The Spaceflights of SpaceShipOne

During the opening decades of the Space Age, crewed spaceflight was restricted to programs sponsored by the world’s largest governments. In order to spur civilian commercial efforts in low-cost crewed spaceflight, the X Prize Foundation (a non-profit organization founded in 1994 that designs and hosts public competitions intended to encourage technological development to benefit humanity) announced a competition in May of 1996 to build and fly the first non-government-developed, reusable crewed spacecraft. Modelled after prizes to spur developments in aviation during the early 20^th century, the $10 million “X Prize” (renamed the “Ansari X Prize” after a sizable donation by entrepreneurs Anousheh Ansari and Amir Ansari in May 2004) was offered to the first non-government team to build a reusable spacecraft and fly it into space, as defined by the 100-kilometer Karman line, twice within two weeks.

Over two dozen teams across the globe competed for the Ansari X Prize and the glory of being the first to exploit a potential commercial frontier. As time passed it was clear that only a handful of the competitors had any realistic chance of winning the prize and in the end only one won the Ansari X Prize 8½ years after it was announced: Scaled Composite’s SpaceShipOne.

The Origin’s of SpaceShipOne

Scaled Composites was established in 1984 in Mojave, California by American aerospace engineer and entrepreneur, Burt Rutan. Specializing in the development and construction of innovative experimental aircraft, Scaled Composites’ first major success was the Rutan Model 76 Voyager which became the first aircraft to circle the globe nonstop and without refueling in December 1986.

A view of Scaled Composites’ Model 76 Voyager as it was approaching landing on December 23, 1986 at the end of its record setting nonstop, unrefueled flight around the globe. (NASA/Thomas Harrop)

While Rutan had considered some suborbital aerospace plane concepts as early as 1994, work on what would become SpaceShipOne started in April 1996 in an internal program dubbed Tier One. Preliminary development started in 1999 with full development commencing in April 2001. A substantial investment in the program was made by Microsoft co-founder, Paul Allen, who formed a joint venture with Scaled Composites called Mojave Aerospace Ventures. The new company would own the intellectual property from the Tier One program and handle its commercial spinoffs.

Developed over the course of three years in secret, SpaceShipOne (also known as Scaled Composites Model 316) was a highly innovative aircraft typical of Rutan’s creations. With a fully loaded mass of 3,600 kilograms, SpaceShipOne had a cigar-shaped fuselage made primarily of graphite-epoxy composites with a total length of five meters and a diameter of 1.52 meters. The front of the fuselage was occupied by the pressurized cabin which could support a pilot and two passengers at sea level conditions. The back of the fuselage housed the propulsion system which consisted of a hybrid solid rocket motor manufactured by SpaceDev. Producing 88 kilonewtons of thrust for up to 87 seconds, this hybrid motor used HTPB (Hydroxyl-Terminated PolyButadiene) as a fuel and liquid nitrous oxide held in a tank under pressure and room temperature which was integrated with the motor’s casing. Unlike normal solid rockets which burn until its propellants are exhausted once ignited, this hybrid motor could be shut down at any point by cutting off the oxidizer supply to meet mission requirements or abort its flight if necessary. The motor had a loaded mass of 2,700 kilograms and was 1,200 kilograms empty.

Drawing showing the side, top and front views of SpaceShipOne. Click on image to enlarge. (Kaboldy)

Probably the most innovative feature of SpaceShipOne was its short, stubby wings. With a span of 5 meters and a chord of 3 meters, each wing sported a large vertical tail boom on its end fitted with horizontal stabilizers. These wings had movable aerodynamic control surfaces to provide attitude control during atmospheric flight. Once above the sensible atmosphere, attitude control was provided by three sets of redundant cold gas thrusters. The most innovative feature of the wing was that it was hinged allowing it and the tail booms to rotate upward during descent. This produced a high-drag yet aerodynamically stable configuration to help slow SpaceShipOne more quickly and at higher altitude just greatly reducing reentry heat loads. With this innovative feature, SpaceShipOne could safely reach altitudes as great as 112 kilometers on a suborbital path – well above the Karman line and comparable to the performance of the X-15 (see “The First Reusable Spacecraft: The Origins and First Test flight of the X-15”)

The Mission & Pilots

In order to start its rocket-propelled climb to the edge of space, SpaceShipOne required a carrier aircraft to get it aloft. This job was given to the purpose-built Scaled Composites Model 318 better known as the White Knight. Yet another example of Rutan’s unconventional aircraft designs, White Knight has a wingspan of 25 meters and a maximum takeoff weight of 8,200 kilograms. Powered by a pair of afterburning GE J85-series jet engines, White Knight can carry payloads as high as 16 kilometers. The first element of the program to fly, White Knight made its first flight on August 1, 2002 as development of SpaceShipOne continued in secret.

