Geoffrey Morrison/CNET

The years following World War II were a fascinating time for aviation. The war had brought incredibly rapid technological advancement, bridging the gap between small and slow propeller aircraft to impossibly fast jets. Aeronautical engineers now had copious amounts of new technology at their disposal and the looming threat of the Cold War provided an impetus for even more development. Countless new ideas were thrown together to see what would stick, or more accurately, fly. From this confluence emerged unique aircraft the likes of which were never seen before or since. Aircraft like the nearly-forgotten 10-engine Convair B-36 Peacemaker.

The B-36 was a huge leap in size and performance over its predecessors. It remains the largest piston-powered combat aircraft ever. Early models "only" had six enormous 71-liter, 28-cylinder radial engines in a rare pusher-prop configuration. These were soon augmented by four jet engines, for a total of 44,000 horsepower, creating one of the only aircraft ever powered by both.

Of the nearly 400 examples built, only 4 intact examples remain. Despite its record size, the B-36 was largely overshadowed by its more famous predecessor, the B-29, and its long-lived successor, the still-flying B-52. The Peacemaker never saw combat and was only in service for 11 years, but its bizarre design is an example of a unique time in aviation history. Here's a closer look.

Peacemaker

The B-36 was designed with one main goal: to be able to attack Nazi-controlled Europe from North America. In the early 1940s, it seemed possible Germany would capture the continent and Britain. Their next stop would be the United States, and they were working on aircraft to do just that. Against this threat the Army Air Corps wanted a bomber that could carry a significant payload from the eastern tip of North America, across the Atlantic, and back again. Remember, this was an era where doing that in one direction with no payload was quite a challenge.

It wasn't until after the war that the Peacemaker would finally fly. It was a huge increase in performance over the B-29s. which entered service late in the war in 1944. Jet-powered interceptors were still a few years away from wide use, and ICBMs were decades away. So the need for an ultralong-range heavy bomber fit right into the US's Cold War strategy.

It's easy now to take the B-36's size for granted. In this age of A380s and 777Xs, the B-36 seems puny. But looking at it in a historical context tells a different story. It was 64% longer than a B-29, a giant of its time. Even today, its 230-foot (70.1-meter) wingspan is the widest of any combat aircraft in history, even wider than a modern 747's. Its payload capacity was so great it could have carried the entire bomb load of a B-17, plus the weight of that entire aircraft, its crew, and the weight of a P-51 Mustang escort.

As for range, a modern Boeing 787-8 can travel up to 8,463 miles (13,620 km). Sixty years earlier, the B-36 could fly up to 7,970 with similar payloads, albeit significantly more slowly. With its massive fuel tanks and incredible endurance, some versions of the B-36 could stay aloft for one-and-a-half to two days. There were bunks in the back for the crew and, mercifully, a toilet.

In terms of propeller aircraft size, only the Spruce Goose makes it look small. But then, the Spruce Goose makes everything look small. One pilot described flying this beast as "sitting in a bay window and flying an apartment house."

Nuclear power

Because of its size and lifting capacity, the B-36 quickly became a platform for engineers create even stranger aircraft. It helped test the delta wing design for what would become the Mach 2-capable B-58. One was converted to carry, launch and capture a modified F-84, like a sort of flying aircraft carrier. The "parasite" fighter was first intended as an escort craft, then later for reconnaissance or as a fast delivery vehicle for tactical nuclear weapons.

A cargo version was built, the even more enormous double-deck XC-99. Though it never entered mass production, the prototype was used by the Air Force for eight years.

National Museum of the Air Force

But in what has to be one of, if not the most outrageous idea in the history of aviation, one B-36 was modified to carry an active nuclear reactor. The idea behind the NB-36H was to see if powering an aircraft with nuclear power was feasible. Externally it was the same as a standard B-36. Inside, however, extensive modifications included heavy lead shielding and foot-thick leaded glass. The NB-36H flew dozens of flights with the reactor active to judge the crew's radiation exposure. And while this aspect proved to be sufficiently "safe," the idea was thankfully scrapped.

Rapid obsolescence

A peculiar aircraft for a unique time, the B-36 quickly became obsolete. With the Soviet Union pumping out thousands of MiG-15s, the development of intercontinental ballistic missiles, and jet engines becoming more powerful, efficient and cheaper to build, the idea of a piston-powered bomber was becoming anachronistic (well, mostly). Convair tried to address this with the YB-60, which was largely a swept-wing, fully jet-powered B-36. It wasn't successful and only the prototype was built.

Geoffrey Morrison/CNET

Instead, the B-36 was pulled from service in 1959 after only 11 years. It was replaced by the main competition to the YB-60, the YB-52. A design so good the production version is not only still in service, but expected to remain so until the 2050s. At that point, the youngest airframe will be approaching 90 years old.

By the mid 1960s, nearly all 384 Peacemakers were scrapped.

The B-36 today

Only four of these enormous aircraft survive intact, and all are in museums you can visit. The last B-36 built, the City of Fort Worth, is at Arizona's incredible Pima Air and Space Museum. Another is at the Castle Air Museum in Atwater, California. Not surprisingly, the last two are at the Strategic Air Command and Aerospace Museum in Nebraska and the National Museum of the United States Air Force in Ohio.

There's not much living history of these planes. They don't have the legendary status of the B-17, B-29 or B-52. None are flying, and they aren't the subject or setting for documentaries or movies (a video clip of the exception is above). Few museums have the space to house such massive aircraft, so it's good that even four are still around and that the B-36 didn't suffer the fate of the Short Sterling.

If those museums aren't on your agenda, check out the gallery above for a look at the B-36 past and present.

As well as covering TV and other display tech, Geoff does photo tours of cool museums and locations around the world including nuclear submarines, massive aircraft carriers, medieval castles, airplane graveyards and more.

You can follow his exploits on Instagram, Twitter, and on his travel blog BaldNomad. He also wrote a bestselling sci-fi novel.