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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.
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 tail is supposed to be deployed during rentey at an altitude where the air is thin. So even though you are going faster the air is thin so the loads are less.
I love Jesus, except for his foreign policy.
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.
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.