✈️ Aircraft Specifications
| Designation | X-51A |
| Manufacturer | Boeing |
| Country of Origin | United States |
| First Flight | 2010 |
| Length | 7.62 m (25 ft) |
| Max Speed (Mach) | 5.1 |
| Max Speed (km/h) | 6,100 km/h |
| Service Ceiling | 21,300 m (69,885 ft) |
| Range | 740 km (460 mi) |
| Engine | 1× Pratt & Whitney Rocketdyne SJY61 scramjet |
| Status | Experimental |
Overview
The X-51A Waverider demonstrated the longest duration flight of a hypersonic scramjet-powered vehicle—over 3 minutes of sustained Mach 5+ flight. Named for its wave-riding design that uses its own shock wave for additional lift, it represents the next step toward practical hypersonic weapons and aircraft.
Design & Development
The X-51 uses a hydrocarbon-fueled (JP-7) scramjet—a significant advance over the hydrogen-fueled X-43A because JP-7 is a practical military fuel. The waverider design generates lift by riding the shock wave created by its own supersonic flight, much like the XB-70 Valkyrie’s compression lift concept applied at hypersonic speeds.
Operational History
Four flight tests were conducted from 2010 to 2013. The most successful, on May 1, 2013, achieved Mach 5.1 for 210 seconds before exhausting fuel. The X-51 program directly informed the development of hypersonic weapons programs including ARRW and HACM.
Armament
The X-51A was an unmanned research vehicle with no weapons. However, its scramjet technology directly informs the development of hypersonic strike weapons including the USAF’s HACM (Hypersonic Attack Cruise Missile) program.
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Frequently Asked Questions
How fast is the X-51 Waverider?
The X-51 reached Mach 5.1 (3,400 mph) during its final test on May 1, 2013 — the longest air-breathing hypersonic flight at 210 seconds.
What is a scramjet?
A scramjet (supersonic combustion ramjet) operates at hypersonic speeds with no moving parts. Incoming air is compressed by the vehicle’s speed alone.
How many X-51s were built?
4 X-51A test vehicles were built by Boeing.
Is the X-51 still in service?
No. It was an unmanned test vehicle. Four flights were conducted between 2010 and 2013.