NASA ‘s X-43A is the fastest Unmanned Hypersonic aircraft which is a part of the NASA’s Hyper-X program that is specially made to test various aspects of hypersonic Flights.X-43A Scramjet is one of the jet-powered aircraft that can achieved speed up to 9.6 Mach nearly 7,000 mph which is equal to the 10 times of speed of sound. And this made it fastest hypersonic aircraft in the world.
X-43A NASA’s Hypersonic Aircraft that can hit the speed of 10 Mach.
X-43A breaks the record of fastest air-breathing manned vehicle, the U.S. Air Force SR-71 which is 3.2 Mach. Later on X-43A moves continuously on its way and make many records. Later on it can achieved speed more then double, triple of SR-71 and made a new world record of Mach 9.6. which is the huge success in the field of hypersonic flights.
You can also check QUADCOPTER-The Unmanned Aerial Vehicle
NASA used this aircraft to test the scramjet engine type and it was propelled with the Pegasus rocket. Basically they were made to test with scramjet design as they offer an escape from the rocket paradigm and with this you can attain speed of rocket as faster you want to go.
It was specially designed as it has to fly at a very high speed. It was designed to be fully controllable in hypersonic speed. It is based on lifting body design in which body of aircraft provides a significant amount of lift for flight rather than only relying upon wings.
X-43A looks like a tip of giant arrow weighing 3000 pounds (approximately 1300 kg) and has a length of 3.7 metres (12ft 2in) and wing span of 1.52 metres(5 ft).It used dual mode ramjet propulsion system. As it flies at high Mach speeds, it produces lot of heat due to compression shock waves. The heat becomes so intense that some metal portion of the aircraft even melts and for compensating it water cycled around the engine cowl and sidewall leading edges just to cool the surfaces. Water circulation is done nearly at Mach 3.
X-43A is made to develop and test a supersonic-combustion ramjet engine variation where external combustion takes place within air at supersonic or hypersonic speeds. Its airframe is the part of the propulsion system as the fore body is the part of the intake airflow while the functioning of aft section is as exhaust nozzle. The fuel used is Hydrogen and at one time test roughly two pounds of fuel is used. It do not carry oxygen along with it.
The engines were specially designed for specific speed range and they work or compress or ignite the air-fuel mixture when there is required speed of airflow.
Other X-43 Vehicles
Some Other X-43 vehicles were planned, but as on June 2013 have been cancelled due to some technical reasons.
It was expected to be made as a full sized vehicle with a turbine based combined cycle(TBCC) engine or also rocket based combined cycle (RBCC) engine. The speed of the X-43B scramjet can be determined by the fact that it can attained the speed of 5 Mach when its engine converted from ram jet to scramjet. This is its jet turbines or Rockets that make it possible by propelling the vehicle to supersonic speed.
X-43C was indefinitely suspended in March 2004 .It was made with the expectation that it will test the viability of hydrocarbon fuel along with the HyTech engine-which was already runs with conventional kerosene-type hydrocarbon fuel. It was planned to made in such a way that it can use its own fuel for cooling-as cooling is necessary because breaking of long-chain hydrocarbons into short chain hydrocarbons produces lot of heat which is dangerous for vehicle.
It was made with the expectations that it can hit the speed of 15 Mach in the future with the same size of X-43A but this concepts fail because it is very difficult or impossible to made such kind of vehicle.
http://www.nasa.gov/audience/forstudents/9-12/features/F_HyperX_Greased_Lightning9-12.html http://www.nasa.gov/missions/research/f_scramjets.html http://en.wikipedia.org/wiki/NASA_X-43