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You have to worry about where the thing will come down if it fails several seconds to a minute or so after launch, and which way it will be flying if it goes way off course. Something that big needs a mile or two radius superposed around an off-site strike point, which in turn could be a few miles off site. Now you know why the oil rigs Musk bought are some 10 miles off shore. This thing is like the old risks associated with Nova and to some extent the N-1. It needs a 10 mile radius to keep the public safe.
GW
]]>We use what is effectively a subterranean block house to protect NORAD personnel against near misses from Megaton-class nuclear warheads. Perhaps nobody can remain above ground when we light this candle, but is there any reason why an underground steel blockhouse couldn't withstand the force of the blast from an on-pad explosion? At least in theory, it seems like that should be doable, although I don't know enough about the water table there to speak to the practicality of that solution.
]]>I see why Elon purchased a couple off-shore oil platforms.
]]>You don't have to have a full detonation shock wave for a fast-deflagration blast wave to do enormous damage. We have known that since the first airplane gasoline tank exploded in response to being hit with bullets from another plane during WW1. It was a center fuel tank explosion that blew TWA-800 fully apart in mid air a few decades ago. That was jet fuel vapor exploding with air in the tank above the liquid pool, not pure oxygen. With pure oxygen, it just explodes more powerfully, and even a bit faster, but still without a shock wave, just a big subsonic blast. There's movie footage of a V-2 that toppled over and exploded, without even pre-mixing, just the sudden exposure of the alcohol fuel on the ground to liquid oxygen. No shock wave, but extreme violence.
I looked closely at the photos taken from above the ammonium nitrate explosion that took place in West, TX, a few years ago. You can see that the supersonic shock wave was "done" by about 1000 feet from the epicenter. You can see it in the nature of the damage to steel objects. From there on out, the blast was a subsonic blast wave. THAT is what destroyed about half the town.
NASA was restricted by these same risks launching Saturn-5's from Cape Canaveral. There were no persons allowed outside within 3 miles of the pad. It was both the explosion risk and the noise risk that created this 6 mile diameter zone. The zone is bigger for bigger rockets; which is in part why the larger-still Nova rockets were never built. Starship/Superheavy is about 1.5 times the thrust and 2 times the propellant of Saturn 5. It's about like the smaller concepts for Nova.
GW
]]>I'm all for SpaceX. I want to see Starship fly. SpaceX has proven that an explosion on landing is not catastrophic. After all, Starship has already exploded several times on landing. But that's with residual fuel for landing, not fully fuelled for launch. And that was Starship, not Super Heavy. I don't think we can dismiss concerns by regulatory bodies.
I met the owner of SpaceDev at a symposium. That company built the rocket engine for SpaceShipOne. A different company supplied the engine for SpaceShipTwo. But the owner of SpaceDev said sometimes it's better to ask forgiveness than permission. That was true when FAA had no clue what they were doing. FAA had never been asked to grant permission for an experimental spacecraft before. NASA had done all the work with human spaceflight up to that point. But now, it's different. Rocket engines for Super Heavy are configured similar to N1, and propellant is even heavier. And that doesn't include propellant of Starship stacked on top. True, problems with N1 were caused by lack of testing on a static test stand. Russian engineers had planned a static test stand for every stage of N1, including Block A. One Russian politician at the time did not believe in space, thought it was a waste of money, so took away the money for the Block A test stand, used that money for something not related to space. The result was the only way to test it was to launch N1. That resulted in 4 consecutive failures. The major reason Saturn V succeeded was all stages including S-1C were tested in static test stands before launch. And the F-1 engine had a major problem with pogo, but because the stage was tested before launch, engineers had a chance to analyze it and fix it before launch.
So I'm arguing IN FAVOUR of testing Super Heavy on a static test stand a Boca Chica. SpaceX has demonstrated landing at Boca Chica is safe, they've demonstrated that catastrophic failure on landing will not destroy the town. I would like to see the first orbital launch from Boca Chica, but I don't think we can dismiss concerns by FAA or EPA.
]]>I have not personally seen anything that has the appearance of a prejudiced permitting process. From my personal interactions with them, FAA is not a punitive agency. They exist to promote aviation with appropriate consideration for public safety. Aviation in general, but especially experimental aviation, is an inherently risky and potentially dangerous activity, so it is in the public's best interest to exercise due caution while permitting new aviation-related technology to benefit the general public.