A view of Scaled Composites Model 318 White Knight in flight. (D Ramey Logan)

A typical flight of SpaceShipOne would start with its drop from White Knight at an altitude of up to 15 kilometers. The pilot would ignite the hybrid rocket and begin the steep climb toward the Karman line. After reaching the preplanned altitude and speed for a mission (which could be in excess of 900 meters per second or Mach 3), the pilot would shutoff the nitrous oxide oxidizer supply to the hybrid motor to stop its burn. SpaceShipOne would then glide towards apogee with the pilot and passengers experiencing up to over three minutes of weightlessness.

Diagram showing the typical flight profile for SpaceShipOne. Click on image to enlarge. (Mojave Aerospace)

After reaching apogee, SpaceShipOne would use a unique feathering reentry system to slow down during its steep descent where deceleration loads could reach as high as 5 gs. Once the craft had descended to an altitude of 10 to 20 kilometers, the wing on SpaceShipOne moved back into its low-drag configuration so that it could glide to a landing on a runway about 20 minutes or so after its launch.

Three pilots would fly SpaceShipOne during its flight program. Brian Binnie, born in 1953, was a former Naval aviator of 21 years and had graduated from the U.S. Naval Test Pilot School in 1988. Mike Melvill, born 1940 in South Africa, had been Scaled Composites’ lead test pilot since Rutan hired him in 1982. Peter Siebold, born 1971, was an aerospace engineer and licensed pilot who had been working at Scaled Composites since 1996. Among other tasks, he was responsible for the development of the SpaceShipOne simulator all the pilots would train on.

First Flights

Shown here is White Knight carrying SpaceShipOne during a captive flight test. (Scaled Composites,LLC)

SpaceShipOne made its first captive test flight, designated Flight 01C, attached to White Knight on May 20, 2003 with nobody aboard. Its first glide flight, designated 03G, was made on August 7 with Mike Melvill at the controls. Peter Siebold made his first glide flight, 08G, on November 14. Flight 11P with Brian Binnie was the first powered flight on December 17 – the centennial of the Wright brothers’ first powered flight. Binnie reached a peak speed and altitude of Mach 1.2 and 20.7 kilometers, respectively, during this 18-minute flight. During the spring of 2004, SpaceShipOne made a series of three additional test flights to higher speeds and altitudes in preparation for its first spaceflight.

Mike Melvill about to board SpaceShipOne for its historic Flight 15P above the Karman line on June 21, 2004. (Scaled Composites, LLC)

Based on the confidence built up from the series of test flights and with the receipt of a one-year license for suborbital rocket flights issued on April 1, 2004 from the US Office of Commercial Space Transport, SpaceShipOne was ready to attempt its first spaceflight with a planned apogee of 110 kilometers. Flight 15P started at 6:47 AM PDT on June 21, 2004 with the takeoff of White Knight from the Mojave Spaceport in California just four days after it had received its official FAA certification as a spaceport.

A view of SpaceShipOne during its descent on Flight 15P with its wings in the feathered position. (Scaled Composites, LLC)

With Mike Melvill at the controls, SpaceShipOne was released from White Knight at 7:50 AM at an altitude of 14.3 kilometers. Melvill immediately ignited the rocket motor and SpaceShipOne started its climb. While there were some issues controlling the craft’s attitude during the climb, the rocket motor shutdown after a 76-second burn at an altitude of 54.9 kilometers with the speed at 961 meters per second. At Mach 2.9, this was already the fastest a civilian aircraft had ever flown. Because of the attitude issues during the climb, SpaceShipOne reached a peak altitude of only 100.1 kilometers – lower than planned but still just above the 100-kilometer Karman line making this the first ever civilian spaceflight. After experiencing about 3½ minutes of weightlessness, Melvill reentered the atmosphere and successfully landed SpaceShipOne at the Mojave Spaceport in front of a crowd of 11,000 people gathered to witness the historic flight which lasted 24 minutes and five seconds. In addition to becoming the first commercial astronaut, Melvill was also the oldest person to fly into space for the first time at the age of 63 years (handily beating the record of 53 years old held since 1985 by Dutch-born American astronaut, Lodewijk van den Berg, who flew on the Space Shuttle Challenger as a Payload Specialist on the STS-51B mission)

Going for the Prize

White Knight taking off from the Mojave Spaceport carrying SpaceShipOne on Flight 16P. (Mike Massee/Scaled Composites, LLC)

