Quote from: Robotbeat on 09/05/2023 02:39 pmBut even if it’s just 5 Starship launches, that’s the equivalent of 50 Falcon 9s. That would already be a substantial effect.OK, please make a prediction on the year in which there will be 5 F9-replacing Starship launches. (i.e., not depot, tanker, HLS,...)Also note that I don't think we know enough about Starlink V.2 versus Starlink V.2 mini. It's possible that SpaceX want to launch the same number of satellites, not the same payload mass. In either case, Starship will replace all F9 Starlink launches as soon as it reaches high cadence. I still think it's 2028, but this is a mostly just an uneducated guess.If they eventually complete the 42,000-satellite system, including replacing all earlier satellites with V.2, and if the SS delivers 72 V.2/launch, then they will need 584 SS launches. If they eventually get to an average satellite lifetime of ten years, this will stabilize as 59 Starlink lunches per year after some peak year of maybe 200 SS Starlink launches.
But even if it’s just 5 Starship launches, that’s the equivalent of 50 Falcon 9s. That would already be a substantial effect.
You then take the ratio of two end points, n months apart, take the n-th root, and find your "monthly growth rate".Then, you plot the graph along with the noisy data and rejoice that it "looks good". And since you have the two end points pre-pegged, of course it'll predict the few next ones rather well, especially with all the noise... any increasing model would do that!
Quote from: DanClemmensen on 09/05/2023 03:10 pmQuote from: Robotbeat on 09/05/2023 02:39 pmBut even if it’s just 5 Starship launches, that’s the equivalent of 50 Falcon 9s. That would already be a substantial effect.OK, please make a prediction on the year in which there will be 5 F9-replacing Starship launches. (i.e., not depot, tanker, HLS,...)Also note that I don't think we know enough about Starlink V.2 versus Starlink V.2 mini. It's possible that SpaceX want to launch the same number of satellites, not the same payload mass. In either case, Starship will replace all F9 Starlink launches as soon as it reaches high cadence. I still think it's 2028, but this is a mostly just an uneducated guess.If they eventually complete the 42,000-satellite system, including replacing all earlier satellites with V.2, and if the SS delivers 72 V.2/launch, then they will need 584 SS launches. If they eventually get to an average satellite lifetime of ten years, this will stabilize as 59 Starlink lunches per year after some peak year of maybe 200 SS Starlink launches.Probably 2025, possibly 2024.SpaceX wants to launch full sized Starlink V2s and already has made stacks of them.
There are 18 missions on the manifest, none of them Starlinks. They need 19 more missions in addition to those to make 100. They've launched 36 Starlinks this calendar year. --Not making a point. Just more data to fit to your curve of choice.
Quote from: meekGee on 09/05/2023 10:07 amYou then take the ratio of two end points, n months apart, take the n-th root, and find your "monthly growth rate".Then, you plot the graph along with the noisy data and rejoice that it "looks good". And since you have the two end points pre-pegged, of course it'll predict the few next ones rather well, especially with all the noise... any increasing model would do that!I'm fairly sure I know what I'm doing, and it's not that. Maybe once you stop trying to tell me what I'm doing and understand what I'm actually doing, we can have a sensible discussion about how I might be able to improve things.
It’s not changing by smaller and smaller multiples. It’s noisy.
Quote from: meekGee on 09/05/2023 10:07 amDec 2022 was 7 launchesJan 2023 was 7 launchesFeb 2023 was 7 launchesMar 2023 was 7 launchesApr 2023 was 7 launchesMay 2023 was 7 launchesJun 2023 was 7 launchesWhere do you get those numbers from?The launch history on wikipedia that I've been using has 7, 7, 6, 8, 6, 9, 7.
Dec 2022 was 7 launchesJan 2023 was 7 launchesFeb 2023 was 7 launchesMar 2023 was 7 launchesApr 2023 was 7 launchesMay 2023 was 7 launchesJun 2023 was 7 launches
It’s not linear, either. Linear would imply negative launch rates in the past. Parabolic/quadratic would imply in the far past, huge launch rates. Exponential is a simple model that while not perfect, has the advantage of being well behaved when extrapolated forward or backward in time.I expect the Falcon launch family to have a sigmoid shaped cumulative launch number function. But as an approximation to a sigmoid, exponential is a better approximation than linear and has no more free variables than linear.
