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Flettner's Fl 265, world's first successful helicopter with intermeshing rotors

Stargazer2006

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The first helicopter with intermeshing rotors was built by Anton Flettner and his team at Berlin's Johannistal airfield in 1938. It was flown by test pilot was former Arado chief test pilot, Flugkapitän (Captain) Richard Perla.

The Fl 265 was commissioned by the RLM and built in deep secrecy with the assistance of the supervising engineers Lucht and Reidenbach. The airframe of a Fw 44 Stieglitz was used as a basis, requiring the crankshaft of the 140 hp Siemens-Halske engine to be extended to the rear, so that the main drive shaft of the rotors could be driven by a bevel gear. The two rotors, each 6.50 m in length were made from seamless drawn steel tube.

The control was carried out by a hanging stick that had to be operated by the pilot. Rod ends transferred the control stick movements to the rotors. Torque was completely abolished and consequently there was no need for a tail rotor.

The test aircraft, designated Fl 265 V1, carried the registration D-EFLV ("E" for weight under 1000 kgs, "FL" for Flettner and "V" for Versuchsflugzeug or research aircraft). It flew in the hands of Captain Perla in a heavily guarded hall in the vicinity of Johannistal airfield. In order to learn this new "flying experience", the helicopter was tethered to the ground during these test flights. In the course of the tests the length of the wires was restricted to 2 meters, until finally the first unfettered flight was made in the open air after 3 months with 5-meter wires.

Designer Anton Flettner promised his test pilot a reward of RM 1,000 if he could maintain the machine still in the air at 10 m for 5 minutes. During the flight tests the aircraft reached altitudes of 1200 m and a horizontal speed of 128 km/h. The plane was then successfully demonstrated in Rechlin before Hitler, Goering, milk, Reidenbach and Lucht.

A second prototype designated Fl 265 V2 was built. Both aircraft were used to detect submarines of warships. Due to its good flying qualities, A. Flettner received a contract to further develop the Fl 265. Its successor was the famous Fl 282 Kolibri.


Adapted from: Luftfahrt International No.5, Sept.-Oct. 1974
 

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famvburg

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Hmm. I've never heard of intermeshing being the same as co-axial.
 

Stargazer2006

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famvburg said:
Hmm. I've never heard of intermeshing being the same as co-axial.

My mistake. I did the translation of the article and somehow got stuck on "koaxial laufenden Rotoren"... You are right, the rotors were intermeshing. I have corrected the topic's title and initial post. Thanks!
 

Stargazer2006

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Another photo of the Fl 265, this time in military guise:
 

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Graham1973

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From a video posted to YouTube about 11 yrs ago. The image shows a temporary landing pad mounted on the Caesar (X) Turret of the light cruiser Koln which was apparently trialed with both the FL 265 & Fl 282.
 

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edwest

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Hello Steve,

I have your excellent book. How do you think this idea that trials with the Köln began? An internet search shows that this 'rumor' is rather common.
 

Steve Coates

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Ed

I'm afraid lazy research or rather none at all - one of the perils of the Internet. It possibly has its roots in some post-war writings. I'll bear this in mind when reviewing my files and if I think I've come across the original source, then I'll post something up here. If someone can definitively cause me to alter my thinking on this, then I'd have no problem with that as the only important thing is the advancement of knowledge.

Steve
 

Steve Coates

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Hello Steve,

I have your excellent book. How do you think this idea that trials with the Köln began? An internet search shows that this 'rumor' is rather common.
Ed

I'm afraid lazy research or rather none at all - one of the perils of the Internet. It possibly has its roots in some post-war writings. I'll bear this in mind when reviewing my files and if I think I've come across the original source, then I'll post something up here. If someone can definitively cause me to alter my thinking on this, then I'd have no problem with that as the only important thing is the advancement of knowledge.

Steve
Ed

Looking back through my files, I think I've located the source. As I half suspected, it was William Green - Flettner Story (RAF Flying Review September 1956). This is not to bash William Green as he was one of the few sources of information available in my (long past) youth and as such I'm prepared to afford him some leeway but things have moved on.

A photograph of the Fl 282 V6 (misidentified as the V5) is referred to as having been taken on the Köln whereas in fact the vessel concerned was the MS Greif. The misidentification of the exact prototype is understandable as the photo as published has been cropped and another photo William Green later published did show the Fl 282 V5 which also took part in the same tests in early September 1942 at E-Stelle Travemünde.

Steve
 
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edwest

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Steve,

Thank you for looking into this. I have an old book by William Green that included, at the time, interesting new information. Now I hope that your correct information begins to spread. Thanks again.

Ed
 

abbadur

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Is something wrong with Nick Karatzides report and/or photos ?
 

Jemiba

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Is something wrong with Nick Karatzides report and/or photos ?
No, it's actually much more, than the title suggests ! If you don't mind, I would split and merge it with
the dedicated Fl 282 thread (renamed thread, the former title was a bit misleading), as it is about that
type.
 

Steve Coates

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Going back a bit further, I believe Green's error may have originated with a post-war interrogation of Flettner (CIC Evaluation Report 155) in which he states that one of his helicopters had landed on the Koeln without giving details as to the type.
 
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