Intro. [Recording date: July 24, 2025.]
Russ Roberts: It’s July 24th, and joining me today is Brian Potter, an engineer and writer affiliated with the Institute for Progress, where he serves as a Senior Infrastructure Fellow. He curates the Construction Physics Substack, an intriguing forum filled with essays and discussions covering a spectrum of engineering, construction, and related subjects.
Today, we’ll delve into one of his essays: “How to Build 300,000 Airplanes in Five Years.” Welcome to EconTalk, Brian.
Brian Potter: Hi, Russ. Thanks for having me.
Russ Roberts: Historians often credit the United States’ remarkable manufacturing capabilities as a key factor in the Allies’ World War II triumph. This idea of the U.S. as the “arsenal of democracy” is often repeated. You mention in your essay:
… between 1938 and 1943, U.S. manufacturing output tripled as munitions production surged. The U.S. produced approximately 5,600 cargo ships, 80,000 landing craft, 2.4 million trucks, 2.6 million machine guns, and 41 billion rounds of ammunition.
However, your focus is on a different aspect: aircraft production. You have a lot to say about it.
To kick things off, here’s an eye-opening statistic:
During the war, the United States manufactured around 325,000 airplanes valued at roughly $46 billion (or about $800 billion in 2024 dollars). This figure surpasses the combined production of aircraft by Germany, Japan, and Italy throughout the conflict, and it even exceeds the total number of commercial aircraft produced in aviation history.
Is that truly accurate? It sounds astonishing.
Brian Potter: Yes, it’s a rough estimate, but the scale makes it plausible. Currently, the commercial aviation sector produces around 1,000 to 1,500 airplanes annually, and given the entire history of aviation, that’s a considerable backlog. The wartime ramp-up was unprecedented.
Russ Roberts: I found some data about the fleets of major U.S. airlines like United, American, and Delta, each operating around a thousand planes. Interestingly, FedEx has even fewer. Yet, during World War II, the U.S. cranked out 325,000 planes, while the Axis powers managed about 200,000. This means the Allies—chiefly the U.S., Russia, and the U.K.—produced three times as many aircraft as their adversaries, with the United States alone exceeding the Axis output by 50%.
One more striking statistic before we dive deeper: At the peak of aircraft production in 1944, the U.S. produced around 96,000 planes in a single year. By contrast, in 1937, it made just 3,100, mostly small private aircraft.
Prior to the war, the aircraft industry’s total output was worth about one-quarter of the canned goods industry.
This highlights just how minor the aviation sector was compared to others, such as the automobile industry, where it accounted for only 3.5% of the value produced. So, how did this transformation happen?
Brian Potter: The process was indeed intricate. The initial plan for wartime mobilization—what they dubbed M-Day (Mobilization Day)—assumed a seamless transition to a wartime economy, but reality was far more complex.
Russ Roberts: Mobilization Day.
Brian Potter: Right, and they thought they could simply flip a switch and transition to producing tanks, guns, and aircraft. But this was overly simplistic, and there wasn’t a concrete plan for such a monumental shift.
Initially, the scale-up began even before the U.S. entered the war, during the late 1930s. Britain and France, sensing impending conflict due to German aggression, started increasing their military capabilities. They placed substantial orders for aircraft and engines from U.S. manufacturers—companies like Boeing and Lockheed. These early orders helped U.S. firms scale up their operations, even rescuing some from near bankruptcy. For instance, Pratt & Whitney was on the brink before a large order from France saved them.
However, the U.S. military itself was not yet prepared for mass production. As late as early 1940, officials projected that over five years, they might build only 5,000 to 10,000 planes—a drop in the bucket compared to what would eventually be required.
But when Germany invaded Western Europe in 1940, the urgency skyrocketed. President Roosevelt asked Congress for permission to produce 50,000 planes annually—a figure that seemed absurd at the time, equating to nearly all aircraft built since their invention, including small private planes.
This shift catalyzed the mobilization process, which accelerated further after Japan attacked Pearl Harbor.
Russ Roberts: It’s easy to overlook that while the U.S. officially entered the war in 1941, it wasn’t until 1942 that we truly ramped up production. We transitioned from making aircraft for Britain and France to full-scale production by 1942, 1943, and 1944. You mentioned that many new factories were built—some expanded, but many were entirely new. Why was that the case, and was it part of a deliberate strategy?
