Little Attention was paid to the characteristics of the fuel for the early aircraft engines. They had available to them a gasoline primarily intended for automobile engines, the earliest of which used wick carburettors. These carburettors required a fuel of extremely high volatility and with the straight run gasolines available at the time, volatility could be related to specific gravity. The lower the specific gravity, the better the volatility and the requirement for low specific gravity endured for about the first twenty years of the life of the aircraft engine.
Note on page 185 * At lower concentrations of lead its effect relative to that of benzole is greater, as it is when engine conditions become more severe.
Note on page 185 † The resultant blend of tetra-ethyl-lead and the halogen compound became known as “Ethyl Fluid”.
Note on page 185 * Much of the early supplies of 100 ON from the USA were found to be deficient in rich mixture performance and were brought up to requirements in the UK by the addition of benzole.
Note on page 186 * Ethylene-di-bromide is added to TEL at a concentration to give theoretically complete chemical reaction with the products of combustion of the TEL. Less ethylene-di-bromide would tend to produce excessive lead deposits and more would cause the formation of corrosive products in the exhaust gases
Note on page 186 † Being composed of a wide range of hydrocarbons, aviation gasoline has a boiling range of from 40°C to 180°C.
Note on page 186 ‡ Power boosting by the injection of water/methanol mixtures was first used in Pratt & Whitney engines and ultimately was widely employed in American and British engines. It was chiefly used to provide increased take-off power.