X-51A flight tests: Passenger passengers wait for sonic boom – CNN

Written by By Karissa Bell, CNN

NASA and the US Air Force conducted the first official flight tests of a hypersonic “Air Force One,” rocket that travels at up to three times the speed of sound.

No regular passenger was aboard the X-51A WaveRider, but they were eager to hear the loud explosion that accompanied each launch.

“We had nearly 1,500 people — family members and reporters — with us on the sidelines and we all heard the sonic boom in our living rooms as the rocket burned up,” said Air Force Major Lynzey Donahue.

The tests involved the WaveRider being launched into the upper atmosphere from NASA’s Wallops Flight Facility on Virginia’s Eastern Shore, to measure the pressures and temperatures — both inside and outside the craft — as it flew through the atmosphere.

The test was part of efforts to develop hypersonic missiles for the Defense Department, such as for use in reconnaissance, warfighting, or responding to disasters.

A manned testing flight for the vehicle is expected to take place in 2019, said the Air Force, with NASA.

The X-51 WaveRider’s first stage

The X-51A includes a scramjet engine, the same engine used on NASA’s past X-plane hypersonic vehicle programs, the Air Force said in a statement, which ignited from flight to initial stall speed in under four seconds.

Shuttles and rockets traditionally use rocket propulsion to reach hypersonic speeds; however, to achieve hypersonic flight the engineers had to overcome several challenges.

First, they had to discover the speed at which the scramjet engine could “unbundle” from the composite fuel module that was guiding the aircraft and point it toward the outer atmosphere — commonly referred to as the “drop zone” — at Mach 5.1 mph.

The second challenge was the high temperatures, which often occur in the test flight environment at the Wallops facility. The heat from the combustion of the solid rocket motor and high temperatures resulted in the explosion of a shield on the aircraft.

After reaching hypersonic speeds, the WaveRider is cleared for suborbital flight. Before the flight is detonated, the WaveRider’s scramjet motor ignites, but before the high temperatures are allowed to do further damage to the liquid oxygen, the military team stresses and removes the explosive fuse from the engine’s combustion chamber.

In flight, the WaveRider’s heat shield erupts as the vehicle accelerates.

There were no injuries during the flight tests and all safety requirements were met.

CNN spoke with Donahue, also known as “Wave Runner” on air.

What was the coolest part of the flight test?

The explosion is really exciting. The X-51A actually didn’t blow up — we just had a controlled flight test of a suborbital hypersonic vehicle.

This is a whole new ballgame, we’re doing full hypersonic flight and we’re all competing with commercial space as well. I guess what I’m finding is we’re all racing to try to compete with the Russians. They have this really amazing system for its launch and landing and we all want to do the same thing for the United States of America.

What did you do after the test was over?

I’m pretty sure everyone and everyone was happy and pumped to know that this technology is coming to its next stage.

Did it seem like your friends and family got a good show out of it?

I would say it was like getting a tour of the Pentagon in a rocket.

What’s it like being an astronaut? What makes being an X-51A astronaut so different?

I think the one thing that separates an X-51A astronaut from an astronaut is, because we’re not in space, we’re still extremely small and fragile. But we put the pilot at the forefront of the vehicle, and he has complete control of the flight. If he thinks the vehicle will make it to space, he’ll fly it to space.

Do you plan to fly another X-51A for a full flight test sometime in the future?

We’re working on additional data that we can bring back to the Pentagon and to our customers. We will probably fly a new X-51A in a full flight test in 2019.

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