This video shows the audible difference between deflagration and detonation, the two main types of combustion. Here, a pulsed detonation engine is operated in deflagration mode (like a pulsejet) using a propane/air fuel mixture. Next, pure oxygen is used instead of air and detonation occurs. The detonation waves have a much more profound effect on the flag and metal plate. The resulting increase in thrust is approximately 200%. These PDE tests took place at the UT Arlington Aerodynamics Research Center in 2008.