[1] The White Knight carrier airplane was designed around the twin afterburning General Electric J85 engines, which were selected for their availability and low cost.

These trailing edge spoilers were designed to greatly increase the glide slope so that the White Knight vehicle could act as a flying simulator for training of SpaceShipOne pilots.

The spoilers deployed into the free stream and began a limit cycle forcing the pilot (Mike Melvill) to abort.

Subsequently, White Knight flew as part of the Tier One program that won the Ansari X Prize on October 4, 2004.

First captive carry flight was on June 21, 2005, and first drop was on April 7, 2006 (the X-37 was subsequently damaged on landing at Edwards Air Force Base).

In late 2006, White Knight flew a seven-flight test program of the adaptive compliant wing developed by FlexSys Inc. with funding by the Air Force Research Laboratory.

[2][3] In July 2014 White Knight made its final planned flight, arriving at Paine Field in Everett, Washington, to become part of the Flying Heritage Collection.