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Fuel octane, TEL, and a little bit of history...

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Had the occasion to watch the 1969 movie The Battle of Britain the other day. It's basically a story about how "Never in the field of human conflict was so much owed by so many to so few" (Winston Churchill). The story characterizes Britain's Royal Air Force ability to stave off the numerically superior German aircraft armada (some excellent aerial combat footage BTW, along with the nominal model aircraft being blown up).
One line in the movie, where the Field Marshall is chiding a commander about what it would take to master the sky, the reply from the German officer is to acquire a squadron of Spitfires (BTW... I own two, Triumphs, that is :)).
Going into the war, the engine technology was basically the same for both Germany and Britain, but the Spits and Hurricanes defeated over France in 1939 and early 1940 were able to outperform the ME-109's and bomber aircraft over Britain. What was the difference? The planes were the same, but the fuel wasn't.
How do I know that?
At the same time as watching the movie, I was catching up on my reading of back issues of Invention & Technology and came upon "the rest of the story" (to paraphrase the late Paul Harvey).
Previously, aircraft engines in the world were designed to run on 87 octane, as that was the limit of fuel obtained through the distillation process at the time. Operators would add TEL to help prevent pre-ignition at high outputs, but they were still limited by its lead fouling and deposits, same as we can experience in our engines. But around early 1940, the US started to ship 100 octane to the Brits as a result of Eugene Houdry's research and work on catalytic cracking. As the article states: “It is an established fact that a difference of only 13 points in octane number made possible the defeat of the Luftwaffe by the R.A.F. in the fall of 1940. This difference, slight as it seems, is sufficient to give a plane the vital ‘edge’ in altitude, rate of climb and maneuverability that spells the difference between defeat and victory.” The Germans did not have the knowledge or capability for catalytic processes. They were stuck with lower performing 87 octane.

You can read the story here ((The Wizard Of Octane | Invention & Technology Magazine). It helps to shed some light on the unleaded debate currently gong on. It also can shed some light on why many of our dinosaur engines, designed in the 1930's and 40's, were certificated for 87 octane. Thought some of you would enjoy the information.
 

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