MD-900

The MD 900 Explorer was developed by McDonnell Douglas Helicopter Systems as a modern light twin-engine utility helicopter. It was notable for being designed with extensive operator input and for using the company's NOTAR system instead of a conventional exposed tail rotor. The aircraft targeted emergency medical services, police aviation, corporate transport, and utility customers that wanted twin-engine safety and low external noise.

Technically, the MD 900's signature feature is NOTAR, which uses directed airflow and tail-boom effects to provide anti-torque control without an exposed tail rotor. This reduces tail-rotor hazard and noise, useful for EMS and urban operations. The aircraft also offers a relatively spacious cabin, twin-engine redundancy, and utility payload capacity in the light helicopter category. Later MD 902 versions refined the design and performance.

Operationally, the MD 900/902 Explorer found its strongest niche in air ambulance, police, and public-service aviation. The NOTAR system is attractive around personnel and confined areas, while the cabin supports medical and mission equipment. Military derivatives and armed concepts existed, but the aircraft never became a large combat-helicopter family. Its value on HiWars is as a utility platform with technology that explains why it appears in public-service and security fleets.