SESKStuff Everyone Should Know
SESK: Stuff Everyone Should Know · sesk.info/aero-ramjet-static

Why can't a ramjet engine start an airplane moving from a standstill?

It needs forward speed to ram air into it.

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  1. It has no fuel tank
  2. It needs forward speed to ram air in ✔
  3. It only works underwater

Why: A ramjet has no compressor. Its forward speed rams air into the engine. Standing still, it makes no thrust, so another engine or rocket must get it moving first.

Huh, didn't know that: Without a compressor, ramjets are lighter and simpler than turbojets.

The dad joke
Why is a ramjet bad at races? It can't get off the starting line.
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References

Answer: It needs forward speed to ram air in. A ramjet has no compressor. Its forward speed rams air into the engine. Standing still, it makes no thrust, so another engine or rocket must get it moving first.

  1. Ramjet Propulsion, NASA Glenn Beginner's Guide to Aeronautics www.grc.nasa.gov/www/k-12/airplane/ramjet.html
    ramjets cannot produce thrust when the engine is stationary or static .
    Checked 2026-10-10.

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