131–140 of 317 posts
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They landed a lot of falcon 9 first stages without legs on the water, vertically, to test the control system. And a number of attempted barge landings with legs failed, before the first successful landing. Now it's almost a routine thing.
That's probably what FAA was peeved about SN8. They might have been expecting a water landing and didn't like that an unproven rocket was sent back to dry land.
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Simulations of certain things are still a problem today, even though less than it was in 1960-s. For example, trans-sonic aerodynamics is still hard. I'd imagine a good simulation of Raptor's inner flow when Starship does active maneuring can be a problem, especially if you also need to take into account material properties under dynamic loads.
Lets assume that is the case. That is where they should spend their cash to produce something of real value that can be reused. Simulation close to perfection is the end game. Not sending something chunky into space.
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We knew this since watching how much the Russians got done in the time they had for the resources. Put the engineers together with the manufactures, build often, test more.
just don't sit near the launchpad
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Lets assume that is the case. That is where they should spend their cash to produce something of real value that can be reused. Simulation close to perfection is the end game. Not sending something chunky into space.
No. It's way easier today to test than to solve that problem.
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No orbital upper stage has been rapidly reusable. No existing rocket has tried to perform either the "belly flop" or the "Landing flip manouver" that SpaceX is trying to do. The failures are due to complex issues (fuel tanks, valves, engine reliability under complex forces) not simple control system issues (choosing wrong thrust, not able to orient using thrusters, etc)
I don't understand the term belly flop or rapidly reusable. Do You mean that it is becoming horizontal to reduce the falling speed rate to land on its belly? shuttle was reused and landed on wheels parallel to its belly.
Rapidly reusable - You can land it directly on (or next to) a launch platform, refuel it and launch it again the same day. Same as a regular aircraft.
The Space shuttle had a disposable tank (which was lost on launch), recovered but basically destroyed solid rocket boosters (ditched into ocean) and finally on landing it had (potentially) damaged heat tiles which all needed inspection and which were all fragile and different.
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At least 60 of those Americans were sent up on the Russian Soyuz: https://en.wikipedia.org/wiki/List_of_Russian_human_spacefli... Also, How are you doing the math to get a 4.4% fatality rate? The numbers are much lower than that. Soyuz has launched 394 people and killed 4 of them. The most recent fatality was 50 years ago. The Shuttle launched 833 people and killed 14 of them, most recently in 2003 (8 years before th…
Of course proving a simple design and sticking with it is safer! Not going to space and being content with remaining on the ground is safer still! Water is wet! The sky is blue! We can all see what happened: the soviets stopped spending money on innovation and tried to re-frame their stagnation as operational brilliance. Sure, Soyuz has a reliability niche, and I'd rather ride on it too, but I'd rather fund efforts t…
On top of that, the Raptor engines used in the Starship, which seem to be considered state-of-the-art, are based on a soviet design from the 60s.
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Also keep in mind that it's already doing what pre-F9 rockets did: go up. The RUDs so far are on landing attempts. Landing is a whole lot harder.
Unfortunately it seems like traditional aerospace now has a very big lever to pull to get SpaceX shut down: public opinion following the reasoning "rocket go boom. go boom bad. rocket bad".
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You can choose to develop rockets - especially of such size - this way instead of putting (much) more efforts in calculating how it would behave and prepare for all cases.
Nasa did the calculation with with ancient computers and these guys are speculating and not using proper technology to achieve success. It makes no sense in 2021. They should not be experimenting. Their simulations should be been solid before this stage. It is good way to burn cash.
They're developing this thing in stages; they've developed and tested the engines, they've developed and are testing launching the thing, they've developed and are testing the re-entry flop. They have partially developed the whole "landing" thing and if you're going to be testing the belly flop, you might as well put whatever you have with regards to landing through its paces as well.
By having a small team develop and test individual parts in stages, you avoid needing a giant team, and you avoid needing to have all of the schedules line up to be ready to go all at once. And it's the engineers who develop the rocket that is expensive, not the manufacturing.
IMHO the benefits of having a completely flexible schedule greatly outweigh the expensive of assuming failure.
I'm very impressed by how it's coasting on the fins down the atmosphere. I had never even heard that idea discussed before I saw SN8 do it. Of course, they'll have to land some other way on Mars or the Moon.
it will be coasting on its fins during atmospheric entry for mars EDL. (Old-ish) video simulation here: https://www.youtube.com/watch?v=xDTZEVMArBE That phase wipes off >99% of the total energy required to get to 0 m/s, which is pretty remarkable because Mars' atmosphere is ~1% of Earth's.
That they (at least on paper) have a solution for this problem good enough for a 60 metrr craft weighting 100+ tons makes the whole thing even mord remarkable! :)