Deep in the mojave, the largest aircraft ever made will soon be making test flights. This is the Stratolaunch, and it’s measured the largest to ever fly based on wingspan. The Stratolaunch was constructed out of two 747s, and is designed for a single purpose: as a mobile launch platform for orbital rockets.
There are a couple of ways to measure the size of an aircraft. The AN-225 Mriya has the highest payload capacity, but only one of those was ever built (though that might change soon). The Spruce Goose was formerly the largest aircraft by wingspan, but it only flew once, and only in ground effect. The Stratolaunch is in another category entirely. This is an aircraft that contains some of the largest composite structures on the planet. Not only can you park a school bus between the fuselages of the Stratolaunch, you can strap that school bus to the plane and carry it up to 30,000 feet.
But why build this astonishing aircraft? The reasons go back more than a decade, and the end result is a spaceplane.