https://twitter.com/rocketrepreneur/status/1556366878276083712QuoteUgh... I love that Relativity is going after a full RLV to compete with Starship, but I wish they were going smaller, instead of larger... someone needs to do a smaller RLV.twitter.com/thetimellis/status/1556381932795183105QuoteEconomics don’t work as well for smaller RLV on a per satellite basis for what the LEO constellations want to do and they need to compete with huge cost advantages of F9/starlink. Number per plane, mass each, spares, etc I think the F9 class is about the smallest that will workhttps://twitter.com/rocketrepreneur/status/1556383827454398464QuoteHuh, ok that's bigger than I would've thought. Are their next gen satellites all planning on being a lot bigger than first gen? I would've thought that $/sat would be more a function of flight rate and total flights per hull than a function of raw rocket size.twitter.com/thetimellis/status/1556384580554334211QuoteCan’t officially say but I’ve seen everyone trend that way. It’s function of doing either an entire orbital plane plus spares or a round number fraction of that (split in half, thirds, etc) and then yes flights per vehicle for reuse. But the mass and logistics of many launches…https://twitter.com/thetimellis/status/1556384682408820736Quote…still is more dominant as we’ve seen it
Ugh... I love that Relativity is going after a full RLV to compete with Starship, but I wish they were going smaller, instead of larger... someone needs to do a smaller RLV.
Economics don’t work as well for smaller RLV on a per satellite basis for what the LEO constellations want to do and they need to compete with huge cost advantages of F9/starlink. Number per plane, mass each, spares, etc I think the F9 class is about the smallest that will work
Huh, ok that's bigger than I would've thought. Are their next gen satellites all planning on being a lot bigger than first gen? I would've thought that $/sat would be more a function of flight rate and total flights per hull than a function of raw rocket size.
Can’t officially say but I’ve seen everyone trend that way. It’s function of doing either an entire orbital plane plus spares or a round number fraction of that (split in half, thirds, etc) and then yes flights per vehicle for reuse. But the mass and logistics of many launches…
…still is more dominant as we’ve seen it
I hope this ends the "Starship is too BIG" argument once and for all.
Quote from: su27k on 08/08/2022 02:47 amI hope this ends the "Starship is too BIG" argument once and for all.Why would it? That discussion is solely on the lower bound of economic (rather than practical or possible) RLV size, it doesn't even mention the upper bound (if any).
Quote from: edzieba on 08/08/2022 11:56 amQuote from: su27k on 08/08/2022 02:47 amI hope this ends the "Starship is too BIG" argument once and for all.Why would it? That discussion is solely on the lower bound of economic (rather than practical or possible) RLV size, it doesn't even mention the upper bound (if any).Well yeah, Relativity - the primary competitor of Starship - saying they need bigger RLV to compete with Starship and that constellation launch economics favor big RLV with smaller # of launches instead of smaller RLV with big # of launches is not relevant to Starship sizing discussion at all... /s
Since their "bigger RLV" is of similar capability as F9 (and Neutron) it doesn't say much about the economic viability of Starship beyond "at least two companies think smaller than Starship is a better option".
This is exactly what SpaceX is doing with Starship and Starlink.
As I was watching the scene where the SS is horizontal on the way down to the ocean, I suddenly heard a voice in my head saying:“And wow! Hey! What’s this thing suddenly coming towards me very fast? Very fast. So big and flat and round, it needs a big wide sounding name like … own … found … round … ground! That’s it! That’s a good name – ground!”“I wonder if it will be friends with me?”
All signs point to Starship being 'too big' for the commercial launch market. That's not a problem for SpaceX because the commercial launch market is secondary to their actual goal (Mars), but it does man that bigger is not necessarily better for other commercial launch providers.
Quote from: su27k on 08/08/2022 01:37 pmThis is exactly what SpaceX is doing with Starship and Starlink.SpaceX are increasing the size of Starlink 2 to fill the mass of Starship, because SpaceX's only launch option is Starship.Other constellation manufacturers are instead looking at the optimum size of the entire available launch market, not wanting to be locked into one launch provider. Note also that Ellis mentioned that the metric of interest is number of launches per plane, not mass of satellites: Starship with the enlarged Starlinks is still launching a single plane per launch, and smaller satellites would be leaving empty capacity.
Multiple commercial providers are targeting medium lift vehicles (there's Stoke Space as well). Elon himself has said that Starship may be 'too big'. All signs point to Starship being 'too big' for the commercial launch market. That's not a problem for SpaceX because the commercial launch market is secondary to their actual goal (Mars), but it does man that bigger is not necessarily better for other commercial launch providers.
Too big (vehicle size) isn't really a problem if the launch cost is competitive with smaller alternatives.
First of all, you don't have to do a single plane per launch, you can launch multiple planes in a single launch, which is exactly what SpaceX is doing with F9 and Gen1. You just need to wait a few months to drift some of the satellites to nearby planes.
