Enigmatics, Inc. is developing a new propulsion engine that could be more efficient and flexible than today's propulsion technologiesâand will be small enough for nano-sized satellites. Called a pulsed detonation engine (PDE), the new technology can allow engines to be built as small as ? inch in diameter.PDE works by detonating fuel in pulses, allowing it to run a more efficient thermodynamic cycle than a conventional rocket, one in which the chamber walls absorb less heat. Although this process, called constant-volume combustion, is inherently more efficient than the constant-pressure process used by conventional rocketry (gas turbine and jet propulsion engines used the constant-pressure process during the first half of the 20th century), it has traditionally had a very slow explosion cycle reaction rate, which limited these engines to very small output thrusts. With intermittent detonation, though, the reaction rate has improved, as a detonation wave travels about two orders of magnitude faster than a typical deflagration wave. As a result, Engimatics has been able to achieve pulse detonation rates of 250 detonations per second in recent tests, with a capability of reaching 500 per second
