Once the use of radar had become widespread and was able to spot enemy aircraft (and friendly planes as well) aircraft engineers started trying to work out how they could avoid detection. Although we think that it was the Americans who first put a stealth bomber in the skies, there was a German plane built during World War II that had stealth characteristics. This was the Horten 229, designed and built by brothers of the same name and was little more than a flying wing – the American F 117 looks remarkably similar). Because of its shape and shallow head-on profile it reflected only about 40% of the radar "signature" of other planes. The 229 was a twin jet-powered plane capable of reaching close to the speed of sound, faster than any plane then in the skies (1943). Made of wood and metal the engineers mixed charcoal with sawdust to coat the plane, thus absorbing, rather than reflecting, radar rays.

The plane was tested under various conditions but its development came too late for it to be used in action during the war. One prototype was captured by advancing American forces and the plane shipped to the States where it was evaluated. Its basic technology was used by the Americans many years later when Lockheed built the F-117, which was basically a flying wing, as was the Horten.

Stealth technology includes not only the shape and materials used, but also the positioning of the fuselage panels which are designed to reflect radar beams away from the transmitter/receiver. There are also other defences including technology to deflect heat-seeking missiles. The F-117 first flew in 1981 though it was a top-secret programme and only came to public notice later. They were used during the 1989 US invasion of Panama, during the Gulf War (1991) and in the war over the former Yugoslavia (Kosovo) when one was shot down by Russian-built missiles.

The F-117s were retired in 2008 as the newer F-22 Raptor came into use. That plane began coming into service in 2005. though its first test flight had been in September 1990. It looks more like a conventional supersonic jet fighter, totally unlike the science-fiction looking F-117. There have been major problems funding the purchase of the originally planned 700 F-22s and the order has fallen back to 187, all for the USA as exports of stealth technology projects are banned under American law. Obviously the cost of developing this plane has been enormous and over $62 billion – about $361 million per plane (by comparison an Airbus A380 costs about $320 million).

At the same time as the F-117 was being developed as a stealth fighter, a bomber version, the B-2, was also under development. July 1989 was the first test flight, the planes coming into service in 1997. A total of 21 were built each costing (with the huge development costs amortised against each plane) a massive $929 million. The B-2 is also a flying-wing design, a crew of two and is powered by four GE engines producing 17,300 lbs of thrust each. It has been used in active service over Kosovo, Afghanistan and Iraq. The fleet of B-2s is still in service.

A new stealth fighter, the F-35 Joint Strike Fighter, is under development at present in the USA. The first test flight was made in December 2006 and a total of 2,443 aircraft has been pencilled in, at a cost per plane of $89 million each. Canada, the UK, Holland, Italy, Denmark, Norway, Australia and Turkey are involved and are understood to be ordering the plane though there have been concerns over the cost, the timetable and also the fact that the USA will not allow the export of vital technology to enable those countries to maintain the planes properly. Israel, Brazil and India are also interested in purchasing. Russia has a stealth flight programme but so far no plane has been launched with stealth capabilities.

The future development of stealth aircraft may, in fact, lie elsewhere with thoughts now progressing towards hypersonic aircraft that can outrun any missile or other weapon. NASA is testing such a plane capable of flying at 7,000 mph.