About payload capacity, since this is the purpose for the thread. I find it amazing that one vehicle can win such a wide range of payloads. As we have seen the F9 can be a beast to LEO and yet still has flights for payloads under a few thousand kilos.
Quote from: wannamoonbase on 09/05/2022 04:12 pmAbout payload capacity, since this is the purpose for the thread. I find it amazing that one vehicle can win such a wide range of payloads. As we have seen the F9 can be a beast to LEO and yet still has flights for payloads under a few thousand kilos.I wonder how much of the cost of those low-mass launches is the Merlin that's expended on the upper stage. The MVac is much harder to make than the SL version.
I wonder if eventually they might fit an older SL Merlin on F9US with very low mass payloads instead?
The new SL engine added to the rotation would be cheaper to make, and could serve multiple launches.
Why do you think the Merlin Vacuum is "much harder to make"? Do you mean it costs more? Or that it takes more labor? Or what?
I actually agree MVac probably is significantly more expensive than the sea level version. It’s an underrated part of Falcon 9’s success.
I wonder how much of the cost of those low-mass launches is the Merlin that's expended on the upper stage. The MVac is much harder to make than the SL version. I wonder if eventually they might fit an older SL Merlin on F9US with very low mass payloads instead?The new SL engine added to the rotation would be cheaper to make, and could serve multiple launches. Cheers, Martin
As you say, using a sea-level engine on the upper stage could allow F9 to compete for less demanding launches. I don't think anybody who knows for sure why it isn't implemented would be allowed to say. At a guess, the size of the small-payload-to-low-orbit market is just too small to justify the NRE cost and the added cost of keeping another version of the upper stage in production.
MP99, good posting. You could improve it by losing the Tapatalk spam.
Quote from: alugobi on 09/05/2022 08:32 pmMP99, good posting. You could improve it by losing the Tapatalk spam. Would love to.I have always configed this away in the past, but I think they may have removed the setting for that at some point.
Staging the fairing significantly earlier, taking less time after stage sep to ignite the second stage. Better understanding of propellant residuals, more aggressive hoverslam.
Quote from: Robotbeat on 08/31/2022 03:39 pmStaging the fairing significantly earlier, taking less time after stage sep to ignite the second stage. Better understanding of propellant residuals, more aggressive hoverslam.SpaceX also has used Starlink missions to experiment with the timing between first-stage separation and second-stage engine ignition. Separating the first stage and immediately lighting the second is better from a second-stage performance perspective, but the plume then hits the first-stage interstage components, increasing wear. “We’re looking at how you light the engine the earliest, but not damage components in the first stage,” Jensen says.So far, SpaceX has worked down to a 1,000-in. separation by decreasing the time between first-stage separation and second-stage ignition in increments of 0.25 sec.Similarly, Starlink missions provide SpaceX a testbed for fairing separation timing. Customers typically have strict requirements on when the fairing is deployed to prevent rarified atmospheric particles in the fringe of space from heating the payload.“On Starlink missions, we incrementally started deploying the fairing earlier and allowing higher and higher heating,” Edwards says. “Now we’re at the point where it’s more than 10 times the heating that is typically allowed on an external customer mission.”
Quote from: MP99 on 09/11/2022 08:53 pmQuote from: alugobi on 09/05/2022 08:32 pmMP99, good posting. You could improve it by losing the Tapatalk spam. Would love to.I have always configed this away in the past, but I think they may have removed the setting for that at some point. Sent from my 21091116UG using TapatalkUser Control Panel or SettingsEdit SignatureMake it blank
Quote from: alugobi on 09/05/2022 08:32 pmMP99, good posting. You could improve it by losing the Tapatalk spam. Would love to.I have always configed this away in the past, but I think they may have removed the setting for that at some point. Sent from my 21091116UG using Tapatalk
Has anyone ever looked at a lengthened second stage or adding a third stage? Greater hardware cost, but perhaps a saving on expended boosters.