[Agent_4573]

There is an engine called a RAM JET engine which actually uses speed and the "ram air" effect. At speeds over mach one, around 700 mph, planes create a shockwave, basically waves of super-compressed air. The engine is designed to direct these shockwaves into the engine to produce forward thrust. At speeds of over mach 3, the "engine" itselft just gets in the way of the compressed air effect. So there are instances in which the air is actually pushed into an engine faster than being sucked in, but it was only really used in the "Blackbird", an air force recon plane. The only problem is this kind of engine is only effective at speeds greater than mach one, so a standard jet-turbine engine must be incorporated in to get the plane going at least that fast before the ramjet can take over... GO here for a more detailed description of how this works: http://www.grc.nasa.gov/WWW/K-12/airplane/ramth.html