Posted on by Nancy Atkinson

Successful Test of Air-Breathing Scramjet Engine

Boeing and the US Air Force tested a supersonic combustion ramjet engine on May 26 with the longest hypersonic flight in history. The X-51A WaveRider was dropped from a B-52 and flew for nearly three and a half minutes, flying at five times the speed of sound – Mach 5. The unmanned aerial vehicle was tested off the southern California coast around 10 a.m. on May 26, and it flew autonomously for more than 200 seconds, but then something then occurred that caused the vehicle to lose acceleration. But the teams who worked on the project are still calling the test a success.

“The technology proven today is something The Boeing Company has worked on for the past seven years,” said Alex Lopez, vice president of Advanced Network & Space Systems, a division of Boeing Phantom Works. “It is thrilling to be a part of history and advance hypersonic science to the next level. Boeing is looking forward to transitioning the technology to operation in the near term, but for now, we are exhilarated.”

Boeing and the Air Force Even will now begin analyzing the terabytes of telemetry data transmitted by the X-51A during flight.

“We are ecstatic to have accomplished many of the X-51A test points during its first hypersonic mission,” said Charlie Brink, X-51A program manager with the Air Force Research Laboratory. “This gives us huge confidence. We built four test vehicles to get a successful flight, and we hit many of our goals right out of the gate, the first time around.”

The B-52H Stratofortress took off from Edwards Air Force Base, and released the X-51A at approximately 50,000 feet over the Point Mugu Naval Air Warfare Center Sea Range. Four seconds later, a solid rocket booster from a U.S. Army tactical missile accelerated the X-51A to about Mach 4.5 before it and a connecting interstage were jettisoned. The X-51A’s engine ignited on a mix of ethylene and JP-7 jet fuel. After a short period, the X-51A ran exclusively on JP-7 jet fuel. The flight reached an altitude of about 70,000 feet and an approximate speed of Mach 5.

Onboard sensors transmitted data to both an airborne U.S. Navy P-3 Orion and to ground systems at Point Mugu, Edwards, and Vandenberg Air Force Base before the X-51A was terminated. The team will review the data from today’s test before scheduling additional flights with the three remaining test vehicles.
“This is a new world record and sets the foundation for several hypersonic applications, including access to space, reconnaissance, strike, global reach and commercial transportation,” said Joe Vogel, Boeing director of Hypersonics and X-51A program manager.

Source: Boeing
, Hobby Space

11 Replies to “Successful Test of Air-Breathing Scramjet Engine”

  1. Think White Knight III, air drop, booster (LOX Methane powered) to SCRAM jet speeds, accelerate to top of trajectory, upon reaching vacuum reconfigure engine and ignite plasma jet rocket engine, achieve orbital speed, vector to lunar orbit…

    This scenario is closer now than you might think!

  2. That was impressive, considering inherent difficulty but also earlier specific difficulties.

    I don’t think much of the possibilities for commercial transportation, as I understand nations, likely including US, prohibit supersonic fly through. But an application could be suborbital and possibly even orbital applications.

    Though I seem to remember that people claim that it costs more than it helps specifically for those applications, both in term of weight and vehicle cost. Oh well, there is always the military.

  3. The Wright Bros first flight didn’t even last this long, and 30 years later we began the jet age.
    Not only impressive they were able to get to M5 at such a low altitude, but if they can get it to run on JP7 from the start then there is no doubt commercial transporation can benefit. No more hazardous cryogenic fuel! Even better if they can get it to run on JP8/Jet A which is already the standard at commercial air ports.
    Although most nations don’t allow commercial super sonic flying, it sure would be nice to get accross the Pacific in half the time!
    Although I do see it in the military’s hand long before it does get into civilian markets.

  4. Though I seem to remember that people claim that it costs more than it helps specifically for those applications, both in term of weight and vehicle cost. Oh well, there is always the military.

    Same day delivery. People are nuts enough to use it, I’m sure.

  5. Ermmm…….in what sense does Joe Vogel mean “This is a new world record”? He can’t be talking about reaching Mach 5.

    The X-15A-2 reached a faster speed of 4,520 mph (7,274 km/h) or Mach 6.72, forty years back on 3rd October 1967, a record that still stands today and may possibly have been dropped from the same B-52.

    It’s a great achievement, just not clear about the claim.

  6. @ TerryG,

    I think that Jon Vogel, when he said, “This is a new world record and sets the foundation for several hypersonic applications”, he was referring to an air-breathing scramjet aircraft, whereas the North American X-15 was a rocket-powered aircraft/spaceplane.

  7. Opps! Thank you Ivan3man_at_large.

    The new record must be the 200 second burn duration of a scramjet engine, beating the previous best of 12 seconds set by the X-43 and not related to speed records of which there are so many.

    Fastest unmanned: X-43 12,144 km/h (7,546 mph), or Mach 9.8 set on November 16, 2004
    Fastest rocket plane: X-15A-2 4,520 mph (7,274 km/h) or Mach 6.72
    Fastest take-your-pick: Space Shuttle 17,500 mph (28,000 km/h) during reenty

    Thanks for setting me straight.

  8. impressive it is, that’s for sure.

    A point I read a while back though is that while you’re not starting out with tanks full of Oxygen, you still have to accelerate every bit of air you use for burning to the vehicle’s speed before you can burn it and spew it out the back even faster – in other words the ram drag represents bringing all of the burned Oxygen to the vehicle’s velocity – except that now you’re also accelerating a bunch of Nitrogen which might act as a propellant (from a reaction momentum point of view) but not as fuel (from an energy point of view)

    The big plus comes from the fact that you don’t accelerate all of it _at once_, which means that you don’t need the large tanks, and associated weight and drag.

    And some of the drag would have been there anyway, except that with a SCRAM you need to fly a shallower profile and so spend more time in the high-drag region.

    So it’s a mixed blessing, not a magic stick.

    But still – damn impressive.

  9. I think the holy grail they are looking for is a combination engine, like that in the SR-71.
    Those have a ramjet inlet with a more traditional turbine in the back, so they can go from runway to mach 3.
    Figuring out how to do this with a scramjet could mean the world to carrier aircraft or first stage engines on larger rockets.

  10. FWIW, here is an article by an aerospace engineer detailing some of the problems surrounding scramjet lifter systems. (Except the point that rocket fuel is cheap, as Wikipedia notes.)

    It is critical and focusing on one-stage closed lifters, but the problems would remain for more moderate uses. The starter and scramjet systems weight is claimed to eat up half of the weight gain from the external oxidizer. Much or all of the rest would be eaten up by heat protection, especially since the thermal load when ascending could exceed the descending reentry thermal load?! [Um, wow.]

    ROI would attach to reusable vehicles, and that means the engine would have to be sturdy.

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