aerospike

noun

aero·spike ˈer-ō-ˌspīk

variants or aerospike engine

plural aerospikes or aerospike engines

: a type of rocket engine in which exhaust is vented along a curved surface on the outside of the engine instead of through an open nozzle

Note: In early versions of this technology, the exhaust was vented along a spike with curved sides emerging from the center of what would have otherwise been an open nozzle. As the technology developed, other curved surfaces and shapes besides those of spikes were found to have similarly useful properties, but by this point the name had become standard.

Essentially an inside-out rocket nozzle, an aerospike gets rid of the traditional bell-shaped nozzle, using atmospheric pressure instead to shape the exhaust plume.—

Jim Skeen, Daily News of Los Angeles, 26 Apr. 2004

The aerospike obviates the need for multiple stages to achieve orbit: Unlike traditional engines, it adjusts to changing air pressure as it ascends, so it never needs to be jettisoned.—

Erick Schonfeld, Fortune, 2 Feb. 1998