After the issues with Flight 15P were analyzed over the next two weeks, it was decided that another test flight was not needed and all efforts turned towards flying the pair of flights required to win the Ansari X Prize. After delays due to early morning winds, Flight 16P got underway with the take off of White Knight at 7:11 AM PDT on September 29, 2004 with Mike Melvill once again at the controls of SpaceShipOne. At 8:09 AM, SpaceShipOne was released and ignited its rocket motor six seconds later. Some 50 seconds into the powered ascent, SpaceShipOne began to roll as it surpassed Mach 2.7 but given the high altitude conditions, there was little aerodynamic stress on the craft so it was not a concern. Once instrumentation indicated the required altitude could be achieved, Melvill shut down the rocket motor after a burn of 76 seconds.

SpaceShipOne shown coming in for a landing at the end of Flight 16P. (Mike Massee/Scaled Composites, LLC)

SpaceShipOne reached a peak altitude of 102.9 kilometers comfortably exceeding the Karman line and satisfying the Ansari X Prize requirements. Melvill was then able to damp out the unexpected roll using reaction jets and proceeded to perform his reentry and glide towards landing. Flight 16P ended with a successful landing at the Mojave Spaceport after a flight of 24 minutes and 11 seconds. SpaceShipOne had become the first civilian spacecraft to fly into space twice while Melvill became the first commercial astronaut to do the same. With this success under their belt, the team had just 14 days to repeat their feat to win the Ansari X-Prize.

Brian Binnie shown at the controls of SpaceShipOne prior to its take off for Flight 17P on October 4, 2004. (Mike Massee/Scale Composites, LLC)

Just five days after Flight 16P, SpaceShipOne was ready for Flight 17P, this time with Brian Binnie at the controls. The flight began with the takeoff of White Knight at 6:49 AM PDT on October 4, 2004 – the 47^th anniversary of the launching of Sputnik and the beginning of the Space Age (see “Sputnik: The Launch of the Space Age”). White Knight released SpaceShipOne at 7:49 AM at an altitude of 13.3 kilometers and Binnie promptly ignited the rocket motor. The climb was nearly perfect with SpaceShipOne hitting Mach 3.09 at burnout and reaching a peak altitude of 112.01 kilometers. This milestone not only secured the Ansari X-Prize but also broke the rocket plane altitude record of 107.96 kilometers set 41 years earlier by Joe Walker flying the X-15-3 (see “The First Reusable Spacecraft: The X-15 Flights Above the Karman Line”). Binnie successfully landed SpaceShipOne at the Mojave Spaceport at 8:13 AM after a flight of 23 minutes 56 seconds.

SpaceShipOne shown climbing during its final flight to secure the Ansari X Prize on October 4, 2004. (Vulcan/Discovery Channel Productions/Scaled Composites,LLC)

Afterwards

A fourth spaceflight using SpaceShipOne that was scheduled for October 13, 2004 was cancelled as were all future flights so as not to risk damaging the historic (and unique!) SpaceShipOne. On October 5, 2005 SpaceShipOne was placed on display in the National Air and Space Museum in Washington, DC where it remains today. Based on the experience with SpaceShipOne, Burt Rutan teamed up with Sir Richard Branson to form Virgin Galactic which is developing the suborbital SpaceShipTwo for space tourists. Peter Siebold, who had previously flown SpaceShipOne, was badly injured (and his copilot, Michael Alsbury, killed) during a test flight of the SpaceShipTwo prototype called VSS Enterprise on October 31, 2014.

A view of SpaceShipOne on display at the Smithsonian Air & Space Museum. (D Ramey Logan)

As for the other pilots of SpaceShipOne, Mike Melvill continued on at Scaled Composites as a Vice President/General Manager. Brian Binnie was a program manager at Scaled Composites until he signed on as a senior engineer and test pilot for XCOR Aerospace in 2014. XCOR’s projects at the time included developing the Lynx suborbital space plane for space tourists but, unfortunately, the company declared bankruptcy in 2017. While the commercial spaceflight market spurred by the Ansari X Prize remains illusive, it is just a matter of time before the next suborbital crewed spaceflight is made and eventually become routine.

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Related Videos

Here is a long documentary produced by the Discovery Channel on the development and flights of SpaceShipOne entitled “Black Sky: The Race for Space”.

Black Sky The Race for Space from Richard Jones on Vimeo.

Related Reading

“A History of Suborbital Crewed Spaceflights”, Drew Ex Machina, May 5, 2016 [Post]

“The First Reusable Spacecraft: The X-15 Flights Above the Karman Line”, Drew Ex Machina, August 22, 2020 [Post]