from flight tests. This yields a highly accurate image of craft behaviour, even in unanticipated modes of flight. (This is one of the first modern aircraft to be designed without wind tunnel testing.) The cockpit replica is on a static base, and so cannot accurately reproduce the equilibrioceptive and accelerative aspects of flight. However, White Knight is equipped to operate as a high-fidelity moving-base simulator. The simulator cockpit is an accurate copy of the SpaceShipOne cabin, including its avionics. It is the system of pilot plus avionics, not just the pilot, that is being simulated to. The flight simulator program drives the sensor inputs that are used by the avionics, and also drives twelve display computers which use commercial graphics software to generate high-resolution images of the outside view for the pilot. These views appear on eleven monitors and one projector screen. Stick force feedback is not simulated in real time. Ground-based flight simulation is not only used for pilot training. It is also used to train ground crew, develop procedures, and test the avionics software and hardware. History and status According to Scaled Composites, the concept for the program originated in April 1996, preliminary development began in 1999, and full development began in April 2001. It was initially kept secret, even after White Knight first flew on August 1, 2002. The program was announced to the public on April 18, 2003, when the program was ready to flight-test SpaceShipOne. Its first flight test, SpaceShipOne flight 01C, took place on May 20, 2003. After months of glide tests, the first powered flight, SpaceShipOne flight 11P, was made on December 17, 2003. Further powered tests followed, reaching increasing altitudes, culminating on June 21, 2004 with the first privately funded human spaceflight, SpaceShipOne flight 15P. Ansari X Prize competitive flights followed. SpaceShipOne flight 16P on September 29, 2004 and SpaceShipOne flight 17P on October 4, 2004 were successful competitive flights, winning the X Prize. The Tier One program run by Scaled Composites concluded after the retirement of SpaceShipOne, transitioning to a successor program for customer Virgin Galactic. Funding The costs of development, construction, and operation of Tier One, although not publicly released, are estimated to be in the range of 20 million to 30 million US dollars, roughly two to three times the value of the Ansari X Prize award. The sole sponsor, initially secret, was revealed to be Paul Allen, a