The hypersonic scramjets are designed to travel with speeds ranging from mach 5 to mach 10.At hypersonic speeds parts of the air vehicle reach very high temperatures at which metals can melt or vaporize. The X-43A is constructed with a tile-based thermal protection system developed by Boeing, carbon-carbon composites and high temperature resistant metals. The materials have been selected to withstand the exceptionally high temperatures and forces on the airframe resulting from the very strong shock waves that are generated in hypersonic flight.
hypersonic jets
The combustion that produces thrust in the ramjet occurs at a subsonic speed in the combustor. For a vehicle traveling supersonically, the air entering the engine must be slowed to subsonic speeds by the aircraft inlet. Shock waves present in the inlet cause performance losses for the propulsion system. Above Mach 5, ramjet propulsion becomes very inefficient. The new supersonic combustion ramjet, or scramjet, solves this problem by performing the combustion supersonically in the burner.
Hypersonic scramjet
As an aircraft moves through the air, the air molecules near the aircraft are disturbed and move around the aircraft. Exactly how the air re-acts to the aircraft depends upon the ratio of the speed of the aircraft to the speed of sound through the air. Because of the importance of this speed ratio, aerodynamicists have designated it with a special parameter called the Mach number in honor of Ernst Mach, a late 19th century physicist who studied gas dynamics.
