The tri-winged Barling Bomber was one of the most notorious military boondoggles of the 1920s. The exorbitantly expensive plane, which never made it out of prototype, was knocked for being ludicrously slow despite being equipped with an unprecedented six engines. It was a prime example of what happens when designers feel obligated to respond to the demands of bean counters (PDF):
At the close of World War I, the Army owned Liberty aircraft engines far in excess of its airframes. Consequently, Congress mandated that the World War I surplus be used before the service could purchase new equipment. The Barling was one of many aircraft that featured government-furnished engines. The Barling’s wingspan of 120 feet (the exact distance of the first sustained heavier-than-air flight and longer than the B-17’s wingspan of 104 feet) made it unwieldy and underpowered, yet it needed only 320 yards to take off. The maximum speed of 96 miles per hour and range of 170 miles were far less than Army-aviation enthusiasts had hoped to achieve with the design. Initially costing $375,000, the aircraft carried a final price tag of $525,000, excluding its special hangar, which cost more than $700,000.
On the plus side, the Barling inspired some pretty heavy-metal art in its day.