for the superheated air to act upon and a cycle of amplification rapidly occurs. This is the explosion, and it causes the meteoroid to disintegrate with hypersonic velocity, a speed comparable to that of explosive detonation. In spacecraft Harry Julian Allen and Alfred J. Eggers of NACA used an insight about ram pressure to propose the blunt-body concept: a large, blunt body entering the atmosphere creates a boundary layer of compressed air which serves as a buffer between the body surface and the compression-heated air. In other words, kinetic energy is converted into heated air via ram pressure, and that heated air is quickly moved away from object surface with minimal physical interaction, and hence minimal heating of the body. This was counter-intuitive at the time, when sharp, streamlined profiles were assumed to be better. This blunt-body concept was used in Apollo-era capsules. See also Ram-air intake – an air intake system that aids in engine performance and cooling, commonly used on aircraft and other high-performance vehicles Ram air turbine – a propeller used by aircraft to generate power Parafoil – a non-rigid parachute airfoil inflated by wind, also known as a ram-air parachute References Fluid dynamics Pressure