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SpaceX is no stranger to delays. The private space firm headed by Elon Musk has pushed back is launch schedule several times in the last few years after rockets have been lost. Now, the Government Accountability Office (GAO) says there may be an issue with the Falcon 9 rocket that delays the expected launch of the first manned mission in 2018.
The report from the GAO (just a preliminary release for now) cites issues with the turboblades used in Falcon 9 rockets. These are the components that move fuel from the tanks to engines. The blades apparently have a tendency to develop cracks, which could cause catastrophic failure if they develop or worsen during a launch.
According to NASA acting administrator Robert Lightfoot (who also has an amazing name) says the agency and SpaceX have been aware of the issue for months (or possibly years). NASA expressed concern to SpaceX that the turboblade cracks presented too great a risk to launch manned missions. Cracks have been found in the turboblades as recently as September 2016.
SpaceX says it has been conducting extensive testing on the Falcon 9 rocket and believes it to be safe. It has made changes to the design of the turboblades in an effort to mitigate the cracking issues. Although, the company may still undertake a full redesign of the blades depending on the upcoming GAO report. If that happens, the manned launch will almost certainly be delayed.
Source:
https://www.extremetech.com/extreme/243883-problems-falcon-9-design-delay-manned-missions
(Score: 2) by DannyB on Monday February 06 2017, @03:09PM
As for problem 1, wasn't the strut not actually built to withstand the stress it was supposed to withstand? Or do I mis-remember? Didn't SpaceX switch manufacturers for that strut? SpaceX tested a bunch of struts and found that quite a few failed at a much lower stress than they were supposed to?
As for 2, if the problem is well understood, then isn't it safe to change the fuel / oxidizer loading procedure to avoid the problem? Sort of like if you change the procedure for working on electrical equipment to require electricians to use insulated gloves? Or any other normal, sane precautions for a problem that becomes well understood? Wear proper safety gear around noxious chemicals, etc. Don't ban the noxious chemicals. Just fix your procedures.
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(Score: 2) by VLM on Monday February 06 2017, @05:10PM
Both situations fail the intrinsic safety goals you'd like to have in a man rated vehicle and would be really difficult to patch around, need to do that at design time.
Intrinsically safe means you eliminate entire categories of failure mode by implementing a safer design. Lets say people keep dying replacing ceiling lights. You could make ever safer ladders. Or airbags underneath ladders. If you want it intrinsically safe, wouldn't it make a heck of a lot more sense to install LEDs that will theoretically last the life of the house? Or even better yet eliminate the high light source so you don't need ladders to change the light? Its hard to fall off a ladder you never put there because there's no light bulb to replace because there's no light bulb installed there.
The intrinsic safety failure of problem 1 is they suspended one tank inside another and if that suspension snaps the tank bowling balls out the bottom of the big tank and you suddenly lose the vehicle. You make that intrinsically safe by merging the tanks with a common bulkhead or mounting the little tank on a bulkhead or somehow firmly attaching the little tank to the bottom of the big tank so if it breaks loose at least it won't "bowling ball" out the bottom of the vehicle causing an explosion. You might lose the mission because the engines shut off early but at least the astronauts would live, unlike going out in a giant explosion. Sure the tank only self destructs 1 in 50 flights and that maybe makes economic sense when launching unmanned GPS satellites, but it doesn't make sense for a manned launcher. It has to be designed in at the start, its a major redesign to move those tanks around.
The intrinsic safety failure of problem 2 is carbon and carbon fiber plus liq or solid O2 equals death and there's no way to work around it. Charcoal and liq O2 was used quite a bit as a "safe" mining explosive a few decades ago but its too unpredictable. Sure they cooled the tank too deeply maybe freezing O2 and a pressure change caused a sudden crack in the solid O2 that was enough friction to ignite the carbon fiber and blow the vehicle to pieces. So ... how abouts making helium tanks out of something less flammable than carbon fiber, I donno titanium or an aluminum alloy? Even bulk magnesium is harder to ignite than carbon fiber. They think they've reduced the odds of another explosion by changing ground procedures but no one really understands cryogenic O2 mixed with carbon. Its like walking around with a balloon full of welding gas, there's things you can do to help with static electricity and improve your odds but its inherently reckless. Again, sure it'll explode 1 in 50 times but thats OK for unmanned and not OK for manned. It might be slightly easier to redesign to use non-flammable tanks inside a liq O2 tank, but it'll throw off weight and balance and lower performance. A block of steel is inherently safer inside a liq O2 tank than a piece of charcoal. There's no non-cheaty way to make the bar of steel more likely to catch fire than the piece of charcoal.
