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Is there a reason why small aircraft don't just use a car engine (with some appropriate gearing I guess)? Those have had so much R&D in them and they're pretty
by geokon 6y ago
Is there a reason why small aircraft don't just use a car engine (with some appropriate gearing I guess)? Those have had so much R&D in them and they're pretty much as efficient as you can get - plus much easier to maintain and repair
- Skunkleton 6y agoReliability would be my first concern. Power to weight is likely an issue as well. Here is some more info I found: https://www.flyingmag.com/aircraft/do-car-engines-make-good-airplane-engines/ https://www.flyingmag.com/aircraft/do-car-engines-make-good-...
- Stevvo 6y agoEfficiency at sea level does not equal efficiency at altitude. That said, there are some very impressive experimentals that do use auto engines.
- Czarcasm 6y agoAutomotive engines are designed to produce power at a wide range of operating speeds, at the detriment of peak power output and peak efficiency. Aircraft engines can take advantage of the fact that they will be operating at a single RPM range for most of their life, which allows you to optimize every single aspect of the system for that speed. Aircraft engines also have much, much higher reliability, lifecycle, and quality control requirements than automotive engines. For these reasons and a few others, you would basically end up redoing most of the engineering work on an automotive engine to repurpose it for aerospace applications, thus negating the savings of reusing the existing design.
- m4rtink 6y agoBut you can do it the other way around, resulting in the M4 Sherman. :-)
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- baybal2 6y agoRead the many reasons below, but one big one not named is that auto engines are not designed to be operated at near peak power constantly. Auto engines are severely derated for use in airplanes, and then all of the advantage is gone.
- xkcd-sucks 6y agoSome do, but not many http://www.epi-eng.com/aircraft_engine_products/big-block_620_hp.htm http://www.epi-eng.com/aircraft_engine_products/big-block_62...
- jasonwatkinspdx 6y agoThey do, though it requires some conversion to meet reliability requirements and to optimize for cruise. Over the years the Subaru boxer engines have been a popular starting point.
- Shacklet0n 6y agoAlthough probably not the majority, many experimental aircraft do use car engines. I'm building a Zenith 750 kit aircraft and installing an engine from a company called Aeromomentum who convert Suzuki engines for use in light aircraft. The model I have installed is a 117HP engine originally designed for use as boat outboard motor. A sibling comment mentions that car engines aren't designed to operate continuously at high power. Outboards are. And there are benefits to using highly developed and tested engines vs traditional aircraft engines - efficiency being the most obvious.