Boeing X-51 (Waverider)

The History of the Boeing X-51 (Waverider)

The Boeing X-51 "Waverider" is an unmanned technology demonstrator designed to advance the concept of high-speed shock wave-assisted flight using internal scramjets. The product stems from the scramjet demonstrator program in 1990, in which the SJX61 hydrocarbon-fueled engine was originally developed for the X-43, a NASA-sponsored unmanned hypersonic demonstrator ("Hyper-X" program) ). Although the X-43 was ultimately rejected, the research was later transferred to the Boeing X-51.

After steady ground testing that began in 2006, the X-51 prototype made its maiden flight on May 26, 2010, during which the test vehicle reached 4,000 miles per hour (Mach 6) when launched from a Boeing B-51. ) at the speed of the Stratofortress becomes the mothership. As of this writing (2013), the X-51 has been produced in four development examples.

A scramjet engine ("Supersonic Combustion RAMJET") - a concept originally developed during technological developments in the 1950s - utilizes incoming air (via an air intake) by flying extremely fast, slowing it down before combustion air speed. The intake gas controls the supersonic compression, then fuel is injected during the combustion process, and the nozzle controls the supersonic exhaust to generate the required thrust. Thus, scramjets are related to "ramjets" in their general approach, although in ramjets, combustion occurs in subsonic rather than supersonic airflow. Capable of delivering speeds specified in Mach values ??- even up to Mach 12 - scramjets are a futuristic alternative to the conventionally powered turbofans in widespread use today.

One of the main limitations of modern scramjet technology is the lack of low-altitude, low-power capabilities that require the use of a "host"/"mother" ship to fly the airframe for launch. From there, the scramjet must also be accelerated with a rocket engine.

The X-51's scramjet uses the same fuel as the Lockheed SR-71 Blackbird, known in the US Air Force inventory as "JP-7". The X-51 was towed into the air by a carrier (B-52) and launched in the air.

The X-51 initially used a modified Lockheed Martin MGM-140 ATacMS (Army Tactical Missile System) solid rocket booster to help clear the main ship and reach initial speed (about Mach 4.5). Once the booster system was exhausted, the components were jettisoned, allowing the Pratt & Whitney Rocketdyne SJY61 scramjet to take over to help the airframe reach speeds approaching Mach 6. The aerodynamic principles of the X-51's fuselage design then react to naturally occurring shock waves to increase the necessary lift (hence the name "Waverider"). The fuselage consists of a well-sloped nose cone assembly, a streamlined, almost rectangular fuselage and a short tail fin of a through design. There is an air intake under the fuselage, and the scramjet is expelled in a conventional manner through the tail of the design.

Essentially, the X-51's configuration resembles a streamlined cruise missile ala "Tomahawk." Despite the unmanned design, the X-51's program data could well be applied to any possible future aircraftsuch as a scramjet-powered civilian aircraft.

The X-51 has a barrel length of 25 feet and a curb weight of 4,000 lbs. Featured range is 460 miles with service capped at 70,000 feet.

As of 2013, the X-51 is still in active testing.

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