Flight rates don't support the development costs
Quote from: Jim on 05/03/2009 02:26 amFlight rates don't support the development costsNaturally your answer would depend on the flight rates, so let me ask you this hypothetical question:Say one of these concepts, by virtue of its reusability, managed to significantly lower the cost per kg to LEO (consider the just the flight cost with all the reusable hardware already built, so you just have to pay for refurbishment/refueling/expendable parts). If this happened, wouldn't it drastically increase the launch market, which would then increase the flight rates?Assuming this were true, the increase in flight rates would certainly change the way people look at those development costs.
Quote from: ntrgc89 on 05/03/2009 02:49 amQuote from: Jim on 05/03/2009 02:26 amFlight rates don't support the development costsNaturally your answer would depend on the flight rates, so let me ask you this hypothetical question:Say one of these concepts, by virtue of its reusability, managed to significantly lower the cost per kg to LEO (consider the just the flight cost with all the reusable hardware already built, so you just have to pay for refurbishment/refueling/expendable parts). If this happened, wouldn't it drastically increase the launch market, which would then increase the flight rates?Assuming this were true, the increase in flight rates would certainly change the way people look at those development costs.You still have a chicken and egg problem. The dramatic increase in flight rates would not occur until after the flyback booster starts flying, but you still have the high upfront development costs.
Quote from: Jorge on 05/03/2009 03:22 amQuote from: ntrgc89 on 05/03/2009 02:49 amQuote from: Jim on 05/03/2009 02:26 amFlight rates don't support the development costsNaturally your answer would depend on the flight rates, so let me ask you this hypothetical question:Say one of these concepts, by virtue of its reusability, managed to significantly lower the cost per kg to LEO (consider the just the flight cost with all the reusable hardware already built, so you just have to pay for refurbishment/refueling/expendable parts). If this happened, wouldn't it drastically increase the launch market, which would then increase the flight rates?Assuming this were true, the increase in flight rates would certainly change the way people look at those development costs.You still have a chicken and egg problem. The dramatic increase in flight rates would not occur until after the flyback booster starts flying, but you still have the high upfront development costs.Well yea, that's the point. I do agree, the logic is somewhat self-serving, but if we can agree that a significantly reduced cost/kg to LEO would increase the launch market then you still have the same effect of spreading out the development costs more quickly.So really you have two hypothetical questions here:1) Can a flyback booster significant reduce launch costs?2) Would a significantly reduced launch cost cause more people to want to launch things into space?I contend that the answer to both questions is yes. To the first one because mutliple studies point to it, and to the second one because you're lowering the barrier to entry for a wide range of audiences. You could fly a lot more educational and amateur payloads, let alone capturing launches from other companies with your reduced rates.
I contend that the answer to the first is "maybe" until actually proven. It is probably true but until one is actually built and flying, investing money in developing one is a risky proposition. That is why it has not been done.
Quote from: Jorge on 05/03/2009 03:57 amI contend that the answer to the first is "maybe" until actually proven. It is probably true but until one is actually built and flying, investing money in developing one is a risky proposition. That is why it has not been done.OK, I'll buy that, but is that really the reason this design has never flown? Technical risk?
In short: you can't influence the market by the availability of RLV technologies because the small increment on return isn't enough to bootstrap more development that radically improves such economics, such that it becomes a dominant trend. Absent that, the subsidy runs out, and then everybody points fingers over how stupid it was to be suckered by the RLV, when all along the ELV netted out cheaper.Applied to Shuttle: the govt LV market was forced through Shuttle to artificially increase demand/flight rate. Instead of reducing costs it increased costs, so there was no increment on return, and so no justification to refine Shuttle to increase its "RLV effect", e.g.you weren't going to make it up on volume.So before Shuttle, which BTW started with a S1C flyback booster approach that already had worse than Shuttle economics (you were reusing a low-pressure, low efficency, not too reusable F1 engines), the bar was set high (perhaps still not high enough) for RLV. This is why Shuttle didn't get flyback replacements for the RSRB's.X-33 was a long shot last ditch approach to "change the RLV recipe". It was a disaster because it didn't/couldn't follow the X vehicle success strategy. The idea was to start again from the ground up and shoot for economics much better than Shuttle, including vehicle turn around costs/time which are a large part of the standing army needed for Shuttle (that just having flyback boosters doesn't get you).It is hard to see how this could have been different, because the demands of the time forced the approach. Most wished X-33/VentureStar hadn't happened. I go back and forth on if a smaller X project (like the subscale X-40 of the X-38) might have been better, but it gets ridiculous after a while. You needed 1) an aerospike that gave better performance/less weight than possible, you needed much lower mass fraction than possible, and you needed more durable/lower weight TPS than possible - three strikes and you're out!
I think there are many people who still don't grasp just how much time, effort, and costs are involved with turnaround processing for reusable LVs. (Especially ones that are designed to haul another large vehicle into the upper atmosphere and then serve as its launch platform.)They still persist in comparing them to passenger and cargo airplane servicing, and the realities are totally different.
...there are many people who still don't grasp just how much time, effort, and costs are involved with turnaround processing for reusable LVs. (Especially ones that are designed to haul another large vehicle into the upper atmosphere and then serve as its launch platform.)They still persist in comparing them to passenger and cargo airplane servicing, and the realities are totally different.