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Crew Dragon Docks with ISS

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Re: Crew Dragon Docks with ISS

#171

Post by kbenson »

pfdietz wrote: post #114
7thaccount wrote: post #22

Earlier quoted context omitted.

Incredibly impressive, but you have to take into account both more modern technology, as well as the fact that they were able to build off the shoulders of giants. It is still amazing of course, but I doubt they could've done the same thing during the era of the mercury program, so not really apples to apples comparison.

Guidance systems are vastly less expensive now, and can take advantage of things like MEMs, fiber laser gyros, and GPS (and, of course, modern computing power). The tanks on Falcon are welded using Friction Stir Welding, which was invented in the early 1990s. The landing algorithm for the first stage uses convex optimization algorithms based on interior point methods, which were not available in the 1960s. However, s…

> Simply evolving the Saturn 1B (which was cheaper, per lb of payload to orbit, than the Saturn V) could have easily beaten the Shuttle's economic performance.

I don't know how much it applies, but sometimes evolving something requires switching out components for other ones, which are more expensive. Not everything scales. Marketing isn't the only reason why 50% more capability often costs 100% more. I imagine with rocketry, you're often operating at the edge of the capability for certain materials and approaches.

Re: Crew Dragon Docks with ISS

#172

Post by simonh »

computerex wrote: post #160
bane wrote: post #15

SpaceX runs basically as a giant R&D program that also happens to accomplish useful things as byproducts of its approach (with the miracle of insurance to cover costs if things get explody). Every flight is data for incremental improvement. If you think of all SpaceX has ever done was try to get to this point, with somewhere around 80 flights on the Falcon 9, but for a variety of mission buyers (NASA, USAF, Commercia…

Whilst I agree with the general sentiment, the Space Shuttle was the single most capable spacecraft that has ever flown. You are not being fair in measuring it simply on the basis of how much mass it could put in Orbit.

It was an amazing vehicle and highly capable in some way, but severely constrained in others. The main problem is it was almost completely useless for any missions or activities beyond LEO. In theory you could use it to put up a small boost stage for a light interplanetary probe, but its cargo capacity was a bit small for that, and there’s just no point using a whole shuttle to do it.

Now that we have Falcon 9 and Heavy moon missions are back on the table, but the Shuttle was incapable of supporting any effective Lunar mission profiles.

Re: Crew Dragon Docks with ISS

#173

Post by dna_polymerase »

pfdietz wrote: post #114
7thaccount wrote: post #22

Earlier quoted context omitted.

Incredibly impressive, but you have to take into account both more modern technology, as well as the fact that they were able to build off the shoulders of giants. It is still amazing of course, but I doubt they could've done the same thing during the era of the mercury program, so not really apples to apples comparison.

Guidance systems are vastly less expensive now, and can take advantage of things like MEMs, fiber laser gyros, and GPS (and, of course, modern computing power). The tanks on Falcon are welded using Friction Stir Welding, which was invented in the early 1990s. The landing algorithm for the first stage uses convex optimization algorithms based on interior point methods, which were not available in the 1960s. However, s…

One dimension to this that is often forgotten is that SpaceX does things, though. Of course, many problems are solvable now that everything is more advanced, but putting them to use and creating actual progress for humanity is the real fantastic feat of SpaceX.

Re: Crew Dragon Docks with ISS

#175

Post by tenpies »

toshk wrote: post #109
bane wrote: post #15

SpaceX runs basically as a giant R&D program that also happens to accomplish useful things as byproducts of its approach (with the miracle of insurance to cover costs if things get explody). Every flight is data for incremental improvement. If you think of all SpaceX has ever done was try to get to this point, with somewhere around 80 flights on the Falcon 9, but for a variety of mission buyers (NASA, USAF, Commercia…

Incredible. Also Tesla seems to be extremely focused on r&d. How does Elon Musk push and run his organisations so differently that he seems to be one of the only few, if not only one, capable of running big organisations that are able to accomplish this extreme level of innovation paired with tangible results?

> Also Tesla seems to be extremely focused on r&d.

