Kaman K-MAX (K-1200)
Medium-Lift Utility Helicopter
The Kaman K-MAX medium lift helicopter is currently under evaluation as an unmanned logistics flight system for the US military.
Authored By: Staff Writer | Last Edited:
The Kaman K-MAX is a general purpose, multi-role, all-weather platform certified for long endurance, repeated external medium-lift missions. The helicopter was purposefully designed for this role, a departure from similar systems that are often times built upon existing - yet proven - airframes and designed with passenger-carrying in mind. As such, the K-MAX supports seating for just one pilot and is powered by a single engine which allows the airframe to be as minimal in profile as possible. Despite its rather fragile appearance, the K-MAX is a heavy-duty workhorse with unsurpassed qualities that allow her to carry a cargo load more than her own listed empty weight. The K-MAX system is known under the Kaman company designation of "K-1200".
The K-MAX series is produced by the Kaman Aerospace Corporation as part of the Kaman Corporation brand name. Kaman began as an aerospace firm founded in 1945 based out of Bloomfield, Connecticut under the leadership of Charles Kaman and immediately dove into the world of helicopter flight. The company designed and produced rotary-wing systems that went on to set several aviation milestones (the first turbine-powered helicopter for instance) and world aviation records. In 1956, Kaman began taking work as a subcontractor to several big-name defense firms including McDonnell Douglas and, in turn, graduated to using more advanced composite materials to overtake the old wooden methods en vogue previously. Kaman's expertise and willingness to branch out from the ordinary also led the firm to designing a composite Ovation-brand guitar - giving rise to Kaman Music.
The K-MAX is categorized as a "synchcropter" which is a helicopter making use of an intermeshing rotor system, the rotors turning in opposite directions and at opposing angles in such a way that they generate lift while steering clear of one another's rotations. This rotor concept was brought to fruition by German engineer Anton Flettner during World War 2 and showcased in his Flettner Fi 256 design. The Fi 256 was a relatively small, one-man helicopter intended for operations from German U-boats in the anti-submarine warfare (ASW) role. The K-MAX essentially utilizes a modernized form of the concept and has proven itself a most viable rotary-wing aircraft. The use of these intermeshing rotors means that the K-MAX does not require a conventional tail rotor to counter inherent torque effect found on helicopters making use of a single spinning rotor or propeller. The intermeshed rotor arrangement provides the K-MAX with an in-born hover capability that makes her relatively easier to control during precise actions. It is said that such rotor arrangements have proven more efficient in the long run when compared to conventional helicopters.
The slim inline design and single-seat layout of the K-MAX allows for excellent views from the cockpit thanks to the bulged side canopy windows. The front view is similarly dominated by a large curved canopy piece and the pilot sits in a raised seat with a commanding vantage point. All critical controls are mounted on the cyclic and collective hand grips. An external instrument panel is thoughtfully set with critical mission gauges to keep the pilot's eyes close to the situation when precise hovering is called for. The engine is fitted within a compartment at amidships, exhausting just above the empennage base through a cylindrical fixture. The twin rotor masts protrude from the topmost portion of the fuselage with each blade controlled by a mechanical servo-flap along the trailing edge. The servo-flaps negate the need for complicated and fault-prone hydraulic- or -electrically-powered systems. The empennage is set low and complemented by a pair of outboard vertical tail fins set on wingstubs. The tail is capped by a slender and tall vertical fin assembly. The heavy-duty undercarriage is of conventional layout, featuring two single-wheeled main landing gear legs and a single-wheeled nose landing gear leg, the latter found just under the sharp nose assembly. There is a specially-designed integrated cargo hook - the heart and soul of the K-MAX system - set up on a trolley system that allows the hook and cargo slide forwards and backwards along the fuselage underside. The hook is cleared for up to 6,000lb loads.
In all, the K-MAX works effectively at lightening pilot workload compared to other helicopter systems attempting to accomplish the same role. There is no multi-engine management or multiple gearboxes to contend with as there is only one turboshaft engine and no tail rotor. There are no flight control hydraulics and there is only one internal fuel tank to manage. Kaman brochures claim the only requirements for the K-MAX are a trained pilot and a trained mechanic - maintenance does not require specialized facilities. Additionally, Kaman touts the K-MAX as the quietest helicopter in the world with noise levels compared to that of an alarm clock at 2 feet distance.
The K-MAX airframe sports a running length of approximately 51 feet, 10 inches while her rotor diameter measures in at 48 feet, 3 inches. When at rest, the K-MAX stands at 13 feet, 7 inches. She weighs in at 5,145lb when empty and can take off at 12,000lb maximum. The K-MAX is powered by a single Honeywell T53-17 series turboshaft engine delivering 1,800 shaft horsepower. This supplies the machine with speeds up to 115mph and a range of up to 306 miles, using up just 82 gallons of fuel per hour.
The rugged K-MAX has since proven effective in a variety of roles including search and rescue (SAR), logistics, heavy duty construction projects, logging, firefighting (waterdrops) and disaster relief. An unmanned version of the K-MAX system debuted in 2008 for evaluation by the US military to validate having the unmanned aerial vehicle deliver supplies to forward operating bases. The unmanned model is also intended for use in the civilian role to test air quality against Nuclear, Biological and Chemical (NBC) components. In either case, the idea behind the unmanned K-MAX is to keep pilots from direct contact with dangerous elements - be they on the battlefield or in the atmosphere. The unmanned K-MAX has already demonstrated itself in front of US Army and Marine Corps authorities in separate evaluations.
It is reported that about 40 or so K-MAX helicopter systems have been built though operators span the world and include (or have included) Austria, Canada, Colombia, Japan, South Korea, Liechtenstein, New Zealand, Switzerland and the United States.