When FAA issues a special certificate of airworthiness for an experimental aircraft, which is what Starship Super Heavy presently is, it comes with certain restrictions, inspections, and evaluation processes to assure compliance with the permitting process.
It would be very unreasonable to think that SpaceX is unfamiliar with this process, because they've been through the complete process several times before. To wit, Falcon 1, Falcon 9, Falcon Heavy, Cargo Dragon, and Crewed Dragon Crew, all had to go through that process. All of those machines are extremely sophisticated, extremely high performance aerospace vehicles that required certificates of airworthiness. Given SpaceX's specific line of business, general understanding, and technical capabilities, there's no acceptable excuse for flying an experimental aircraft without a valid airworthiness certificate issued by the FAA. That would be the equivalent of Lockheed-Martin somehow "forgetting" that their next stealth fighter had to receive FAA approval prior to first flight. They knew it was required and deliberately ignored the rules because someone really wanted to go flying that day. As a result, FAA is probably (rightfully) concerned that SpaceX does what has been agreed upon and permitted by FAA and nothing else.
As previously noted, this new rocket that SpaceX is developing is every bit as powerful as a Saturn V and then some. If Starship fails catastrophically over someone's home, there is a very high probability of injury or death. Generally speaking NASA tests these sorts of machines far, far away from occupied areas for that very reason. No matter how good you think your design is, the possibility of failure is ever-present. Seemingly inconsequential things can and do kill people not involved in experimental aviation, so FAA would not be faithfully executing its duties without careful consideration given to public safety.
As far as risk tolerance is concerned, all risk is relative. There are always trade-offs to be made. What a person considers too risky is generally related to how an undesirable outcome will personally affect them. Ask your average computer engineer what he or she thinks about a new jet design that they worked on, and you'll get a shrug or a "that's not my responsibility". Ask your average pilot at the controls of that shiny new machine and they'll have an entirely different perspective, since the pilot is utterly responsible.
The Apollo Astronauts no doubt held a very different view of how well or poorly engineered their spacecraft was, which is why that feedback loop exists between the Astronaut Office and NASA's engineering divisions. Can you imagine what the Astronaut Office would think of the idea of flying someone to the moon aboard an untested launch vehicle?
Rightly or wrongly, nuclear power has been stigmatized by pop culture and the media as "black magic". In some respects, it is. Nothing else in the universe that we humans know how to use stores that kind of power in such a tiny amount of space. All the general public knows about anything nuclear is that it's powerful beyond their comprehension, intrinsically dangerous, and that they don't understand what constitutes an acceptable risk with nuclear power. As such, most people naturally fear things that are both intrinsically dangerous and wildly powerful. The general public knows what a gallon of gasoline is and how powerful that can be, but has no clue about how powerful a gallon of fissile material is, because there's literally nothing else to compare it to. Handing a metal golf ball to someone and telling them that it represents the total amount of energy they'll use during a human lifetime is like transitioning directly from a Cessna to the Space Shuttle. They both have wings on them and are still subject to basic flight physics, but nothing else is remotely comparable. How do you convince a pilot that the Space Shuttle is "safe" when that beast lands at speeds greatly in excess of what their little prop job could achieve in a dive? Your guess is as good as mine.
]]>Calliban,
SpaceX will file their launch permit application with the FAA, and then the FAA will work with SpaceX to devise risk mitigation strategies and range safety protocols with multiple safeguards in place to prevent a situation where loss of control of the vehicle leads to death and destruction. That process includes comprehensive risk assessments.
That sounds to me like proper due process. It does take time, but it is essential. Anyone concerned about the cost of safety, should carefully consider how much an accident will cost them (and others).
Is there any reason to believe that SpaceX are being treated unfairly in the execution of this process? Is the burden of proof unusually high, or the process unusually drawn out? I notice that some of the same people that are bemoaning FAA due process here, also consider nuclear power to be too risky. Could it be that they are not in a position to assess the tolerability of risk, or understand the work involved in such a determination?
]]>SpaceX will file their launch permit application with the FAA, and then the FAA will work with SpaceX to devise risk mitigation strategies and range safety protocols with multiple safeguards in place to prevent a situation where loss of control of the vehicle leads to death and destruction. That process includes comprehensive risk assessments.
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