QuoteFalcon 9 back in the hangar at Cape Canaveral. No damage found, ready to fire again.Isn't this news almost as significant as the landing itself?Refurbishment cost is often cited as a reason why re-use may not be economic. This seems like a pretty significant datum point against that argument to me.
Falcon 9 back in the hangar at Cape Canaveral. No damage found, ready to fire again.
QuoteFalcon 9 back in the hangar at Cape Canaveral. No damage found, ready to fire again.Gosh, and here I thought we had an interesting thread going, and Mr Buzzkill Elon Musk tells us that no refurbishment may be necessary - other than soot removal and a fresh coat of paint.
Anybody know what the theoretical or static-tested value is for the number of times the engines can be re-fired? Surely this must have been measured through rigorous ground testing.
Shouldn't be surprising. The center engine was fired 4 times during the launch and landing; two other engines were fired 3 times (I think - launch, boostback, and braking burns?) Unless there was physical damage due to interaction with stuff on the ground (sand, grit, gators ...), there's no reason they couldn't just be fired up again - they're designed to be both reusable and restartable.
QuoteFalcon 9 back in the hangar at Cape Canaveral. No damage found, ready to fire again.Isn't this news almost as significant as the landing itself?
While speculation is popular and is often justified by the absence of facts, there ARE some facts available. In an interesting article, space historian David Portree cites a study that looked at the refurbishment costs of the X-15 program that provides probably the most relevant real-world data we have:"In November 1966, James Love and William Young, engineers at the NASA Flight Research Center at Edwards Air Force Base, completed a brief report in which they noted that the reusable suborbital booster for a reusable orbital spacecraft would undergo pressures, heating rates, and accelerations very similar to those the X-15 experienced.""The average X-15 refurbishment time was 30 days, a period which had, they noted, hardly changed in four years. Even with identifiable improvements, they doubted that an X-15 could be refurbished in fewer than 20 days."At the same time, Love and Young argued that the X-15 program had demonstrated the benefits of reusability. They estimated that refurbishing an X-15 in 1964 had cost about $270,000 per mission. "Love and Young cited North American Aviation estimates when they placed the cost of a new X-15 at about $9 million. They then calculated that 27 missions using expendable X-15s would have cost a total of $243 million. This meant, they wrote, that the cost of the reusable X-15 program in 1964 had amounted to just 3% of the cost of building 27 X-15s and throwing each one away after a single flight.My bold.http://www.wired.com/2013/05/the-x-15-rocket-plane-reusable-space-shuttle-boosters-1966/
Quote from: Senex on 01/02/2016 07:03 pmWhile speculation is popular and is often justified by the absence of facts, there ARE some facts available. In an interesting article, space historian David Portree cites a study that looked at the refurbishment costs of the X-15 program that provides probably the most relevant real-world data we have:"In November 1966, James Love and William Young, engineers at the NASA Flight Research Center at Edwards Air Force Base, completed a brief report in which they noted that the reusable suborbital booster for a reusable orbital spacecraft would undergo pressures, heating rates, and accelerations very similar to those the X-15 experienced.""The average X-15 refurbishment time was 30 days, a period which had, they noted, hardly changed in four years. Even with identifiable improvements, they doubted that an X-15 could be refurbished in fewer than 20 days."At the same time, Love and Young argued that the X-15 program had demonstrated the benefits of reusability. They estimated that refurbishing an X-15 in 1964 had cost about $270,000 per mission. "Love and Young cited North American Aviation estimates when they placed the cost of a new X-15 at about $9 million. They then calculated that 27 missions using expendable X-15s would have cost a total of $243 million. This meant, they wrote, that the cost of the reusable X-15 program in 1964 had amounted to just 3% of the cost of building 27 X-15s and throwing each one away after a single flight.My bold.http://www.wired.com/2013/05/the-x-15-rocket-plane-reusable-space-shuttle-boosters-1966/That means almost nothing for F9R reuse.X-15 was an experimental aircraft with 50 yr old tech.X-15 used outdated rockets, used wings, outdated structural materials, and was a government driven program.The Shuttle used far more up to date technology, but the need to do orbital re-entry with all of those thermal tiles. And there are many other big problems.SpaceX has designed this first stage to be reusable. With the state of the art materials (that aren't uber expensive).I suggest reviewing discussion pre F9R first flight that Musk demanded massive margins (for a single flight) precisely in order to make reuse possible.
Quote from: macpacheco on 01/03/2016 05:46 amThat means almost nothing for F9R reuse.X-15 was an experimental aircraft with 50 yr old tech.X-15 used outdated rockets, used wings, outdated structural materials, and was a government driven program.The Shuttle used far more up to date technology, but the need to do orbital re-entry with all of those thermal tiles. And there are many other big problems.SpaceX has designed this first stage to be reusable. With the state of the art materials (that aren't uber expensive).I suggest reviewing discussion pre F9R first flight that Musk demanded massive margins (for a single flight) precisely in order to make reuse possible.Nothing? Surely it gives an approximate baseline? They doubt it could be refurbed in 20 days. F9R should be less than that for exactly the reasons you specify.
