I expect refurb after each ten, retirement after 100.
No-one (except SpaceX) has ANY idea of the refurb costs after each ten flights.
Forgive another car analogy, but I'd expect the refurb to be on the order of a new set of brake pads. Not an every day occurrence, but certainly not a transmission rebuild which is often not cost effective.
Quote from: john smith 19 on 08/31/2017 10:24 pmQuote from: mvpel on 08/31/2017 06:56 pmTheir long-term aim is at least 100 reflights of each booster core, and I heard this directly from the SpaceX VP of business development at the CRS-8 launch viewing on the OMB-II verandah.Well so far they Shotwell on the Space Show said they are looking to do 3 launches off a booster and V5 will be good for 10 without major So either V5 will do that with a lot of refurb work above "inspection" or they are at least another generation to go from 10 to 100. I expect refurb after each ten, retirement after 100. No-one (except SpaceX) has ANY idea of the refurb costs after each ten flights. Forgive another car analogy, but I'd expect the refurb to be on the order of a new set of brake pads. Not an every day occurrence, but certainly not a transmission rebuild which is often not cost effective.
Quote from: mvpel on 08/31/2017 06:56 pmTheir long-term aim is at least 100 reflights of each booster core, and I heard this directly from the SpaceX VP of business development at the CRS-8 launch viewing on the OMB-II verandah.Well so far they Shotwell on the Space Show said they are looking to do 3 launches off a booster and V5 will be good for 10 without major So either V5 will do that with a lot of refurb work above "inspection" or they are at least another generation to go from 10 to 100.
Their long-term aim is at least 100 reflights of each booster core, and I heard this directly from the SpaceX VP of business development at the CRS-8 launch viewing on the OMB-II verandah.
Going with the brake pad analogy the items that are the ones receiving the most degradation from use are the engines, grid fins, and landing legs. I would expect significant replacement (re-manufacturing) of these parts. Basically replace all the engines, the grid fins and legs. Send them off for evaluation to determine if they can be individually refurbished or just cheaper to scrap. The then refurbished stage has new or like new engines, grid fins and legs. The other item the tank and avionics are such that failed avionics are replaced as needed regardless of what the flight number. The tank if down checked, then the stage is basically scrapped by removing all the usable parts putting them back into inventory. That can also happen at anytime or even the stage (tank) could fly more than 100 times. The real nature of re-flying tanks multiple times is not well known (except for the the two flights is almost completely unknown).
There is just a lot of unknowns.Info is such that F9 can reliably do at least 2 flights. The refurb time from info on last re-flight was 2 months with new info that should be forthcoming on the next that give light of whether the time and manpower/ related costs are leveled out or continue to decline.
If you're not using LH2 but you do want reusability I find it very hard to understand why you would not use LOX cooling. AFAIK all other LRE's use the oxidizer for the cooling, some of which are very nasty. Both Rotary Rocket and NASA ran LOX cooling tests in the early 90's, without mishap, including deliberate leaks into the CC, but the folklore around this subject is very tenacious and the facts difficult to get hold of. BTW thanks for that figure of $500/day for staff costs. With fairing reuse on the verge of happening it might time for a new version of my cost modelling game.
The norm for LREs is to use the fuel for cooling the CC, not LOX.John
AFAIK all other LRE's use the oxidizer for the cooling, some of which are very nasty.
Quote from: john smith 19 on 09/02/2017 09:57 amIf you're not using LH2 but you do want reusability I find it very hard to understand why you would not use LOX cooling. AFAIK all other LRE's use the oxidizer for the cooling, some of which are very nasty. Both Rotary Rocket and NASA ran LOX cooling tests in the early 90's, without mishap, including deliberate leaks into the CC, but the folklore around this subject is very tenacious and the facts difficult to get hold of. BTW thanks for that figure of $500/day for staff costs. With fairing reuse on the verge of happening it might time for a new version of my cost modelling game.Quite interesting post. But isn't the lack of use of LOX cooling quite easily explained if you take into consideration that the Merlin engine was designed by a start-up and that it is also designed to be affordable in expendable mode.
If you look at it that way LOX cooling would have added significant development risk.
Furthermore the Raptor engine uses Methane which does not have the disadvantages of RP-1. Methane should contain (almost) no sulfer and deposit much less carbon.
And how does LOX cooling affect TWR?Edit: Fixed broken quote
Quote from: Krankenhausen on 09/07/2017 10:35 amQuote from: john smith 19 on 09/02/2017 09:57 amIf you're not using LH2 but you do want reusability I find it very hard to understand why you would not use LOX cooling. AFAIK all other LRE's use the oxidizer for the cooling, some of which are very nasty. Both Rotary Rocket and NASA ran LOX cooling tests in the early 90's, without mishap, including deliberate leaks into the CC, but the folklore around this subject is very tenacious and the facts difficult to get hold of. BTW thanks for that figure of $500/day for staff costs. With fairing reuse on the verge of happening it might time for a new version of my cost modelling game.Quite interesting post. But isn't the lack of use of LOX cooling quite easily explained if you take into consideration that the Merlin engine was designed by a start-up and that it is also designed to be affordable in expendable mode. In fact the first Merlin was ablatively cooled. Which is an even odder choice for a design if you're planning to make reusable, which has always been Musks goal.
Long road to reusabity of Falcon 9 primary boost stage…When upper stage & fairing also reusable, costs will drop by a factor >100.
https://twitter.com/elonmusk/status/908254079092002816QuoteLong road to reusabity of Falcon 9 primary boost stage…When upper stage & fairing also reusable, costs will drop by a factor >100.This seems considerably more certain than prior pronouncements.And clearly means that upper/lower/fairing each can't have >100K spent on them to refurb and get back to the launch site. (counting fuel)
Quote from: speedevil on 09/14/2017 12:56 pmhttps://twitter.com/elonmusk/status/908254079092002816QuoteLong road to reusabity of Falcon 9 primary boost stage…When upper stage & fairing also reusable, costs will drop by a factor >100.This seems considerably more certain than prior pronouncements.And clearly means that upper/lower/fairing each can't have >100K spent on them to refurb and get back to the launch site. (counting fuel)It's a truism of launch vehicle economics. If I were guessing I'd say the team have a firmer handle on the physics of US reentry and they are ready to give it a serious try. But we've been here before. Let's see how they handle the 26x bigger energy dissipation problem that orbital entry has over booster recovery.
And Dragon.
Same way the Space Shuttle, Buran, X-37B and Dream Chaser does it, with some type of reusable TPS. Its not like we haven't done this before. It is different in that it is more of lifting body (smaller aero-surfaces).