VSS Enterprise


VSS Enterprise was the first SpaceShipTwo spaceplane, built by Scaled Composites for Virgin Galactic. As of 2004, it was planned to be the first of five commercial suborbital SS2 spacecraft planned by Virgin Galactic.
It was also the first ship of the Scaled Composites Model 339 SpaceShipTwo class, based on upscaling the design of record-breaking SpaceShipOne.
The VSS Enterprise's name was an acknowledgement of the USS Enterprise from the Star Trek television series. The spaceplane also shared its name with NASA's prototype Space Shuttle orbiter, as well as the aircraft carrier USS Enterprise.
It was rolled out on 7 December 2009.
SpaceShipTwo made its first powered flight in April 2013. Richard Branson said it "couldn't have gone more smoothly".
Enterprise was destroyed during a powered test flight on 31 October 2014, killing one pilot, Michael Alsbury, and seriously injuring another, Peter Siebold. This was the first spacecraft-related accident in which part, but not all, of the crew survived. An investigation revealed the accident was caused by premature deployment of the "feathering" system, the ship's descent device; the NTSB also faulted the spacecraft's design for lacking fail-safe mechanisms that could have deterred or prevented early deployment.

Flight test program

Initial projections by Virgin Galactic in 2008 called for test flights to begin in late 2009 and commercial service to start in 2011. This schedule was not achieved, with captive carry and glide flight tests beginning in 2010, and the first test flight under rocket power in 2013.
In October 2009, Virgin Galactic CEO Will Whitehorn outlined the flight test program for SpaceShipTwo. The test program includes seven phases:
  1. Vehicle ground testing
  2. Captive carry under White Knight Two
  3. Unpowered glide testing
  4. Subsonic testing with only a brief firing of the rocket
  5. Supersonic atmospheric testing
  6. Full flight into suborbital space
  7. Execute a detailed and lengthy appraisal process with the FAA/AST to demonstrate the system's robustness and eventually obtain a commercial launch license to begin commercial operations.
On 22 March 2010, the SpaceShipTwo vehicle VSS Enterprise underwent a captive carry test flight, with the parent White Knight Two aircraft, VMS Eve, performing a short flight while carrying the Enterprise.
A second test flight was made on 16 May 2010, reaching SS2's launch altitude and lasting nearly five hours, in order to facilitate "cold soak" testing of SS2's avionics and pressurization system. Thereafter, "a simulated spaceship descent/glide mission was made from altitude."
Between these two flights, the SpaceShipTwo airframe was modified by the addition of two interior fins, with one fin being added to the inside of each of the craft's twin vertical stabilizers.
On 15 July 2010, VSS Enterprise made its first crewed flight. The craft remained attached to VMS Eve as planned, and underwent a series of combined vehicle systems tests. The flight lasted a total of 6 hours and 21 minutes. A second, similar crewed flight of VSS Enterprise and VMS Eve was carried out on 30 September 2010, lasting approximately 5 hours. Among the objectives of these flights was the improvement of pilot proficiency, and the results of the flights were deemed to show that the systems were capable of supporting future glide missions.
On 10 October 2010, VSS Enterprise made its first crewed gliding test flight. It was released from VMS Eve at 45,000 ft and glided to a safe landing at the Mojave Air and Spaceport. A second gliding test flight took place on 28 October 2010 and a third on 17 November 2010., Scaled reported that the flight test program was exceeding expectations. The fourth test flight took place on 13 January 2011, while the fifth and sixth glide flights occurred on 22 and 27 April 2011, respectively. Following this, the feathered reentry configuration was tested in flight on 4 May 2011, with weekly test flights continuing through the end of May.
On 9 June 2011, SS2 failed to separate from White Knight Two during its 11th planned glide flight due to a technical problem. Testing resumed with five successful glide flights in June 2011.
In July 2011, after 15 successful glide flights, flight testing of SS2 was halted for two months while planned revisions to the spaceplane were made. Flight tests resumed in late September 2011, although the 16th glide flight – on 29 September – was marred by a brief loss of control aboard SS2, forcing the crew to utilise the feathered wing configuration to land safely. This test was followed by another hiatus, during which some of the spacecraft's engine components were installed. In June 2012, Scaled Composites received an FAA permit to conduct rocket-powered supersonic test flights. SpaceShipTwo flight tests resumed in June 2012.
In September 2012, Virgin Galactic announced that the unpowered glide flight test program was essentially complete. The company thereafter stated its intention to fit the hybrid rocket motor and control system to the vehicle, before resuming the glide flight test program with the rocket motor installed, in order to recharacterize the spacecraft's glide performance with slightly different weight distribution and aerodynamics. In October 2012, Scaled Composites installed key components of the rocket motor, and SpaceShipTwo performed its first glide flight with the engine installed in December 2012.
The spacecraft's first powered test flight took place on 29 April 2013, briefly driving SpaceShipTwo to a supersonic velocity. Richard Branson said it "couldn't have gone more smoothly".
On 5 September 2013, the second powered flight was made by the SpaceShipTwo. It broke the sound barrier achieving a speed of mach 1.43, and climbed to 69,000 feet over the Mojave Desert under rocket power and descended using its tilt-wing "feathering" maneuver. Space journalist Doug Messier reported that "the engine plume featured white smoke, not the black smoke seen on the April flight."
On 10 January 2014, the third powered flight climbed higher than the previous flights, testing a new coating on the tail boom and other systems.

