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> a turboprop has a propeller attached to the jet engine. Since this is the pedant thread I feel obliged to point out that turboprops are propellers attached t
by MichaelCollins 4y ago
> a turboprop has a propeller attached to the jet engine.
Since this is the pedant thread I feel obliged to point out that turboprops are propellers attached to gas turbine engines, not jet engines. Jet engines are gas turbine engines that produce thrust using a jet of hot exhaust gas out the back. Gas turbine engines that don't produce thrust using a jet of exhaust gas aren't jet engines; examples are turboprop engines and turboshaft engines (popular in helicopters, some tanks, etc.) Turbofan engines produce at least some of their thrust with an exhaust jet, so it's fair enough to call those jet engines. Probably the truest sort of jet engines are turbojet engines, which are no longer used for commercial aviation and only have some niche applications remaining (for instance cruise missiles.)
Then there are the "jet engines" which aren't gas turbines at all; jetskis use gasoline powered piston engines to produce thrust using a jet of water. And rockets, which don't breath air, could be called jet engines in a sense because they produce thrust using a jet of exhaust gas. But if you go around calling rocket engines "jet engines" you're going to get a lot of people correcting you by pointing out that rocket engines don't breath air. Many rocket engines do contain gas turbines though, using gas turbines to power propellant pumps, e.g. turbopumps...
And if we really want to get into the weeds, some piston powered aircraft get a small amount of thrust from their exhaust too. And some exploit the "Meredith effect", wherein air over the radiators gets heated and produces a small amount of thrust. These effects may contribute a few percentage points of the total thrust of the plane, and in truth, some turboprop configurations do this too. But >90% of the thrust is coming from the propeller, not the exhaust.
- cjbgkagh 4y agoThat is true, I was restricting my vocabulary to avoid adding additional concepts.