How so? Tesla spends a tiny bit of revenue on R&D and a solid chunk of that is on "research" grants that get converted to manufacturing grants (e.g. the NY plant).

See: https://ir.tesla.com/static-files/bbc6e137-897a-4543-857a-59...

Don't get me wrong, I guess there could be research spending elsewhere since Tesla is notoriously bad at financial reporting (e.g. the only company in history to double its factory count without increasing OpEx, or the only company in history to build a factory with zero CapEx spending), but I'm curious what the "extremely focused" claim is backed by.

Re: Crew Dragon Docks with ISS

#176

Post by bkanber »

yellowapple wrote: post #49
bane wrote: post #26

Earlier quoted context omitted.

I wonder, as a percentage of launch vehicle, how much mass the shuttle program managed to reuse after a mission vs. the F9Heavy? It turns out not having to "shuttle" half a dozen humans up to orbit every time you want to get something up there is a good idea.

Was the full crew necessarily just to put things in orbit? My impression was that most of the crew was doing other sorts of science and such because they might as well do so while the Shuttle's out in space (and later to get as many people into the ISS as possible per trip, which the Crew Falcon should now be able to do - maybe not to the same degree as the Shuttle, but certainly to a better degree than Soyuz).

Most shuttle missions had 5-7 crew members. https://en.wikipedia.org/wiki/List_of_Space_Shuttle_crews

At minimum, each mission had a commander and pilot. Then there were missions specialists and payload specialists, which depended on the specific mission the shuttle was carrying out.

There's always a lot of work to do, so it makes sense that they'd maximize for productivity.

Re: Crew Dragon Docks with ISS

#177

Post by marvin »

hinkley wrote: post #36

I recall Elon was hoping to get an order of magnitude reduction in cost per launch, but Wikipedia claims it costs $160 million per launch versus the Soyuz price of $76 million per astronaut. That would “only” be a 3x reduction with a crew of seven, but they’ve configured for a crew of four, which is a hair under 2x. I wonder how reuse affects the math, and what they’ll be able to do to lower those prices further. Obv…

Well, we don't know what it costs SpaceX to do these launches. We only know what NASA pays.

SpaceX could have very nice margins.

Re: Crew Dragon Docks with ISS

#178

Post by bkanber »

hinkley wrote: post #36

I recall Elon was hoping to get an order of magnitude reduction in cost per launch, but Wikipedia claims it costs $160 million per launch versus the Soyuz price of $76 million per astronaut. That would “only” be a 3x reduction with a crew of seven, but they’ve configured for a crew of four, which is a hair under 2x. I wonder how reuse affects the math, and what they’ll be able to do to lower those prices further. Obv…

I read once that a lot of the cost NASA pays per astronaut is there to manage the overhead of all the bureaucratic stuff and extra regulations required for sending a NASA astronaut up. I believe that it is (/ will be) cheaper per seat for citizen space tourists.

Re: Crew Dragon Docks with ISS

#179

Post by joshvm »

avian wrote: post #147
danpalmer wrote: post #121

Earlier quoted context omitted.

Worth noting that Dragon also carries tons of cargo, whereas the Soyuz “sticker price” is for just a seat.

> Dragon also carries tons of cargo Does it? I seem to remember reading somewhere that the "trunk" section will be mostly empty on crewed vehicles. It makes sense. We've seen that Dragon aborts with the trunk attached for aerodynamic reasons. It seems likely that hauling a bunch of cargo together with an escaping crewed capsule isn't feasible. You could also see that during the Demo-2 launch stream when the Dragon se…

During an abort they would dump the service module, which is where the unpressurised cargo is stored.

Re: Crew Dragon Docks with ISS

#180

Post by bkanber »

gpm wrote: post #97
Kaibeezy wrote: post #2

“flew exactly like the simulators”

They did complain about the thermal camera cutting out as the thrusters fired in real life and not in the simulator at one point. Was that fixed in the later test?

I thought what I heard is that the thermal cameras did cut out even in the sim, but that on-ship they cut out differently. My assumption is that this is something that gets fixed on the ground.
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