Eurocopter High-Speed X3 Helicopter
Eurocopter’s X3 highspeed helicopter hopes to outrace Sikorsky’s X2…
Hot on the tail of the world’s fastest helicopter – the Sikorsky X2 – Eurocopter’s aptly named X3 hybrid helicopter hopes to be the next in line to break the helicopter world speed record.
The X3 made its first flight on September 6th, 2010, however it’s was only unveiled to the public last week – just days after Sikorsky’s X2 was filmed breaking the helicopter world speed record by cruising at 250 knots (287mph).
Eurocopter X3 High-Speed Hybrid Helicopter
Eurocopter hopes that the X3 will be cruising at speeds of 180 knots (207mph) by December. The aircraft will then undergo a three month upgrade in hope of returning to the field with a top speed of 220 knots (253mph).
The X3 design is based upon Eurocopter’s High-speed Hybrid Helicopter (H3) concept – a design that combines the vertical takeoff and landing capabilities with high cruise speeds over 200 knots.
The X3 has a 5 blade main rotor, which is supported by two forward facing propellers mounted on short span fixed wings. The typical fenestron (tail rotor) has been removed and replaced with twin vertical stabilizers with rudders.
Hybrid airplane/helicopter technology is by no means a new concept. As early as the 1940’s Spanish civil engineer Juan de la Cierva, had come up with the Autogiro, or ‘windmill’ aircraft design.
Sud-Quest Farfadet Covertiplane
This technology gave way to other designs such as the 1950’s Sud-Quest Farfadet covertiplane, the Fairey Rotodyne XE521 compound gyroplane, and 1960’s compound helicopters such as Lockheed Martin’s AH-56A Cheyenne.
Fairey Rotodyne XE521 Gyroplane
These hybrid aircraft cruised at speeds much faster than conventional aircraft of that era. However recent advancements in rotor technology now allow the X2 and X3 to fly at high speeds much more efficiently than craft like the AH-56A Cheyenne – with an impressive top speed of 212 knots.
AH-56A Cheyenne Compound Helicopter
Traditionally, reaching such speeds in rotor powered aircraft posed stability problems because as the craft beings to reach high speeds, the even faster moving rotor tips approach supersonic speeds.
The X3 counters this problem by trading off speed on the overhead rotor for extra propulsion from the wing props. By altering the rpm of the overhead rotor, the X3 effectively ‘reduces the drag of the advancing blade and increasing the airspeed at which the retreating blade starts to stall.’ [Ares Defense Blog]
The Sikorsky X2 opts for twin counter rotating blades – ‘that neutralize the spinning force’ – and a pusher prop on the tail.
As well as the difference in rotor technology, the X3 has a bigger cabin, a feature that may make it more applicable for civilian operations including search-and-rescue and medical-evacuation.
- Jesus Diaz: X3 Gyroplane Uses 15 Blades to Race at 253MPH. Gizmodo, 09/29/2010.
- Steve Douglass: Eurocopter’s X3 unveiled – part plane part helicopter. Black Horizon, 09/27/2010.
- Jason Paur: Eurocopter X3 Enters Race for Fastest Helicopter. Wired, 09/28/2010.
- Lizzie Schiffman: Eurocopter Launches X3 Propeller-Powered High-Speed Helicopter, Hopes to Outrace Sikorsky's X2. PopSci, 09/28/2010.
- Bill Sweetman: Eurocopter Sees Sikorsky X2, Raises (Video Update). Ares Defense Blog, Aviation Week, 09/27/2010.