The Convair XC-99 was the largest piston-driven transport aircraft ever built — and only one was ever made. Born from the massive wing of the B-36 Peacemaker bomber, this double-deck giant could haul 100,000 pounds of cargo or 400 fully equipped troops in a single sortie. Powered by six Pratt & Whitney R-4360 Wasp Major engines producing a combined 21,000 horsepower, it logged over 7,400 flight hours and moved more than 60 million pounds of freight across nearly a decade of service. It supported Korean War logistics, supplied Arctic DEW Line stations, and proved that very heavy strategic airlift was no theory — it was an operational reality. Yet the Air Force never ordered a second one. Not because it failed, but because the jet age made it obsolete. The concept it validated wouldn’t be fully realized until the C-5 Galaxy arrived over twenty years later. This is the story of a machine th

Source: America’s Largest Piston Driven Transport Ever Built | The Convair XC – 99