India to test ramjet engine

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The competition heats up: India plans to test an experimental air-breaking scramjet rocket engine sometime next week.

The article provides almost no details about the August 28 test, including whether it is a static fire test on the ground or will be flown.


One comment

  • Dick Eagleson

    The first sentence of the article contains the answer:

    “The Indian Space Research Organisation (ISRO) is readying to conduct air-breathing propulsion experiment next week using its RH-560 rocket fitted with a supersonic combustion ramjet (Scramjet) engine.”

    Scramjets have to be moving at Mach 4 – 5 before they start working. American scramjet tests have achieved speeds of up to Mach 10. India is doing what we have always done when testing scramjets; using a rocket to boost the test article up to operating speed.

    There really isn’t any alternative. There are very few wind tunnels anywhere that can generate flows in the Mach 4 – 10 range. None of them can do so for more than a second. That’s a useful duration for testing shapes and structures, but one needs sustained airflow to test engines.

    One also needs the flow to be actual air. The best hypersonic wind tunnel in the U.S. is Hypervelocity Wind Tunnel 9 in Silver Spring, MD. It can generate flow speeds up to Mach 16, but the flows are pure nitrogen.

    Hypersonic wind tunnel flows are hot as well as fast. One supposes that using actual air would likely result in the oxygen and nitrogen combusting into various oxides of nitrogen. Not a good environment in which to test anything dependent on any other form of combustion.

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