Brian Potter: Initially, there was hope that the industry could scale up on its own, funded by new government orders. The early phase of aircraft mobilization aimed to facilitate this self-financing. Adjustments were made to profit margins and amortization periods to assist manufacturers.
However, as the scale of production needed became clear, it became apparent that existing methods were inadequate. Aircraft were traditionally built by hand, similar to early automobile manufacturing. Each plane was somewhat unique, built through a craft production process. But to meet wartime demands, manufacturers had to adopt assembly line methods, which required entirely different facilities than what was previously utilized.
Consequently, the government ended up financing the construction of these massive factories, which were often government-owned and contractor-operated. This was a widespread model for wartime mobilization.
Russ Roberts: The size of these plants was staggering.
Brian Potter: Absolutely. The new factories were colossal, covering millions of square feet. One plant, for example, was roughly the size of the lower part of Manhattan, cranking out vast quantities of aircraft. Some of these facilities, like the Dodge plant outside Chicago, eventually became O’Hare International Airport due to their size.
Russ Roberts: And they weren’t particularly useful after the war, which posed the challenge of what to do with them.
For context, the Dodge Chicago plant was 6.3 million square feet. To visualize that, imagine ten New York City blocks from 50th to 60th Street between Seventh and Ninth Avenues—it’s enormous.
Moreover, the Willow Run plant’s assembly line stretched over a mile long. At its peak in 1944, they produced a B-24 bomber roughly every hour. Just picture that: a fully finished B-24 rolling off the assembly line every sixty minutes. By 1945, Willow Run was producing 70% of its B-24s in two nine-hour shifts, with pilots and crew members even sleeping on cots nearby, ready to take off as soon as the planes were completed. This is simply extraordinary.
Brian Potter: The output was indeed remarkable. Ford’s Willow Run plant mirrored car manufacturing by establishing an assembly line that ensured a constant flow of products. However, transitioning to aircraft manufacturing was a significant challenge, given the complexity involved.
Aircraft are far more intricate than cars; for instance, a mid-sized car from that era had around 5,000 parts, while an aircraft could have upwards of 150,000 parts, not to mention hundreds of thousands of rivets. The engines were also far more powerful, requiring a design that prioritized both performance and lightweight construction.
Achieving such high output with these complex, high-precision products was incredibly challenging, requiring time and substantial adjustments to manufacturing processes.
Russ Roberts: Most of the workforce was unskilled. Each plant likely had a core group of skilled workers, but the majority were new to this kind of manufacturing. You describe how intricate the processes were, especially with metal bending. It must have been a steep learning curve for these workers.
Brian Potter: Indeed, it was quite challenging. The majority of these aircraft manufacturers began as relatively small operations. For the five largest companies that produced the bulk of U.S. planes during the war, their workforce averaged about 1,000 to 1,500 employees at the war’s onset, some even smaller. They rapidly expanded to employ hundreds of thousands.
While management was often experienced, the line-workers were predominantly new hires with little to no prior manufacturing experience. Remarkably, almost half a million women found roles in airframe and engine assembly plants. The transition from a knowledge-based workforce to one dependent on standardized processes was a daunting task.
One source I came across suggested that the available workforce largely dictated the production system. Given that many of the workers were women and lacked the physical strength traditionally associated with manufacturing roles, the production processes had to be adapted to fit their capabilities.
Russ Roberts: Naturally, many men were off fighting, which opened up these roles for women.
Russ Roberts: Your essay highlights the daunting inspection process, given the narrow margins for error. You note:
An aircraft engine and its components could undergo as many as 70,000 inspections during manufacturing. When Ford engineers visited a Pratt & Whitney factory, they initially thought the process looked simple, but after studying the engines’ performance requirements, they quickly realized the extreme precision needed.
It’s staggering to think that 20% of the workforce in some plants were inspectors, ensuring quality control.
Brian Potter: Yes, the precision required was immense. Even a minor scratch on a gear could necessitate discarding a part, as it could lead to stress concentrations that were unacceptable given the high-performance demands.
For traditional car engines, you could conduct a brief break-in period after assembly. But with aircraft engines, they would run them for extended periods, disassemble them, inspect every component, and if any part showed excessive wear, it would be replaced before reassembly, ensuring maximum reliability.
