One plane made flying affordable for passengers and profitable for airlines, and helped win World War II: the DC-3. Wing flaps. A circular fuselage. Swept back wings. A little bit of the historic DC-3 exists in every plane that flies today. This masterpiece of engineering went against all received aviation wisdom when it was created in the 1930s, but the gamble paid off magnificently, and created a revolution. The DC-3 helped boost an economy still reeling from the Depression, played the lead role in the D-Day invasion, and through its versatility, rugged reliability, and economy, changed air travel forever.