German Helicopter Prototypes & Projects

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Hi,

here is a strange helicopter Projects,designed by Mr. Hans Lemmerzahl,it had one main blade
only ?,the first was from 1954 and second was from 1959,the later had paddle wheel ;

People's helicopter Lemmerzahl HL 1
In 1954, the German designer Hans Lemmerzahl won an international award for his design for an inexpensive
helicopter. The double seater should fly with just one jack screw. The project was not realized, but today a
single-bladed helicopter seems to be up to date again.

I was able to find a bit more info about the HL 1 in a July 13, 1956 copy of the Chicago, Illinois-based Catholic newspaper "Draugas: Lithuanian Daily Friend."

Roughly translated:

Helicopters will conquer cars -- Last year, German engineer Hans Lemmerzahl won a gold medal at the International Helicopter Competition in France for his new helicopter design. Now the German press is writing extensively about that achievement and is paying close attention to the future. It is claimed that the new type of helicopter is very practical, driven in the air very easily, like any machine on the road, and most importantly - cheap. It has a German Volkswagen 30 PS engine and, when mass-produced, only costs about 4,000 DM, which is almost cheaper than the most popular and cheapest German car "Volkswagen." It only needs 20x20 square meters to take off and land, at an angle of up to 45 degrees and developing a speed of 160 km per hour, and using only 6-8 liters of petrol (gasoline), which is the most economical for a German car. It is expected that in 2-3 years the new type of cheap helicopter will be mass-produced and, due to its cheapness and convenience, will be easily accessible to everyone and will be used as widely as cars.
 

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The first concepts of the Bo-105 were also planned with a single-bladed rotor. Any idea what's the reason for these asymmetric rotor layouts?

Before the MBB 105 helicopter success, the company built a couple of experimental airframes. The first experimental airframe: MBB 102 was little more than a ground test project with a single, glass-fibre, main rotor blade. The single blade reduced parts count, weight, manufacturing cost, etc. but introduced some massive 1 to 1 vibration problems.
The single-blade MBB 102 prototype was permanently tethered to a three-jointed arm. At one point MBB tried marketing it as a ground training aid for student pilots. It never got off the ground.
Then MBB built a flyable 103 prototype with a similar single-bladed rotor. It never entered produciton. Again, the MBB 103 was a bare-bones, minimalist, single-seater prototype.

As an aside, Sikorsky also modified an R-4 to fly with a single blade main rotor, but only tested it briefly.

All subsequent MBB helicopters have 4 main rotor blades semi-rigidly attached to the hinge-less hub. All the flex is in the blade roots.
 
The helicopters you mentioned were developed by the Bölkow company before merging with Messerschmitt and Blohm.
 

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From Aviation magazine 1972.
 

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Why did one of the FW 61's have the registration D-EKRA? DEKRA is the Deutsche Kraftfahrzeug Überwachungs Verein (German Motor Vehicle Monitoring Association). It was established 1925 and still exists. Did DEKRA provide financing in exchange for advertising?
 

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Here's the one from the german aerotechnik GmbH, built and flown in 1969. Four rotors on movable arms, driven by BMW engine of 54 hp.

And here's the proposed two-seater, the WGM 22. Estimated cruise at 108 kts for 431 nm, seems ambitious.

From JAWA 1974-75.
 

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