Image via WikipediaOn Oct. 4, 2004, SpaceShipOne completed flight 17P, its second manned spaceflight in five days, thereby securing the Ansari X Prize as the first viable private manned spacecraft in human history. To get there, SpaceShipOne first had to get US Federal Aviation Administration approval to fly -- which was somewhat complicated given that there was no existing registry category for a private passenger spaceplane.
Scaled Composites, the manufacturer of SpaceShipOne, applied for the registry number N100KM. N is the prefix for all US-registered aircraft. The 100KM was a reference to the 100-kilometer altitude that SpaceShipOne needed to achieve to qualify for the X Prize. Unfortunately, N100KM was already listed, so SpaceShipOne instead got the registry number N368KF for 368 kilo-feet, which is roughly equal to 100 kilometers.
To get that aviation equivalent of a license plate, SpaceShipOne had to be shoehorned into an existing passenger aircraft classification.
What class of aircraft does the FAA consider SpaceShipOne?
SpaceShipOne -- the first viable private manned spacecraft -- is officially classified as a glider by the FAA.
Yes, the FAA's Office of Commercial Spaceflight licensed SpaceShipOne's rocket motor for suborbital flight. Yes, you wouldn't expect anything with a rocket motor to be called a glider. That said, for most of SpaceShipOne's independent flight, it is an unpowered glider.
After the White Knight parent launch aircraft drops SpaceShipOne, it engages the rocket motor to achieve suborbital flight. Once space altitude is achieved, the motor disengages and SpaceShipOne deploys its "shuttlecock" glide planes that allow it enter a controlled glide back to Earth. For the entire descent portion of its flight, SpaceShipOne is a glider -- if a wildly unconventional one.
That's not just some non-traditional technical taxonomy, it's an aerodynamically extraordinary example of the Truly Trivial