> It was also designed ultra-conservatively using mostly existing designs so there was no technical risk.
Politicians can't design a rocket and cannot get what is "ultra-conservative". Rockets are not Lego blocks that you can just mix and match. They're explicitly designed a certain way to support a certain load profile. Even if the parts of the SLS _look_ like they have low risk, they do not and that's why the vehicle has taken so long to develop.
One example, if the shuttle boosters were could actually have been used directly they wouldn't have needed to extend the number of segments from 4 to 5, redesign the liner between the segments, and completely redesign the nozzle. It's a new booster.
Second example, even though the shuttle external tank looks like it's being used, in previous iterations the shuttle external tank did not support any axial loads, it was simply held on to the bottom of the Orbiter. Now the external tank has to withstand the entire axial load of the rocket so it's basically redesigned from scratch.
Yes, it's still rocket engineering. It's never trivial.
What would have been a more conservative design? Reusing the Apollo design was considered and discarded because so much knowledge and tooling had been lost that it was considered to be less conservative than the SLS design.
I love the whole "lost Saturn V engineering" trope. It sounds so good despite being bullshit. Rocket dune and NASA did an extensive knowledge retention project for the F-1 and J-2 engines. NASA also maintains several copies of extant F-1 and F-1A engines. If we approached Rocketdyne tomorrow with a billion dollars they could restart F-1A production. The J-2X is in fact the second stage engine for the SLS stack.
The SSME was selected for the SLS (and Ares V before it) because it had twice the burn hours of the F-1 and the SRBs existed and were a known quantity. The SLS (and Ares V) can reuse more of the Shuttle's infrastructure than an F-1 based design. The SRBs allow for use of smaller first stage tankage and the less powerful SSMEs which allow for reusing Shuttle launchpads which replaced the Saturn launchpads at LC-39.
While the SLS is moving into boondoggle territory the Ares V and SLS designs made economic sense to reuse Shuttle designs and infrastructure. It didn't have anything to do with the myth of lost engineering knowledge.
> It was also designed ultra-conservatively using mostly existing designs so there was no technical risk.
Politicians can't design a rocket and cannot get what is "ultra-conservative". Rockets are not Lego blocks that you can just mix and match. They're explicitly designed a certain way to support a certain load profile. Even if the parts of the SLS _look_ like they have low risk, they do not and that's why the vehicle has taken so long to develop.
One example, if the shuttle boosters were could actually have been used directly they wouldn't have needed to extend the number of segments from 4 to 5, redesign the liner between the segments, and completely redesign the nozzle. It's a new booster.
Second example, even though the shuttle external tank looks like it's being used, in previous iterations the shuttle external tank did not support any axial loads, it was simply held on to the bottom of the Orbiter. Now the external tank has to withstand the entire axial load of the rocket so it's basically redesigned from scratch.