http://en.wikipedia.org/wiki/Delta-v
Wikipedia
Delta-v
In astrodynamics a v or delta-v (literally "change in velocity") is a scalar which takes units of speed. It is a measure of the amount of "effort" that is needed to change from one trajectory to another by making an orbital maneuver.
Delta-v is produced by the use of propellant by reaction engines to produce a thrust that accelerates the vehicle.
http://en.wikipedia.org/wiki/Chaff_(disambiguation)
Wikipedia
Chaff (disambiguation)
Chaff may refer to:
Chaff, dry, scaly, inedible plant material, especially that surrounding edible grain
Chaff (countermeasure), a radar countermeasure in which aircraft spread a cloud of small, thin pieces of aluminum foil, or sheets of metal-coated plastic.
http://en.wikipedia.org/wiki/Chaff_(countermeasure)
Wikipedia
Chaff (countermeasure)
Chaff, originally called Window by the British, and Düppel by the Second World War era German Luftwaffe (from the Berlin suburb where it was first developed), is a radar countermeasure in which aircraft or other targets spread a cloud of small, thin pieces of aluminium, metallized glass fibre or plastic, which either appears as a cluster of secondary targets on radar screens or swamps the screen with multiple returns.
Modern armed forces use chaff (in naval applications, for instance, using short-range SRBOC rockets) to distract radar-guided missiles from their targets. Most military aircraft and warships have chaff dispensing systems for self-defence. An intercontinental ballistic missile may release in its midcourse phase several independent warheads, a large number of decoys, and chaff.
The idea of using chaff developed independently in the UK and in Germany.
As far back as 1937, R. V. Jones had suggested that a piece of metal foil falling through the air might create radar echoes. In early 1942, a Telecommunications Research Establishment (TRE) researcher named Joan Curran investigated the idea and came up with a scheme for dumping packets of aluminium strips from aircraft to generate a cloud of false echoes. From a practical point of view it was found the most effective version were strips of black paper backed with aluminium foil cut to strips exactly 27 centimetres by 2 centimetres and packed into bundles each weighing one pound .
The Head of the TRE, A. P. Rowe, code-named the device as "Window".
Meanwhile in Germany, similar research had led to the development of Düppel. Once the idea had been passed to the US, Fred Whipple developed a system (according to Harvard Gazette Archives) for dispensing strips for the USAAF, but it is not known if this was ever used.
The systems were all essentially identical in concept: small aluminium strips (or wires) cut to one-half of the target radar's wavelength. When hit by the radar, such lengths of metal resonate and re-radiate the signal. Opposing defences would find it almost impossible to pick out the "real" aircraft from the echoes from the chaff.
