Strangely enough, the User Guide omits payload capacity. Some payload masses are published, but some are not.Max capability of 22 tons to LEO has been cited, but F9 maxes out at half that for ISS missions, so the 22 tons must be for expendable flights to 28 degrees, very low.Is there a decent source that can make sense of the available payload mass numbers, and that provides what is missing from the Users Guide?
https://twitter.com/elonmusk/status/1563760585363185664QuoteSqueezing extra performance out of Falcon 9 – almost at 17 metric tons to an actual useful orbit with booster & fairing reusable!
Squeezing extra performance out of Falcon 9 – almost at 17 metric tons to an actual useful orbit with booster & fairing reusable!
What's the price for a 'no frills' F9 launch these days?With the new max demonstrated payload, how does the $/kg for F9 compare to those old 90s RLV and SSTO proposals?Given inflation since the 90s I wouldn't be surprised if it's comparable or better.
Quote from: Vultur on 08/28/2022 05:36 pmWhat's the price for a 'no frills' F9 launch these days?With the new max demonstrated payload, how does the $/kg for F9 compare to those old 90s RLV and SSTO proposals?Given inflation since the 90s I wouldn't be surprised if it's comparable or better.last I heard, $50 million is roughly what the going price was for cheapest launch. At 16.7mt, that’s $3000/kg to LEO.In 1997, Goldin said Venturestar would enable $1000/lb. So $2200/kg. Or $3000/kg in today’s money.So F9 equals the SSTO RLV projections for offered price (which you might need to bargain hard, for, including maybe having a lot of launches). SpaceX says the internal full cost is less than $30m, so SpaceX is internally beating it, and getting a significant profit.
Staging the fairing significantly earlier, taking less time after stage sep to ignite the second stage. Better understanding of propellant residuals, more aggressive hoverslam.
https://twitter.com/alexphysics13/status/1566601586012524546QuoteKeeping an eye today for any potential changes to the Falcon 9 launch countdown sequence. Last launch had LOX load wrapped up later than usual. This is in order to keep LOX being loaded as late as possible and helps keep it as cold as possible much closer to launch.twitter.com/alexphysics13/status/1566602157436149762QuoteWhich in turn means an improvement in performance. More mass of propellant in the tanks for no added dry mass means more delta-v available. Denser propellant also means more flow rate into the engine which largely means more thrust.https://twitter.com/alexphysics13/status/1566602376051580928QuoteThe colder temperatures bring its own issues though, not just because of the COPVs inside the LOX tanks as we saw back in 2016 with Amos 6 but also with how you manage a propellant that is denser and, most likely, more viscous.twitter.com/alexphysics13/status/1566602616938848256QuoteViscosity at colder temperatures is of special importance with kerosene for example, it may actually make the engines underperform as it is harder to push through the pumps if it's more viscous.https://twitter.com/alexphysics13/status/1566602846358872064QuoteAll in all, this is a careful and gradual process that SpaceX is now doing on their Starlink missions and will for sure mean they'll gather even more data into how to manage cold propellants at temperatures not previously handled by more traditional US launch companies.https://twitter.com/alexphysics13/status/1566609098170310656QuoteYep this is the late LOX load sequence
Keeping an eye today for any potential changes to the Falcon 9 launch countdown sequence. Last launch had LOX load wrapped up later than usual. This is in order to keep LOX being loaded as late as possible and helps keep it as cold as possible much closer to launch.
Which in turn means an improvement in performance. More mass of propellant in the tanks for no added dry mass means more delta-v available. Denser propellant also means more flow rate into the engine which largely means more thrust.
The colder temperatures bring its own issues though, not just because of the COPVs inside the LOX tanks as we saw back in 2016 with Amos 6 but also with how you manage a propellant that is denser and, most likely, more viscous.
Viscosity at colder temperatures is of special importance with kerosene for example, it may actually make the engines underperform as it is harder to push through the pumps if it's more viscous.
All in all, this is a careful and gradual process that SpaceX is now doing on their Starlink missions and will for sure mean they'll gather even more data into how to manage cold propellants at temperatures not previously handled by more traditional US launch companies.
Yep this is the late LOX load sequence
Scott Manley's video on the new payload record also suggests that F9US / Merlin Vacuum may have 7% higher thrust than previously, from analysis of the telemetry numbers from SpaceX's video.If so, presumably testing on Starlink launches.
Quote from: Vultur on 08/28/2022 05:36 pmWhat's the price for a 'no frills' F9 launch these days?With the new max demonstrated payload, how does the $/kg for F9 compare to those old 90s RLV and SSTO proposals?Given inflation since the 90s I wouldn't be surprised if it's comparable or better.last I heard, $50 million is roughly what the going price was for cheapest launch.
Has anyone heard $50M recently? I think IPXE (contracted pre-covid, launched late 2021) was the last flight to fly at that price. Special/unusual circumstances included competitively bidding against Pegasus XL.
Quote from: DeimosDream on 09/05/2022 02:22 pmHas anyone heard $50M recently? I think IPXE (contracted pre-covid, launched late 2021) was the last flight to fly at that price. Special/unusual circumstances included competitively bidding against Pegasus XL. SpaceX raised their prices by about 10% earlier this year, so by now those launches should be more like $55M.I'll also note that the launch contract for IXPE was cheaper than that, at $42M, including five mission-unique services. The $50.3M cost often quoted, was NASA's cost for launching, which included various NASA-internal costs. See this message in the IXPE launch thread.
QuoteKeeping an eye today for any potential changes to the Falcon 9 launch countdown sequence. Last launch had LOX load wrapped up later than usual. This is in order to keep LOX being loaded as late as possible and helps keep it as cold as possible much closer to launch.Which in turn means an improvement in performance. More mass of propellant in the tanks for no added dry mass means more delta-v available. Denser propellant also means more flow rate into the engine which largely means more thrust.
Keeping an eye today for any potential changes to the Falcon 9 launch countdown sequence. Last launch had LOX load wrapped up later than usual. This is in order to keep LOX being loaded as late as possible and helps keep it as cold as possible much closer to launch.Which in turn means an improvement in performance. More mass of propellant in the tanks for no added dry mass means more delta-v available. Denser propellant also means more flow rate into the engine which largely means more thrust.
Here is a comparison of the webcast telemetry from Starlink 4-27 and 4-20.Although 4-20 may have utilized a late load of propellant, there was no evidence of the increased acceleration evident in 4-27 or 4-23. The 4-20 booster landed some 40km less distance downrange, velocity at MECO was some 43m/s less, and peak S2 acceleration was 3.8g vs 4g for 4-27.Overall, it was a much more relaxed affair.
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.
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.
Quote from: alugobi on 09/11/2022 09:14 pmQuote 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 blankThat's a relief. Thanks! Cheers, Martin
