [3 BEFORE 1943; plus 20 during 1943 and 1944] and it saw limited use in World War II.


Who're you going to believe?
I'll go with the very researched and detailed book 'Helicopters of the Third Reich' by Steve Coates.


Dave

Last edited by Dave_Jackson; 20th Dec 2006 at 06:25. Reason: To add clarification
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Old 20th Dec 2006, 14:02
  #42 (permalink)  
 
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Just as with your ability to bend aerodynamics to suit your proclivities, you can sometimes embrace new versions of history that suit your need for "symmetry" in your life (and also that the forces of evil hold back the clearly superior designs that you love so much)!

The truth is not quite so boldly deceptive as you would wish (that web site you use as "proof" is a Luftwaffe web site that goes out of its way to show how wonderful everything was back then when Nazis ruled the known world):

The Flettner Fl 282 was very successful, and about 24 were built. It did operate from ships in tests in 1942, when only 3 experimental prototypes existed. That limited trial is what your web site photo shows. These sea trials were possibly before an R-4 landed aboard ship in 1942, I cannot find dates for either right now.

Regarding "rate production" I believe the story is also not so clear as your revisionist theorists would believe. Thanks in part to US 8th Air Force bombardiers, starting in 1942, a total of 24 282's were produced before production ended sometime around mid 1943. During that time, 130 R-4's were built and delivered to the US and British military from the Bridgeport plant. It could be that the R-4 was earlier, or that the two were contemporaries. By war end, over 400 R4's were delivered.

No doubt, the Flettner was very maneuverable, safe, and effective, and if its factory had not been bombed, it might have given the R4 a run for its money. As it is, the story is not as clear as you seem to believe.

http://www.centennialofflight.gov/es...ettner/HE6.htm
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Old 20th Dec 2006, 18:34
  #43 (permalink)  
 
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Dave, why are you basing your arguements on machines that flew over half a century ago? Outside of the historical interest, i couldn't care less whether R4 or FL282 are technically better or which did what first. Both are good pieces of engineering, both had flaws which have needed to be overcome.

There is only one way for a good idea to survive, and that is through technical merit. This means that a specific problem must be identified, in order to start the process of finding a solution. If the problem is retreating blade stall, you will get no arguement from anybody that counterrotating is the solution. If the problem is just aesthetics, you will get no support from anybody. Engineers just don't think like that, and rightly so. When sales have asked the impossible, finance has offered a pittance, and service just want something that works, it it the engineer that has to dig his way out of the resulting hole. Aesthetics just are not part of the decision process.

You frequently site nature as being the inspiration of technology, so let me ask you this: Did nature make it to the Moon?

Mart
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Old 20th Dec 2006, 19:35
  #44 (permalink)  
 
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The truth and revisionist history.

Nick,
You say;
The truth is not quite so boldly deceptive as you would wish (that web site you use as "proof" is a Luftwaffe web site that goes out of its way to show how wonderful everything was back then when Nazis ruled the known world):
Not quite "the truth".

The picture in my posting comes from the book Hubschrauber und Tragschrauber

The production statistics come from 'Helicopters of the Third Reich'. Appendix II lists and provides information on everyone of the Fl-282s and Fa-223s. Oh, by the way it's author is Steve Coates, who lives in England and published the book in 2003. You may wish to read the Editorial Review and the Customer Review if you appreciate facts and detail.

When evaluating Fact versus Fantasy, consider the factual competence of the above versus Igor Sikorsky's "Two rotors are like two women in the kitchen. You might think they would do twice as much work, but the efficiency of each is lower-ed by 35 percent.", previously mentioned by IFMU.

Perhaps one of Sikorsky's newly hired 'Quality Inspectors' should be sent over to the Marketing department.

___________________________

Mart,
why are you basing your arguements on machines that flew over half a century ago?
Because the title of this thread is 'Why are Helicopters with the Flettner-System so slow?' All I am showing is that the 'Flettner-System' was not slow. The direction that Kaman took the interleaving (synchropter) configuration created the conception of slowness.

Did nature make it to the Moon?
If 'nature' means 'life' then appears that the answer is; - Yes. 'Life' rode a comet. Is not the comet an appropriate 'vehicle' for the enviroment of space?


Dave

Last edited by Dave_Jackson; 20th Dec 2006 at 20:46. Reason: Source of picture corrected.
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Old 20th Dec 2006, 20:36
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Originally Posted by Dave_Jackson View Post
All I am showing is that the 'Flettner-System was not slow. The direction that Kaman took the interleaving (synchropter) configuration created the conception of slowness.
Good point well made.

Originally Posted by Dave_Jackson View Post
If 'nature' means 'life' then appears that the answer is; - Yes. 'Life' rode a comet. Is not the comet an appropriate 'vehicle' for the enviroment of space?
Well, not sure i'll let you get away with that one. What i mean is that no natural lifeform can achieve a deliberate Earth-Moon-Earth voyage without technical means of some description.

Mart
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Old 20th Dec 2006, 20:47
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Dave,
I think you used those web sites, so I criticized them. I guess someone ELSE posted them in your comments. Those Nazis are everywhere...

Nonetheless, the only 23 Flettners ever built were built around the same time as the 130 R4's. Seems like a draw to me, at best.

The shipboard landing of the Flettner seems to have been performed first, but specific dates are hard to come by. Perhaps the Flettner experimental helos were first. Perhaps not.

It is interesting that you cannot help but grab obsolete data from Jurrasic helicopters to support your theories. With approximately 25,000 aerospace professionals employed daily in helicopters, and world helicopter expenses in the $10,000,000 every year, precisely how many dollars are being spent on your pet configuration?
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Old 21st Dec 2006, 02:12
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Smile

Nick,
The first R-4 landings on the Bunker Hill were May 6 & 7, 1943.

