Nov 122014
 

As the National Transportation Safety Board (NTSB) is piecing together the structural mishap with the Virgin Galactic SpaceShipTwo braking system, the agency has released details from surviving pilot, Peter Siebold, about how he managed to escape the exploding spacecraft. Photo Credit: Scaled Composites, Peter Siebold

The NTSB operations and human performance investigators interviewed the surviving pilot on Friday, November 7.

According to pilot, Siebold, “he was unaware that the feather system had been unlocked early by the co-pilot, Michael Alsbury.”

Siebold’s description of the vehicle motion was consistent with other data sources in the investigation, the NTSB reports.

Siebold stated that “he was extracted from the vehicle as a result of the break-up sequence and unbuckled from his seat at some point before the parachute deployed automatically.”

Peter Siebold, 43, who was injured, when his parachute deployed, as he fell from the SpaceShipTwo spacecraft, suffered major injuries to his shoulder and underwent surgery, Kern County Sheriff Donny Youngblood’s office confirmed later on after Saturday, November 1, according to Mashable.

On October 31, 2014, SpaceShipTwo abruptly pulled apart nearly nine miles above sea level—at about 50,000 feet in the stratosphere. The test pilots, apparently noticing little that was happening inside the spacecraft cockpit that would be deemed as extremely catastrophically abnormal during the plus Mach 1 flight of SpaceShipTwo, were shocked suddenly, when the spacecraft tore apart all around the helpless test pilots, plunging them into the harsh conditions of the upper stratosphere.

Co-pilot Michael Alsbury, 39, sadly was found dead in the SpaceShipTwo wreckage scattered across the Mojave Desert floor.

NTSB investigators are looking further into the causes of why the test co-pilot, Alsbury, was trapped inside the spacecraft wreckage.

But miraculously, the test pilot, Siebold, was ejected from the spacecraft, while still strapped in his seat, moving at about 600 miles per hour through stratospheric air that was at temperatures of about minus 70 degrees Fahrenheit.

Both test pilots were not wearing spacesuits.

Siebold’s discussion with NTSB investigators on Friday, November 7, is the only specific knowledge of time and place we have about how he survived, as he fell through the harsh stratospheric conditions.

Before he was quickly knocked unconscious, Siebold remarkably recalls feeling his moist tongue actually boiling from his body temperature spontaneously reacting in the high elevation, extremely cold, low pressure stratospheric conditions, the test pilot was suddenly ejected into, as he fell at 600 miles per hour, according to the NTSB report.

You can read more specific details about the pilot’s ordeal, falling through the harsh stratospheric environment, inside an excellent piece in Bloomberg.

Siebold’s parachute deployed automatically, as he fell for about 15 seconds through the stratosphere, before regaining consciousness, as he floated closer to the Mojave Desert floor.

The test pilot was extremely fortunate doctors and high-speed flight experts say, as he suffered no permanent damage from the lack of oxygen. It is a miracle Peter Siebold survived the SpaceShipTwo crash on October 31.

Christopher Hart, NTSB acting chairman, said the safety investigative agency has gathered much of the wreckage of SpaceShipTwo scattered over five miles of the Mojave Desert.

The NTSB is now pouring over the spacecraft debris, which includes the broken spaceship hull, fuel tanks and the rocket engine, to determine the facts, and not quite yet the causes, surrounding the downed Virgin Galactic SpaceShipTwo on Friday, October 31.

Hart said in a press conference on Sunday, November 2 that the rocket engine “came down intact, with no signs of breach or burn-through,” signaling many to surmise that the spacecraft crash was not allegedly caused by engine failure.

Hart described the additional facts about the NTSB’s preliminary investigation of the spacecraft wreckage that focused instead on a structural mishap received by the telemetry and cockpit video feed sent down by the spacecraft, that may have caused a loss of engine thrust power of SpaceShipTwo, while performing its test flight to 62 miles in attitude on Friday over the Mojave Desert.

Hart alluded that as SpaceShipTwo was performing its normal flight envelope outside of the pilot and copilot controls, a catastrophic structural mishap of the feather — “essentially a giant speed brake” — malfunctioned as the SpaceShipTwo was accelerating through its rocket engine power in relatively dense atmosphere that would significantly impede the rocket engine’s designed thermal ratio, thrust power and overall efficiency at its normally high operational Mach number, say at close to one and a half times the speed of sound.

“The spaceship was released normally,” said Acting NTSB Chairman Chris Hart, referring to SpaceShipTwo’s separation from the WhiteKnightTwo aircraft carrier at 45,000 feet in normal flight operation. Subsequently thereafter release, the rocket engine ignited.

The rocket’s hybrid rocket motor, consuming a mix of nitrous oxide and a plastic-based solid fuel mix, ignited a few seconds after SpaceShipTwo’s release from the carrier aircraft.

Friday’s test flight marked the first time the rocket motor was used on SpaceShipTwo, since Virgin Galactic switched from a rubber-based to a plastic-based fuel, according to Space Flight Now.

