The modern airliner was born in the USA in the mid-1930s. The long intercity distances, a powerful business culture and strong government support for an airmail system, all combined to sponsor airline development.

The essential element of the new 'stressed skin' airliners was to make them leaner and more aerodynamic by using the surface skin of aluminium alloy to contribute to the strength. Making the skin share the structural loads in this way was a major task for engineering design and for mathematical analysis. The aircraft also took advantage of the developing science of aerodynamics.

Boeing led the field with the 247 airliner in 1933, quickly followed by Douglas with the DC-1, DC-2 and DC-3 and Lockheed with the Electra. All three companies used similar engineering solutions. Boeing and Douglas relied crucially on wind-tunnel data from the new research facility at the California Institute of Technology (Caltech) set up by the eminent aerodynamicist Theodore von Karman. The rival Lockheed company used aerodynamic analysis from the University of Michigan and the researcher involved, Clarence L. ('Kelly') Johnson, joined Lockheed to complete the aircraft. He then helped to follow up the Electra with a series of outstanding aircraft, including the Constellation, which made Lockheed for many years one of the major builders of airliners.

Although jet engines have replaced piston engines and propellers, the basic architecture and construction techniques of the airliner today still follow the pattern established by influential aircraft such as the Electra.

Inv. 1982-964