Quote from: Barley on 05/26/2023 09:17 pmQuote from: drzerg on 05/26/2023 08:58 pmWhat is worst case scenario for the starship stack on ascend? There is no such thing as a worst case, it can always be worse. A hole in and collapse of a StarShip (second stage) methane tank is worse than a Super Heavy (first stage) failure you give as a worse case.Airliner analogy to this is wing could fall off. Is it deadly? yes if you are not f15. Is in frequent? No.If you add probability to equation worst case start to appear as the severity*probability entity
Quote from: drzerg on 05/26/2023 08:58 pmWhat is worst case scenario for the starship stack on ascend? There is no such thing as a worst case, it can always be worse. A hole in and collapse of a StarShip (second stage) methane tank is worse than a Super Heavy (first stage) failure you give as a worse case.
What is worst case scenario for the starship stack on ascend?
To match motorcycles you can have 30 fatalities per 100 million miles travelled. So around 4000 orbits. Or 250 days in orbit continuously.Or a fatality every 10 days.That seems achievable.
I was wondering what the fatality rate was at the dawn of commercial aviation. I don't think life is as cheap now as it was then, but I think it's still a useful comparison point.Finding the stats is actually a little tricky, but seems there were 40-odd crashes a year in the late 1940s, at a time when about a million passengers were being carried a year on planes with a capacity of ~20 people.
Quote from: Robotbeat on 05/27/2023 03:35 amWhen will Starship fly a million times? It’ll take longer than that to prove 1 in a million reliability, but at least it becomes numerically possible.If it takes giving each flip and burn engine it's own header tanks, it will be done to get the reliability needed.
When will Starship fly a million times? It’ll take longer than that to prove 1 in a million reliability, but at least it becomes numerically possible.
The goal is to improve the cadence and reliability to the point that the comparison IS fairly valid.
Quote from: Robotbeat on 05/30/2023 05:44 amThe goal is to improve the cadence and reliability to the point that the comparison IS fairly valid.Sure, but my point is that that goal is unrealistic.
I don't think it helps that SpaceX and Elon Musk often make comments like "imagine if you had to throw away a 747 after every flight". In this case, in my opinion, people subconsciously start equating rockets to airplanes when really it's a pretty apples to oranges comparison. I think some of this comparison has leaked over here, and I'm not sure how helpful it is. Just my 2 cents.
Quote from: chopsticks on 05/30/2023 12:34 pmQuote from: Robotbeat on 05/30/2023 05:44 amThe goal is to improve the cadence and reliability to the point that the comparison IS fairly valid.Sure, but my point is that that goal is unrealistic.You forgot "IMO".
Quote from: chopsticks on 05/30/2023 05:05 amI don't think it helps that SpaceX and Elon Musk often make comments like "imagine if you had to throw away a 747 after every flight". In this case, in my opinion, people subconsciously start equating rockets to airplanes when really it's a pretty apples to oranges comparison. I think some of this comparison has leaked over here, and I'm not sure how helpful it is. Just my 2 cents. It's not subconsciously. SpaceX put out this video. What does this look like to you? To me, it looks like going to an airport, getting on a train to a terminal, walking out a jetway to get on an airliner, and flying to your destination. It's this sort of nonsense that leads people to think of Starship as an airliner - because SpaceX explicitly said so. It's the same sort of thing thing that leads people to think Tesla's can drive themselves - the name of the service, "full self driving", which it isn't.If you're going to claim the same conops as an airliner, it needs to be as safe as an airliner, which you correctly state is unrealistic."Starship will be capable of taking people from any city to any other city on Earth in under one hour."
Quote from: woods170 on 05/30/2023 01:04 pmQuote from: chopsticks on 05/30/2023 12:34 pmQuote from: Robotbeat on 05/30/2023 05:44 amThe goal is to improve the cadence and reliability to the point that the comparison IS fairly valid.Sure, but my point is that that goal is unrealistic.You forgot "IMO".No I didn't. I'm sorry, but if you believe that rocket travel/space travel can become as safe or routine as commercial air travel, I don't know what to tell you. It's orders of magnitude more complex and way more things to go wrong with far fewer redundancies.
Quote from: chopsticks on 05/30/2023 12:34 pmQuote from: Robotbeat on 05/30/2023 05:44 amThe goal is to improve the cadence and reliability to the point that the comparison IS fairly valid.Sure, but my point is that that goal is unrealistic.Right. With hard work and a lot of flights, that might be able to take us from 5 orders or magnitude worse than an airliner down to 4 orders of magnitude worse. But not 1 or 0.
Quote from: chopsticks on 05/30/2023 02:16 pmQuote from: woods170 on 05/30/2023 01:04 pmQuote from: chopsticks on 05/30/2023 12:34 pmQuote from: Robotbeat on 05/30/2023 05:44 amThe goal is to improve the cadence and reliability to the point that the comparison IS fairly valid.Sure, but my point is that that goal is unrealistic.You forgot "IMO".No I didn't. I'm sorry, but if you believe that rocket travel/space travel can become as safe or routine as commercial air travel, I don't know what to tell you. It's orders of magnitude more complex and way more things to go wrong with far fewer redundancies.I see this more complex claim a lot. With very little to explain why.So, why is it more complex? Why is it orders of magnitude more complex?For example, rocket engines probably have fewer moving parts, but run at higher temperatures, that a modern turbofan. There's a trade off there, but as material technology improves, rocket engines could become just as reliable as jet engines. Is there some fundamental law of physics that means a rocket engine (effectively a well controlled deflagration, just like, for examples, an ICE) cannot be made as reliable as a modern jet engine? How do you get to orders of magnitude complexity more than airliners?