List of test flights

Sources:
Legend
CodeDetail
GFxxGlide Flight
CCxxCaptive Carry Flight
CFxxCold Flow Flight
PFxxPowered Flight
FxxFeathering deployed

Flight designationDateDurationMaximum altitudeTop speedPilot / co-pilotNotes
41 / GF0110 October 201013 min EAS 2 gSiebold / Alsbury
44 / GF0228 October 201010 min, 51 sec EAS 3 gStucky / Alsbury
45 / GF0317 November 201011 min, 39 sec EAS 3.5 gSiebold / Nichols
47 / GF0413 January 201111 min, 34 sec EAS 3.8 gStucky / Nichols
56 / GF0522 April 201114 min, 31 secSiebold / Shane
57 / GF0627 April 201116 min, 7 secStucky / Alsbury
58 / GF074 May 201111 min, 5 secSiebold / NicholsF01
59 / GF0810 May 201113 min, 2 secStucky / Shane
60 / GF0919 May 201111 min, 32 secSiebold / Binnie
61 / GF1025 May 201110 min, 14 secAbove Stucky / BinnieF02
62 / 9 June 2011Siebold / ShaneRelease failure during flight intended as GF11
64 / GF1114 June 201113 min, 18 secSiebold / Shane
65 / GF1215 June 201110 min, 32 secStucky / Nichols
66 / GF1321 June 20118 min, 55 secSiebold / Nichols
67 / GF1423 June 20117 min, 33 secStucky / Nichols
68 / GF1527 June 20117 min, 39 secSiebold / Binnie
73 / GF1629 September 20117 min, 15 secStucky / NicholsF03
87 / GF1726 June 201211 min, 22 secSiebold / Alsbury
88 / GF1829 June 201213 minStucky / Mackay
90 / GF1918 July 201210 min, 39 secSiebold / Nichols
91 / GF202 August 20128 minStucky / NicholsF04
92 / GF217 August 20129 min, 52 secSiebold / ColmerF05
93 / GF2211 August 20128 min, 2 secStucky / Binnie
109 / GF2319 December 201213 min, 24 secStucky / Alsbury
113 / GF243 April 20139 minStucky / NicholsF06
114 / CF0112 April 201310 min, 48 secStucky / Alsbury
115 / PF0129 April 201313 minMach 1.22Stucky / Alsbury
130 / GF2525 July 201311 min, 52 secStucky / Mackay
131 / GF268 August 201310 minStucky / MackayF07
132 / PF025 September 201314 minMach 1.43Stucky / NicholsF08
141 / GF2711 December 2013.11 minStucky / Masucci
147 / PF0310 January 201412 min, 43 secMach 1.4Mackay / StuckyF09
149 / GF2817 January 201414 min, 12 secSiebold / Sturckow
156 / GF2929 July 201412 minMasucci / Siebold
164 / CF0228 August 201413 minSiebold / Alsbury
170 / GF307 October 201410 min, 30 secSiebold / SturckowF10
?? / PF0431 October 20140 min, 13 secroughly ? Siebold / AlsburyUnintended feathering destroys vehicle in-flight

Crash

On 31 October 2014, Enterprise broke apart in flight during a powered test flight over California's Mojave Desert.
The flight began smoothly, with Enterprise being dropped from its WhiteKnightTwo carrier and igniting its engine at an altitude of. About 60 to 90 seconds into the flight, an "anomaly" was reported which resulted in destruction of the ship. The pilot in command, Peter Siebold, escaped from the craft and parachuted to safety; the copilot, Michael Alsbury, was killed in the crash.
The National Transportation Safety Board conducted an independent investigation into the accident. In July 2015, the NTSB released a report which cited inadequate design safeguards, poor pilot training, lack of rigorous federal oversight and a potentially anxious co-pilot without recent flight experience as important factors in the crash. The NTSB determined that the crash resulted from the pilot's premature deployment of the feathering mechanism, which is normally used to aid a safe descent. The NTSB also faulted the ship's designers for failing to protect against human error, noting that the spacecraft lacked fail-safe systems that would have prevented or deterred a premature deployment of the feathering mechanism. The NTSB recommended that the FAA establish human factors guidance specific to commercial spaceflight operators and create a more rigorous application process for experimental spaceflight permits.

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