You see intrinsically safe in a lot of medical hardware. Oh 12 volts would kill a patient? Lets power the thing off 5 volts then no body can get electrocuted no matter how they F it up. Oh 10 mA will kill the patient, well, lets put a resistor in series such that if you shorted the power supply thru the resistor thru a zero ohm "patient" that it would flow less than 10 mA. Lightning from a thunderstorm could electrocute the patient? Well we COULD F around with lightning protection but wouldn't running off a battery be infinitely safer? Lithium batteries explode at sterilization temperatures so our pacemaker will use a different battery technology. etc.
(Score: 2) by DannyB on Monday February 06 2017, @05:17PM
I see your point about problem 2.
I also see your point about problem 1 as a design issue. My point about problem 1 was that no matter what design you use, if someone makes inferior parts that don't meet specs, this is not a design problem. You could try to address poor quality manufacturing (or sabotage) in the design. But I think that is the wrong place to address either of those.
So if you didn't have struts fail due to poor quality or sabotage, then problem 1 isn't really a problem. But I take your point about trying to design so that the strut isn't even an issue.
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(Score: 2) by VLM on Monday February 06 2017, @07:34PM
But I take your point about trying to design so that the strut isn't even an issue.
You could even take the helium tank/strut problem further. So the problem is if the mounting fails it bowling balls thru the bottom of the ship and blows it up. Well, if you're going to replace one big tank inside the O2 tank with a dangerous strut, why not put like 3 small tanks right on top of the engines and get rid of all that high pressure gas line (which is heavy) and install three one-way valves and if a tank broke off the vehicle not only would it not smash thru the bottom but if it happened late enough in the flight and the one-way valve worked, it might not even affect the flight. Oh maybe booster recovery would literally run out of (pressurized) gas, but that wouldn't kill any astronauts. Inherently safe by design.
The nuke people like inherently safe stuff too. Go ahead, slowly overheat it, the structure expands and it falls out of criticality. Go ahead, cut the wires to the control rods, the rods are attached to the actuators by giant electromagnets so cut the wire and they fall into place shutting down the reactor if you take an axe to the control wires.
(Score: 2) by choose another one on Monday February 06 2017, @08:31PM
> Sure the tank only self destructs 1 in 50 flights and that maybe makes economic sense when launching unmanned GPS satellites, but it doesn't make sense for a manned launcher.
What number makes sense for a manned launcher? 1 in 65 fatality rate perhaps? 1.5% of flights?
Would a 1 in 50 flight fail rate with a launch abort be better that 1.5% with no abort option? Which would you rather ride on?
The shuttle took the baked-in-from-the-start approach to man rating and chose to use SRBs (which at the time had around 1 in 50 fail rate), chose segmented SRBs vs. single piece SRBs (why have a joint that can fail if you can build in one piece?), chose to use manned vehicle heat shielding that was fragile and then put the manned vehicle not on the top of the stack (like every manned rocket before or since, out of harms way as much as possible), but instead put it _behind_ most of the main tank, which was covered in an insulation jacket that was sprayed on rather than manufactured and was known to shed fragments.
The shuttle had multiple intrinsic safety failures _despite_ having baked in man-rating from the start, and despite this had no launch abort / escape option, Falcon9 will also probably (inevitably?) have multiple intrinsic safety failures, but it will have have a launch abort / escape option, and the kinks will be ironed out first with unmanned flights.
The COPV tanks are safe as long as the struts are manufactured to spec and the launch temps are "correct", except no one really knows what "correct" is. Sounds bad - except it is exactly the same as the O-Rings on the shuttle, not intrinsically safe, vehicle could have been designed without it, safe if used at the right temps but no one knew what those were in advance. The big difference is that the O-Rings were a man-rated-baked-in design and were tested at new launch temps with a crew on board, SpaceX only tested new launch temps with a satellite on board.
Which is the best approach? Only time will tell, but time has not been kind to NASA's shuttle approach. NASA's approach also carried a cost premium of 10x (maybe 100x if SpaceX does get reusable). Was it worth it?
(Score: 2) by VLM on Monday February 06 2017, @09:21PM
The shuttle had multiple intrinsic safety failures _despite_ having baked in man-rating from the start
They baked in political deals from the start. Hard to have a SRB failure if you don't have SRB although you don't get the Utah vote without SRBs so we gotta have SRBs even if they kill people.
The insulation deaths were the same way. The ET spray on foam is environmentally negligible but they couldn't use the good stuff because it looks bad to be anti-environment on TV, so instead they killed a bunch of people by using stuff that is more environmental but falls off and cracks heatshields. Sure we littered parts of the shuttle and parts of the astronauts all over Texas but thank god we didn't use environmentally unfriendly insulation, that's what really matters in a human-life space program, not mere human lives.
You have to balance SpaceX is doing questionable things vs NASA just plain old sucks.