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Pure gasoline is not that great of a motor fuel because it knocks (explodes when it's not supposed to during the internal combustion engine cycle). This is a m
by photochemsyn 5y ago
Pure gasoline is not that great of a motor fuel because it knocks (explodes when it's not supposed to during the internal combustion engine cycle). This is a major problem with high-compression airplane engines.
However, tetra-ethyl-lead (think one lead atom bonded to four ethanols minus the oxygen atoms) was never necessary to combat the problem. Ethanol's anti-knock properties at a blend of 85% gasoline 15% ethanol were well known, and issues with corrosion in fuel lines had been dealt with. However, that meant giving farmers (the only ethanol producers) 15% of the profits, and the famously monopolistic Rockefeller didn't like that. Indeed, about that whole Rockefeller-financed ethanol temperance movement, and Prohibition in general...
In addition, alkylation strategies in World War II by Shell produced 100-octane aviation gas for prop engines, with no lead. It's been reintroduced it seems (wiki):
Shell Unleaded 100-Octane Fuel
"In December 2013 Shell Oil announced that they had developed an unleaded 100 octane fuel and will submit it for FAA testing with certification expected within two to three years. The fuel is alkylate-based with an additive package of aromatics. No information has yet been published in its performance, producibility or price. Industry analysts have indicated that it will likely cost as much as or more than existing 100LL."
In the long run though, electric airplanes look far more attractive for the short-haul prop-driven world.
- ohazi 5y ago> In the long run though, electric airplanes look far more attractive for the short-haul prop-driven world. In the interim, the Rotax 912/914 series is a nice, modern, reliable powerplant for smaller/lighter airplanes that will happily burn autogas.
- missedthecue 5y agoA Tesla battery weighs as much as a Cessna 172. I don't know how practical a battery powered GA aircraft with competitive range would be.
- stephen_g 5y agoApparently there are diesel prop engines that can run with Jet A1 (see [1]). This is apparently especially convenient given that at some airports Avgas isn't easily available compared to jet fuel (at least here in Australia, according to a pilot/aviation YouTuber that I was watching about this just yesterday). 1. https://newatlas.com/cessna-turbo-182-nxt/23465/ https://newatlas.com/cessna-turbo-182-nxt/23465/
- iamtheworstdev 5y agokerosene, diesel, and jet fuel are basically interchangeable in any motor supporting one of them. the liability becomes lubrications in the fuel. avgas is only popular in the US and Canada. jet a is universally cheaper avgas engines can be overhauled at the end of their life, which saves money. diesel engines are basically thrown away and you buy a new one, which negates the cost savings of jet fuel over avgas
- CRConrad 5y ago> diesel engines are basically thrown away Because they're "genuinely" absolutely broken, or "just" because of high aviation safety standards? That is, do they really have to be "thrown away" -- or could you buy one, refurbish it, and run it in your light truck, accepting a slight risk of breaking down on the highway in exchange for getting the engine really cheap?
- twistedpair 5y agoDon't forget UL94 as well. You can already buy it at select airfields.
- jedi3335 5y agoThis summer a company well known for GA engine mods actually completed FAA approval for a 'drop in' unleaded avgas replacement: https://www.aopa.org/news-and-media/all-news/2021/july/27/gami-receives-unleaded-avgas-stc https://www.aopa.org/news-and-media/all-news/2021/july/27/ga... It's limited to a subset of the GA engine fleet initially, but the plan is to broaden over the next year or so.