Stealth Technologies

Techniques, designs, and materials employing scientific advances for deceiving radar or other means of detection. Some techniques used in stealth technology can be as simple as pigments that make it hard to see objects against their background or applying materials that absorb radio waves. Others may involve complicated [Page 678]designs to scatter enemy radar signals, confuse infrared detectors, or cloak electromagnetic energy.

While radar-absorbing coatings had been in use since World War II, better stealth designs were made possible by computers. In the early 1970s, the Defense Advanced Research Projects Agency (DARPA) began work on stealth technologies aimed at reducing an object's radar cross section (RCS), or the measure of radio waves reflected back to their point of origin. Diamond-shaped objects proved most able to reduce the RCS, so much so that some planes appeared invisible to conventional radar. Just as looking in a mirror reflects your image, flat perpendicular surfaces returned radio waves directly to the radar antennas.

Stealth technologies are used primarily in aircraft and ships and have proven successful in warfare. During the 1991 Gulf War, the F-117A Nighthawk was heavily used and suffered no losses. Since its debut in 1982, only one Nighthawk aircraft has been lost in combat, and the U.S. Air Force intends to continue flying the planes well into the next decade. However, critics maintain that stealth aircraft are susceptible to low-cost defensive measures, such as the 1960s era missile launcher that brought down a Nighthawk over Yugoslavia in 1999.

Most stealth aircraft fly at subsonic speed to avoid the attention generated by a sonic boom, making the aircraft vulnerable to attack by faster flying jets as well. The high price of development and maintenance of stealth aircraft is also a concern. The B-2 bomber, which reportedly has the RCS of an aluminum marble, became a byword for cost overruns, and the high-tech Joint Strike Fighter (JSF), whose RCS is near that of a golf ball, is currently $1 billion over cost due in large part to its stealth features. Costly radar-absorbing paints and tapes must be regularly reapplied and the planes themselves must be sheltered from the weather.

Stealth aircraft are often painted in dark colors to blend with the night sky, although advances in materials science may make it possible for planes to change color on the fly. Electrochromic polymers are similar in principle to the technology found in some new car mirrors that sense bright lights and darken accordingly. Such technology may work its way onto stealth aircraft and ships of the future.