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).
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