Designed in the early 1990s by McDonnell Douglas Helicopter Systems, it is currently produced by MD Helicopters. There have been two models, the original MD 900, and its successor, the MD 902. In January 1989, McDonnell Douglas Helicopters officially launched the development of the Explorer, initially referred to as MDX. The Explorer was the first McDonnell Douglas helicopter to incorporate the NOTAR system from its initial design. McDonnell Douglas partnered with Hawker de Havilland of Australia to manufacture the airframes. 10 prototypes were built with seven being used for ground tests. McDonnell Douglas Helicopters became a launch customer for Pratt & Whitney Canada's PW200 series of engines, with an exclusive agreement to power the first 128 Explorers with two PW206As. The MD Explorer features the NOTAR anti-torque system, with benefits including increased safety, far lower noise levels and performance and controllability enhancements. Instead of an anti-torque tail rotor, a fan exhaust is directed out of slots in the tail boom, using the Coandă effect for yaw control. Boeing retains the design rights to the NOTAR technology despite selling the former McDonnell Douglas civil helicopter line to MD Helicopters in early 1999. The Explorer also features a bearingless five blade main rotor with composite blades, plus carbonfibre construction tail and fuselage. The MD900 is used extensively in police ans air ambulance rolls. The aircraft in the photo above, G-SASH, is operated by the Yorkshire Air Ambulance and is featured in the Foxtel TV program Air Ambulance. For details of the development and 6 variants, click here.
