Old airplane

It stands to reason that the better the performance of the fuel the better the performance of the aircraft. However in the 1930s, with the majority of aircraft engines designed to run on 87-octane fuel, new higher-specification 100-octane fuel was seen to be of little benefit due to its higher cost.

One man, however had a different view – James Harold ‘Jimmy’ Doolittle who became the Aviation Manager in the USA for Shell Oil Company in 1935. Doolittle was a gifted stunt and test pilot and air racer, as well as being a trained aeronautical engineer with a doctorate from Massachusetts Institute of Technology. He was a flying instructor during World War I and a reserve officer in the United States Army Air Corps. This combined expertise as a pilot and engineer led him to recognise the potential of the new higher-specification 100-octane Avgas fuel being developed by Shell.

Despite a lack of demand, Doolittle persuaded Shell to invest in refining capacity for the more expensive 100-octane fuel. Tests in the late 1930s demonstrated significant improvement in aircraft performance and the US military began to order the 100-octane fuel in large quantities. By 1938, the US was producing some 4.2 million gallons of 100-octane Avgas per month, as it became the standard fuel for the US Air Force, with Shell alone making more than 60% of this volume. The 100-octane fuel gave aircraft an important combat edge. The British Spitfire, for example, would gain an extra 25-34mph by using 100-octane, a crucial advantage in aerial combat. As more 100-octane was produced, the price came down and it also entered service powering commercial airliners after the Second World War helping to improve performance, including cutting take-off distances by up to 45%.

Doolittle was recalled to active service with the US military during the Second World War. He was awarded the Medal of Honor for personal valour and promoted to the rank of Lieutenant General. After the war, he continued to be active in aviation and played a role in the early developments of the US space programme.

Doolittle’s influence on the introduction of 100-octane fuel resulted in a legacy of improvement in aviation fuel and aircraft performance that would last long after the Second World War. Shell has continued to work closely with partners such as Rolls-Royce on fuel performance, including research and development into fuel for Concorde, as civil aviation went supersonic in the 1970s.


R. van Egmond and A. Westra, Shell and aviation. The story of more than a century of collaboration. Shell International B.V., 2019, p. 61-65 &80-81
Website of the School of Advanced Air & Space Studies, ‘Jimmy Doolittle, The Commander Behind the Legend’, https://media.defense.gov/2017/Nov/21/2001847256/-1/-1/0/DP_0017_BISHOP_JIMMY_DOOLITTLE.PDF
100-Octane (narkive.com)
Shell historical archives.

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