The B-17 and the B-29 established Boeing's reputation as a builder of heavy bombers. Until the Flying Fortress and the Superfortress flew, only a few four-engine bomber designs had been successful. The two big Boeing bombers set the pattern for large, high-flying military aircraft for years to come. Once the war was over, their design contributed to the development of subsequent transports and airliners as mass transportation by air became a way of life.