The FH just put the roadster, estimated at 1250 kg, on an orbit with Mars apogee. But the first launch left a lot on the table. How much can a recoverable FH lift to Mars?First, it appears the first flight used a very tame throttle profile, with the center core not even at full thrust for liftoff,
and only 30 seconds of single-core operation after separation. A more aggressive throttle up at liftoff, then further down during 3 booster flight, could save more fuel for after booster sep, giving some of the benefit of cross-feed. A crude guess indicates they could get perhaps 500 m/s more staging velocity with this.
Second, SpaceX had the ASDS close to shore.
Putting it further out means no boostback burn. Another crude guess indicates they could get 500 m/s from this.
One estimate can be obtained from NASA's Launch Vehicle Performance Website. ...
Where is this claim based on?
https://twitter.com/johnkrausphotos/status/960985711825620993
Quote from: meithan on 02/11/2018 05:22 pmOne estimate can be obtained from NASA's Launch Vehicle Performance Website. ...This is a very good website to use, but note that the performance figures are older and much lower than what are on SpaceX's website. For instance, to TMI (i.e. about c3= 7km^2/s^2, optimistically), Falcon Heavy gets >16t, but the KSC website just gives 10t. So at high energy, I'd bet the actual figures SpaceX thinks they can do are at least 60% higher than on the KSC website.
Quote from: Robotbeat on 02/12/2018 12:40 amQuote from: meithan on 02/11/2018 05:22 pmOne estimate can be obtained from NASA's Launch Vehicle Performance Website. ...This is a very good website to use, but note that the performance figures are older and much lower than what are on SpaceX's website. For instance, to TMI (i.e. about c3= 7km^2/s^2, optimistically), Falcon Heavy gets >16t, but the KSC website just gives 10t. So at high energy, I'd bet the actual figures SpaceX thinks they can do are at least 60% higher than on the KSC website.Ah, I suspected the figures might not be updated. You're right, they do seem lower than the current official figures.Any idea where one can get an updated performance curve for FH like those shown there?
QuoteSecond, SpaceX had the ASDS close to shore. No, it did not.QuotePutting it further out means no boostback burn. Another crude guess indicates they could get 500 m/s from this.The ship was NOT very close to the shore. There were rumours about it, but those rumours were incorrect. The ship was much further away than the staging point.It did NOT boost BACK. the "boostback burn" was just practically braking most of the horizontal velocity, which had to be done anyway. If it was not done by the "boostback burn" it would have needed a much longer "entry burn".There is very little savings available by doing a smaller "boostback burn".Your "1000m/s" if total bogus. It's maybe about 150m/s in reality.
The ASDS position was known from SpaceX's FCC applications/grants for use of radio spectrum.
Your "1000m/s" if total bogus. It's maybe about 150m/s in reality.
OK, first glance, a larger drone ship with two boosters landing on Gravitas?
Quote from: Kansan52 on 02/12/2018 04:49 pmOK, first glance, a larger drone ship with two boosters landing on Gravitas?On twitter he said two ships for two booster cores, center expended... At only $5 million more... my guess is FH with 3 core recovery just went out the window...
Not enough ignition fluid to light the outer two engines after several three engine relights. Fix is pretty obvious.
Quote from: John Alan on 02/12/2018 04:54 pmQuote from: Kansan52 on 02/12/2018 04:49 pmOK, first glance, a larger drone ship with two boosters landing on Gravitas?On twitter he said two ships for two booster cores, center expended... At only $5 million more... my guess is FH with 3 core recovery just went out the window... No, I don't think so:QuoteNot enough ignition fluid to light the outer two engines after several three engine relights. Fix is pretty obvious.https://twitter.com/elonmusk/status/963107229523038211Landing boosters on two drone ships and expending the core gets you 90% of expending all 3.
Quote from: hkultala on 02/11/2018 08:52 pmWhere is this claim based on?This is what the claim is based on:Quote from: FutureSpaceTourist on 02/06/2018 08:44 pmhttps://twitter.com/johnkrausphotos/status/960985711825620993The whole way up you can tell that the center core was not throttled up as high as the side boosters.
Expend the core and land each side booster on an ASDS, and you can send over 15 tonnes on TMI, for only $3M more than an expendable Falcon 9.
Quote from: sevenperforce on 02/20/2018 06:09 pmExpend the core and land each side booster on an ASDS, and you can send over 15 tonnes on TMI, for only $3M more than an expendable Falcon 9. I'm not sure we can start estimating prices for an expendable Falcon 9/H yet, since a Block 5 has a lot of residual value after it's built, so the price of expending one may depend on how many flights it has made, or conversely, how many it can fly before requiring some amount of significant additional investment (i.e. refurbishment).For instance, if you wanted to expend the center core of a Falcon Heavy, the price may be prohibitive if a brand new core is all that is available. But if there is a center core that has already flown 9 times, and after the tenth flight it would require extensive refurbishment, then the price may be far less than an un-flown core.
