Hypersonic Jet Screams Through the Stratosphere at Mach 5

By Joseph Calamia | May 27, 2010 10:41 am

Yesterday morning, about 70,000 feet over the Pacific Ocean, the Boeing-designed X-51A Waverider “scramjet” set a new record. Reaching Mach 5 (almost 4,000 miles per hour), it wasn’t the fastest jet flight, but by burning for over 200 seconds it became the longest flight of its kind. The previous scramjet record, held by the NASA X-43, was 12 seconds.

A scramjet is similar to a simpler engine called a ramjet, but faster. The engines on most commercial jets have turbines to push air inside, but a ramjet is basically a tapered tube. As air flows through it, the shape of the tube compresses the air and, once the engine mixes this air with fuel, it ignites.

Unlike well-understood ordinary ramjets, which slow the air passing through them to subsonic speeds, the X-51 is intended to maintain combustion in a supersonic internal airflow — hence the name scramjet, for supersonic combustion ramjet — a feat often likened to “striking a match in a hurricane”. [The Register]

Since it needs moving air to fire, a ramjet can’t start from a standstill. Yesterday, a NASA-operated B-52 Stratofortress took the unmanned jet under its wing and dropped it at about 50,000 feet. Then a solid rocket booster accelerated the X-51 to about Mach 4.5. Then, on its own power, the scramjet climbed 20,000 feet, accelerated to Mach 5, and burned it engine for a total flight time of about 200 seconds.

“We are ecstatic to have accomplished most of our test points on the X-51A’s very first hypersonic mission,” said Charlie Brink, a X-51A program manager with the Air Force Research Laboratory at Wright-Patterson Air Force Base, Ohio. “We equate this leap in engine technology as equivalent to the post-World War II jump from propeller-driven aircraft to jet engines.” [U.S. Air Force]

NASA’s X-43A scramjet still holds the record for fastest jet engine flight, achieving about a 12 second run at Mach 9.6 in 2004. But the X-43A used hydrogen, which would require huge tanks if the jet found commercial use. The X-51A does not have this liability; it uses an easier-to-carry hydrocarbon fuel.

Joe Vogel, Boeing’s director of hypersonics, said, “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.” [Washington Post]

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  • Steve

    What’s the speed of sound that high?

    Did this thing basically travel a roughly a mile per second for 3 and 1/3 minutes?

  • rabidmob

    Since there are 3600 seconds in a hour, it did just a little better than 1 mile/sec.

  • Bob

    Speed of sound is a bit slower at that altitude than at sea level. Speed of sound depends only on temperature, not pressure, and of course temperature is lower at high altitudes. According to a standard atmosphere calculator:


    the speed of sound is 971 feet per second at 70,000 feet vs. 1116 at sea level.

  • http://NadaNada.com Lee Johnson

    Did they recover the scram jet or is it in the ocean. That must be one expensive 3 and 1/2 minutes If it was ditched in the ocean-

  • http://shineinnovations.com Ron Bennett

    Great simulation, although this is several decades away from any commercial use as was the jet engine before its first commercial flight, it does show the hype of the scramjet over the last several decades is now starting to pay dividends.

    History of the jet engine:

    “Examples of this type of design were Henri Coandă’s Coandă-1910 aircraft (first jet-propelled aircraft ever built, with the first flight on 16 December 1910), and the much later Caproni Campini N.1, and the Japanese Tsu-11 engine intended to power Ohka kamikaze planes towards the end of World War II. None were entirely successful and the CC.2 ended up being slower than the same design with a traditional engine and propeller combination.”

    “In 1913 René Lorin came up with a form of jet engine, the subsonic pulsejet, which would have been somewhat more efficient, but he had no way to achieve high enough speeds for it to operate, and the concept remained theoretical for quite some time.”


    Imagine traveling mach 6 in a commercial airline 80,000 feet above the surface of the earth. In a three hour flight you can go anywhere in the world, depending on what direction you go and there’s no traffic up that high yet. With the speeds and the efficiency only getting better who knows theatrically scramjets can travel up to mach 15 which would mean a commercial flight anywhere in the world with an approximate one hour flight time.

  • Sum Gai

    Nice to see new technology in action! It was a flawless launch and a good flight.


    Did they have to have the winner of the “Darth Vader sound-a-like” contest as the narrator?!?!?

  • Craig porter

    Speed of sound,
    Metric – 1067km/h, 296.4m/s
    Empirical – 662mph, 970.9 ft/s

  • Craig porter

    At 70000 ft that is. (662mph)/60mins/60sec= 0.184 miles/second


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