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Editor’s note: This is the sixth article in a limited series celebrating American defense technologies born from wartime and their effects on broader national security, politics, and society. This series will run for several weeks to commemorate America’s 250th anniversary, and winners will be selected by a reader vote undertaken through our newsletter later this summer. Prior installments can be found at the Arsenal of Innovation page.
The impact of chance and poor logistics on warfare is especially acute when a battle or campaign is a close-run thing, as it was over the skies of England in 1940. After all, for want of a nail, the kingdom was lost. Luckily for Britain in 1940, the 20th-century equivalent of a nail was in plentiful supply. High-octane fuel allowed the Royal Air Force to enjoy a horsepower advantage over the Luftwaffe that oftentimes made the key difference. The Allies as a whole would leverage this advantage for the remainder of the war.
The development of high-octane aviation fuel isn’t just the story of one man — it involves hundreds of individuals working in business, chemistry, aircraft engineering, military logistics, and operations. Given enough time, it is completely possible that these actors would have randomly found a way to develop a high-octane fuel industry. However, without Jimmy Doolittle in the right place at the right time, along with his ability to combine operational, technical, and business expertise, it is improbable that enough high-grade fuel would have been produced by 1940 to significantly impact the war, let alone by 1940 in time to make a difference during the Battle of Britain.
The triumphs of innovation that Doolittle catalyzed and accelerated in the aviation petroleum industry also had a wider postwar impact. The industrial infrastructure built to win the air war on Doolittle’s fuel did not demobilize when Japan surrendered — it became the foundation of postwar American prosperity in ways that nobody planned, and almost nobody remembers.
Throughout the 1920s and early 1930s, a few key steps had been taken that would eventually allow Doolittle and others to turn high-octane fuel into a scalable military advantage.
H.R. Recardo’s 1921 publication of the impact of fuel-knock on engine performance and Graham Edgar’s development of the octane rating system for fuels, and Midgley’s creation of the first high-performance synthetic (though non-scalable) fuel provided a basis of fundamental research.
On the engine design front, Captain T.E. Tillinghast, then-Chief of the Power Plant Section at McCook Field in 1928, began a holistic study of the effects of fuel knock quality on engine performance. The 1930 U.S. Army Specification Y3557 mandated 68-octane fuel. This directive represented the first aviation fuel requirement for specific knocking properties in octane number. While some fear was expressed regarding the petroleum industry’s ability to supply fuel to this standard, these fears proved to be unfounded.
Unfortunately, outside these limited technical circles, there existed few who seriously considered the possibility of mass-producing high octane. The little commercial aviation that did exist in the 1930s had no pressing need for 100-octane fuel. Only three percent of aircraft at the time could take advantage of 100-octane fuel, and almost none were actually burning it yet. High-octane fuel cost $2.50 a gallon to produce at a time when Shell was selling 87-octane fuel to the Army for 15 cents. The Army Air Corps, operating under severe Depression-era budget constraints, had no appetite for the premium cost, and most Army leadership desired standardization of fuel for all motor vehicles to avoid logistical complications and reduce per-unit cost. At the same time, the petroleum industry was unwilling to invest heavily in the infrastructure needed to reduce per-unit costs, absent any guarantee of a government customer.
Overcoming this catch-22 would require the sustained, concerted effort and leadership from a determined, forward-looking group of technologists, oil men, and military leaders throughout the 1930s. While Jimmy Doolittle and Shell were the first to heavily invest in high-octane fuel, other companies and business leaders like Eddie Aldrin of Standard Oil of New Jersey and Billy Parker of Phillips Petroleum were not all that far behind.
Doolittle’s unique background was the key factor behind his unique success. By the early 1930s, Doolittle had already established himself as one of the most accomplished aviators in America. He was the first pilot to complete a blind flight using only instruments, a winner of the Schneider Trophy air race, and holder of multiple speed records. He held a doctorate in aeronautical engineering from the Massachusetts Institute of Technology. In 1930, he resigned his regular commission in the Army Air Corps to accept a reserve commission and work at Shell Oil’s aviation division, bringing all of his operational and technical experience into an industrial setting.
