According to the SpaceX website (http://www.spacex.com/falcon-heavy) the falcon Heavy can carry 16.8 tons to Trans Mars Injection (TMI) and 26.7 tons to Geostationary Transfer Orbit (GTO). How much can it carry to Trans-Lunar Injection (TLI)?
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1$\begingroup$ It can carry atleast 28,000kg according to ArsTechnica $\endgroup$– faroukcharkasMar 22, 2018 at 15:02
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4$\begingroup$ Item of interest: Apollo Command and Service Module weighed 28,800kg en.wikipedia.org/wiki/Apollo_Command/Service_Module $\endgroup$– ORcoderMar 22, 2018 at 22:01
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1$\begingroup$ The lunar module comes in at 16,400kg, so Falcon Heavy would not be able to launch the whole Apollo stack to the moon (45,200kg). I wonder if a hypothetical Falcon Superheavy (4 side boosters) could plausibly manage... $\endgroup$– ORcoderMar 22, 2018 at 22:04
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1$\begingroup$ @ORcoderI'll bet an Apollo-like replica made with 21st century materials would be a heck of a lot lighter, and so I've asked How much lighter could a modern, working replica of an Apollo payload and crew be at launch? $\endgroup$– uhohMar 22, 2018 at 23:32
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1$\begingroup$ The "crew around the moon" mission Ars was referring to was a free return trajectory in a Dragon 2 I believe $\endgroup$– ORcoderMar 23, 2018 at 0:22
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3 Answers
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One can use the NASA Performance Vehicle Estimator to get a decent idea of this, although it does have errors now with the Falcon Heavy. It does not have a TLI option, but it does have a negative C3.
To calculate the C3 required, one must know the delta V from LEO to Escape Velocity and to TLI. The escape velocity is requires a delta v of 3.22 km/s, the TLI for Apollo was between 3.08-3.25 km/s. Bottom line is, the delta v is roughly equivalent to escape velocity, so let's just use that. The mass is 6,000 kg with the recoverable Falcon Heavy, and 12,000 kg for the expendable.
Of course, we know these are wrong, because the Falcon Heavy can carry 16.8 tonnes to Mars, and that isn't quite there. The required C3 for Mars is about 8.1 km^2/s^2, so the plot shows about 10,300 kg or so. The amount to GTO is about 13,500 kg according to the plot (C3=-4.1 km^2/s^s).
All of this taken in to account, and trusting SpaceX's numbers, let's say about 2/3rds of the way between the two measurements, as that is where it falls on the C3 curve. Thus it should be about 23.4 tons, give or take.
answered Mar 24, 2018 at 0:11
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1$\begingroup$ You know that still might be able to carry Orion haha. Maybe with the service module finishing the last bit of the injection burn. $\endgroup$– ORcoderMar 24, 2018 at 3:07
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2$\begingroup$ No. Orion Injected lunar mass: 58,467 lb (26,520 kg) (wikipedia) We'll have to wait for SLS or human-rated Starship. Which we get first is still very much in play. $\endgroup$ Dec 22, 2019 at 14:21
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$\begingroup$ Aside from the Orion injected lunar mass won't we also have to account for the Orion launch mass, which includes the 7.7t (7.0t?) launch escape tower and capsule shroud. That will burn up a non-trivial amount of FH's propellant. As of 2021 FH's payload figures are unknown. The 63.8t LEO number (for reference) has not been updated to reflect the Block 5 performance. Of only academic interest for Orion, but still applies to Gateway, etc. And who doesn't love to dream up other missions... $\endgroup$ Sep 5, 2021 at 3:57
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We can bound the payload capacity from the top and the bottom using the GTO and TMI numbers.
Suppose we are already in low Earth orbit.
GTO delta-v requirements: 2.5 km/s
TLI delta-v requirements: 3.05 to 3.25 km/s
TMI delta-v requirements: 3.8 km/s
Falcon Heavy GTO payload: 26,700 kg
Falcon Heavy TLI payload: ???
Falcon Heavy TMI payload: 16,800 kg
Therefore we know the TLI payload of Falcon Heavy is at least 16,800kg, but no more than 26,700kg. It is probably around 21,000kg*, but due to the nonlinear nature of rocket delta-v, that could be off by a couple tons.
*This value is between the results of a logarithmic fit of the delta-v/payload data for 3.25 km/s TLI and 3.05 km/s TLI
Sources:
https://en.wikipedia.org/wiki/Trans-lunar_injection#history
https://en.wikipedia.org/wiki/Delta-v#Around_the_solar_system
https://en.wikipedia.org/wiki/Falcon_Heavy#Capabilities
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1$\begingroup$ Wilipedia says that is how much the Saturn V injections varied on their TLI page. Perhaps it's the difference between a most efficient hohmann trajectory versus a free return trajectory? $\endgroup$– ORcoderMar 23, 2018 at 22:47
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Say 20,000 kilograms and using a SpaceX state of the art mission capsule and I fail to see the problem with TLI plus flight return for the falcon heavy.
Just replace the kerolox boosters with SRBs and still maintain full re-usability. Just because the capsule is human rated doesn't mean you have to use an actual human for the test flight...not that there would be a shortage of volunteers!
Anyhow the entire system is now proven as human rated for all the little hops to the ISS and back.
Tired of all the Government sandbagging on this at this point and especially with Falcon Super Heavy ready for flight checkouts imminently this Year 2021 on or about June at the moment..
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$\begingroup$ “Just replace the kerolox boosters with SRBs and still maintain full re-usability.” What? SRBs would be much harder to reuse. $\endgroup$– ORcoderJun 16, 2021 at 19:02