Drag-reducing aerospike

A drag-reducing aerospike is a device (see nose cone design) used to reduce the forebody pressure aerodynamic drag of blunt bodies at supersonic speeds.

The Trident aerospike consists of a flat circular plate mounted on an extensible boom which is deployed shortly after the missile breaks through the surface of the water after launch from the submarine.

This was required because the Trident I C-4 was fitted with a third propulsion stage to achieve the desired increase in range over the Poseidon C-3 missile it replaced.

At the same time (middle 1970s) an aerospike was developed in KB Mashinostroyeniya (KBM) for the 9M39 surface-to-air missile of 9K38 Igla MANPADS (in order to diminish heating of infrared homing seeker fairing and reduce wave drag), giving the name to the whole system (Russian: игла means 'needle').

[citation needed] In 1995 at the 33rd Aerospace Sciences Meeting, it was reported that tests were performed with an aerospike-protected missile dome to Mach 6, obtaining quantitative surface pressure and temperature-rise data on the feasibility of using aerospikes on hypersonic missiles.

Detail crop of nose and aerospike of http://commons.wikimedia.org/wiki/File:Trident_C4_first_launch.jpg
UGM-96 Trident I first launch on 18 January 1977 at Cape Canaveral . The thin antenna-like structure mounted on the nose cone is the aerospike, which is composed of two parts. 1) The Extensible Boom is the long, slender, slightly tapered cylindrical structure; the wider "underside" is mounted to the nose cone. The narrow, top end of the Boom is for mounting: 2) "flat, circular, metallic" plates (brownish/yellow color, above). The plates are mounted perpendicular to the Vertical Axis--much like an upturned Martini glass , the container representing the nosecone , with the stem and base representing the Boom and plate, respectively.