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SpaceShipTwo's Rocket Engine Did Not Cause Fatal Crash
astroengine writes It wasn't SpaceShipTwo's hybrid rocket motor — which was flying on Friday with a new type of fuel — that caused the fatal crash, the head of the accident investigation agency said late Sunday. The ship's fuel tanks and its engine were recovered intact, indicating there was no explosion. "They showed no signs of burn-through, no signs of being breached," Christopher Hart, acting chairman of the National Transportation and Safety Board, told reporters at the Mojave Air and Space Port in Mojave, Calif. Instead, data and video relayed from the ship show its hallmark safety feature — a foldable tail section designed for easy re-entry into the atmosphere from space — was deployed early, causing the in-flight break-up.
Why does it need a foldable tail? Its not like it reenters at orbital velocities...
If parts survived on impact, surely both pilots could have parachuted to safety?
"The engine burn was normal up until the extension of the feathers," said Hart.
Normally, the feather system wouldn’t be unlocked until the rocket-powered spaceship is moving about Mach 1.4, or 1.4 times faster than the speed of sound.
Instead, the co-pilot moved the lever from locked to unlock when the spaceship was traveling at about Mach 1, Hart said.
[...]
The accident claimed the life of Scaled Composites test pilot Mike Alsbury, who was serving as the spaceship co-pilot, Scaled’s website shows. Pilot Pete Siebold, who was able to parachute to the ground, survived with a serious shoulder injury.
This will be amusing to watch the fallout. (Note: the incident itself is not amusing, but rather the nutjobs who will come up with some, shall we say, interesting theories.)
In other news, I've got some gently used chemtrails for sale. Just $20/gram! Get yer chemtrails!
Just like the liberal media believes its their business to bring up the relationship between a test pilot and the space engineering company he works for and that if there is ever a death in an inherently risky venture - we need to cancel everything. So lets cancel it all, NASA, shutdown the private companies. Shut it all down because a test pilot did not survive a test flight. Whatever the liberal media decides is a problem, it is one. And whatever solution they can reactively come up with, we need to follow blindly.
Last week saw the Orbital Sciences Antares explosion on Tuesday, this fatal Virgin Galactic crash on Friday, and a plane crash in Wichita on Thursday that killed 4 (The pilot, and 3 in the building it crashed into).
Hopefully we have some good weeks ahead to balance this.
Russian underwear. From the 60s. How is yet unknown. Perhaps Putin?
Let's see...
Normally, the feather system wouldn’t be unlocked until the rocket-powered spaceship is moving about Mach 1.4, or 1.4 times faster than the speed of sound. Instead, the co-pilot moved the lever from locked to unlock when the spaceship was traveling at about Mach 1, Hart said. “I’m not stating that this is the cause of the mishap,” he added. “We have months and months of investigation to determine what the cause was.” In addition to the possibility of pilot error, Hart said the NTSB is looking a variety of other issues that may have caused or contributed to the accident
This posting is provided 'AS IS' without warranty of any kind, implied or otherwise.
Typical KSP. You click the wrong button, unfold the lander module's legs during take off and everything goes to heck.
https://twitter.com/NTSB
Normally, the feather system wouldn't be unlocked until the rocket-powered spaceship is moving about Mach 1.4, or 1.4 times faster than the speed of sound.
Instead, the co-pilot moved the lever from locked to unlock when the spaceship was traveling at about Mach 1, Hart said.
Modern cars have a feature where you can't take the key out of the ignition if you forget to put the thing in park. This feature saves me from stupid about twice a year. Humans are error-prone - there's a whole field, poka yoke dedicated to preventing these sorts of errors.
Test pilots are the best of the best. If one of them can make a catastrophic mistake then so can any commercial pilot.
Now, they may have figured that that sort of safety gear was "for later" and test craft are often bare-bones, and test pilots are often relied on to not make those kinds of mistakes. Assuming the premise here, we might see more automation early in the design process going forward. Virgin might be able to survive a year-long investigation but that kind of delay is an ongoing liability. It may turn out to be faster and cheaper in the long run to add in those costs up front, if delays are calculated into the cost.
