Definition
A jet engine that has no moving compressor or turbine. It compresses incoming air solely by the forward speed of the aircraft, mixes that compressed air with fuel, burns the mixture in a combustion chamber, and expels the hot exhaust through a nozzle to produce thrust. Because it depends entirely on ram compression, a ramjet cannot produce thrust from a standstill and must be accelerated to high speed by another means before it will operate.
Plain English
A very simple jet engine with no spinning parts inside. It works by using the aircraft's own forward speed to shove air into the engine, where fuel is added and burned to push the aircraft forward. It will not work unless the aircraft is already moving fast.
Context Anchor
Seen in aircraft powerplant and high-speed propulsion discussions, especially when comparing different types of jet engines.
Derivation
Ram' comes from the idea of forcing or shoving something with force, like a battering ram. Air is 'rammed' into the engine inlet by the aircraft's own forward motion, which is what gives the engine its name and explains how it works without a mechanical compressor.
Why Pilots Care
Understanding the ramjet helps clarify why most aircraft engines need a compressor: at normal flight speeds, ram compression alone is not enough. Ramjets only become efficient at very high speeds (typically supersonic), which is why they are not used on conventional aircraft.
Analogy
A ramjet is a little like holding a scoop into a strong wind: the faster you move, the more air is forced into it. The engine is built to use that forced-in air for burning fuel and making thrust.
Grounding Statement
Picture an engine opening facing into very fast airflow; the speed of the aircraft itself is what packs air into the engine before fuel burns.
Intuition Check
Do not read “ram” as meaning the engine hits or pounds the air. Here it means forward motion forces air into the engine and raises its pressure.
Example Sentence 1
The instructor explained that a ramjet engine has no compressor or turbine, so it cannot start producing thrust until the aircraft is already traveling at high speed.
Example Sentence 2
Technicians inspected the ramjet engine inlet and combustor for thermal damage after the test flight.