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Old April 15th 18, 01:52 AM posted to sci.space.policy
Jeff Findley[_6_]
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Default More Flights of SLS Block 1

In article ,
says...

It's important to consider that at the time the Shuttle was killed,
"COTS" had not proven itself yet AND NASA was now stuck with lots of
"rocket business" staff with nothing to do.


I'm talking about today. SLS is bull$hit today. You don't allow
something this expensive and useless to keep on going due to decisions
made in the past based on assumptions that have changed.

A make work project for NASA's rocket busines makes sense to keep the
organisation going so that if commercial doesn't pan out, NASA can
return to making rockets to fill the gap commercial had failed to fill.


Commercial launch vehicles are here and they're cheaper than ever.
Falcon Heavy works. Delta IV Heavy works too (it's just a lot more
expensive). Even Atlas V works for slightly smaller payloads (like
Boeing's Starliner spacecraft which will carry crew to ISS).

Imagine if the "make work" mandate had been to let engineers loose and
given a mandate to develop the warp drive or whatever else they could
come up with. (aka: a true R&D organisation for the rocket business,
just as NASA does a lot of R&D for commercial airplanes).

While NASA might not have come up with a "rocket" system, surely its
engineers would have come up with a number of useful technologies and
also tested certain tech and found them to not be the way to go.


This is the classic spin-off argument. That's almost always bull$hit
too because the SLS program isn't doing much in the way of scientific
research, it's engineers doing standard R&D work. If you want better
welding techniques for aluminum-lithium alloy, invest in R&D for that.
Don't spend billions on a huge government program that will invest a few
million in better welding techniques.

On 2018-04-14 12:18, Jeff Findley wrote:

Agreed. Waste of perfectly good SSME's.


In a context where SLS is to have a fixed number of flights, then yeah,
you want each flight to count as much as possible since any additional
test flight ends up killing a real flight at the end.

In a context where production of SSMEs has restarted and is fully funded
forever, then it matters less that it takes 3 more flights to get the
new second stage.


But they'll still be dropping *all* of the SLS hardware in the ocean for
each and every flight. In a world where reusables are coming into their
own, that's just stupid.

Plus it's putting people on an
upper stage that wasn't planned to be "man rated". But NASA writes the
rules and the waivers, so that's never been a real problem.


From a hardware/software point of view, is there much difference between
a man rated second stage and one that isn't?

(apart from the obvious need to support capsule and its ejection system).

At launch, apart from the design to allow capsule ejection, is the
second stage otherwise considered inert, so man rating is all about its
mission after MECO and when Stage1 has separated?


It's about margins of safety, redundancy, failure monitoring systems,
and etc. Not all of that is needed for an unmanned launch.

Jeff
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