The other day I was thinking about the economics of re-use (thinking with a spreadsheet) and re-using a first stage like Falcon’s is wildly different from re-using the Shuttle. The Shuttle had to successfully recover each and every time, and doing that of course cost a fortune for reasons we’re all well aware of. Other questions aside, such a vehicle really needs something like a 98+% success rate to be remotely viable.
But with Falcon, even if you botch the landing one time out of four, you’re still getting 80 percent of the cost savings a perfect system would yield, and most of the launch cost is that first stage hardware and its nine engines. The recovery doesn’t need to become very reliable to yield huge cost benefits, and the return on making further improvements in reliability rapidly diminishes.
If you recover one out of two you get half the possible benefits. Four out of five is 80 percent of the benefits. From there, becoming perfect only gets you 20 percent more savings. When you’re at nine out of ten there’s only 10 percent more savings to be had, and cutting that failure rate in half again would only result in 5 percent more savings. Cutting costs elsewhere would make more financial sense than having the engineers going nuts over the remaining recovery failures.
It’s not like an airliner where the profit from a particular flight is a tiny, tiny fraction of the cost of the airliner, so that you can’t afford to have one in ten thousand flights end in a crash because the airliner cost perhaps 4,000 times more than the price of all a particular flight’s tickets combined.
–
It’s only when everybody is flying reusable rockets and fuel costs start to dominate that it would even make sense to push the recovery rate towards several nines.
And of course the biggest savings in spaceflight would come from recovering the SLS first stage and its RS-25’s, but it’s already so expensive and one-off that they’d never be able to develop and test the ability. They might waste a lot of money studying it, though.
That seems to focus on a ‘dollar value’ assessment of the recovery.
I think some of the actual key benefits would be highlighted in a man hour assessment. And, also skill concentration.
The ‘first stage construction’ and ‘first stage engine construction’ departments would have massive personnel, real estate, and other logistics requirements at a 24/year pace if performed under “No reuse.”
Contrast that with a 0%, 80%, 90%, 95%, 99%, … reuse rate. No, I don’t know the effort required for revalidation either. But scaling up the revalidation department seems fundamentally simpler to me than scaling up the initial production department.
Very nice video. My only complaint is that the captions disappeared too quickly. They didn’t allow much time to read them.
Rick, when you zip along at 17,000 mph you have to learn to read real fast. Just practice!
In seventy years
Of brushin’ soap on
Gramps coulda painted
The Pentagon
Use brushless
Burma-shave.
Space is big
Space is dark
It’s hard to find
A place to park
The other day I was thinking about the economics of re-use (thinking with a spreadsheet) and re-using a first stage like Falcon’s is wildly different from re-using the Shuttle. The Shuttle had to successfully recover each and every time, and doing that of course cost a fortune for reasons we’re all well aware of. Other questions aside, such a vehicle really needs something like a 98+% success rate to be remotely viable.
But with Falcon, even if you botch the landing one time out of four, you’re still getting 80 percent of the cost savings a perfect system would yield, and most of the launch cost is that first stage hardware and its nine engines. The recovery doesn’t need to become very reliable to yield huge cost benefits, and the return on making further improvements in reliability rapidly diminishes.
If you recover one out of two you get half the possible benefits. Four out of five is 80 percent of the benefits. From there, becoming perfect only gets you 20 percent more savings. When you’re at nine out of ten there’s only 10 percent more savings to be had, and cutting that failure rate in half again would only result in 5 percent more savings. Cutting costs elsewhere would make more financial sense than having the engineers going nuts over the remaining recovery failures.
It’s not like an airliner where the profit from a particular flight is a tiny, tiny fraction of the cost of the airliner, so that you can’t afford to have one in ten thousand flights end in a crash because the airliner cost perhaps 4,000 times more than the price of all a particular flight’s tickets combined.
–
It’s only when everybody is flying reusable rockets and fuel costs start to dominate that it would even make sense to push the recovery rate towards several nines.
And of course the biggest savings in spaceflight would come from recovering the SLS first stage and its RS-25’s, but it’s already so expensive and one-off that they’d never be able to develop and test the ability. They might waste a lot of money studying it, though.
That seems to focus on a ‘dollar value’ assessment of the recovery.
I think some of the actual key benefits would be highlighted in a man hour assessment. And, also skill concentration.
The ‘first stage construction’ and ‘first stage engine construction’ departments would have massive personnel, real estate, and other logistics requirements at a 24/year pace if performed under “No reuse.”
Contrast that with a 0%, 80%, 90%, 95%, 99%, … reuse rate. No, I don’t know the effort required for revalidation either. But scaling up the revalidation department seems fundamentally simpler to me than scaling up the initial production department.
Very nice video. My only complaint is that the captions disappeared too quickly. They didn’t allow much time to read them.
Rick, when you zip along at 17,000 mph you have to learn to read real fast. Just practice!
In seventy years
Of brushin’ soap on
Gramps coulda painted
The Pentagon
Use brushless
Burma-shave.
Space is big
Space is dark
It’s hard to find
A place to park
Burma Shave
(as seen on asteroids in a S. Harris cartoon)