That means almost nothing for F9R reuse.X-15 was an experimental aircraft with 50 yr old tech.X-15 used outdated rockets, used wings, outdated structural materials, and was a government driven program.The Shuttle used far more up to date technology, but the need to do orbital re-entry with all of those thermal tiles. And there are many other big problems.SpaceX has designed this first stage to be reusable. With the state of the art materials (that aren't uber expensive).I suggest reviewing discussion pre F9R first flight that Musk demanded massive margins (for a single flight) precisely in order to make reuse possible.
Quote from: macpacheco on 01/03/2016 05:46 amQuote from: Senex on 01/02/2016 07:03 pmWhile speculation is popular and is often justified by the absence of facts, there ARE some facts available. In an interesting article, space historian David Portree cites a study that looked at the refurbishment costs of the X-15 program that provides probably the most relevant real-world data we have:"In November 1966, James Love and William Young, engineers at the NASA Flight Research Center at Edwards Air Force Base, completed a brief report in which they noted that the reusable suborbital booster for a reusable orbital spacecraft would undergo pressures, heating rates, and accelerations very similar to those the X-15 experienced.""The average X-15 refurbishment time was 30 days, a period which had, they noted, hardly changed in four years. Even with identifiable improvements, they doubted that an X-15 could be refurbished in fewer than 20 days."At the same time, Love and Young argued that the X-15 program had demonstrated the benefits of reusability. They estimated that refurbishing an X-15 in 1964 had cost about $270,000 per mission. "Love and Young cited North American Aviation estimates when they placed the cost of a new X-15 at about $9 million. They then calculated that 27 missions using expendable X-15s would have cost a total of $243 million. This meant, they wrote, that the cost of the reusable X-15 program in 1964 had amounted to just 3% of the cost of building 27 X-15s and throwing each one away after a single flight.My bold.http://www.wired.com/2013/05/the-x-15-rocket-plane-reusable-space-shuttle-boosters-1966/That means almost nothing for F9R reuse.X-15 was an experimental aircraft with 50 yr old tech.X-15 used outdated rockets, used wings, outdated structural materials, and was a government driven program.The Shuttle used far more up to date technology, but the need to do orbital re-entry with all of those thermal tiles. And there are many other big problems.SpaceX has designed this first stage to be reusable. With the state of the art materials (that aren't uber expensive).I suggest reviewing discussion pre F9R first flight that Musk demanded massive margins (for a single flight) precisely in order to make reuse possible.Nothing? Surely it gives an approximate baseline? They doubt it could be refurbed in 20 days. F9R should be less than that for exactly the reasons you specify.
Quote from: mheney on 01/02/2016 04:32 pmShouldn't be surprising. The center engine was fired 4 times during the launch and landing; two other engines were fired 3 times (I think - launch, boostback, and braking burns?) Unless there was physical damage due to interaction with stuff on the ground (sand, grit, gators ...), there's no reason they couldn't just be fired up again - they're designed to be both reusable and restartable.Would they do it that way, wouldn't that tend to make them unnecessarily swap engine positions later? Wouldn't it be cheaper to apply a sequential even spread choice (with the possible exception of the center engine for the final single engine burn), as even as the octagon allows? I guess I am asking for photo evidence or other information on engine use.
The center engine is used in all burns. And as far as why you would use the same other two engines for multiple burns - we don't know - but it has been assumed, since when each engine has a its own supply of ignition fluids (TEA/TEB) it makes more sense to just give 3 engines more of it instead of giving all engines the same restart capability. (It is nasty dangerous stuff) But I could be wrong on the last point.
So on the one hand there's the idea that across multiple reflights, you keep the same engines in the same spots, using them in exactly the same way again and again. This means that the 3 engines used for multiple burns within a flight are a bit more suped up - particularly that central engine that gets used for landing.Then on the other hand, there's the idea that you "rotate the tires" across multiple reflights - swapping the less used engines in place of the more used ones, so that they all get their fair share of wear and tear.Which way is the better way out of those 2 approaches - and why? Are there any other approaches that might be better still? Why?
Quote from: sanman on 01/02/2016 09:22 pmAnybody know what the theoretical or static-tested value is for the number of times the engines can be re-fired? Surely this must have been measured through rigorous ground testing.I don't know if they have tested any of the engines to destruction, so it's hard to say. I recall Ms. Shotwell noting at one point, a good year ago, that they were figuring on being able to fly each stage at least 10 times, but that their then-current testing indicated that the actual number of re-flights might become open-ended. The phrase "maybe 40 or 50, maybe more" sticks in my head.I won't be surprised if the actual number is a lot less than 40 or 50. But I don't think anything official has been stated in terms of expected number of re-uses, and that SpaceX seems to think that 10 re-flights is a good number to toss out, but might be really conservative.
Here is the quote " If you are able to refly your first stage, you need to establish how many times can you refly it -- is it 20 times, 40 times, 50 times? SpaceX does not know. http://www.bloomberg.com/news/articles/2015-04-13/spacex-plans-to-try-again-to-land-rocket-booster-on-barge-at-sea