Author Topic: Can the SLS evolve into a reusable rocket?  (Read 3357 times)

Offline Tywin

In the future, can the SLS change its side boosters for liquid hydrogen rockets, or another propellant, and the RS-25 evolve in re-ignition like the Merlin?


Could the SLS do this in order to survive future decades?
« Last Edit: 12/10/2022 12:42 am by Tywin »
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Offline su27k

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Re: Can the SLS evolve into a reusable rocket?
« Reply #1 on: 12/10/2022 01:54 am »
No.

Also already covered by other threads:

sls reusable possible?

Make SLS Reusable


Online TomH

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Re: Can the SLS evolve into a reusable rocket?
« Reply #2 on: 12/24/2022 05:49 am »
The core climbs too high and fast to be recovered, almost to full orbital velocity. No way to jettison and recover the engines for the same reason.

Recoverable/reusable liquid boosters are theoretically possible, but hydrogen could not be the fuel. While hydrogen has higher energy per kilogram (ISP) than kerosene or methane, hydrogen is exceptionally light. To get much energy, the H2 tanks have to be immense. Due to VAB door width, boosters can be a maximum of 5.49 meters wide and only as high as the upper thrust beam in the core. Liquid boosters of that size could not hold enough hydrogen and also the booster base would not be wide enough to accommodate enough engines. While RP-1 and methane have lower ISP than H2, they have greater density in mass and energy. Reusable Methane or RP-1 boosters could be designed and built, but completely new engines might be required as well. For the low SLS flight rate, the investment in any part of this would not be worth it.

None of the rest of the vehicle could ever be recovered. Starship will stage low and slow for booster RTLS. As previously stated, the SLS core flies so high that it would require tiles, a bulbous nose, and aerodynamic surfaces to return. It would have to carry any upper stage and cargo internally. Make all those changes and you have what will soon fly, namely Starship.

In summary, reusable boosters are theoretically possible, but far too expensive for the flight rate. Nothing else could be reused under any circumstances.

Although NASA is now discussing production of 2 SLS per year at slightly reduced price, it never will come close to competing economically with SH/SS. IMHO, the political support for SLS will some day drop low enough that SLS is discontinued and only SS (and possibly New Armstrong) will fill the role of SHLV.
« Last Edit: 12/24/2022 05:56 am by TomH »

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