Imagine flying from New York to London in less than an hour. The X-51A Waverider was created to accomplish such a feat, able to fly at Mach 6. That’s six times the speed of sound and nearly three times as fast as the now-retired Concorde. To those in the field of aviation management, particularly pilots and anyone with an aircraft engineering background, this type of evolving hypersonic flight technology is of prime interest. The latest test flight of the X-51A Waverider off the California Coast on August 15, 2012, ended in failure, emphasizing that there is still much to learn.
Purpose of the X-51A Waverider Project
The X-51A Waverider project is conducted as a joint venture between the U.S. Air Force, NASA and the Pentagon. The aircraft is of particular interest to the military because of its speed. A weapon using X-51A Waverider technology could evade current anti-missile systems, none of which fly as fast. There is also the commercial aspect, allowing cargo and people to be transported around the world in a fraction of the time taken by conventional aircraft. Four Waveriders were built, with one yet to fly.
Mechanics of the X-51A Waverider
The propulsion system, called a Scramjet, is built by Pratt & Whitney Rocketdyne. Oxygen from the atmosphere is pulled into the engine by a forward facing collector. The oxygen is mixed with hydrogen injected into the airstream when it reaches the engine. Ignition occurs when the two gases are compressed. The resulting hot gases are ejected out the back of the aircraft, providing thrust. The sleek aerodynamic design of the Waverider, along with its hypersonic speed also allows the craft to ride its own shockwave, created when it breaks the sound barrier.
The X-51A Waverider cruises at 70,000 feet. The atmosphere is thinner, causing less drag on the craft and contributing to its speed. Compare this to the Concorde that cruised at 58,000 feet or a modern day Boeing 747 designed to fly at 31,000 feet.
Testing the X-51A Waverider
The X-51A Waverider is 25 feet long with its solid rocket booster intact. The craft is attached under the wing of a B-52 bomber and dropped at an altitude of 50,000 feet. After a four-second freefall the rocket booster fires, increasing the Waverider’s speed to Mach 4.5 (3,425 mph). The spent rocket booster detaches and then the Scramjet ignites, taking the craft to Mach 6 (over 4,000 mph) and an altitude of 70,000 feet. A complete test has the Scramjet engines cutting out after five minutes, with the Waverider falling into the Pacific Ocean. The testers receive real-time data from the flight.
X-51A Waverider Test Flight Failure
The launch of the X-51A Waverider on August 14, 2012 went as planned until it separated from the B-52. After a 16-second flight a cruiser control fin failed. The test flight was terminated when the Air Force could no longer control the craft. The research team was unable to fire or test the Scramjet engine.
There was no problem with the control subsystem on the prior two test flights of the X-51A Waverider. The most successful of those flights was in May of 2010 where the aircraft reached Mach 4.88 and stayed at that speed for over three minutes. The second flight was in June of 2011. The Scramjet fired up but when the Waverider reached Mach 5 it stalled. Attempts to restart the craft failed. A considerable amount of data was received from the Waverider before it crashed into the ocean.
As of now there is no word on when or if the remaining X-51A Waverider will be tested.