This level of inspection and quality control was crucial to guarantee operational readiness in combat situations.
Russ Roberts: I often think of Southwest Airlines, which has been remarkably successful in part due to its strategy of using a single aircraft model for its fleet, minimizing complexity in operations. You touch on the challenges of constantly modifying aircraft for performance improvements during the war, which had implications for the production process.
Can you elaborate on that? You mention the P-47 underwent five major design revisions and numerous smaller updates, which meant the manufacturing process had to adapt continuously.
Brian Potter: Absolutely; that was a significant hurdle. In traditional mass production, manufacturers aim to “freeze” designs to streamline production. Changes are generally avoided unless necessary. However, during the war, constant improvements were essential to keep up with enemy advancements.
As a result, modifications were frequently introduced, whether to fix issues identified in the field or to enhance performance. This influx of design changes complicated manufacturing as companies attempted to produce large quantities of aircraft while simultaneously adapting to new specifications.
To manage such a dynamic environment, an effective Production Control System was crucial. This system helped track what to build, when, and by whom, streamlining operations. The shift from small-scale production to mass production necessitated the development of robust management systems.
Russ Roberts: As an illustration:
Flight testing of the B-29 led to 900 design changes before large-scale production even began. The Cyclone engine manufactured by Chrysler for Pratt & Whitney required over 6,000 modifications throughout the war, resulting in nearly 50,000 separate change orders. North American’s B-25, which first flew in 1940, underwent roughly two million engineering hours for redesigns and updates over five years.
That’s remarkable.
Russ Roberts: How did you come to write this essay, and what was the duration of your research process?
Brian Potter: I have a keen interest in manufacturing and the evolution of production methods. This theme runs through many of my essays. When I stumbled upon this topic, I realized I wanted to explore it more deeply.
I don’t recall the exact timeline, but typically, I spend several days to a week conducting research, followed by a few days of writing. For this particular 5,000-word piece, I’d estimate around two to three weeks of work.
Russ Roberts: I imagined it would take a year or more!
Russ Roberts: There’s an emotional dimension to this narrative that mere statistics can’t convey. The monumental effort—2 million engineering hours, the influx of women into manufacturing roles—while significantly less dramatic than the battlefield, carries its own heroism, especially as the war came to a close.
I often reflect on the Churchill War Rooms in London, where British leadership operated during the Blitz. They turned off the lights and left when the war ended, and someone later realized the historical significance of the site. There’s a haunting simplicity to it—the modest accommodations and the map rooms where plans were made during perilous times.
For those working in immense factories, the stakes were similarly high. Day after day, they contributed to a cause they believed vital to their nation and perhaps to the world itself. The intensity of engineering and production must have been both exhilarating and incredibly stressful. Can you reflect on that?
Brian Potter: Stress was indeed a significant factor, as noted in various documents. The rapid scale-up posed tremendous challenges for managers, many of whom struggled to adapt to the complexities of larger operations. Some found the pressure so overwhelming that they had to step down for health reasons. I came across a statistic indicating that at Lockheed, around 30% of the designers of the P-80 experienced health issues due to the intense demands of the project.
Bill Knudsen, a key figure in U.S. wartime mobilization, exemplified this dedication. An immigrant who began his career at Ford, he rose to become GM’s president. He left his lucrative position to work for the government for just $1 a year, believing it was his duty to contribute to the war effort. His expertise in scaling manufacturing systems was invaluable, and although he eventually left that post, his influence on mobilization was profound.
Russ Roberts: There’s a palpable sense of urgency in your essay, as everyone was racing against time. In retrospect, it’s easy to marvel at how quickly production ramped up, but the reality was that building a 6.3 million square foot facility or a mile-long assembly line took significant time. It wasn’t a typical construction project; the war created an environment where urgency was paramount, yet construction still required time.
For instance, you mentioned earlier that it took over a year to go from producing the fifth aircraft to the 500th. You also noted that even manufacturers experienced in mass production faced challenges. Despite significant focus on Ford’s Willow Run factory, its initial performance was underwhelming.
For the first two years, the factory produced almost nothing as it grappled with the challenges of aircraft production. At one point, the government even considered taking over the facility. Ultimately, though it improved and produced aircraft in large volumes, by that time, the military’s needs had shifted toward larger, longer-range aircraft.
