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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...
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.
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
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Typical KSP. You click the wrong button, unfold the lander module's legs during take off and everything goes to heck.
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)
To continue my rant, the article even includes this quote:
“I’m not stating that this is the cause of the mishap,” [Hart] added.
No-one knows why SS2 crashed yet.
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.
If this deployed it would have created a massive pitch up manuver. The G forces may have been enough to knock the pilots unconscious.
I love Jesus, except for his foreign policy.
This factor, not mere ideology or efficiency of free markets, is the reason we need to privatize risky technologies. The problem with a government effort is not that it is marginally less 'efficient' than a private one, but that in a Luddite-dominated culture a government effort, unless we can make it military and secret, will be doomed by its inevitable first accident. The Challenger crash caused a two-year delay of NASA's most advanced manned system, and the Columbia crash killed it for good.
Nope - under ICAO, for air crashes, preliminary report is supposed to be within one month.
Plus, this was a test flight, and was probably instrumented to death - very likely they have full real time telemetry before they even need to go near recorders in the wreckage. Apparently they have cockpit video too - something the aviation industry has always resisted (at least the unions).
Eh? No, the crew of Columbia did not survive all the way down. Perhaps you are thinking of challenger, where there is some debate on if they survived until impact. In the case of Columbia the crew was dead four times over before impact. The lethal factors NASA identified were:
1. Depressurization of the crew module at or shortly after orbiter breakup.
So, we start with denying the crew oxygen. None closed their helmets when pressure dropped to 0 in a fraction of a second at the start of the breakup.
2. Exposure of unconscious or deceased crew members to a dynamic rotating load environment with a lack of upper body restraint and non-conformal helmets.
Then we bang them around a bit in what can be best described as a rolling garbage compressor full of sharp and heavy things, in helmets not designed to protect against this kind of force and without proper seat belts.
3. Separation of the crew from the crew module and the seat with associated forces, material interactions, and thermal consequences.
Then we break the box apart, exposing the crew to an unprotected reentry into atmosphere
4. Exposure to near vacuum, aerodynamic accelerations, and cold temperatures.
Finally we let them free-fall back to earth...
The Columbia Crew Survival Investigation Report is a 400 page long and very dark document, but the executive summary is just a couple pages. You can find it here:
http://history.nasa.gov/columb... The bodies of the astronauts were mangled beyond recognition, which is hinted in the report, but out of respect of the astronauts details of the injuries are redacted from the report.
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.
I guess I should always trust my physics and chemistry classes over reporters.
Frankly it's a wonder you've stayed sane this long if you've only just realised this.
That's assuming you have stayed sane, of course.
systemd is Roko's Basilisk.
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.
If Orrin Hatch had not used his power to keep the shuttle booster manufacturing in Utah then the crew of Columbia would be alive today.
Since Utah is nowhere near where the shuttle is launched they had to be made in pieces so they could be shipped across the country. A less safe design. The original design called for the boosters to be made completely in one piece. O ring seals can't fail when there aren't any O rings to begin with.
The crew of Columbia died because of pork barrel politics.
Ha! Rather than merely point out that you have confused the names "Columbia" and "Challenger" everybody has decided you needed a new arsehole tearing.
All I want is a secure system where it's easy to do anything I want. Is that too much to ask ~~ Randall Munroe
I managed to miss that one.
So now you have to make me aware of a new realm of stupidity in media. Gee, thanks....
"I do not agree with what you say, but I will defend to the death your right to say it"
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.