Everyone loves big planes. The bigger they are the more interesting they become. Famed mammoths like Howard Hughes' HK-1 "Hercules," otherwise known as the "Spruce Goose," and Antonov's gigantic An-225 "Dream" conjure up feelings that man has somehow cheated physics by creating such flying hulks.

Even today's Airbus A380s, the grand star of any international airport that can receive them, make's people stop mid-traffic just to marvel at their imposing form. So what makes the cut as a gigantic airplane? There is no real criteria, it's just one of those things that you know when you see it.

Buried deep among Aviation's long line of flying juggernauts is a little known but very remarkable machine that rivals almost anything today in shear size and visual impact, the one of kind Convair XC-99. The XC-99 was first flown on a sunny day in San Diego in the year 1947, seemingly a good year for mammoth aircraft (the Spruce Goose took its only flight that same year). The XC-99 was a transport derivative of the legendary B-36 Peacemaker strategic bomber. The 400,000lb Peacemaker sported six piston engines that featured pusher props and a long slender fuselage. It became the staple of America's long-range nuclear strike capability for almost a decade following WWII.

The idea of adapting the B-36 for the intercontinental transport role was fairly intuitive as the Peacemaker had true intercontinental reach and a sizable payload capability to begin with. Curtis utilized key components of the B-36 to produce the XC-99, although the fuselage was designed quite differently than the bomber configuration. The XC-99 disposed of the B-36′s long and slender lines and replaced it with a massive double-decker cavernous fuselage. The XC-99 truly looked like the grandfather of the Airbus A380 as we know it today. In it's final configuration the aircraft could haul some 400 fully outfitted troops over long distances, or over 100,000lbs of cargo.

Although the aircraft was considered literally a large success, the USAF never ordered any production examples. The jet age was right on the horizon and although the XC-99 was highly capable, many in the USAF's leadership believed that investing further in maintenance intensive and finicky piston powered aircraft was something of a dead-end. Regardless, the XC-99 was put into service for 7 years, mainly as the B-36 fleet's cargo hack. During the Korean War the lone XC-99 would fly from B-36 base to B-36 base loaded with spare parts in order to keep the complex and finicky Peacemakers flying, which was a high-priority at the time as they sat alert "cocked and locked" as a nuclear deterrent.

By 1957 the XC-99 was increasingly expensive to maintain and operate and after 55+ million pounds of cargo and 7500 hours of flightime she was retired at Kelly Air Force Base. She remained at Kelly for almost a half century until 2004 when she was disassembled and flown to Wright Patterson AFB via C-5 for restoration and eventual display. Sadly, she has remained in pieces outside at Wright Patterson for years as the museum has been struggling with how involved the restoration of the now highly corroded aircraft would be. Regardless of her unfortunate state today, the XC-99 was one seriously massive piece of hardware, and to think she could fly almost 10,000 miles on piston motors is just astonishing…

An interesting aspect of the XC-99 program was Convair's almost successful attempt at turning the massive double-decker cargo-ship into a luxury airliner. Resembling the Airbus A380 of today, the Convair Model 37 would have had open living areas, circular staircases and many other luxury features more reminiscent of high-end trains and cruise-liners than an airliner as we know them today. The "Model 37" as it was called was configured to carry 210 passengers in an all luxury layout over a 4500 mile distance. Continental Airlines even went as far as ordering 15 of these super jumbos of yesteryear, but once they came to the realization of just how much fuel and oil their six massive piston engines would consume they pulled out of the project stating that it was economically unmarketable and unless the aircraft could be fitted with turboprops, a cutting edge technology at the time, they could not purchase the planes. Unfortunately turboprops never made it to the Model 37 and what would have been the largest airliner of it's kind never made it off the drawing board.

Pictures via USAF and Public Domain