26 April 1939: The United States Army Air Corps placed an order for 524 Curtiss-Wright P-40 Warhawks. This was the largest production order for any U.S.-built fighter since World War I. The total cost was $12,872,398.
This photo shows Curtiss-Wright chief test pilot H. Loyd Child in the cockpit of a P-40A during that time. Loyd Child was an inaugural inductee in the Niagara Frontier Aviation and Space Hall of Fame in 1985.
See more details at the excellent This Day in Aviation website.