The K-MAX is classified as a “synchcropter”, meaning a helicopter that uses 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. It is believed that such a scheme greatly simplifies the control of the helicopter in hover mode or at low speed. Using this scheme helps the K-Max eliminate conventional tail rotor.

The K-MAX has a very thin fuselage. The pilot sits in a cockpit with bulged side canopy windows, giving him a great view of the front and sides. Kaman K-MAX is made of light alloy. The blades and flaps are of high-strength carbon and glass fibre-reinforced plastic materials.

The engine drives two pairs of intermeshing and contra-rotating rotor blades. Two rotors are connected by gears in transmission, so the rotors never hit each other. The undercarriage of conventional layout, with two single-wheeled main landing gear legs and a single-wheeled nose landing gear leg.

The K-Max is powered by a Honeywell T53-17A-1 turboshaft engine, with 1,350 hp. Kaman’s helicopter can reach a top speed of 190 km/h, a range of up to 560 km with full load. The Kaman K-MAX can carry suspended loads of over 2,700 kg. It is in service with various civil operators around the world and is used for construction, forestry, logging, agricultural work, firefighting and transportation.

Kaman Aerospace said that the upgraded version of the K-Max will receive a new more powerful turboshaft engine, as well as a new on-board electronics. In addition, the synchroopter case and its rotors will be subjected to some modifications.

Today in the world fly around 40 K-Max. Most of them belong to the United States Marine Corps. The helicopters were also delivered to the ground forces of Colombia and civilian companies in Germany, New Zealand, Peru and Switzerland.

Source: https://military-wiki.com/kaman-k-max-k-1200-an-unusual-synchropper-helicopter-design/