One 1118kW (1500shp) Honeywell T53-17A-1 turboshaft flat rated to 1007kW (1350shp) for takeoff driving two intermeshing two blade main rotors.
Max normal operating speed 185km/h (100kt) or 130km/h (75kt) with an external load. Initial rate of climb 2500ft/min. Hovering ceiling out of ground effect 29,120ft. Range with max fuel 555km (300nm).
Operating empty 2334kg (5145lb), max takeoff without jettisonable load 2948kg (6500lb), with jettisonable external load 5443kg (12,000lb).
Rotor diameter (each) 14.73m (48ft 4in), length overall rotors turning 15.85m (52ft 0in), height to centre of hubs 4.14m (13ft 7in). Total rotor disc area 340.9m2 (3669.0sq ft).
Accommodates pilot only but certificated with fuselage side mounted external seats (one either side). Designed to lift external loads such as Bambi firefighting buckets. The K-Max's maximum hook lifting capability is 2720kg (6000lb).
The first K-Max was delivered in January 1994. By January 2001 36 had been ordered.
Aerial crane and utility helicopter
Kaman's first civil helicopter since the Ka-225 was certificated in 1949, the K-Max is a specialised helicopter designed specifically for aerial crane work.
The unusual looking K-1200 K-Max is easily identified by its characteristic intermeshing main rotors. The two main rotors have the dual advantages of allowing a low rotor disc area loading and that all the engine's power produces lift, and none is "wasted" driving an anti torque tail rotor. The two main rotors are also fitted with trailing edge servo flaps that control the blades' angle of attack, negating the need for hydraulic power.
Power is supplied by a Honeywell (formerly AlliedSignal and Lycoming) T53-17A-1 turboshaft (equivalent to the military T53-L-703), the T53 also powers the Bell UH-1 Iroquois series (and the equivalent commercial Bell 204 and 205, described separately). The extremely high power to weight ratio of the K-Max means it can lift loads of up to 2720kg (6000lb).
The prototype K-Max first flew on December 23 1991, piloted by company test pilot Al Ashley. Certification was delayed somewhat by an early decision to improve the rotor system to increase performance margins, changes including lengthening the main rotors' diameters and increasing the rating of the transmission. US FAA certification was awarded in September 1994.
Recognising that the K-Max's high power to weight ratio may place inexperienced operators in difficult situations, Kaman took a very cautious approach to marketing the aircraft and leased out the first six production aircraft while flight experience was gained.
As an aerial crane the K-Max is suited to firefighting operations carrying various size Bambi buckets, logging, construction, surveying and aerial spraying. It has also been demonstrated to the US Navy in the vertrep (vertical replenishment) role (due to USN requirements Kaman certificated the K-Max for IFR operations, awarded in 1999).