My God, it's Full of Source!
OUTSIDE_IP=$(dig +short my.ip @outsideip.net)
The part I don't get is why one would unlock the feathering system at the start of the burn, well before it is expected to be used -- something that the in-flight videos apparently show. I can see that keeping the feathering system locked would be a safe thing to do before the release, but was the feathering system designed to be used while SpaceShipTwo was in powered flight? I was under the impression that it was not, so it would seem prudent to keep it locked until the burn was complete. Am I missing something?
I confess that I am reminded of Evel Knievel's abortive jump of the Snake River in his Skycycle X-2, which failed when his recovery mechanism (in this case, a drogue parachute) deployed during the first few seconds of powered flight. The design of recovery systems is a difficult problem.
SpaceShipTwo's Rocket Engine Did Not Cause Fatal Crash
All they've said so far is that indications are that it was most likely not the engine that caused the crash.
Instead, data and video relayed from the ship show its hallmark safety feature — a foldable tail section designed for easy re-entry into the atmosphere from space — was deployed early, causing the in-flight break-up.
Who has said this?
We can blame the headline on TFA, since it's been copied-and-pasted, but it appears that the latter is the invention of the submitter.
So, is someone making shit up, or what?
systemd is Roko's Basilisk.
What the reporter states doesn't make sense.
If there was a structural failure related to the tail, one would imagine it would be because it was deployed while the vehicle was traveling faster than the design speed for the tail, causing greater than planned aerodynamic stresses. Saying it failed because they were going slower than the normal deployment speed just doesn't make sense. Things break when you overstress them, not when you under-stress them.
Am I missing something?
When Fascism comes to America, it will call itself Anti-Fascism, and tell you to give up your guns.
Doesn't it normally take months for the NTSB to reconstruct wreckage and issue a report? This timing seems odd...
How dare an article not jump to a conclusion before they are facts to back it up. You must be watching too much Cable News.
I know we live in the internet age where we demand information right away. However some things takes time.
Make sure they are keeping the investigation productive, but stop pressuring people to find who to blame so we can do a token fire of that person, then carry on like nothing has happened.
If something is so important that you feel the need to post it on the internet... It probably isn't that important.
What the hell for? Pilots are no longer required in these automated tin can joyrides, surely?
Even if the feathering system was unlocked early it points to another issue with the feathering deployment system. Its probably a pretty easy fix and maybe something caused (as you noted) by this craft being a test article without the full fail safes. But as with most things it is looking like this tragedy was a combination of some minor fault with a little human error.
It's a billionaire playboys pet project, he should have gone in with others to consolidate the effort.
Nothing more than a mantle piece project.
"If any question why we died, Tell them because our fathers lied."
Normally, the feather system wouldn't be unlocked until the rocket-powered spaceship is moving about Mach 1.4, or 1.4 times faster than the speed of sound.
Instead, the co-pilot moved the lever from locked to unlock when the spaceship was traveling at about Mach 1, Hart said.
Modern cars have a feature where you can't take the key out of the ignition if you forget to put the thing in park. This feature saves me from stupid about twice a year. Humans are error-prone - there's a whole field, poka yoke [wikipedia.org] dedicated to preventing these sorts of errors.
Test pilots are the best of the best. If one of them can make a catastrophic mistake then so can any commercial pilot.
Now, they may have figured that that sort of safety gear was "for later" and test craft are often bare-bones, and test pilots are often relied on to not make those kinds of mistakes. Assuming the premise here, we might see more automation early in the design process going forward. Virgin might be able to survive a year-long investigation but that kind of delay is an ongoing liability. It may turn out to be faster and cheaper in the long run to add in those costs up front, if delays are calculated into the cost.
In test aircraft, you start with highly trained pilots and allow them to do what they need to do with the controls, since you don't know when an unusual use of the controls might save the crew or the ship. In later iterations, you build automation to model what the pilots did successfully.
