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For US gasoline it ranged from a low of 38? to high of about 70. The oil in the US varies considerably as it was spread out from Pennsylvania to California. And oddly enough, the general progression of "gasoline" from those oil fields follows from the low 38-40 fuel of Pennsylvania to higher in Texas and ending up with the around 70 fuel California.I don't know what kind of octane rating can we 'attach' to the gasoline used in that time.
This reminded me of this...It was well known that Tetraethyl Lead was toxic by the time that it became an additive to fuel for knock resistance.
Benzene is absolutely lethal stuff. Barely better than TEL for health reasons. There was quite a bit of research going on in early WW2 period in the USA on getting the "unleaded" knock value of fuels up, as it was recodnised that TEL was really damaging engines above certain concentrations and could not be just increased and increased to get higher boost limits.People were also adding benzene to the gasoline in late 1920s/early 1930s (at least?). The mixure of benzene/gasoline 80/20 was used on the BMW VI 7,3 (denotes 7.3:1 compression ratio), for 750 HP. The VI 6,0 was using the benzene/gasoline 40/60 mix, for up to 660 HP. The BMW VI 5,5 that used only the gasoline of the day was good for 650 HP.
All per data from January 1929. I don't know what kind of octane rating can we 'attach' to the gasoline used in that time.
The higher the anti-knock rating the higher compression ratio you can run, which dramatically impacts fuel economy. So I`d have a careful think about your first statement.I doubt that removing TEL or replacing it with something else would have had that much of an effect on range or reliability.
Most sorties didn't use an aircraft's full load of fuel. Most engine reliability issues were due to factors other than exact fuel composition (e.g., oil/coolant systems).
Extreme long range ferry operations and bombing raids (e.g., Doolittle Raid) might have been negatively affected, as well as CAP operations where every bit of fuel counted.
Operationally, perhaps a tiny fractional increase in non-operational aircraft and/or reduced range might have had an impact for extremely long-range bomber operations like the RAF and USAAF offensives of 1943-45. Unfortunately, it's almost impossible to get the sort of boring operational readiness figures needed to make intelligence comparisons, even for well-organized and victorious air forces like the USAAF.
OTOH, widespread use of TEL might have had bad effects on childrens' IQ scores even a few years after its introduction (although things like lead paint, lead solder for food cans, and lead in the soil would have been much more serious problems at the time). By 1940, that means that your average 18 year-old recruit might have lost a point or two of IQ or otherwise suffered slight mental impairment, at least if they came from heavily urbanized areas. That means a slightly smaller pool of suitable Air Force recruits or recruits with subtle mental problems. So, maybe TEL in fuel was a wash overall - slightly reduced engine problems, but slightly less effective mechanics and aircrew to operate and maintain the aircraft.
Here is a Bureau of mines study of the various base stocks used to produce av gas in WWII. It also shows the effects of adding various amounts of TEL to base stocks as well as the effect of adding aromatics such as Cumene and CS (Cumene substitute).For US gasoline it ranged from a low of 38? to high of about 70. The oil in the US varies considerably as it was spread out from Pennsylvania to California. And oddly enough, the general progression of "gasoline" from those oil fields follows from the low 38-40 fuel of Pennsylvania to higher in Texas and ending up with the around 70 fuel California.
During WW I and through parts of the 1920s the US military specified the fuel by area (east coast vs west coast or Penn vs Cal fuel) as they knew there was a difference, they just couldn't measure it.
Alcohol has several problems for aircraft fuel, only one of which is the reduction in heat energy per gallon.
While gasoline and water do not mix, alcohol mixes with both and can pull water into the "mix" rather than allow water to collect at the bottom of a tank.
Alcohol has a higher freezing temperature than gasoline and a higher auto ignite temperature which makes cold weather operation more difficult. Operation can be cruising at higher altitudes, not just staring up.
Benzene also has cold temperature problems
There are charts in old text books showing what 1cc to 6 ccs per US gallon would do to certain kinds of gasoline.
However I don't think that the Allies used more than 4.6 ccs per gallon in any fuel spec.
Post war (Korean war) fuel specs called for not more than 4.6ccs in in MILITARY 91/96, 100/130 and 115/145 fuels and commercial fuel was limited to 2.0ccs in 91/96, 3.0 ccs in 100/130 and 108/135 and 4.6 ccs in 115/145.
The higher limits for military fuel was to allow much increased production, should it be needed. Depending on fuel base stocks, available additives/blending agents and whatnot military fuel didn't always have the max limit of allowable lead.
It was well known that high amounts of lead, even with additives, could lead to exhaust valve and valve seat problems (durability ?) and spark plug fowling problems (reliability).
Commercial operators were willing to trade more expensive fuel for lower maintenance costs and/or less down time for maintenance. A plane that is sitting on the ground waiting for spark plug changes isn't making any money.
Edit, just saw the other thread which has veered off into fuel/s.
I don't know if 100/150 fuel was a "standard" fuel. It was certainly used in Britain and N W Europe but perhaps not in the quantity that some people think?
I am not sure it was used much of anywhere else. Like Italy of the Far East?
Calum,Benzene is absolutely lethal stuff. Barely better than TEL for health reasons. There was quite a bit of research going on in early WW2 period in the USA on getting the "unleaded" knock value of fuels up, as it was recodnised that TEL was really damaging engines above certain concentrations and could not be just increased and increased to get higher boost limits.
The British switched the majority of their prediction to 100/150 in 1944. of course their total production was dwafed by the US.