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Scramjet Test Successful

Posted by michael on from the zero-to-six-thousand-in-one-second dept.

An Anonymous Coward writes: "The Sacramento Bee is running this story about the first powered device to achieve "hypersonic" speeds in the Earth's atmosphere. In a series of DARPA-sponsored tests, at Arnold Air Force Base in Tennessee, a scramjet engine, encased in a titanium projectile, was fired from a 130-foot cannon, at an initial velocity of Mach 7.1. The scramjet's engines then ignited, and the object moved another 260 feet, in just 30 milliseconds, before it came to rest in a series of steel plates designed to halt the flight. Peak acceleration: about 10,000 G's. Elapsed time, including cigarettes & pillowtalk: less than a second. PS: According to this nifty page at NASA, Mach 7.1 is about 5406 MPH, whereas 260 ft, per 0.03 seconds, is about 5909 MPH."

3 of 300 comments (clear)

  1. The cannon is more interesting by redelm · · Score: 3, Insightful
    I can see how this short test worked, and how they can get some scramjet performace data in the 30 ms of free flight. Ain't microelectronics wonderful?

    But frankly, I'm more interested in that super cannon. Mach 7.1 is 7,500 ft/s (2,300 m/s) which is extremely high. It would have a max range (neglecting aerodrag) of 300 miles! Did they use a gas-gun?

    1. Re:The cannon is more interesting by KFury · · Score: 3, Insightful

      Sorry, there's a big difference between 'sending things into outer space' and 'achieving escape velocity.' The first simply means it could shoot something outside the atmosphere, or around 90 miles up. Having reached outer space, it can fall back down to Earth.

      Reaching escape veolcity means that, ignoring aerodynamic drag while departing the atmosphere, the object has enough velocity to fully escape Earth's gravity well, so that it'll never come back. This is a couple orders of magnitude faster.

      As for the replies to the post talking about sending things into orbit, that presents a different problem, because you couldn't stabilize an orbit without a burn at the apogee of the flight, to stabilize the flight path from a parabola, which would come back and slam into the earth, to a circular or elliptical orbit. So in addition to having to protect the electronics from the tremendous G-forces (or making it all out of a ferrous metal, so you can pile it through a railgun and not have to worry about it because every piece of the craft is being accellerated identically) you also have to put in enough fuel and an engine to make that stabilizing burn. Of course, ferrous fuel is hard to find...

      --

      Kevin Fox
  2. stupid question? by Marcus+Brody · · Score: 3, Insightful
    From the article:


    Scramjets, or supersonic combustion ramjets, burn hydrocarbon fuel but scoop oxygen out of the atmosphere to combust it....


    ...The Pentagon and National Aeronautics and Space Administration are both studying scramjet technology since it would allow missiles or spacecraft to travel longer distances and carry larger payloads than rockets.


    I'm sure i'm missing something fundamental here, but where the hell are spacecrafts supposed to get the oxygen from?
    I guess they must just mean using scramjet untill leaving the atmosphere, and then use onboard oxygen, but it is a little misleading