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The Kaman K-MAX is an American helicopter with intermeshing rotor-blades built by Kaman aircraft. It is optimized for external load operations, and is able to lift a payload of over 6,000 (max. about 12,000) pounds, which is more then the helicopter's empty weight.


In 1947 Anton Flettner, a former German teacher and inventor, was brought to the United States as part of Operation Paperclip. He was the developer of the former German helicopter Flettner Fl 282 "Kolibri" (Hummingbird), which had the principle of counter-rotating side-by-side intermeshing (combing) rotors, as the means to solve the problem of torque compensation, normally countered in single rotor helicopters by a tail rotor or vented blower exhaust. Anton Flettner stayed in the United S

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First flown on 23 December 1991, the K-MAX uses a pair of intermeshing side-by-side main rotors, made of carbonfibre-reinforced plastics, to ensure proper strength and lightness, as well as good lift qualities. Only 6 built.

tates and became the chief designer of the Kaman company. He started to design new helicopters, using the Flettner double rotor.

The K-MAX series are the latest in a long line of Kaman synchropters, the most famous of which is the HH-43 Huskie. The first turbine-powered helicopter was also a Kaman synchropter.

The K-1200 K-MAX "aerial truck" is the world's first helicopter specifically designed, tested, and certified for repetitive external lift operations and vertical reference flight (Kaman received IFR Certification in 1999), an important feature for external load work. Other rotorcraft used for these tasks are adapted from general-purpose helicopters, or those intended to primarily carry passengers or internal cargo. The aircraft's narrow, wedge-shaped profile and bulging side windows gives the pilot a good view of the load looking out either side of the aircraft.

The transmission has a reduction ratio of 24 in three stages, and is designed for infinite life. The rotor blades are built with a wooden spar and fiberglass trailing edge sections. Wood was chosen for its damage tolerance, fatigue resistance and to take advantage of field experience and qualification data amassed from a similar spar on the HH-43 helicopter, built for the U.S. Air Force in the 1950s and 1960s.

The K-MAX relies on the two primary advantages of synchropters over conventional helicopters. The first of these is the increased efficiency compared to conventional rotor-lift technology; the other is the synchropter's natural tendency to hover. This increases stability, especially for precision work in placing suspended loads. At the same time, the synchropter is more responsive to pilot control inputs, making it possible to easily swing a load, to scatter seed, chemicals, or water over a larger area.


There is a drone version of this aircraft used the USAF and are being deployed in Afghanistan.


General Characteristics[]

Crew: 1

Capacity: 6,000 lb (2,722 kg) external load

Length: 51 ft 10 in (15.8 m)

Rotor diameter: 48 ft 3 in (14.7m)

Height: 13 ft 7 in (4.14 m)

Empty weight: 5,145 lb (2,334 kg)

Useful load: 6,855 lb (3,109 kg)

Max. takeoff weight: 12,000 lb (5,443 kg)

Powerplant: 1 × Honeywell T53-17 turboshaft, 1341 kW (1,800 shp), flat rated to 1118 kW (1500 shp) for take-off / 1350 shp in flight)


Maximum speed: 100 knots (185.2 km/h)

Cruise speed: 80 knots (148.2 km/h)

Range: 267 nm (494.5 km)