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Kellymcdonald78 t1_j6aw1is wrote

Falcon 9 performance has continued to improve since 2018. However, let’s go with the 16,000kg number, SLS block 1 still doesn’t have 3 times the payload to TLI, it doesn’t even have twice the payload. We’ll likely get block IB, but it’s unclear if block 2 will ever get funded.


Correct_Inspection25 t1_j6b0yzy wrote

I was using the current SpaceX Falcon Heavy sales spec sheet, and given the amounts to LEO, GEO and Holman Mars transfer window kg hasnt changed from the April 2017 SpaceX website to today, it kinda follows. Now the turn around time per booster reuse has improved markedly with the newer blocks, but the fully disposable mode kg to optimal falcon apogee has not changed since they shifted focus to starship in the beginning of 2018. SpaceX abandoned the falcon platform improvements for the next Gen starship in 2018. If you can show me where on SpaceX’s site or elsewhere the fully disposable kg to LEO/GEO/solar/mars has changed since April 2017, I would be interested why SpaceX hasn’t updated the Falcon Heavy website but gladly concede your point that Falcon could deliver 26,000kg in 3-4 days to TLI.


Kellymcdonald78 t1_j6b60vw wrote

As mentioned folks have done the delta V analysis of the published GEO and TMI numbers and come to the 20,000kg value, but let’s say your 16,000kg number is correct. SLS Block 1 is 27,000kg TLI, so not even twice that of Falcon Heavy.


Correct_Inspection25 t1_j6b8vzu wrote

Who are “folks” and why isn’t SpaceX updating their sales specs to show these performance upgrades to their customers? Updating’s falcon Heavy page costs them nothing and the folks could update the Falcon Heavy wiki if they don’t have access to SpaceX’s webpage.

Want to add SpaceX stated with their last Falcon Heavy performance upgrade, 16,000kg TLI was the high end without much more significant Falcon Heavy R&D/investment/changes to get to 18,000kg TLI that were never studied or developed. SLS Block I 26,000kg to TLI perf isn’t intended to be used beyond Artemis II/III, and 1B will be 42,000 kg to TLI , so more than 2x compared to the max SpaceX said they could do with the most efficient planned production block then and now. SpaceX Falcon Heavy was optimized for different mission use cases than the SLS, and SpaceX told NASA and the press that publicly. That said SLS program will likely be the end of an era for non-interplanetary crewed missions, and private space flight by 2025/2030 will replace NASA except for cutting edge research/deep space missions like new nuclear drives and unproven engine designs too risky for private companies.


Kellymcdonald78 t1_j6bd8ed wrote

SpaceX doesn’t currently publish their TLI payload so I’m not sure what you want them to “update”

Plus the SLS Block IB won’t even fly until 2027 (at the earliest) and that will be the crew version which has a lower payload of 38,000 kg to TLI. So while that version will be more than twice the payload of Falcon Heavy (using your numbers), it will be competing against Starship and Superheavy by then


Correct_Inspection25 t1_j6beblk wrote

Yeah I am not talking about including what food/water/re-entry/life support systems/cargo load for 8-10 days with crew of 4 in a red dragon would be, as SpaceX never produced anything except really rough mock-ups and no test vehicle specs.

I am comparing gross SLS block performance to gross falcon heavy performance to fast TLI (not month long one way insertion). SpaceX has told publications and NASA what the TLI would be. I would say trust SpaceX over some random stack exchange or Quora post (which are the only people I can find referring to your numbers).


Kellymcdonald78 t1_j6bh5ms wrote

As I said, let’s assume your numbers are correct. 16,000kg for TLI for Falcon Heavy. SLS Block I is 28,000kg TLI. That IS NOT 2-3 times the performance of Falcon Heavy. (Twice is 32,000kg which is greater than 28,000kg).

However if you’re going to start comparing what the hypothetical future SLS performance might be in 4-5 years, then expect to compare it against what the hypothetical future SpaceX performance might be in 4-5 years which will be Starship and Superheavy. Falcon Heavy likely won’t even be flying by 2027


Correct_Inspection25 t1_j6bi9ep wrote

Hypothetical also applies to starship HLS and its in orbit refueling, and at least one orbital HLS tanker.

I think they will do it, SpaceX and SLS, just saying we know SpaceX stopped investing in Falcon heavy performance because the math didn’t work for non-LEO missions in 2018. Falcon Heavy BFR is more hypothetical than a vehicle and 80-90% (may be more like 98% as the biggest changes to 1B is just more main tank and SRB fuel capacity segments) of its components that just launched on SLS that will be reused for the newer blocks, as well as the Starship HLS and tankers prototype testing in Texas hopefully kicking off next month. Though the first lunar orbital flight TBD, but hopefully when you suggest, but if we adjust for SpaceX delivery estimation historically 2027-2028 worst case for a crewed NASA lunar mission.)


Kellymcdonald78 t1_j6bjvpz wrote

Yes, I said hypothetical to both. Either you compare the vehicles that are flying today or you compare hypothetical vehicles from 4-5 years in the future.

In either scenario SLS IS NOT carrying 3 times the payload of its competition.

BTW Block II will have completely new SRBs, a new upper stage and a new version of the RS-25. Hardly “80%-90%” of what was used on Artemis I


Correct_Inspection25 t1_j6blzeq wrote

Okay so 16,000 kg to TLI is equal to 26-27,000kg TLI? I was talking about 2023 block Falcon Heavy, not starship, Vulcan, or New Glenn. I will give you it’s not 3x this month, it is 1.7-1.8x, and 2-3x neighborhood is designed and assembly lines with known manufacturing techniques operating right now and has been fitted to test stands. Falcon Heavy isn’t going to get another block in the next 2-3 years, we know that for sure as of Dec 2018.


Kellymcdonald78 t1_j6bo3x2 wrote

Now you’re creating a strawman. I never claimed that the Falcon Heavy was equivalent to Block I SLS. I disputed your claim that it had 3 times the payload.

RS-25E is a completely new assembly line using new production methods and new engine controllers (as the original RS-25 hasn’t been built in decades)

BOLE (the new SRBs) use completely different casings (composite) and a new propellant mixture.

EUS is net new (but will be introduced for Block IA). Heck the mobile launch platform needed for Block 1A and Block 2 is having substantial issues. The only thing common, is the core tanks and thrust structure


Correct_Inspection25 t1_j6bovrz wrote

Ah I thought you implied Falcon Heavy could do what SLS is doing, my error and I did say 2-3x when right now i am off by 0.3x until the block 1B launches. You are right 2 of the new RS-25s testing today haven’t flown before and use 3D printed parts along with parts that have flown on the Space shuttle, but it’s a little different than saying it doesn’t exist and they are completely hypothetical. Same goes for the SRBs. Two other conversations where folks didn’t understand NASA did try and see if Falcon Heavy could replace the SLS key payload to TLI needs several times, the last in 2018, and SpaceX said no and I may have crossed the threads in my head. Let’s hope HLS and the Starship booster and refueling will meet the SLS 1B on time how ever relatively hypothetical they are right now.