At the time it was built, the Willow Run B-24 factory in Michigan was the largest and most ambitious aviation project ever undertaken.
When the Second World War broke out in 1939, the United States was an economic power, but a military weakling. Most of its aircraft were obsolete, and it had virtually no standing army to speak of. President Franklin Roosevelt launched a desperate effort to expand American war production, both to help support its allies overseas and to beef up its own sub-par military strength.
As part of this effort, the Army Air Force contacted the Consolidated Aircraft Corporation to ask them to produce B-17 Flying Fortresses under a license from Boeing. But Consolidated did not want to manufacture a design which was then already four years old (and it especially did not want to license a design that had been made by another company). So instead, Consolidated offered to design and make a new heavy bomber to the Army’s specifications. The result was the B-24 Liberator, a long-range four-engine heavy bomber with a longer range, faster speed, and heavier bomb load than the B-17.
When the US entered the war in December 1941, it needed bombers desperately, and the B-24 was well-suited for conditions in both the European and Pacific theaters. To keep up with the heavy demand, Consolidated produced B-24s at both of its own aircraft plants, and also licensed their production to other plants run by Douglas Aircraft, North American Aircraft, and the Ford Motor Company.
Henry Ford’s company had of course pioneered the idea of the “assembly line” to churn out Model T’s at an astounding rate, and now he planned to apply the principles of automobile manufacturing to aircraft. When the War Department asked him to produce enough parts and subassemblies for 1,200 B-24s, Ford countered by offering to mass-produce completed B-24 bombers, at the rate of over ten a day, continuously.
The giant new factory would be built just outside of Dearborn MI, at an airfield known as Willow Run. Ford engineers broke down the assembly process into a series of single steps, then planned out an assembly line to carry it out. The final assembly line snaked around for over a mile inside a massive building of over 3 million square feet.
One of the difficulties Ford had was that Consolidated’s blueprints for the B-24 were not up to automobile machining standards. Ford finally had to send a team of his own engineers to draw up their own blueprints. The factory’s layout was also hampered by the Army Air Corps, which kept changing the bomber’s design, adding new gun positions and bigger bomb bays. As new models appeared, older models had to be sent back to the factory to be refitted and upgraded. At some points in time even Consolidated’s own factories were unable to keep up with all the changes and bombers were already obsolete as they were produced, and ended up being sent back directly from the end of the assembly line to be upgraded.
Another difficulty was the herculean task of providing for the 40,000 new workers who would be needed to run the massive factory. With most young men off fighting the war, many of Ford’s workers were local women (it was at Willow Run that the legend of “Rosie the Riveter” was born), and others were imported from the South. All these workers needed housing, schools, highways, and other amenities, and local cities like Ypsilanti and Belleville swelled with the influx of people and struggled to meet it. Some 1500 workers a year were quitting their jobs in the plant because of housing difficulties, and Ford had to retrain replacements for all of them.
In the end, all of these difficulties were overcome. Ford outsourced the individual B-24 parts to various subcontractors: Packard made the engines, and much of the mechanical structure was made in other Ford plants. Even local refrigerator factories contributed by making fuselage panels. These parts went in at one end of the assembly line, and finished B-24s came out the other end: it was one of the first factories in the world to use a “just-in-time” method of parts logistics.
The Willow Run plant began production just 14 months after construction began. At its peak in 1944, the workers were turning out a finished B-24 every hour. A total of 19,200 Liberators of various models were produced during the war—the most of any American airplane—and almost half of these came from Willow Run.
The last B-24 made at Willow Run rolled off the assembly line on June 8, 1945. The plant was bought by the Kaiser-Frazer Automobile Company which used it to make both cars and cargo aircraft until 1953. The airport next door was obtained by the University of Michigan and was used for missile research, then later sold to Wayne County. It still runs as a cargo airport.
The former B-24 factory, meanwhile, was sold to General Motors and used to produce car transmissions, but the plant was closed down in 2010 when GM had financial difficulties. Nearly all of the old factory was then demolished.
Today, the only remaining portion of the once-massive factory complex is the 144,000 square foot Finishing Hangar, where B-24s had their bombsights installed and were then fueled, started up, and tested. It is owned by the Yankee Air Museum and is used for restoring the museum’s collection of WW2 and Cold War aircraft. Plans call for the hangar to eventually be restored to the condition it was in during Willow Run’s service.
The Museum exhibits a B-24 cockpit and a fuselage that was manufactured at Willow Run along with its collection of warbirds.