Quote from: su27k on 08/08/2022 04:02 pmFirst of all, you don't have to do a single plane per launch, you can launch multiple planes in a single launch, which is exactly what SpaceX is doing with F9 and Gen1. You just need to wait a few months to drift some of the satellites to nearby planes.I agree but want to add:IMHO trying to match the size of a plane to the size of a launcher is, and always will be, pre-mature optimization. It's going to hurt if you need to add 10kg to each satellite. Or you need to launch southeast instead of northeast due to North Atlantic winters. Or you need to insert into a 50km higher orbit because of sunspots or any number or things not predictable years in advance.Also IMHO the number of planes and satellites per plane should be regarded as notional. A large constellation will never be exactly filled. There will always be holes and spares maneuvering to fill the holes. They should be able to operate just fine with a couple of holes per plane. In some ways this contradicts the above, since it allows you to adjust the satellites per plane, but livestock rather than pets.
https://www.skyperfectjsat.space/en/news/detail/sky_perfect_jsat_signed_launch_service_contract_for_superbird-9_satellite_with_spacex.htmlSKY Perfect JSAT signed Launch Service Contract for Superbird-9 satellite with SpaceX
Quote from: TrevorMonty on 08/20/2022 11:17 amFor 300ISP engine it will need 7.5t of fuel for 47ms DV required and engine of 3.3kn or 7klbs. This will need to be purpose built vehicle with SpaceX or NG being my pick given their excellent record servicing ISS.Either that, or I could imagine something derived from one of the many new space tugs, especially MEV and Photon. NG seems pretty open about collaboration, and they have a great platform to start with.My guess for an evaluation would be:1) Modified Cygnus2) MEV (+ Cygnus?)3) Cygnus + Photon4) Obligatory SpaceX bid with varying quality depending on their mood5) A happy mix of companies you've never heard of proposing ludicrous budgets or nonexistent spacecraft
For 300ISP engine it will need 7.5t of fuel for 47ms DV required and engine of 3.3kn or 7klbs. This will need to be purpose built vehicle with SpaceX or NG being my pick given their excellent record servicing ISS.
From the "NASA RFI for ISS deorbit module" threadQuote from: niwax on 08/20/2022 11:54 amQuote from: TrevorMonty on 08/20/2022 11:17 amFor 300ISP engine it will need 7.5t of fuel for 47ms DV required and engine of 3.3kn or 7klbs. This will need to be purpose built vehicle with SpaceX or NG being my pick given their excellent record servicing ISS.Either that, or I could imagine something derived from one of the many new space tugs, especially MEV and Photon. NG seems pretty open about collaboration, and they have a great platform to start with.My guess for an evaluation would be:1) Modified Cygnus2) MEV (+ Cygnus?)3) Cygnus + Photon4) Obligatory SpaceX bid with varying quality depending on their mood5) A happy mix of companies you've never heard of proposing ludicrous budgets or nonexistent spacecraftFor the 4)A stripped down expendable Starship with 50 tonnes of hypergolic propellants and many draco thrusters. So we will have high pressure COPV tanks on a Starship.
Quote from: Zed_Noir on 08/20/2022 01:07 pmFrom the "NASA RFI for ISS deorbit module" threadQuote from: niwax on 08/20/2022 11:54 amQuote from: TrevorMonty on 08/20/2022 11:17 amFor 300ISP engine it will need 7.5t of fuel for 47ms DV required and engine of 3.3kn or 7klbs. This will need to be purpose built vehicle with SpaceX or NG being my pick given their excellent record servicing ISS.Either that, or I could imagine something derived from one of the many new space tugs, especially MEV and Photon. NG seems pretty open about collaboration, and they have a great platform to start with.My guess for an evaluation would be:1) Modified Cygnus2) MEV (+ Cygnus?)3) Cygnus + Photon4) Obligatory SpaceX bid with varying quality depending on their mood5) A happy mix of companies you've never heard of proposing ludicrous budgets or nonexistent spacecraftFor the 4)A stripped down expendable Starship with 50 tonnes of hypergolic propellants and many draco thrusters. So we will have high pressure COPV tanks on a Starship. A stripped-down, filled up Starship (/slight/ stretched maybe… like basically a depot variant, ideally with long duration capability if you wanted it to do destination orbit insertion) could push ISS all the way to Mars orbit LOL.
Quote from: Robotbeat on 08/20/2022 02:06 pmQuote from: Zed_Noir on 08/20/2022 01:07 pmFrom the "NASA RFI for ISS deorbit module" threadQuote from: niwax on 08/20/2022 11:54 amQuote from: TrevorMonty on 08/20/2022 11:17 amFor 300ISP engine it will need 7.5t of fuel for 47ms DV required and engine of 3.3kn or 7klbs. This will need to be purpose built vehicle with SpaceX or NG being my pick given their excellent record servicing ISS.Either that, or I could imagine something derived from one of the many new space tugs, especially MEV and Photon. NG seems pretty open about collaboration, and they have a great platform to start with.My guess for an evaluation would be:1) Modified Cygnus2) MEV (+ Cygnus?)3) Cygnus + Photon4) Obligatory SpaceX bid with varying quality depending on their mood5) A happy mix of companies you've never heard of proposing ludicrous budgets or nonexistent spacecraftFor the 4)A stripped down expendable Starship with 50 tonnes of hypergolic propellants and many draco thrusters. So we will have high pressure COPV tanks on a Starship. A stripped-down, filled up Starship (/slight/ stretched maybe… like basically a depot variant, ideally with long duration capability if you wanted it to do destination orbit insertion) could push ISS all the way to Mars orbit LOL.Was thinking of an austere refurbished Starship with no orbital refueling capability. Hence the hypergolics. The job is to de-orbit the ISS after all.
How about just cutting the axels and suspension off an Airgas Argon delivery tanker, bolting on a few ion thrusters and plugging into the station solar array. Cheap and easy! Weight wise not a problem for a Starship to deliver.How far could 7,000 gallons of liquid Argon push the space station? 🤔
Quote from: Tangilinear Interjar on 08/22/2022 04:13 pmHow about just cutting the axels and suspension off an Airgas Argon delivery tanker, bolting on a few ion thrusters and plugging into the station solar array. Cheap and easy! Weight wise not a problem for a Starship to deliver.How far could 7,000 gallons of liquid Argon push the space station? 🤔 Just how much thrust do you think an ion thruster has?