From what we've seen so far, SpaceX has been offering discounts to customers who are willing to fly on reused rockets. I anticipate a shift as SpaceX begins making reuse standard and charges a premium for customers who demand a brand-new booster.
Quote from: sevenperforce on 02/20/2018 07:08 pmFrom what we've seen so far, SpaceX has been offering discounts to customers who are willing to fly on reused rockets. I anticipate a shift as SpaceX begins making reuse standard and charges a premium for customers who demand a brand-new booster.Mathematically, those are the same thing. But there is a vast perception/marketing difference.
Falcon Heavy can send 3.17 tonnes on a Hohmann transfer to Mars with full recovery of all three boosters (side boosters RTLS, core on ASDS). Note that Falcon 9, on the other hand, can send up to 4.04 tonnes to Mars when flying expendable.Expend the core and land each side booster on an ASDS, and you can send over 15 tonnes on TMI, for only $3M more than an expendable Falcon 9. Source.
Quote from: sevenperforce on 02/20/2018 06:09 pmFalcon Heavy can send 3.17 tonnes on a Hohmann transfer to Mars with full recovery of all three boosters (side boosters RTLS, core on ASDS). Note that Falcon 9, on the other hand, can send up to 4.04 tonnes to Mars when flying expendable.Expend the core and land each side booster on an ASDS, and you can send over 15 tonnes on TMI, for only $3M more than an expendable Falcon 9. Source.Actual source for those figures (you don't link any source in your linked post, so that's not a source)? Importantly, at what C3? The launch energy for Mars Hohmann transfers can vary quite a bit (as Mars' orbit is elliptic).The NASA performance website I quoted in the previous page shows around 4.0 tonnes with full recovery (sides RTLS, core ASDS) at C3 = 12 kmē/sē (which is a conservative "typical" estimate; some windows, like this year's, require as little as 7 kmē/sē). However Musk recently tweeted that those figures are based on the Block 1 F9 performance, and that current figures should be higher. So 3.17 tonnes to Mars with full recovery is probably a substantial underestimation.
See also this thread"Comprehensive Falcon Family Performance"https://forum.nasaspaceflight.com/index.php?topic=45033.0A merger suggestion was made but I think they are different, and should stay standalone.
Adding any number of enhancements (Raptor second stage, cross feed, kick engine,
And also note that the FH just flown is a test vehicle. The Block 5 version up next should be substantially beefier. Adding any number of enhancements (Raptor second stage, cross feed, kick engine, down range booster landings, etc.) could significantly increase the Mars injection numbers if this becomes a significant need. Think of the difference between Block 1 SLS and the eventual Blocks 1B/2.
Quote from: AncientU on 02/21/2018 06:10 pmAnd also note that the FH just flown is a test vehicle. The Block 5 version up next should be substantially beefier. Adding any number of enhancements (Raptor second stage, cross feed, kick engine, down range booster landings, etc.) could significantly increase the Mars injection numbers if this becomes a significant need. Think of the difference between Block 1 SLS and the eventual Blocks 1B/2.Raptor upper stage won't happen, and neither will crossfeed. Kick engine could be part of a payload, but then it's part of the payload, so...yeah. Downrange booster landings with a recoverable core is very unlikely; the side boosters need to RTLS for the core to be able to stop at all.The numbers I gave above were based on the Block 5 Falcon Heavy with triple recovery. However, the other thread did point out that the 8 tonnes to GTO currently advertised by SpaceX are Block 3 numbers. Block 5 FH will likely be able to do about 4 tonnes to TMI and almost 10 tonnes to GTO.
Quote from: sevenperforce on 02/21/2018 07:02 pmQuote from: AncientU on 02/21/2018 06:10 pmAnd also note that the FH just flown is a test vehicle. The Block 5 version up next should be substantially beefier. Adding any number of enhancements (Raptor second stage, cross feed, kick engine, down range booster landings, etc.) could significantly increase the Mars injection numbers if this becomes a significant need. Think of the difference between Block 1 SLS and the eventual Blocks 1B/2.Raptor upper stage won't happen, and neither will crossfeed. Kick engine could be part of a payload, but then it's part of the payload, so...yeah. Downrange booster landings with a recoverable core is very unlikely; the side boosters need to RTLS for the core to be able to stop at all.The numbers I gave above were based on the Block 5 Falcon Heavy with triple recovery. However, the other thread did point out that the 8 tonnes to GTO currently advertised by SpaceX are Block 3 numbers. Block 5 FH will likely be able to do about 4 tonnes to TMI and almost 10 tonnes to GTO.FH numbers for down range boosters and expendable core should be very impressive. Theyll have two easy coast ASDS.
