Convair XC-99 - Prototype Heavy Cargo Aircraft Based on the B-36 Peacemaker
First flew in 1947. Could carry over 100,000 lbs of cargo or 60,000 lbs of cargo 12,000 nautical miles. Only one was built, but it served with the United States Air Force until 1957, primarily ferrying spare parts for B-36 Peacemaker bombers - 7.400 hours of flight time and 60 million pounds of cargo were carried. The sole XC-99 is part of the National Museum of the United States Air Force collection, awaiting restoration.