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Tandem-rotor helicopters have the advantage of being able to hold more weight with shorter blades, since there are two sets. However, the rear rotor works in the aerodynamic shadow of the front rotor, which reduces its efficiency. This loss can be minimized by increasing the distance between the two rotor hubs, and by elevating one hub over the ...
An intermeshing-rotor helicopter (or synchropter) is a helicopter with a set of two main rotors turning in opposite directions, with each rotor mast mounted with a slight angle to the other, in a transversely symmetrical manner, so that the blades intermesh without colliding.
The Kaman HH-43 Huskie is a helicopter developed and produced by the American rotorcraft manufacturer Kaman Aircraft. [2] It is perhaps most distinctive for its use of twin intermeshing rotors, having been largely designed by the German aeronautical engineer Anton Flettner.
The H-3 was a two-seat general purpose helicopter. It had a duraluminium tube superstructure, an open cockpit and landing gear of metal skids. The design is typical of ultralight helicopters of the period, being powered by tip-jets — two ramjets, one at the tip of each rotor blade.
The number of rotors is also important, many helicopters have two rotors in a single line, and another configuration is 4 rotors. [22] An example of two-blade rotor is the Bell 212, and four blade version of this helicopter is the Bell 412. [23]
It was followed by a similar MC-4C and three evaluation helicopters for the United States Army (as the YH-30). The MC-4C was slightly larger than the MC-4. When the MC-4C was certified in 1953, it was the first tandem-rotor helicopter to be certified in the United States for commercial use. Three examples were evaluated by the United States ...
The Kellett XR-8 (later redesignated XH-8) was a helicopter built in the United States during World War II.It was a two-seat machine intended to demonstrate the feasibility of a twin-rotor system and, while it accomplished this, it also demonstrated a number of problems that prevented further development of this particular design.
The two rotors were synchronised through a shaft to prevent blade collision, allowing the aircraft to operate through only one engine in the event of an emergency. In that case, the remaining engine would automatically run up to double power to compensate. [4] Bristol attempted to market a civilian variant of the helicopter, designated the Type ...