There’s some pretty exciting stuff going on at Edwards Air Force Base as the flight test center team gets ready to conduct an awe-inspiring X-51 first flight. The plan is to air launch the X-51A WaveRider using an expendable solid rocket booster from under the wing of a B-52, this spring.
Lt. Col. Todd Venema, director of the Hypersonic Combined Test Force explained just how the test team plans to do that. “We’re going to take the WaveRider and launch it from a B-52 at 50,000 feet over the Pacific Ocean and the vehicle is going to drop away.”
Colonel Venema further explained that if all goes as planned, the vehicle will be accelerated by a solid rocket booster up to about Mach 4.5. Once it reaches that speed the booster will drop away and the vehicle and the engine will ignite and accelerate the vehicle up to Mach 6, about six times the speed of sound.
Johnny Armstrong, chief engineer of the Hypersonic Combined Test Force explained what a scramjet is. “A scramjet is an engine that has no internal moving parts. It takes in air, you mix fuel in it and it automatically burns and because of the high speed and high temperature that you get in flight, it’s able to produce a thrust.”
Developed by Boeing, the jet-fueled, air breathing hypersonic vehicle is expected to demonstrate a reliable system capable of operating continuously on jet fuel and accelerating through multiple Mach speeds.
Testing hypersonic technology at Edwards is not new. The concept began in 1959 with the X-15 program, which Mr. Armstrong was also involved in. Work on the program pretty much stopped until recently, but as a result of advancements in technology, interest in the program has rekindled and has allowed testers to go forward.
Colonel Venema said the upcoming first flight is a fairly complicated test. He said the altitude is at the top of the B-52 capability and said testing will call for flight test chase planes. “Telemetry has to be relayed to the Naval Air Station at Pt. Magu to a control room with about 35 people, all watching the various telemetry. So there will be a lot of team work aspects to the whole project,” he said.
Dawn Waldman, chief of broadcast for the 95th Air Base Wing Public Affairs, explained in a recent newscast that testers say the purpose behind the X-51A program is to demonstrate the ability to use air-breathing, hydro-carbon propulsion in the hypersonic flight regime, which is flight more than five times the speed off sound. Charlie Brink, X-51 program manager at the Air Force Research Laboratory says what makes that a challenge for the test team is that conventional turbine engines are physically limited to about 2.5 Mach or 2 .5 times the speed of sound.
“The scramjet in the X-51 will be able to take in the air flight speeds over Mach 4 and up to Mach 6,” Brink said, explaining, as Armstrong did, that the engine achieves its speed by taking in air from the atmosphere, burns it and uses it for thrust, a capability, he said, that will be able to be applied to many other flight applications that the Air Force might use.
Ms. Waldman said in her report that as scramjet technology is developed testers believe that in the near future it could be used to aid warfighters as a weapons delivery system. She said officials believe that in the future the scramjet technology will make space access easier.
“The application really is all about space lift,” Mr. Brink agreed, and said, “This is the one, I think, in the Air Force Research Lab we’re most excited about.”
Mr. Brink pointed out that they currently transport payload into space with the shuttle, which has to carry all of its oxidizers for the propulsion concept. He said the shuttle is a pure rocket system and said if they can incorporate scramjet engine technology into the space lift systems, they wouldn’t have to carry the oxidizers and could carry more payload instead.
Calling the X-51 program the highlight of his career, Mr. Armstrong said, “For me personally, this is a real reward toward the end of a career where I’ve worked hypersonics and now all of a sudden this program is here and after 32 years since the X-15 last flew, I’m able to go back into a control room and experience a hypersonic flight test program.”
The X-51 program is a consortium between Boeing and Pratt and Whitney Rocketdyne. The customers are the U.S. Air Force Research Laboratory and the Defense Advanced Research Projects Agency, with support from NASA.