Nevertheless, said Hart, “Approximately two seconds after the feathering parameters indicated that the Lock/Unlock lever was moved from “Lock” to “Unlock,” the feathers moved toward the extended position, the deployed position, even though the feather handle itself had not been moved.”

Basically, said Hart, “the feather operated prematurely.”

“Normal launch procedures are that after the release (of SpaceShipTwo from the WhiteKnightTwo carrier aircraft), the ignition of the rocket (thrust power is initiated) and acceleration (of the spacecraft commences).”

At this point, “the feathering devices are not to be moved — (that is) the lock/unlock lever is not to be moved into the unlock position — until the acceleration up to Mach 1.4 (or nearly one and a half times the speed of sound). Instead, as indicated, that (feathering) occurred (at) approximately Mach 1.0 (spacecraft flight speed),” Hart said.

According to a definitive technical description of the proper flight performance reported on Monday, November 3 in Popular Mechanics:

“The ship uses a unique design devised by SpaceShipOne designer Burt Rutan to return to safely to Earth after rocketing out of the atmosphere. After the engine cuts off and the ship coasts through its highest point, or apogee, the twin tail booms are designed to hinge upward. When the ship comes back through the atmosphere, the upward-hinged, or “feathered,” booms are designed to catch the air like the feathers of a shuttlecock and slow the craft down in what Rutan called a “carefree reentry.” Once the ship has slowed enough, the feather swings back down, and the pilots spirally glide the ship back down to the runway for landing.”

Hart added: “We have months and months of investigation to determine what the cause was. We’ll be looking at training issues. We’ll be looking at, was there pressure to continue testing. We’ll be looking at safety culture. We’ll be looking at the design, the procedure. We’ve got many, many issues to look into much more extensively before we can determine the cause.”

Appendix A

Here’s a crib sheet synopsis of the facts, given by acting National Transportation Safety Board (NTSB) Chairman Christopher Hart, shown above at the press conference on Sunday, November 2, 2014, as briefly conveyed to reporters at the Mojave Air and Space Port in Mojave, California [Courtesy: @ObservingSpace].

Hart: About to provide statements of facts and not of cause.

Hart: Preliminary review of the telemetry and optical data for the SpaceShipTwo investigation revealed the following facts:

Hart: The vehicle had a nominal release followed by a nominal ignition.

Hart: Approximately 9 seconds after ignition, the “feather” parameters — “essentially a giant speed brake” — changed from lock to unlock.

Hart: In order for feathering to be commanded by pilots, a “feather” handle must be moved in addition to the unlock handle.

Hart: Approximately 2 second later, just above Mach 1.0, feathers moved toward the extended position … even though the “feather” handle was not moved, after which the telemetry data terminated.

Hart: Engine burn was nominal up until feather extension.

Hart: Review of cockpit forward looking camera shows that the feather was unlocked by the co-pilot.

Hart: Normal procedures are to unlock feathers after Mach 1.4, so aerodynamic forces do not extend feathers prematurely.

Hart: When the wreckage is dispersed like that [over 5 square miles], it indicates the likelihood of inflight breakup

Hart: There is still a great deal of investigative work to do to understand all of the issues in the SpaceShipTwo investigation.

Hart: I’m not stating that this is the cause of the mishap … We have months and months of investigation to determine what the cause was.

Hart: There is much more that we don’t know and our investigation is far from over.

Appendix B

NTSB Investigative Update on Crash of Virgin Galactic SpaceShipTwo

National Transportation Safety Board
Office of Public Affairs

November 12, 2014

The National Transportation Safety Board issued an investigative update today into the crash of SpaceShipTwo on October 31, 2014, in Mojave, California.

  • The on-scene portion of the investigation into the crash of Virgin Galactic SpaceShipTwo, a test flight conducted by Scaled Composites, has concluded and all NTSB investigators have returned to Washington, DC.
  • The SpaceShipTwo wreckage has been recovered and is being stored in a secure location for follow-on examination.
  • The NTSB operations and human performance investigators interviewed the surviving pilot on Friday. According to the pilot, he was unaware that the feather system had been unlocked early by the copilot. His description of the vehicle motion was consistent with other data sources in the investigation. He stated that he was extracted from the vehicle as a result of the break-up sequence and unbuckled from his seat at some point before the parachute deployed automatically.
  • Recorded information from telemetry, non-volatile memory, and videos are being processed and validated to assist the investigative groups.
  • An investigative group to further evaluate the vehicle and ground based videos will convene next week at the NTSB Recorders Laboratory in Washington, D.C.
  • The systems group continues to review available data for the vehicle’s systems (flight controls, displays, environmental control, etc.). The group is also reviewing design data for the feather system components and the systems safety documentation.
  • The vehicle performance group continues to examine the aerodynamic and inertial forces that acted on the vehicle during the launch.

The investigation is ongoing. Any future updates will be issued as events warrant. Follow the investigation on Twitter at @ntsb, on our website at ntsb.gov, or sign up to receive NTSB news releases.

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