Unlike the commercial aviation industry and much of the U.S. Army, Doolittle understood from his time as an air racer that octane rating was a true performance multiplier. Higher-octane fuel allowed aircraft engines to run at higher compression ratios and boost pressures without detonating, which translated directly into more horsepower, higher speeds, and greater climb rates. The difference between 87-octane and 100-octane was the difference between catching an adversary and not. In a bomber, the greater fuel efficiency enabled by higher-performance engines would have a direct impact on their greatest operational attribute: range.
Doolittle’s familiarity with the thinking of both technologists at Wright Field and Army Air Corps leaders like Hap Arnold’s desire for larger and more advanced aircraft allowed him to make a forceful case to Shell on the likely future market demand for the fuel. This was not an easy case to make, with some of his fellow executives dubbing the scheme “Doolittle’s million-dollar blunder.”
In 1934, Shell delivered the first 1,000 gallons of 100-octane fuel for testing purposes to Wright Field at a price of 50 cents a gallon, which was more than three times the price of lower-grade 87-octane fuel. It had cost Shell five times as much to make the stuff.
The test fuel Shell delivered to Wright Field had an almost immediate impact, with test results showing that 100-octane fuel obtained 15–30 percent higher output compared to a comparable amount of 75-octane gasoline. When the report failed to achieve an immediate change from the Army General Staff, its author, Lieutenant Frank Klein, published his findings.
Doolittle’s advocacy did not stop at his own boardroom. In 1936, he helped arrange for fuel laboratories across the oil industry, including Shell’s chief rival, Standard Oil of New Jersey, to share a common batch of 70,000 gallons of reference iso-octane for antiknock testing, which could be standardized industry-wide through the Cooperative Fuel Research Committee. This committee, created in the 1920s, allowed the National Bureau of Standards, engine manufacturers, and the petroleum industry to each provide expertise, personnel, and funding to projects of interest. Doolittle was thus taking advantage of an innovation ecosystem that was already learning to cooperate and simply made it his job to make it move even faster.
The Cooperative Fuel Research Committee and Wright Field information sharing efforts set off a flurry of activity. Industry leaders like Wright Aeronautical almost immediately began designing engines capable of maximizing the potential of high-octane fuel to achieve not only power gains but also fuel savings. These fuel savings were an especially important selling point for an Army Air Corps led by Hap Arnold — at the time, becoming increasingly vocal about the need for long-range bombers.
Despite the clear operational benefits of the fuel, Army leadership still expressed doubts about the petroleum industry’s ability to produce at scale and preferred the logistical simplicity of land and air vehicles using the same fuel. While on active status in 1936, Doolittle worked to overcome the latter charge by conducting a follow-on 1936 study “on the availability of 100-octane gasoline to meet needs of [the] Army and Navy in war.” Doolittle was well-positioned to conduct this study. In 1934, Shell created a small octane plant and by 1935 had created three more large-scale production facilities. By 1936, these Shell facilities alone would be capable of creating 6 million gallons a year, and together, Shell and Standard Oil were producing 10,000 tons a year. Perhaps motivated by this experience, Doolittle would in 1939 go on to have Shell Oil produce its own monthly report, which measured its own and its competitors’ production capacities.
Spurred by Klein and Doolittle’s studies, an Army committee was convened in November 1936 to study the issue and finally mandated that by 1938, all Air Corps engines should be designed to use 100-octane fuel. The petroleum industry finally had a clear demand signal from the U.S. government.
Most of the early gains in reducing the cost of high-octane fuel production came from economies of scale, additional production facilities coming online, and a string of process improvements. As early as 1934, Shell sold octane at 71 cents a gallon and at 20 cents a gallon by 1937. By 1939, with refining plants finally coming online at Baton Rouge, Martinez, Wilmington, and Houston, this price tag would be pushed down even further.
