Discovery Science: Transport Technology – Airplanes: Speed

Transport Technology – Airplanes: Speed

Military aircraft are highly specialized, and often pioneer new technologies before these are used for civilian purposes. Of particular importance are the speed and stealth abilities of these vehicles.

Naval aircraft carriers bring military aircraft to all parts of the world. Military aircraft have many purposes, including transport, recon- naissance, air warfare, and interception. Modern fighter aircraft may travel at supersonic speed-faster than the speed of sound in air.

Supersonic speeds are measured in Mach numbers: the speed of the aircraft divided by the speed of sound in the air that the aircraft
is moving in. Mach 1 is the speed of sound—about 745 miles per hour (1,200 km/h). Using afterburners and special high-performance jet engines, military jets can achieve speeds of around Mach 2; some reach Mach 3

As a plane moves through the air, it “pushes” the air in front of it, producing a front of compressed air. At speeds faster than the speed of sound in air, the sound waves cannot move past the front of com- pressed air created by the plane, and thus pressure builds. This pressure creates spherical shock waves at the tip and rear of the plane that spiral outward along the flight path.

Although these waves are not themselves sound waves, when they reach the human ear, they are perceived as a single or double bang. Temperature variations, humidity, pollution, and winds can all have an effect on how a sonic boom is perceived on the ground.


Military flights currently use acoustic and radar camouflage techniques. Stealth technology includes surfaces that deflect rather than reflect radar signals and the use of radar-absorbent materials, such as iron ball paints, which convert electromagnetic energy into heat.

Active or optical camouflage is mostly still in the development stage. Active camouflage makes the camouflaged object appear not merely similar to its surroundings, but effectively invisible through the use of mimicry; secondly, active camouflage changes the appearance of the object as changes occur in the background.

Strategies could involve coatings or panels capable of changing color or luminosity, or the use of organic light emitting diodes to create “invisibility cloaks.”


The first privately funded manned spaceflight took place in the summer of 2004. Motivated by a $ 1 0-million incentive from the Ansari X Prize (but incurring development costs of approximately $25 million), Scaled Composites built a suborbital space plane with a hybrid rocket engine.

Boosted by a launch craft to a height of 50,000 feet (15 km)—it achieved an altitude of more than 328,000 feet (100 km) above the ground. The crew experienced some three-and-a-half minutes of weightlessness. SpaceShipOne is officially designated a glider, as most of its independent flight is actually unpowered.


Civilian aviation experienced a rapid expansion alter the Second World War, with larger and faster jets transporting ever more passengers With the advent of the Concorde, even the sound barrier was no longer a limit

However, after a disastrous crash on July 25, 2000. and further declines in demand tor the luxury service, operations of the Concorde ceased in 2003


BUSINESS FLIGHTS using supersonic vertical takeoff planes as air taxes are currently being developed.