I think the big takeaway is new launch systems are and have been built to support launch rates that are higher than needed by the payloads. We do not need to look far, the 1990's collapse, Saturn, Shuttle, Delta III, EELV... Saturn was built to support a program that would have been so expensive the nation would never have funded it. All through the program it was cut and refocused to smaller and smaller goals.Shuttle was built to support a launch rate that could not be achieve and cheaper (Ariane) alternatives ate it's payloads. Delta III was to meet a demand that evaporated.EELV was based on commercial projections that did not happen, leading to two very costly systems.I think people like building new rockets, and like to assume the need for a new launcher is the problem and the payloads will materialize. One can argue that new space companies are still doing that.(but that should be debated in that new space companies numerous threads. The busiest and most cool-aid filled part of NSF )
I'm still not understanding what this thread is about.
Is this thread asking if designing for reusability is the overbuild?
I'm not so sure about that. They started with Falcon 1, and it seemed like it was intended to serve as both a test and a production vehicle (think of the Orbcom satellites). But then they decided that GTO/Dragon was where they thought it was best to concentrate, and so they cancelled Falcon 1. They also seemed to do Falcon 9 v1.1, in part, to enlarge the market they could address.Not that I'm saying there's anything wrong with this, in fact the reverse. I think its good for any business to consider their potential market demand (consider.. which doesn't mean you have to bend over backwards to address every possible request)
I didn't mean to imply that the market is irrelevant to them. I just see a lot of posting all over the site where markets and waiting payloads are the overriding driver in in the specs of what SpaceX flies, to which I disagree.
Quote from: faramund on 01/16/2014 09:05 amI'm not so sure about that. They started with Falcon 1, and it seemed like it was intended to serve as both a test and a production vehicle (think of the Orbcom satellites). But then they decided that GTO/Dragon was where they thought it was best to concentrate, and so they cancelled Falcon 1. They also seemed to do Falcon 9 v1.1, in part, to enlarge the market they could address....Yes, but Falcon 1 was all that they were capable of building at the time. With a government contract shortly after the successful launch they were able to "upgrade" and did. There may still have been some market for F1 (or F1 v1.1) flights, assuming really good pricing but they could then afford to go for more capability with the resources that they had. I didn't mean to imply that the market is irrelevant to them. I just see a lot of posting all over the site where markets and waiting payloads are the overriding driver in in the specs of what SpaceX flies, to which I disagree.
I'm not so sure about that. They started with Falcon 1, and it seemed like it was intended to serve as both a test and a production vehicle (think of the Orbcom satellites). But then they decided that GTO/Dragon was where they thought it was best to concentrate, and so they cancelled Falcon 1. They also seemed to do Falcon 9 v1.1, in part, to enlarge the market they could address....
Let's think about the BIG picture here. Elon wants to go to Mars. Elon WILL go to Mars! Everything SpaceX (and maybe his other ventures) is doing is to further that goal. Each new rocket is just another step to that end, and as such has capabilities that will be used on the next generation vehicle. OCCUPY MARS!!!!!
FWIW, I agree with almost everything in the above post, and its including quotes, well, except maybe the last sentence. Why Falcon 1 was cancelled, and what that means is one of the inconconclusive things I sometimes wonder about.
OCCUPY MARS!!!!!
Quote from: faramund on 01/16/2014 05:16 pmFWIW, I agree with almost everything in the above post, and its including quotes, well, except maybe the last sentence. Why Falcon 1 was cancelled, and what that means is one of the inconconclusive things I sometimes wonder about.Why Falcon 1 was cancelled is off topic for this thread. I'll try to edit in where it could go, if I can find it. So far no luck...
In answer to the OP, we don't know if Falcon 9 v1.1 was overbuilt, because we don't know the spec to which it was built.Is its design life 5 launches? 15 launches? It seems possible to me that the current v1.1 vehicle is not really designed for reuse without further modifications. In other words, SpaceX more or less might have tried to feel its way through the design.However, even if reusability is taken off the table, sizing the factory to 400 engine peak annual output seems ambitious.
I just see a lot of posting all over the site where markets and waiting payloads are the overriding driver in in the specs of what SpaceX flies, to which I disagree.
In answer to the OP, we don't know if Falcon 9 v1.1 was overbuilt, because we don't know the spec to which it was built.
I have seen some express their belief that the F9 would have flown 2 years sooner had Elon not insisted on making an engine so robust you could drop a stainless steel nut into the fuel lines.
Quote from: Dudely on 01/17/2014 11:40 amI have seen some express their belief that the F9 would have flown 2 years sooner had Elon not insisted on making an engine so robust you could drop a stainless steel nut into the fuel lines.IIRC, this was one of the things they did with the F-1 engine.
True, we don't know, but we can infer that robustness is an important feature from two important facts:1) Quotes from engineers expressing their frustration at Elon's insistence on extreme reliability. I have seen some express their belief that the F9 would have flown 2 years sooner had Elon not insisted on making an engine so robust you could drop a stainless steel nut into the fuel lines.2) They increased the weight of the baffle between the engines. It does not make sense to take a payload hit to protect the engines from each other unless you plan on routinely flying in situations where you expect an engine could fail (flying the same engines multiple times, for example). You would not want an engine failure to ruin an otherwise reusable stage.You could also expand 1) to quotes from Spacex management, though I take those with a grain of salt. They have always claimed that reusability was a concern going way back.But really we don't know.
Quote from: Dudely on 01/17/2014 11:40 amTrue, we don't know, but we can infer that robustness is an important feature from two important facts:1) Quotes from engineers expressing their frustration at Elon's insistence on extreme reliability. I have seen some express their belief that the F9 would have flown 2 years sooner had Elon not insisted on making an engine so robust you could drop a stainless steel nut into the fuel lines.2) They increased the weight of the baffle between the engines. It does not make sense to take a payload hit to protect the engines from each other unless you plan on routinely flying in situations where you expect an engine could fail (flying the same engines multiple times, for example). You would not want an engine failure to ruin an otherwise reusable stage.You could also expand 1) to quotes from Spacex management, though I take those with a grain of salt. They have always claimed that reusability was a concern going way back.But really we don't know.Elon is a perfectionist, won't settle for less, plus it's not like SpaceX has 30 years of rocket experience. So it's the wise thing to do, maybe they can engineer Raptor rockets with a little less extra margin. But given that's when reusability should start to happen in high volume, maybe should use the exact same margins.It's not like F9R has a crappy payload, is too expensive, or some other bad consequence of an over-engineered rocket.So this thread seem very out of touch with reality. Elon wants to do everything ULA can, he wants a rocket that stands a good chance of never ever loosing a primary payload, so that's the natural way to achieve that.
True, f9 doesnt have a crappy payload. But had it been designed as a single use it would have more. Designing an expendible means you arent limited by low cycle fatigue issues (pressurisation cycles etc). I am sure the large components that are difficult to change manufacturing processes are already designed for full reusability, but simple components or ones where it is easy to integrate a design change might have been left as less robust versions to be changed later when there was more flight data available.
But reliability for 1 launch is different to reliability for 100. It could be 99.99 for 1 launch but only 50 for a second depending on design. And when you are designing for minimum weight, all structural failure modes are important.Aircraft stuff? How about fuel line pressurisation cycles, tanks, feederd, accumulators, helium tanks, low cycle thermal stresses, etc...
