FASTEST AIRCRAFT 2004

FASTEST AIRCRAFT 2004

NASA's X-43 (Article from http://www.universetoday.com/tag/hyper-sonic/)



Hyper sonic (or hypersonic) speeds are defined as those greater than or equal to Mach 5. Meaning, at least five times the speed of sound.

Among the supersonic (faster than sound) planes in the world, only two can be considered of the hyper sonic kind: the X-43A and X-15. Not even the SR-71, which already cruises at Mach 3 can make it to this extremely short list. Well, you may add the Space Shuttle, which is part aircraft part spacecraft, to this list if you want. The Space Shuttle can reach up to Mach 25.



The aircraft that holds the record as the fastest is NASA's X-43A. Having reached Mach 9.6, this unmanned aircraft can definitely be considered a hyper sonic. X-43s are powered by highly modified ramjets called scramjets or Supersonic Combustion Ramjets. When the designers of this record-breaking engine first started out, they claimed such jets could top at Mach 15.

It is too early to tell whether they overestimated the capabilities of this particular technology.

Regardless whether the Mach 15 barrier can be breached by a scramjet powered aircraft, it looks like NASA is hell-bent (as always) on making new hyper sonic records in the not-so-distant future. Already they have partnered with universities and industries in California, Texas and Virginia, designating them as national hyper sonic science centers.

The main objective of these centers is to design more powerful propulsion systems as well as other aircraft components that, when brought together, will usher in a new breed of hyper sonic planes. The University of Virginia in Charlottesville, Texas A&M University in College Station, and Teledyne Scientific & Imaging LLC of Thousand Oaks, California, have been tapped for this purpose.

There are certain things to consider when designing an aircraft that might reach hyper sonic speeds. Perhaps the most crucial is the temperature of flow around the aircraft. At such fast speeds, the temperature can rise very high. This can affect the chemical properties of the air around it. Even low hypersonic speeds (a little over Mach 5) can provide the conditions that will allow molecular bonds to vibrate vigorously.

This in turn can increase or decrease the forces exerted by the surrounding air on the aircraft. As the aircraft accelerates to high hypersonic levels the bonds can break and the surrounding air becomes ionized, i.e., they turn into plasma. To even complicate matters, accompanying shock waves can cause rapid increases to pressure, temperature and density. These and many other factors will have to be looked into by researchers in the hyper sonic science centers.