A step change in production was eventually achieved via the introduction and refinement of Eugene Houdry’s catalytic cracking process, which pulled far more high-octane material out of each barrel of crude than the previous thermal cracking methods. While Houdry developed this technology in 1937, substantial licensing and investment cost concerns led both Standard Oil of New Jersey and Shell to prefer simply expanding their own alkylation facilities, while simultaneously developing their own “fluid” catalytic process to get around the licensing fee. The first such refineries came online in 1942. As a result, no single company, chemical breakthrough, or manufacturing process can be said to have made the tidal wave of high-octane fuel going into 1943 to 1945 possible.
By the war’s end, American combat forces alone were burning some 20 million gallons of 100-plus-octane fuel a day, a scale nobody — least of all the Army General Staff — had thought possible a decade earlier.
Adoption of 100-octane had very real near-term advantages for America’s ally, Great Britain. As early as 1937, the British placed contracts with Shell and Standard Oil for 100-octane fuel, and in 1938, British firms partnered with Shell to build a British-based refining facility. By 1940, the United States was exporting over 70,000 tons of 100-octane fuel to Britain alone. By the time the Battle of Britain was fought in the summer and autumn of 1940, Royal Air Force Hurricanes and Spitfires were running on high-octane fuel that gave their Merlin engines a significant power advantage over their Luftwaffe counterparts. Looking back in 1942, Geoffrey Lloyd, British Secretary of Petroleum, mused that “I think we wouldn’t have won the Battle of Britain without 100-octane…but we did have 100-octane.”
53 percent of this high-octane fuel came from the United States. The early investment of U.S. industry into aviation fuel ensured that fuel availability would never be an issue from which the Allies meaningfully suffered. However, this investment was far from inevitable.
When the war ended in 1945, the refineries, factories, and industrial know-how that had powered the Allies to victory remained. The United States emerged from the conflict with enormous refinery capacity configured to produce high-octane blended fuels, and with a generation of chemical engineers who had spent the war pushing the boundaries of the discipline. This capacity and knowledge, created by combining the best efforts and wisdom of American scientists, technologists, military operators, and business leaders, did not demobilize. Instead, it found new markets under the hoods of American automobiles and in the emerging field of petrochemical refinement.
The postwar automotive industry moved aggressively toward high-compression V-8 engines that required premium-grade gasoline to realize their advertised performance — engines that would have detonated on the 87-octane fuel standard before the war. These cars were possible in a logistical, technical, and business sense because the fuel was available at scale and cheaply — the war had required it.
The chemical processes required for mass-produced aviation fuel, including catalytic cracking and alkylation, scaled to produce aviation gasoline, were not narrowly specialized technologies. They were general-purpose tools for transforming crude oil fractions into more valuable products. When demand for aviation fuel contracted, that same infrastructure was redirected towards producing petrochemical feedstocks — synthetic rubber, plastics, fertilizers, and agricultural chemicals. The postwar American petrochemical industry, which supplied key inputs to the consumer economy of the 1950s and 1960s, grew directly from the technical foundation the high-octane fuel program had built.
High-octane fuel was not produced at scale just because one individual saw further than everyone else. Doolittle himself mused that his “weird” name made it memorable and as a result made it more likely for people to single him out for recognition; in reality, the effort was highly collective and collaborative. A corporate history of Shell published in 1957 similarly insisted on spreading the credit widely for America’s dominance in high-octane fuel. Doolittle did not invent catalytic cracking or alkylation, and he did not standardize fuel specification by himself. What he did was refuse to let a fragmented, competitive industry and chronically underfunded defense establishment default to the cheap and easy solution. This insistence by figures like Doolittle, Klein, and numerous other technologists and aviators with the Army Air Corps turned out to matter as much as any single piece of chemistry.
Aidan Poling is a non-resident fellow at the Mitchell Institute for Aerospace Studies. He works as a space industrial base analyst.
The views expressed are the author’s own and do not necessarily reflect those of their institutions or the United States government.
Image: Bridge B, Royal Air Force photographer, via Wikimedia Commons.
