Definition
A cone-shaped, movable center body mounted in the air inlet of a supersonic turbine engine. The spike slides forward or aft to position a series of shock waves at the inlet, slowing incoming air to subsonic speed before it reaches the engine compressor and maintaining efficient airflow across a range of supersonic speeds.
Plain English
A pointed cone sticking out the front of a supersonic jet engine intake. It moves in and out to slow the fast-moving air down before it enters the engine, because the engine itself can only handle slower air.
Context Anchor
Seen in discussions of supersonic jet engine inlets and high-speed aircraft engine operation.
Derivation
‘Spike’ comes from the Old Norse ‘spik,’ meaning a sharp pointed object. The name fits the part’s shape — a sharp cone protruding from the inlet. Once you picture a literal spike sticking out of the engine intake, the term explains itself.
Why Pilots Care
Proper operation prevents engine disruptions and ensures efficient thrust at supersonic speeds, which is critical for performance and safety in high-speed aircraft.
Grounding Statement
At supersonic speed, the inlet spike helps slow the air in controlled steps before it reaches the engine’s rotating parts.
Intuition Check
An inlet spike is not a sudden rise in pressure, temperature, or speed. Here, “spike” means a physical pointed cone inside the engine inlet.
Example Sentence 1
At cruise Mach, the inlet spike was fully retracted to position the shock waves correctly at the engine inlet.
Example Sentence 2
During cruise the inlet spike automatically adjusted its position for best engine performance.