Quote from: Robotbeat on 09/05/2023 09:23 pmIt’s not linear, either. Linear would imply negative launch rates in the past. Parabolic/quadratic would imply in the far past, huge launch rates. Exponential is a simple model that while not perfect, has the advantage of being well behaved when extrapolated forward or backward in time.I expect the Falcon launch family to have a sigmoid shaped cumulative launch number function. But as an approximation to a sigmoid, exponential is a better approximation than linear and has no more free variables than linear.Why should it be any function? This is like econonmics therory "...first assume a spherical frictionless horse with perfect information interacting with it's own best interests in mind..." etc. Gravity has an underlying function that is near perfect at moderate levels but why assume something as chaotic and rare like a lauch (compared with say the common exhange of money and goods) will fit some simple function like a straight line or exponential or anything that basic?
Quote from: Robotbeat on 09/05/2023 09:23 pmIt’s not changing by smaller and smaller multiples. It’s noisy.This.@meekGee, I'm now convinced you are just trolling us. I'm done.
Quote from: steveleach on 09/05/2023 05:46 pmQuote from: meekGee on 09/05/2023 10:07 amDec 2022 was 7 launchesJan 2023 was 7 launchesFeb 2023 was 7 launchesMar 2023 was 7 launchesApr 2023 was 7 launchesMay 2023 was 7 launchesJun 2023 was 7 launchesWhere do you get those numbers from?The launch history on wikipedia that I've been using has 7, 7, 6, 8, 6, 9, 7.I was puzzled by meekGee's count also. But I'm also puzzled by your count, SteveLeach. Here's what I get (and my source is the "List of Falcon 9 and Falcon Heavy Launches" on Wikipedia):# of launches per month (sum of Falcon 9, Falcon Heavy, and Starship)----7 launches, December 20227 launches, January 20236 launches, February 20238 launches, March 20237 launches, April 20239 launches, May 20237 launches, June 20238 launches, July 20238 launches, August 2023I assume that meekGee got his 7, 7, 7, ... pattern by smoothing things out. For instance he replaced 6 launches, February 20238 launches, March 2023with 7 launches, February 20237 launches, March 2023And that's not literally what happened. But I get the point and it's not a bad way to look at things.Except when I smooth things out, I get a different pattern:7 launches, December 20227 launches, January 20237 launches, February 20237 launches, March 20237 launches, April 20238 launches, May 20238 launches, June 20238 launches, July 20238 launches, August 2023It's the same numbers of launches as actually occurred. It's just been smoothed out. And what this suggests is that around May of 2023, the launch rate went up from 7 per month to 8 per month.
Why should it be any function?
What was the 2020 to 2021 launch rate change, meekgee?
Quote from: steveleach on 09/05/2023 05:46 pmQuote from: meekGee on 09/05/2023 10:07 amDec 2022 was 7 launchesJan 2023 was 7 launchesFeb 2023 was 7 launchesMar 2023 was 7 launchesApr 2023 was 7 launchesMay 2023 was 7 launchesJun 2023 was 7 launchesWhere do you get those numbers from?The launch history on wikipedia that I've been using has 7, 7, 6, 8, 6, 9, 7.I was puzzled by meekGee's count also. But I'm also puzzled by your count, SteveLeach. Here's what I get (and my source is the "List of Falcon 9 and Falcon Heavy Launches" on Wikipedia):# of launches per month (sum of Falcon 9, Falcon Heavy, and Starship)----7 launches, December 20227 launches, January 20236 launches, February 20238 launches, March 20237 launches, April 20239 launches, May 20237 launches, June 20238 launches, July 20238 launches, August 2023
Quote from: xyv on 09/06/2023 01:25 amQuote from: Robotbeat on 09/05/2023 09:23 pmIt’s not linear, either. Linear would imply negative launch rates in the past. Parabolic/quadratic would imply in the far past, huge launch rates. Exponential is a simple model that while not perfect, has the advantage of being well behaved when extrapolated forward or backward in time.I expect the Falcon launch family to have a sigmoid shaped cumulative launch number function. But as an approximation to a sigmoid, exponential is a better approximation than linear and has no more free variables than linear.Why should it be any function? This is like econonmics therory "...first assume a spherical frictionless horse with perfect information interacting with it's own best interests in mind..." etc. Gravity has an underlying function that is near perfect at moderate levels but why assume something as chaotic and rare like a lauch (compared with say the common exhange of money and goods) will fit some simple function like a straight line or exponential or anything that basic?The field of operations research is devoted to this sort of analysis. You are supposed to start by creating the best model you can for the phenomenon you are analyzing. I think that both the linear growth model and the exponential growth model are far too simplistic to yield any useful analysis.