Even in light airplanes, with only a few seats, it is frequently possible to set the controls in a way that will damage the engine or airplane, with no interlocks. It's why learning to fly takes time and has some expense. It's also why there are additional ratings for more complicated airplanes. On most business jets that are 20 years old or more, you can damage the engines by starting them incorrectly. You can certainly set the engines to a fuel burn that will overheat the engines during flight, the pilots can choose 115 to 120% of normal power for a few minutes during takeoff (safely, and routinely) but cannot use that for cruising flight.
Also, automation works well when all variables are known and controlled. In this case, the ship is not meant to feather while the engine is running, and also not while the ship is in the thicker atmosphere. It's supposed to only feather when the ship is in the higher, thinner air and the engine is shut down. At that higher altitude, Mach 1.4 could be under 200 miles per hour of indicated airspeed. Mach changes with altitude, which is why it's used instead of indicated airspeed. Reentering from the edge of the atmosphere would likely be a bit complicated for automation, but can be taught to a test pilot in a few days in the simulator.
As much as we may not like to admit it, the human brain has a much more advanced sensor pack and faster processing power than dedicated computers, plus the ability to handle edge cases very well.
I'd point out that if they had some kind of automated interlock, and that system prevented feathering (incorrectly) when feathering was needed, that would also cause loss of the vehicle due to letting it get too fast upon reentry.
Every failsafe is an invitation for another fault. Imagine: Interlock fails to allow unlocking tail section, aircraft plummets through atmosphere without tail, tumbles, breaks up and crew dies ... It's a risk management decision, not a "more is better" approach.
Why unlock the feathers during powered flight?
Because if you get into space and find you can't unlock them, the aircraft is going to burn up on reentry. So you unlock them during powered flight. If they don't unlock, you can shut down the engines and still have enough atmosphere to control the aircraft and direct it out of its trajectory into space.
Why do this during powered flight and not before, perhaps just before the aircraft is released from its carrier?
Because the aerodynamics and stress on the aircraft at engine start are dynamic to say the least. Once under stable, powered flight there's much less risk in unlocking the feathers. The aerodynamic loads should not be high enough that they would overcome the hydraulics keeping the feathers in place after being unlocked.
The big question right now is why did the feathers deploy. The NTSB says they saw nothing to indicate the pilots had tried to deploy them; the handle used to do this was untouched based on the internal cockpit video they have.
It's way too early to even speculate that it even might be pilot error. That the unlock happened a couple seconds early should not have caused the feathers to deploy on their own. Unless the transition to supersonic speed induces stresses that could overcome the hydraulics and force the feathers to deploy and the unlock happened just before or during that transition.
We need to find out why the feathers deployed before we start blaming anyone or anything.
Hopefully this will put an end to all the pundits explaining that they just KNEW the new engine was going to explode and how irresponsible it was to fly it.
I don't know about you but the problem I often have is accidentally putting the a command in the wrong action group, they can be rather difficult to locate especially in complex launch systems. One time I had a dual lander rig that I got all the way to one of the moons of Jool before i realized that I had the separators for the "lander" from the decent stage and the separators for the "lander/descent stage" from the transit stage switched around, so basically I have a couple really small satellites tumbling around in the moons orbit and some perfectly good rocket motors on a stage I can't control.
Normally, the feather system wouldn’t be unlocked until the rocket-powered spaceship is moving about Mach 1.4, or 1.4 times faster than the speed of sound. Instead, the co-pilot moved the lever from locked to unlock when the spaceship was traveling at about Mach 1, Hart said. “I’m not stating that this is the cause of the mishap,” he added. “We have months and months of investigation to determine what the cause was. If we find the problem right away, we don't get paid nearly as much. I've been told we need to generate about $2 Million in billables before we can write up any conclusions ” In addition to the possibility of pilot error, Hart said the NTSB is looking a variety of other issues that may have caused or contributed to the accident
I presume others read my added words as well?
