150 Octane Avgas

[Trojan1981]

Someone asked me today what the colour of 150 Octane avgas is. I didn't know that 150 Octane avgas was even being produced, let alone the colour. I remember hearing about some purple or red fuel that used to power the 'Bou (I think that was 145 Octane?).
Anyway, I can't find it anywhere on the net or in my books, so does anybady know?

Cheers.

[Deaf]

115/145 was (is?) purple

[Dog One]

It has being years since 115/145 was available. And you are correct - purple was the colour

[Trojan1981]

Yeah, I anwered purple but that was wrong.
I was told it is widely available. I am only relitively new to piloting, but I have not heard of it before.

[Dog One]

Back in the days when round engines ruled the world it was as common as 100/130. But, I understand it is not available now, as HARS have to run their Connie on 100/115, and as a result cannot use full power for take off due to the risk of detonation. The fuel colours were 80/87 - red 100/115 - green and 115/145 - purple. In the dim dark recesses of my brain I think there was anotther rating between 80/87 and 100/115. I think it was 90/96 but never saw it in use even when I started flying 45 years ago. Every where you went, only 80 or 100 octane. Tankers at major airports had 145octane plus water methanol on tap.

[TBM-Legend]

Read this>

During World War II, Germany received much of its oil from Romania. From 2.8 million barrels (450,000 m3) in 1938, Romania’s exports to Germany increased to 13 million barrels (2,100,000 m3) by 1941, a level that was essentially maintained through 1942 and 1943, before dropping by half, due to Allied bombing and mining of the Danube. Although these exports were almost half of Romania’s total production, they were considerably less than what the Germans expected. Even with the addition of the Romanian deliveries, overland oil imports after 1939 could not make up for the loss of overseas shipments. In order to become less dependent on outside sources, the Germans undertook a sizable expansion program of their own meager domestic oil pumping. After 1938, the Austrian oil fields were made available, and the expansion of Nazi crude oil output was chiefly concentrated there. Primarily as a result of this expansion, the Reich's domestic output of crude oil increased from approximately 3.8 million barrels (600,000 m3) in 1938 to almost 12 million barrels (1,900,000 m3) in 1944. Even this was not enough.

Instead, Germany had developed a synthetic fuel capacity that was intended to replace imported or captured oil. Fuels were generated from coal, using either the Bergius process or the Fischer-Tropsch process. Between 1938 and 1943, synthetic fuel output underwent a respectable growth from 10 million barrels (1,600,000 m3) to 36 million. The percentage of synthetic fuels compared with the yield from all sources grew from 22% to more than 50% by 1943. The total oil supplies available from all sources for the same period rose from 45 million barrels (7,200,000 m3) in 1938 to 71 million barrels (1.13E+7 m3) in 1943.

By the early 1930s, automobile gasoline had an octane reading of 40 and aviation gasoline of 75-80. Aviation gasoline with such high octane numbers could only be refined through a process of distillation of high-grade petroleum. Germany’s domestic oil was not of this quality. Only the additive tetra-ethyl lead could raise the octane to a maximum of 87. The license for the production of this additive was acquired in 1935 from the American holder of the patents, but without high-grade Romanian oil even this additive was not very effective. 100 octane fuel, designated either 'C-2' (natural) or 'C-3' (synthethic) was introduced in late 1939 with the Daimler-Benz DB 601N engine, used in certain of the Luftwaffe`s Bf 109E and Bf 109F single-engined fighters, Bf 110C twin-engined fighters, and several bomber types. Some later combat types, most notably the BMW 801D-powered Fw 190A, F and G series, and later war Bf 109G and K models, used C-3 as well. The nominally 87 octane aviation fuel designated 'B-4' was produced in parallel during the war.

In the US the oil was not "as good," and the oil industry had to invest heavily in various expensive boosting systems. This turned out to have benefits: the US industry started delivering fuels of increasing octane ratings by adding more of the boosting agents, and the infrastructure was in place for a post-war octane-agents additive industry. Good crude oil was no longer a factor during wartime, and by war's end American aviation fuel was commonly 130 octane, and 150 octane was available in limited quantities for fighters from the summer of 1944. This high octane could easily be used in existing engines to deliver much more power by increasing the pressure delivered by the superchargers.

In late 1942, the Germans increased to octane rating of their high-grade 'C-3' aviation fuel to 150 octane. The relative volumes of production of the two grades B-4 and C-3 cannot be accurately given, but in the last war years perhaps two-thirds of the total was C-3. Every effort was being made toward the end of the war to increase isoparaffin production; more isoparaffin meant more C-3 available for fighter plane use.

A common misconception exists concerning wartime fuel octane numbers. There are two octane numbers for each fuel, one for lean mix and one for rich mix, rich being greater. The misunderstanding that German fuels had a lower octane number (and thus a poorer quality) arose because the Germans quoted the lean mix octane number for their fuels while the Allies quoted the rich mix number. Standard German high-grade 'C-3' aviation fuel used in the later part of the war had lean/rich octane numbers of 100/130. The Germans listed this as a 100 octane fuel, the Allies as 130 octane.

[Feather #3]

90/96 was light blue, although a bit like rocking horse manure in Oz.

FWIW we run the Connie mostly on 100LL without drama.

G'day ;)

[TBM-Legend]

reading about synthetic fuel makes you wonder why we don't do it here with our almost endless supplies of coal..:hmm:

[Trojan1981]

OK, thanks guys, especially TBM. So Ze Germans had it during the war (beat them twice you know) but its not around anymore?