This is an experimental tracked landing gear unit trialled on the B-36 Peacemaker. With a wingspan of 70 meters (230 ft) and a length of 50 meters (160 ft), the B-36 is one of the largest aircraft ever built.

This is an experimental tracked landing gear unit trialled on the B-36 Peacemaker. With a wingspan of 70 meters (230 ft) and a length of 50 meters (160 ft), the B-36 is one of the largest aircraft ever built.
With its great size came great weight. Initially, the B-36 was to have a single enormous wheel with a 600 kg tire on each main landing gear. These wheels had a relatively small contact area for an aircraft of this weight, resulting in immense ground pressure. With this setup, the B-36 was limited to just a handful of air bases.
The US trialled a tracked landing gear that improved the bomber's weight distribution on the ground. This idea had actually been circulated by J. Walter Christie, a tank designer, in the 1930s and researched throughout the 1940s.
Previous trials had shown some success, but the B-36 was simply too heavy for such a system to cope with. A single flight in March 1950 was performed with the system fitted. The B-36 would eventually receive four-wheel bogies.