Is it just my observation, or are there way too many stupid people in the world?
As I understand it, the big problem with the engine was uneven combustion and the vibrations it caused, not explosion. Hybrid engines are unlikely to explode, though I believe some oxidizer tanks have.
Do you have a credible reference for the vibration theory? The engines had undergone multiple ground/static tests to verify that they performed consistently and within spec. Most space protoflight hardware is ground tested for 3dB or 6dB above the baseline random vibration PSD profile, though I don't know what end-to-end tests the SS2 underwent. (fwiw, the protoflight testing is based on requirements for space shuttle payloads, but I think we tested some expendables to the same criteria)
Oxidizer tanks are just pressure tanks. The NO2 used for hybrid rocket motors is pretty stable stuff. They're no more likely to explode (or more dangerous) than a SCUBA tank or the CO2 tank that pushes beer and soda at your local pub.
Is it just my observation, or are there way too many stupid people in the world?
This is a horrible event, but for the future of Virgin Galactic it is one of the better scenarios for the failure not to be in the rocket engine itself (which is always a challenging situation, putting the strength of materials at the edge of breaking), but instead on a faulty deployment of the feathering system. Hopefully it should be simply to work out a solution to avoid pre-mature feathering.
I'll bet the cause will be something really simple and stupid and mundane, like a technician installing a bolt or a relay upside down.
I read in Bob Hoover's book, in the 50's a number of F-86's crashed when their ailerons locked up if the wings flexed a certain amount. It was due to an aileron bolt mounted upside down. They traced the source to one technician at North American factory who, when interviewed said of course he knows how those damn bolts are supposed to go, he's been doing it that same way for 15 years, ever since before WW2!
They didn't have the heart to tell that guy how many pilots he killed.
Coincidentally in Chuck Yeager's book, he tells the story of a pilot in his F-86 squadron -- at the time Yeager was the squadron commander -- named Emmett Hatch. (Hatch was the lone black pilot in the squadron). He was coming down on approach one day, was feeling good so he did some rolls. Then his ailerons locked up, lost all control and had to eject.
The wing commander was a man named Col. Ascani, a really meticulous numbers guy who was obsessed with keeping the accident numbers down. When the Col. heard about this accident he went ballistic and poor Emmett was going to have his azz court-martialed. So when the Col. asked Yeager, "Why the hell was Hatch doing a roll down so low?"
Yeager replied, "All ours pilots do that, we do a roll on final approach to make sure we're not landing on top of somebody else." And so he saved Emmett's career.
Unless I'm missing something, the Columbia event had nothing to do with the SRBs
There is an interesting counterpoint to this in victorian era railway signalling systems.
Now the operator interface for these consisted of banks of levers that worked the signals and points by means of a system of wires running over pullys, visibility from the signalboxes was not always brilliant and especially in fog keeping track of what was where was problematic.
In a fit of absolute genius it was realised that the (mechanical) logic could be implemented so as to prevent a signal being set at green if the segment was occupied and also to prevent the points in an occupied section being moved (this in an age before Turing, you will note). This was clearly a good thing, right?
Well, the signal men protested that sometimes they had to do the unusual and that they were highly experienced professionals (all the usual) and the system was modified so that a special key could be used to override the interlock logic, this key being held by the supervisors office.
So many train crashes over the following few years featured that key, that it ended up being UK practise that any collision between trains that caused a fatailty would automatically result in the signalman being arrested on suspicion of manslaughter.
It is a fine line between stopping the professional applying an override to fix a critical situation and leaving them able to tear the wings off by accident.
Regards, Dan.
because the explosion was in the oxidizer lines.
Look at the images shot from the ground, you can see the engine had broken off very early in the sequence.
So how does the strongest part of the the entire craft just drop off huh?
People are trying to cover their ass because they were warned that the oxidiser can go off early under certain conditions. Remember the same guys managed to kill several of their people while running the engine with just the oxidizer in it and no fuel back in 2007.
...the first suicide in a spacecraft?