. . .

You say;
... approximately 25,000 aerospace professionals employed daily in helicopters, and world helicopter expenses in the $10,000,000 every year ...
I'm sorry to hear that it's so small. Where did things go so wrong?
Igor said;
We shall see hundreds of thousands of privately owned direct-lift machines carrying Americans about their business and their pleasures.
.

Dave
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Old 21st Dec 2006, 12:18
  #48 (permalink)  
 
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Dave, the VS-300 flew in late 1939, and did many trials during the early years. I will ask Sergei Sikorsky if he recalls any shipboard landings or boat/barge landings in that period. I have seen several photos of the test work then, including boat tow and hoist tests, but none specifically of landings, so the Flettner could be first.

Regarding everyman's helo, that can only come when we solve the problem that kills the trained professionals who fly today, probably with computer controlled/stabilized machines where the crew tells the machine where to go, and IT sees terrain, avoids traffic and harsh weather, and lands itself. With the cost of processing today, some micro-modeler will graft his dime sized control system onto a robbie and the solution will be had.

If everyman flew today's aircraft, there would be no need for birth control!
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Old 21st Dec 2006, 19:17
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Nick,
The current list price for a "robbie" on their website for an average equipped 22 is $215,000.
Will a computer chip bring the cost down?
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Old 21st Dec 2006, 19:23
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Nick,

Your comment "Regarding everyman's helo" recalls the last two paragraphs in post #34 on this thread.

The provocative 'Letter to the Editor' will be posted on a new thread and the responses (if any) may be interesting.


Dave
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Old 22nd Dec 2006, 00:14
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Igor said;
We shall see hundreds of thousands of privately owned direct-lift machines carrying Americans about their business and their pleasures.
Igor was a technical visionary, but I believe he fell short in some of the business vision. Part of his early business vision was that flying boats would always be more viable that landplanes that needed runways, and that many smaller aircraft would be more practical than lesser large ones. On the bright side, when the flying boat market failed, he got to get back to his dream of perfecting the helicopter. Interesting that although his technical vision started with coaxials, it matured into the conventional single main rotor and tail rotor.
-- IFMU
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Old 22nd Dec 2006, 16:10
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Originally Posted by slowrotor View Post
Nick,
The current list price for a "robbie" on their website for an average equipped 22 is $215,000.
Will a computer chip bring the cost down?
Slowrotor, i began in an industry which pumps out 5000 vehicles every week for an average model. The modern car delivers reasonable quality at a good cost because of these volumes: Tooling for a panel can be $1'000'000, but each car makes a very small profit (including paying off tooling investment).

If helicopters are made easy enough to fly that training becomes less of an issue then production volumes will go up. This means that parts which are machined can be forged, parts which are forged can be ADI pressure cast and so on. It also means that suppliers are willing to risk more development capitol for system development, so more components become off the shelf.

I don't think that there will be a helicopter on every driveway, primarily since a low disk loading still requires good piloting common sense. I do think that by further increasing the versatility of this incredible machine, production volumes will at least double. A future rotorcraft equivalent of today's Robbie might be $107'500.

Besides, the next aerospace breakthrough may not be so far away.

Mart
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Old 22nd Dec 2006, 18:31
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IFMU said;
Interesting that although his technical vision started with coaxials, it matured into the conventional single main rotor and tail rotor.
True, the single main rotor and tail rotor has reached its maturity.

Now Sikorsky, and Bell with its tiltrotors, are moving into Generation II rotorcraft, which necessitates the use of twin main rotors.

Dave
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Old 22nd Dec 2006, 20:12
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I believe if you look into the production cost of the R-22 it would be very similar to that of a production Cessna 172. Between 60 and 80 thousand dollars of that cost is attributed to product liability which has to cover the aircraft for its anticipated life. Unlike the automobile industry liability costs for an aircraft have to be absorbed by a relatively small production run. i.e. a few thousand vs. millions. The actual cost for materials and manufacture is only a small element of the sale price.
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Old 22nd Dec 2006, 23:20
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Interesting comment, Jack. To my mind this highlights the importance of developing "various computer controlled/stabilized machines where the crew tells the machine where to go, and IT sees terrain, avoids traffic and harsh weather, and lands itself". Once developed the suppliers would have a natural incentive to aim these systems at smaller/cheaper rotorcraft.

Mart
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Old 23rd Dec 2006, 00:32
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Originally Posted by Dave_Jackson View Post
True, the single main rotor and tail rotor has reached its maturity.
Now Sikorsky, and Bell with its tiltrotors, are moving into Generation II rotorcraft, which necessitates the use of twin main rotors.
Dave
However, I doubt that the single main rotor and tail rotor configuration will go away. As you add stuff that is good for speed, like pusher props & another entire rotor system, or tilt rotors, you are adding weight that is bad for hover. There is an axiom:
"What is good for high speed flight is bad for hover. What is good for hover is bad for high speed flight."
Now granted if you can invent your plastic rotors that change shape as they sling around, then you can scoff at that statement. But to whip out one more Igor Sikorsky quote:
Originally Posted by I.I. Sikorsky
"To invent a flying machine is nothing. To build it, little. To make it fly is everything."
-- IFMU
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Old 23rd Dec 2006, 01:43
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IFMU
However, I doubt that the single main rotor and tail rotor configuration will go away.
Don't be so pessimistic.



Wow! At the top of this page is your axiom and below it is your 'plastic rotor'.
"Great minds think alike."



Originally Posted by I.I. Sikorsky
"To invent a flying machine is nothing. To build it, little. To make it fly is everything."
OK, I give up. Which of his helicopters is he talking about?



Dave
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