Development of Commercial Aviation - US Airway
The Douglas DC-3 airplane began passenger service in 1936. The DC-3 featured several technological improvements over earlier airplanes, such as streamlining, and soon became the world’s most popular passenger airplane.
Commercial aviation began in January 1914, just 10 years after the Wrights pioneered the skies. The first regularly scheduled passenger line in the world operated between Saint Petersburg and Tampa, Florida. Commercial aviation developed slowly during the next 30 years, driven by the two world wars and service demands of the U.S. Post Office for airmail. (Development of Commercial Aviation - US Airway)
In the early 1920s the air-cooled engine was perfected, along with its streamlined cowling, or engine casing. Light and powerful, these engines gave strong competition to the older, liquid-cooled engines. In the mid-1920s light airplanes were produced in great numbers, and club and private pleasure flying became popular. The inexpensive DeHavilland Moth biplane, introduced in 1925, put flying within the financial reach of many enthusiasts. The Moth could travel at 145 km/h (90 mph) and was light, strong, and easy to handle. (Development of Commercial Aviation - US Airway)
Instrument flying became practical in 1929, when the American inventor Elmer Sperry perfected the artificial horizon and directional gyro. On September 24, 1929, James Doolittle, an American pilot and army officer, proved the value of Sperry’s instruments by taking off, flying over a predetermined course, and landing, all without visual reference to the Earth. (Development of Commercial Aviation - US Airway)
Introduced in 1933, Boeing’s Model 247 was considered the first truly modern airliner. It was an all-metal, low-wing monoplane, with retractable landing gear, an insulated cabin, and room for ten passengers. An order from United Air Lines for 60 planes of this type tied up Boeing’s production line and led indirectly to the development of perhaps the most successful propeller airliner in history, the Douglas DC-3. Trans World Airlines, not willing to wait for Boeing to finish the order from United, approached airplane manufacturer Donald Douglas in Long Beach, California, for an alternative, which became, in quick succession, the DC-1, the DC-2, and the DC-3. (Development of Commercial Aviation - US Airway)
The DC-3 carried 21 passengers, used powerful, 1,000-horsepower engines, and could travel across the country in less than 24 hours of travel time, although it had to stop many times for fuel. The DC-3 quickly came to dominate commercial aviation in the late 1930s, and some DC-3s are still in service today. (Development of Commercial Aviation - US Airway)
Boeing provided the next major breakthrough with its Model 307 Stratoliner, a pressurized derivative of the famous B-17 bomber, entering service in 1940. With its regulated cabin air pressure, the Stratoliner could carry 33 passengers at altitudes up to 6,000 m (20,000 ft) and at speeds of 320 km/h (200 mph). (Development of Commercial Aviation - US Airway)