Quote from: meithan on 02/20/2018 10:48 pmQuote from: sevenperforce on 02/20/2018 06:09 pmFalcon Heavy can send 3.17 tonnes on a Hohmann transfer to Mars with full recovery of all three boosters (side boosters RTLS, core on ASDS). Note that Falcon 9, on the other hand, can send up to 4.04 tonnes to Mars when flying expendable.Expend the core and land each side booster on an ASDS, and you can send over 15 tonnes on TMI, for only $3M more than an expendable Falcon 9. Source.Actual source for those figures (you don't link any source in your linked post, so that's not a source)? Importantly, at what C3? The launch energy for Mars Hohmann transfers can vary quite a bit (as Mars' orbit is elliptic).The NASA performance website I quoted in the previous page shows around 4.0 tonnes with full recovery (sides RTLS, core ASDS) at C3 = 12 kmē/sē (which is a conservative "typical" estimate; some windows, like this year's, require as little as 7 kmē/sē). However Musk recently tweeted that those figures are based on the Block 1 F9 performance, and that current figures should be higher. So 3.17 tonnes to Mars with full recovery is probably a substantial underestimation.That was using a trans-Martian injection dV of 4.3 km/s from LEO. Don't know what C3 that corresponds to.
I hope that SpaceX provides updated figures to the NASA folks in charge of that website (assuming there's still some one in charge).
Quote from: sevenperforce on 02/21/2018 01:32 pmQuote from: meithan on 02/20/2018 10:48 pmQuote from: sevenperforce on 02/20/2018 06:09 pmFalcon Heavy can send 3.17 tonnes on a Hohmann transfer to Mars with full recovery of all three boosters (side boosters RTLS, core on ASDS). Note that Falcon 9, on the other hand, can send up to 4.04 tonnes to Mars when flying expendable.Expend the core and land each side booster on an ASDS, and you can send over 15 tonnes on TMI, for only $3M more than an expendable Falcon 9. Source.Actual source for those figures (you don't link any source in your linked post, so that's not a source)? Importantly, at what C3? The launch energy for Mars Hohmann transfers can vary quite a bit (as Mars' orbit is elliptic).The NASA performance website I quoted in the previous page shows around 4.0 tonnes with full recovery (sides RTLS, core ASDS) at C3 = 12 kmē/sē (which is a conservative "typical" estimate; some windows, like this year's, require as little as 7 kmē/sē). However Musk recently tweeted that those figures are based on the Block 1 F9 performance, and that current figures should be higher. So 3.17 tonnes to Mars with full recovery is probably a substantial underestimation.That was using a trans-Martian injection dV of 4.3 km/s from LEO. Don't know what C3 that corresponds to.From a 200 km circular Earth orbit, a Δv of 4.3 km/s gives C3 ~ 25 kmē/sē; that's a bit higher than the typical Mars launch (for reference, MAVEN was launched with C3 = 12.2 kmē/s^2, ExoMars with C3 = 7.4 kmē/sē). C3 = 12 kmē/sē would require Δv = 3.8 km/s from that orbit. On the other hand, the FH did the TMI burn at perigee on a 142 x 6862 km orbit; for C3 = 12 kmē/sē that was a Δv of 2.5 km/s.Considering that large launch energy your 3.17 tonnes figure now makes sense. For one, it's substantially higher than the outdated value reported in the NASA performance website (2395 kg at C3 = 25 kmē/sē for recoverable FH). Where are you getting the figures from (I did not catch a source in the other thread)? I hope that SpaceX provides updated figures to the NASA folks in charge of that website (assuming there's still some one in charge).
ULA's Zegler gave values for a "typical" Mars burn from LEO at 4.3 km/s (page 4). Wikipedia's "delta v budget" page gives minimal TMI cost at 3.6 km/s, which would change quite a few of my values but would probably still keep everything pretty close.Also, note that the other thread has as discussion suggesting that the "8 metric tonne" limit on FHR is Block 3, and that 10 tonnes is closer to correct.Plus, if they can successfully bring back the booster after Hispasat on Sunday, that'll be a HUGE datapoint for ASDS landings.
ULA's Zegler gave values for a "typical" Mars burn from LEO at 4.3 km/s (page 4). Wikipedia's "delta v budget" page gives minimal TMI cost at 3.6 km/s, which would change quite a few of my values but would probably still keep everything pretty close.
speedevil, was that telepathy?