Thank you woods170.I'll take that as occasional engine bell replacement then. The 'wild claim' might just be my poor memory as I didn't record it, but I don't think I was that far out.John's speculation about foreign object damage was interesting as I guess it is relevant to Lunar and Martian landing and launch.Maybe I should start a thread about how to change an engine bell in near vacuum and low G and whether it's worth carrying a spare..:-)
Quote from: alang on 12/29/2019 03:09 pmThank you woods170.I'll take that as occasional engine bell replacement then. The 'wild claim' might just be my poor memory as I didn't record it, but I don't think I was that far out.John's speculation about foreign object damage was interesting as I guess it is relevant to Lunar and Martian landing and launch.Maybe I should start a thread about how to change an engine bell in near vacuum and low G and whether it's worth carrying a spare..:-)The Merlin 1D booster engine's Main Combustion Chamber and bell nozzle are one piece. You cannot replace just the bell.John
That is entirely correct. Replacing a bell automatically means replacing the entire engine.As I had already pointed out - in my previous post - the story about reuse requiring replacing the bells (and thus the entire engine) is false. It is just another one of many b*llshit stories thrown into the world to deliberately throw a false shade on the success of booster reuse.
Quote from: alang on 12/28/2019 07:37 pmI then realised that a launch failure is likely to cause a six month launch hiatus whatever the reason for launch failure … .What would prevent SpaceX doing an internal, Starlink launch shortly after a failure? Isn't it mostly SpaceX's call on whether they want to take the risk?Delay may be the NASA/DoD way, but how much say do they get when they are not the customer? The FAA appears to mostly care about not hurting bystanders, and the normal launch procedures should see to that (or they would object to things like in flight abort tests.)
I then realised that a launch failure is likely to cause a six month launch hiatus whatever the reason for launch failure … .
Maybe this is the best place to ask this question, rather than in a Starlink thread or in a stand-alone thread.Is it possible that SpaceX will eliminate static fires for Starlink launches?Per what we've been told, SpaceX plans to launch Starlink every two weeks. At that pace, static fires become a significant portion of the workload and schedule. Booster reflights are common now, the IFA will be the 3rd 4th flight.I'm not aware of the static fires catching any issues in a long time (correct me if I'm wrong). Is SpaceX reaching the point where static fires are not useful enough to continue? Another cycle on tanks and engines that doesn't put payload on orbit.I can see them rolling the dice on Starlink launches and going straight to launch.What do you guys think?
ULA eliminated the WDR (Wet Dress Rehearsal) from its Atlas launch campaigns, except for high profile launches (like to Mars, crew flights, etc.), several years ago for that very reason, they weren't finding issues by doing them.
Quote from: whitelancer64 on 01/08/2020 02:45 pmULA eliminated the WDR (Wet Dress Rehearsal) from its Atlas launch campaigns, except for high profile launches (like to Mars, crew flights, etc.), several years ago for that very reason, they weren't finding issues by doing them.I'm interested in what proportion of ULA flights they deem "high profile," and wheather they also caught any anomalous behavior. It is interesting that a company that only flies fully expendable LV's should feel they are confident enough in their processes (and the build quality and existing sub system tests) that they no longer regard this as essential. For SX I'd have said the static fire would be the few seconds before launch. A key benefit of LRE's being if you do pick something odd you can still shut the launch down. Not something you can do easily once SRB's are involved.
Quote from: john smith 19 on 01/09/2020 06:07 amQuote from: whitelancer64 on 01/08/2020 02:45 pmULA eliminated the WDR (Wet Dress Rehearsal) from its Atlas launch campaigns, except for high profile launches (like to Mars, crew flights, etc.), several years ago for that very reason, they weren't finding issues by doing them.I'm interested in what proportion of ULA flights they deem "high profile," and wheather they also caught any anomalous behavior. It is interesting that a company that only flies fully expendable LV's should feel they are confident enough in their processes (and the build quality and existing sub system tests) that they no longer regard this as essential. For SX I'd have said the static fire would be the few seconds before launch. A key benefit of LRE's being if you do pick something odd you can still shut the launch down. Not something you can do easily once SRB's are involved.A SF in the seconds before launch is not a SF. It's already the standard launch procedure, where the engines are spun up and have to meet health checks before the clamps release.SF is for schedule. If it's hurting the schedule more than helping it, it will go.
A SF in the seconds before launch is not a SF. It's already the standard launch procedure, where the engines are spun up and have to meet health checks before the clamps release.SF is for schedule. If it's hurting the schedule more than helping it, it will go.
SFs are SFs iff there's a chance for review that is not available during the hold-down of a real launch. This review can be manual or automated, it doesn't matter.
IMO SFs will go once SpaceX feels that data from the previous launch can replace them. New boosters will therefore still get SFs.
SpaceX's next rocket launch on track to break a 20-month-old booster reusability recordBy Eric RalphPosted on February 7, 2020Scheduled as early as next week, SpaceX’s next rocket launch could see the company break a 20-month-old record that is closely intertwined with the reusability of its Falcon 9 and Falcon Heavy boosters.[…]Now, SpaceX wants to launch B1056 for the fourth time as early as February 15th. Close observers will note that that would imply just 61 days between B1056’s Kacific-1 and Starlink V1 L4 launches, a feat that would make it SpaceX’s fastest ‘booster turnaround’ ever.
The info on the turnaround time also said they had 11 boosters at the Cape, but obviously not all used boosters are equally usable.
Quote from: Stefan.Christoff.19 on 02/07/2020 04:58 pmThe info on the turnaround time also said they had 11 boosters at the Cape, but obviously not all used boosters are equally usable.That's not obvious at all.If they have lots of boosters to choose from, just because they choose to use booster A instead of booster B doesn't mean B isn't perfectly usable. If all 11 of those boosters are perfectly usable, they have to choose some to use and some not to. There might be very marginal differences. They might choose to reuse a particular booster several times in a relatively short period just to show that they can.We don't really know why they choose any particular booster for any particular launch, so we can't reasonably draw any conclusions from their choices.
Euroconsult tracked SpaceX's reuse of Falcon 9 rocket boosters and found that the company has cut its turnaround time from ~250 days between flights to ~75 days between flights.That's about a 70% reduction in reusability time:spacenews.com/op-ed-spacexs-…
Elon Musk’s SpaceX is about to land its 50th Falcon 9 boosterOnce thought impossible, reusing rocket boosters has become routineBy Christian Davenport Feb. 14, 2020 at 8:21 p.m. GMTThe effort to return booster rockets to Earth had been tried and had failed several times; it turns out landing a rocket back on Earth safely is pretty difficult. So Elon Musk was not deluding himself in 2014 when he calculated the odds that his company, SpaceX, would eventually get it right: “not great — perhaps 50 percent, at best.”