From the 747 and its iconic 'hump', to the FA/18 Super Hornet, for nearly 100 years Boeing aircraft have been among the most recognisable and common aircraft in the world. But here are a few concept and production aircraft conceived by Boeing over the past century that you may not have heard of and the reasons why they weren't so popular.
1. The 2707 SST Project (1960)
The Boeing 2707 Super Sonic Transport (SST) was a canceled concept that was America's answer to the Concorde. It was designed to hold significantly more passengers than Concorde and capable of cruise speeds of around Mach 3.
The project was eventually canceled after bad publicity over concerns of economic viability, sonic booms and environmental issues.
2. The Monomail (1930)
One of the first examples and often credited for diverting from biplane-style manufacturing and featuring an early example of retractable landing gear, the Monomail was initially developed for air-mail routes within the US.
Only 2 aircraft were ever built and due to restrictions in technology and other multi-engined models, (such as the Boeing 247) surpassing the design with various more advanced technologies.
Intended as a bomber-crew trainer, two airframes were ordered by the US Air Corps. Shortage of building materials resulted in the fuselage being built primarily of wood with a steel airframe.
Due to America's entry into World War 2, the project was not of priority and an order of 1,000 aircraft canceled.
4. The YC-14 (1976)
With the Lockheed C-130 Hercules the primary tactical airlifter of the US Air Force, Boeing developed its own medium STOL aircraft in the form of the YC-14. With its unusual design incorporating high-mounted jet engines, the project was considered very successful.
However the necessity for a strategic vs. tactical mission designed military transporters, meant the YC-14 design later graduated into the C-X program, which brought about the larger and upgraded C-17 Globemaster that is currently in service.
5. The L-15 Scout (1947)
While not marketed as a General Aviation aircraft, Boeing developed the L-15 in an attempt to expand its product range following the slow in production of combat aircraft after World War 2. Designed as a STOL aircraft, it was powered by a Lycoming 125hp engine.
Only 12 units were ever produced and due to lack of financial success of the project, they were eventually used by the government for minor roles and Boeing abandoned producing single-engine small aircraft as a result.
6. The Sonic Cruiser (2001)
A concept airliner that never entered production, this was to be Boeing's next generation of airliner. With a delta wing and a high sub-sonic speed, the intention was to offer a faster aircraft of near-sonic or supersonic speeds.
With airlines holding preferences of lower operating costs over higher speeds, the project was eventually abandoned and the Dreamliner project was pursued instead.
7. The XP-8 (1928)
A private ventured protype and intended as a biplane fighter, the aircraft was uniquely noted as incorporating its engine radiator into the lower wing root, and a more rounded nose to reduce aerodynamic drag.
With slower than required speed of what was expected from a fighter plane, and various engine fluid leaks that were never resolved, the single prototype never progressed into production and the project was abandoned.
A video of the unveiling of the Sonic Cruiser.