Only Merkel I can find is the no longer active Edwin W. Merkel Airplane Company in Wichita and Valley Center, KS, who built the Mark IIA aircraft. Nothing rotary related.
In 1966, the BMVg awarded a series of systems analyses studies for helicopter speed improvement. Peter Richter was the project manager. Dr. Just was an advisor to the project. The M-133, intended to conduct the flight tests.
Power: two Daimler Benz DB 720/PTL 6 turboshaft engines, each with 1,500 kW (2,000 hp) to drive the main and tail rotor; in addition, each engine was connected to an aft fan to augment forward propulsion
Rotor: five-blade rotor, automatic reduction of blade angle at positive flapping angle or automatic increase of blade angle at negative flapping angle.
The M-133 demonstrators were to use the two Bo 46 fuselages. For hovering and low-speed flights, the engines drove the rotor. At high-speed flights, the main rotor was offloaded and additional thrust was produced by the aft fans.
at the end of 1967, all BMVg projects for high-speed helicopters were declined
Power: DB 730/ZTL 6 engines with 993 kW (1,350 hp)
Rotor: diameter 11.00 m (36 ft)
Speed: 545 km/h (295 kt)
Length: 12.36 m (40.6 ft)
Width: 6.65 m (21.8 ft)
Maximum Take-off Weight: 3,100 kg (6,800 lb)
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lllllAs of 2019 I have transitioned; My name is now Rei. Please don't deadname or misgender me, thank you. <3 lllll
Established at Oedheim, acquired from Dr. Winter of Brunswick Technical College license to build Kiebitz two-seat STOL monoplane. In 1956 began development of SM-67 Turbomeca Artouste-powered five-seat helicopter, initially as private venture and later to government contract.