|A HELOG Heliswiss Kaman K-Max|
|Role||Medium lift helicopter|
|First flight||23 December 1991|
The Kaman K-MAX (Company designation K-1200) is an American helicopter with intermeshing rotors (synchropter) built by Kaman Aircraft. It is optimized for external load operations, and is able to lift a payload of over 6,000 pounds, which is more than the helicopter's empty weight. A remote controlled unmanned aerial vehicle version is being developed and in extended practical service in the war in Afghanistan.
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 States and became the chief designer of the Kaman company. He started to design new helicopters, using the Flettner double rotor.
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.
|RC version of K-MAX at Ft. Eustis|
|Autonomous K-MAX at Yuma[dead link]|
|Unmanned K-MAX at Yuma|
|K-MAX with wrecking ball|
Thirty-eight K-1200 K-MAX helicopters have been built. As of February 2012, 13 of these were not airworthy or have been written off in accidents. The production line was shut down in 2003, but may restart if the U.S. Marine Corps orders more autonomous K-MAXs.
Unmanned remote control version 
An unmanned remote-control version, the K-MAX Unmanned Multi-Mission Helicopter, is planned for hazardous missions. It could be used in combat to deliver supplies to the battlefield, as well as civilian situations involving chemical, biological, or radiological hazards. A prototype of this was shown in 2008 for potential military heavy-lift resupply use, and again in 2010.
In December 2011 an unmanned K-Max was reported to be at work in Afghanistan. On December 17, 2011, the United States Marine Corps conducted the first unmanned aerial system cargo delivery in a combat zone using an unmanned version of the Kaman K-MAX. The unmanned KMAX moved about 3,500 pounds of food and supplies to troops at Combat Outpost Payne.
As of February 2013, the K-MAX has delivered 2 million pounds of cargo in 600 unmanned missions, with over 700 flight hours.
A third unmanned K-MAX, based in the US, was tested in 2012 to deliver cargo to a small homing beacon with 3 meter precision.
On July 31, 2012, Lockheed announced a second service extension for the K-MAX in Afghanistan for the Marines. This extended operation time to the end of March 2013, with the option to extend through to the end of September 2013. On March 18, 2013, the Marine Corps extended their use of the unmanned K-MAX helicopters indefinitely. The Marines do not currently have plans to buy more, but the two aircraft in use will remain "until otherwise directed." At the time of this announcement, they had flown over 1,000 missions and hauled over 3 million pounds of supplies. Assessments for their use after deployment are being studied. While proving useful, their "niche" in future Marine Corps aviation is not yet clear.
- Rotex Helicopter AG
Specifications (K-MAX) 
Data from K-MAX Performance and Specs
- 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)
See also 
- Related development
- Aircraft of comparable role, configuration and era
- Boyne, Walter J. (2011). How the Helicopter Changed Modern Warfare. Pelican Publishing. p. 45. ISBN 1-58980-700-6.
- "Anton Flettner"; Hubschraubermuseum Bückeburg
- "Twin Turborotor Helicopter." Popular Mechanics, August 1954, p. 139.
- 'K-Max Intermeshing Rotor Drive System' 53rd Annual Forum Proc., AHH, 1997.
- 'Composites take off ... in some civil helicopters.' March 1, 2005. Retrieved: 26 June 2011.
- Karman III, John R. (18 August 2008). "Demolition precedes new construction for Ursuline schools".
- The Kaman K-MAX Current Status SwissHeli.com by Markus Herzig
- Padfield, R Randall (March 2012). "Civil Tiltrotor and K-Max Aerial Truck Back in the Saddle?". AINonline.com. Retrieved 31 March 2012.
- "Lockheed Martin And Kaman Aerospace Demonstrate Unmanned Supply Helicopter To U.S. Army". Retrieved 13 August 2009.
- "Team K-MAX demonstrates successful unmanned Helicopter Cargo resupply to U.S. Marine Corps", Lockheed Martin press release, 8 February 2010. Retrieved 14 March 2010.
- "Lockheed Martin awarded $45.8 million for unmanned KMAX" Defense Update, 6 December 2010. Accessed: 11 December 2010.
- "Lockheed Martin/Kaman K-MAX Completes US Navy Unmanned Cargo Assessment", 8 September 2011. Accessed: 9 September 2011.
- John Roach. "Robotic helicopters at work in Afghanistan". Future of Technology, MSNBC. Retrieved 22 December 2011.
- "Unmanned helicopter makes first delivery for Marines in Afghanistan". USMC. Retrieved 28 December 2011.
- McLeary, Paul. "K-MAX Chugging Along in Afghanistan" Aviation Week, 3 February 2012. Accessed: 4 February 2012.
- "Beacon improves UAV’s cargo-delivery accuracy" Marine Corps Times, 8 July 2012. Retrieved: 9 July 2012.
- U.S. Marine Corps to Keep K-Max Unmanned Cargo Re-Supply Helicopter in Theater for Second Deployment Extension - Lockheed press release, July 31, 2012
- US Marines extend K-MAX unmanned helicopter's use in Afghanistan - Reuters.com, March 18, 2013
- "Unmanned K-MAX Wins Top Innovation Honors, USMC Praise". HeliHub. 9 Jan, 13. Retrieved 26 February 2013.
- "Unmanned K-Max is nominee for Collier Trophy". HeliHub. 11 Feb, 13. Retrieved 26 February 2013.
- "colombian army aviation". helis.com. Retrieved 05-January-2013.
- "HELOG". helis.com. Retrieved 05-January-2013.
- Markus Herzig. "Swiss Helicopters - Current Fleetlist". Swissheli.com. Retrieved 2012-06-18.
- "Swanson group aviation". DNA Web Agency. Retrieved 05-January-2013.
- "Timberline Helicopters". Retrieved 05-January-2013.
- "US Marine Corp K-Max". helis.com. Retrieved 05-January-2013.
- "K-MAX Performance and Specs". Kaman Aircraft. Retrieved 2012-10-02.
- Kaman K-1200 "K-MAX"
- "Kaman K–1200 FAA Approved Rotorcraft Flight Manual" Page 1–4. Kaman, February 17, 2004. Retrieved: October 2, 2012.
|Wikimedia Commons has media related to: Kaman K-MAX|
- Kaman Aerospace's K-MAX page
- Superior Helicopter K-MAX with Firemax system
- Austrian Wucher Helikopter
- Video of a K-MAX starting up