Intermeshing rotors on a

helicopter A helicopter is a type of rotorcraft in which lift and thrust are supplied by horizontally spinning rotors. This allows the helicopter to take off and land vertically, to hover, and to fly forward, backward and laterally. These attributes ...

are a set of two 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 arrangement allows the helicopter to function without a

tail rotor The tail rotor is a smaller rotor mounted vertically or near-vertically at the tail of a traditional single-rotor helicopter, where it rotates to generate a propeller-like horizontal thrust in the same direction as the main rotor's rotation. Th ...

, which saves power. However, neither rotor lifts directly vertically, which reduces efficiency per each rotor. This configuration is sometimes referred to as a synchropter. Yaw is accomplished through varying torque, which is done by increasing

collective pitch A helicopter pilot manipulates the helicopter flight controls to achieve and maintain controlled aerodynamic flight. Changes to the aircraft flight control system transmit mechanically to the rotor, producing aerodynamic effects on the rotor bla ...

on one of the blade sets. Most intermeshing designs have two blades per mast, although exceptions such as the

Kellett XR-10 The Kellett XR-10 was a military transport helicopter developed in the United States in the 1940s that only flew in prototype form. It was designed in response to a USAAF Technical Instruction issued for the development of a helicopter to transpo ...

with three blades per mast do exist. The arrangement was developed in

Germany Germany,, officially the Federal Republic of Germany, is a country in Central Europe. It is the second most populous country in Europe after Russia, and the most populous member state of the European Union. Germany is situated betwe ...

Anton Flettner Anton Flettner (November 1, 1885 – December 29, 1961) was a German aviation engineer and inventor. Born in Eddersheim (today a district of Hattersheim am Main), Flettner made important contributions to airplane, helicopter, vessel, and automob ...

for a small

anti-submarine warfare Anti-submarine warfare (ASW, or in older form A/S) is a branch of underwater warfare that uses surface warships, aircraft, submarines, or other platforms, to find, track, and deter, damage, or destroy enemy submarines. Such operations are t ...

helicopter, the

Flettner Fl 265 The Flettner Fl 265 was an experimental helicopter designed by Anton Flettner. Design and development This helicopter, developed in 1938 with the support of Nazi Germany's ''Kriegsmarine'', made it possible, for the first time, to transition fro ...

as the pioneering example, and later the Flettner Fl 282 Kolibri. During the Cold War the American

Kaman Aircraft Kaman Corporation is an American aerospace company, with headquarters in Bloomfield, Connecticut. It was founded in 1945 by Charles Kaman. During the first ten years the company operated exclusively as a designer and manufacturer of several h ...

company produced the

HH-43 Huskie The Kaman HH-43 Huskie is a helicopter with intermeshing rotors used by the United States Air Force, the United States Navy and the United States Marine Corps from the 1950s until the 1970s. It was primarily used for aircraft firefighting and re ...

, for

USAF The United States Air Force (USAF) is the Aerial warfare, air military branch, service branch of the United States Armed Forces, and is one of the eight uniformed services of the United States. Originally created on 1 August 1907, as a part ...

firefighting purposes. One example of the

Kaman K-225 The Kaman K-225 is an American experimental helicopter developed by Kaman Aircraft. One example was modified to become the world's first gas turbine-powered helicopter. Design and development The K-125 was Charles Kaman's first helicopter, whi ...

experimental synchropter was fitted with a small turboshaft engine in late 1951, becoming the world's first

gas turbine A gas turbine, also called a combustion turbine, is a type of continuous flow internal combustion engine. The main parts common to all gas turbine engines form the power-producing part (known as the gas generator or core) and are, in the directio ...

-powered helicopter. Intermeshing rotored helicopters have high stability and powerful lifting capability. The latest Kaman K-MAX model is a dedicated sky-crane design used for construction work, and has been modified for trials by the

USMC The United States Marine Corps (USMC), also referred to as the United States Marines, is the maritime land force service branch of the United States Armed Forces responsible for conducting expeditionary and amphibious operations through co ...

as an optionally-unmanned cargo transporter.

Unmanned aerial vehicle An unmanned aerial vehicle (UAV), commonly known as a drone, is an aircraft without any human pilot, crew, or passengers on board. UAVs are a component of an unmanned aircraft system (UAS), which includes adding a ground-based controll ...

s with intermeshing rotors have also been flown.

List of intermeshing rotor helicopters

(1939) *

Flettner Fl 282 The Flettner Fl 282 ''Kolibri'' ("Hummingbird") is a single-seat intermeshing rotor helicopter, or ''synchropter'', produced by Anton Flettner of Germany. According to Yves Le Bec, the Flettner Fl 282 was the world's first series production hel ...

(1941) * Kellett XR-8 (1944) *

(1947) *

(1947) * Praga E-1 (1947) * SNCAC NC.2001 Abeille (1949) *

Kaman HH-43 Huskie The Kaman HH-43 Huskie is a helicopter with intermeshing rotors used by the United States Air Force, the United States Navy and the United States Marine Corps from the 1950s until the 1970s. It was primarily used for aircraft firefighting and ...

(1953) * Kaman K-700 (1969) (abandoned) * Clybouw CW-105F (1973) * DeGraw RDX1091 Hummingbird (1984) * Kaman K-MAX (1991)

References

External links

* Rotorcraft Helicopter components {{Component-aircraft-stub

List of intermeshing rotor helicopters

See also

References

External links