3 ms·
Jet engines achieve higher speeds and efficiencies.
by eloff 5y ago
Jet engines achieve higher speeds and efficiencies.
- baybal2 5y agoNo, not efficiencies. Jet engines have lower efficiencies than propellers up to near 0.8 speeds of sound, and terrible ones at low speeds, and low altitudes. Last generation airliners have designed cruise speeds below 0.8 speeds of sound. So, a propeller can still be a viable option at that speed, it will just have to be enormous.
- eloff 5y agoIf propellers are more efficient, then why do airlines use jet engines? Noise? Reliability? There's a reason jet engines completely dominate the market for commercial airliners. Would making the propellers electric change that?
- yetihehe 5y agoBecause jet engines have better power to weight ratio than cylinder engines.
- xyzzyz 5y agoThe comparison talked about here is not between jet and piston engines, it’s about turbofans and turboprops.
- baybal2 5y ago> then why do airlines use jet engines? Noise? Reliability? - Noise, yes. EU effectively bans turboprops by noise limits - Reliability, yes. Gearboxes needs frequent, and expensive overhauls. That's acceptable on smaller regional planes, but not airliners costing tens of megabucks. - Size. There is an upper limit on propeller blade size after which aeroelastic effects cannot be overcome by any known material.
- eloff 5y agoI would argue then if you can't practically build a propeller to replace a jet engine on an airliner, that being more efficient in theory is meaningless. I'll refine my initial claim to say jet engines are more efficient in many practical uses and configurations. Would you agree with that?
- baybal2 5y agoWould agree partially. 5-6 seat abreast planes can be switched to powerful turboprops for practical use. Widebody airliners, not at the current level of technology.