This complexity, combined with the wartime pressure to deliver, must have been a formidable challenge.
Brian Potter: Yes, the entire endeavor was extraordinary. It raises the question of whether the U.S. could replicate such a rapid scale-up today if needed.
Willow Run is particularly interesting because, unlike most manufacturers who adapted existing methods gradually, Ford jumped straight into mass production techniques without first understanding aircraft design and production requirements. This approach resulted in initial struggles and significant delays, leading to government concerns about the factory’s performance.
Russ Roberts: Imagine the managers at Willow Run going home after two years of producing nothing. Those must have been some sleepless nights.
Brian Potter: Indeed. The daily reality involved an onslaught of challenges: shortages of materials, untrained workers, and the constant churn of issues. The struggle was relentless, making it difficult to truly appreciate the enormity of their task.
Russ Roberts: Many assume the U.S.’s manufacturing prowess was inevitable, given its economic strength in the 1940s. Yet, you highlight the complexity and uncertainty of that time. You conclude your essay with this thought:
It wasn’t until 1942, three years after Germany invaded Poland, that U.S. aircraft production truly escalated. This was only feasible due to significant early orders from Britain and France and the efforts of visionary leaders like Bill Knudsen. Had circumstances been different, the trajectory of both the aircraft industry and the war itself might have been vastly different.
Could it be that without the early orders from Britain and France, U.S. production might not have peaked until 1947 or 1948, potentially altering the war’s outcome?
Your piece is a treasure trove of fascinating facts, but the underlying concept is compelling: while the outcome was favorable for the Allies, the path taken was anything but guaranteed.
Brian Potter: Absolutely. This leads to an ongoing debate among historians regarding whether the U.S. manufacturing output was crucial to the war’s outcome. On the eve of the conflict, the U.S. was already the largest manufacturer globally, producing more cars, steel, and machine tools than any other nation combined. So, while the economic disparity certainly favored the U.S., the question remains: how much did the specific decisions made along the way impact the war’s outcome?
Russ Roberts: A recent article in The Free Press, penned by Chris Power, CEO of a defense and manufacturing company, argues that every great power in history lost its supremacy once it relinquished its industrial edge. He claims, “The U.S. must act now to avoid the same fate.” Many economists contest this notion, asserting that while the U.S. manufacturing workforce has declined, output remains robust. Yet, there’s a valid concern regarding our dependence on foreign production, especially should we require military capabilities in the future. What are your thoughts on this? Should the U.S. prioritize strengthening its manufacturing capacity for security reasons?
Brian Potter: I agree that U.S. manufacturing capabilities have been significantly offshored, creating vulnerabilities that could hinder rapid scale-up in times of need. A pertinent example is the injection molding industry, where the U.S. relies heavily on foreign production for the molds essential to manufacturing plastic parts. This dependency could jeopardize our ability to produce critical components quickly.
Moreover, during recent conflicts, the U.S. struggled to meet artillery shell production demands, at one point being outproduced by North Korea. This scenario underscores the challenges of scaling up manufacturing capabilities effectively.
While the U.S. still produces a significant amount of output, we must recognize the risks associated with this outsourcing trend. It’s not simply a matter of having the capacity to produce; it’s about retaining the ability to mobilize efficiently—and we seem to have lost some of that capability.
Russ Roberts: Let’s engage in thought experiments. Suppose you were transported back to Willow Run during its early struggles, armed with your current knowledge. How would you approach the challenges there? Additionally, if you were tasked with establishing a new facility from scratch, how would your expertise play a role?
Brian Potter: For the time travel to World War II, I’d focus on the organizational bottlenecks rather than getting bogged down in material or manufacturing processes. The key would be to engage with government leaders in the late 1930s and emphasize the need for a well-defined plan for scaling up production. Roosevelt’s ambitious goals for aircraft production should have been established much earlier, well before the war began.
Today, a similar strategy would involve having a comprehensive mobilization plan in place to scale up manufacturing effectively. Without such preparations, we risk repeating past mistakes.
Russ Roberts: My guest today has been Brian Potter, whose Substack is called Construction Physics. Brian, thank you for joining us on EconTalk.
Brian Potter: Thank you for having me.
