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Do y'all think the Space-X Super heavy/Star ship would work out?


Cloakedwand72

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15 minutes ago, sevenperforce said:

but that would most likely make it LESS safe, not more safe. 

This I simply don't get. An integral crew compartment in the nose with chutes is dangerous how? The explosive bolts go off accidentally (has that ever happened on any rocket yet?)? The LES propellants explode (have any RCS systems spontaneously blown up yet?)?

I can see it making little difference, but I can't see it making it less safe than nothing, there are people alive today because of LES systems, and more dead for lack of them. Zero dead because of them.

Again, my use case is low-crew vehicles, long, long before they have hundreds or thousands of flights under their belts.

Combat aircraft (vs support aircraft) have ejection seats because they are more likely to sustain damage that requires ejecting. None the less, combat aircraft have used this feature in regular flight many times, not just airshows. Helos don't have this functionality because the rotor blades are in the way, and transports don't for the same reason airliners don't, it's simply not practical.

15 minutes ago, sevenperforce said:

I think we all systematically overestimate the cost-per-launch with a fully-reusable LV.

No, I've fully internalized this. Even so, Musk is not Bezos, and he's "bet the company" on Starlink. I think they won't launch each say 1 (or even 10) at a time, even if marginal launch costs were 6M$ a flight. I think they would do as many as they could practically do. They also have to consider the FAA. They need to launch when they can without messing up air travel, and shipping. It would be a tour de force for them to be able to maintain even a 1 a week cadence, frankly (and I'm assuming aircraft-like turn around here on the LV, added time is payload integration and logistics/permits). They also have to operate around other vehicles (no flying with an NRO payload on a nearby pad!). They have 5 years to get 2200 sats in orbit, then they can slow down for the second half of the constellation.

Edited by tater
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9 minutes ago, sevenperforce said:

As I said before, fighter jets are not necessarily the best analogue here, for several reasons.

Risk is risk, no matter how you slice it. It doesn't matter if the risk comes from being on an experimental vehicle or pushing a well-tested vehicle beyond its limits: an abort mode still makes risky endeavors significantly safer.

11 minutes ago, sevenperforce said:

Contrast should be drawn between Starship and STS. The Shuttle would have been safer with full-envelope LES, but did not have the mass budget for it. Starship has the mass budget for full-envelope LES (seriously, it can carry multiple Dragons to orbit easily) but that would most likely make it LESS safe, not more safe. 

If the Starship is extremely reliable, far beyond what I predict, then adding an LES might make it slightly less safe... but still well within acceptable bounds.

If the Starship is not extremely reliable, then a robust LES can be quite useful.

14 minutes ago, sevenperforce said:

And this is where indefinite reuse comes in handy, because you can launch the same vehicle dozens of times at a fraction of conventional LV cost in order to prove complete reliability. That's where those orders of magnitude evaporate.

First: prove it.

Second, there are unknown risks in reuse. Equipment wears out, and needs to be replaced. Metal fatigue accumulates. Foreign objects get left inside on accident. There are micro-fractures in Merlin engine turbines: what if those become worse over time? While the bathtub model does suggest a lot of failures occur at the beginning of equipment lifespan, it also suggests a lot of failures occur at the end of lifespan, and nobody yet knows where the end of that bathtub is.

21 minutes ago, sevenperforce said:

The Space Shuttle had ample redundancy in a handful of systems, but zero redundancy in the systems that really mattered.

Yes, and the Space Shuttle is not the only OLV to have failed or to have redundant systems.

Half the time, it's the things you don't see coming that cause failures. Accelerometers hammered in backwards. Foam shaking loose and punching through an aluminum wing. An unexpected interaction between your new fueling procedure and your COPVs. Redundancy is not a magic cure-all wand.

24 minutes ago, sevenperforce said:

The problem is that if you make the entire crew compartment its own capsule, then at some point it just makes more sense to re-enter separately, which means you have a three-stage vehicle rather than a two-stage vehicle. And then complexity overwhelms safety.

The point of all of this is to put crew in a simple, robust, well-understood capsule design for escape or reentry. There's a reason why, despite the magnificently complicated engineering in many OLVs, their escape systems are designed with robustness and simplicity over cutting-edge performance. If the really complicated bit (the high-performance OLV) fails, use well-understood pyrotechnic or hydraulic separation and high-thrust, solid or pressure-fed rocket motors to get off the stack, followed by reentry in a simplified, reentry-only vehicle.

27 minutes ago, sevenperforce said:

No argument on use case. I desperately want one, but...yeah. I'm talking more about the vehicle itself. Ejection seats (and all the pyros required to make them work) on a Chinook introduces more failure modes than the likelihood of needing the ejection seats; the same is true for an operational Starship.

Prove it. The closest analogies to the Starship are vehicles that very much need abort systems. Until you have solid Starship reliability data, I assume it'll be about as reliable as more conventionally built OLVs: not nearly reliable enough for no-abort manned missions.

The Chinook and similar vehicles have plenty of reliability data, and look like vehicles that have not traditionally needed abort modes. The Starship... does not resemble something with which we have extensive experience.

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I should be clear, that I think if they eventually get demonstrated safety over huge numbers of launches, that changes things. That requires of course no substantial changes between crew/cargo variants (mold line, etc).

The trouble is that until the market at large internalizes a new reality of incredibly cheap access (payload integration is still likely non-trivial, however), they have the same customers as before (maybe 20 a year). The fact that we could bootstrap a Moon base in one flight would be very attractive, but I still see them delivering the crew with extant vehicles, and maybe disembarking them as well (NASA could contract a flight from ISS to the Moon and back, for example, perhaps with pre-placed propellants in lunar orbit).

 

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46 minutes ago, sevenperforce said:

The problem is that if you make the entire crew compartment its own capsule, then at some point it just makes more sense to re-enter separately, which means you have a three-stage vehicle rather than a two-stage vehicle. And then complexity overwhelms safety.

Sorry, missed this before.

I don't think this is true, ejection seats/pods almost never get used as a function of take offs. B-52s have what, 6 ejection seats, and have been flying for 60 years (often the same airframes). Most all seats have never been used, over vast numbers of flights. I see this as the same. I remember my gf telling me about the shuttle exploding, and I ran into the living room to turn on the tv, and skipped class, and watched the replays with a phone in one hand, chatting with a friend (also a total space geek). We saw, that morning in the first replays (and I was watching live before all the debris hit the water) that the crew compartment was intact all the way down. We wondered on the phone then about making the crew compartment a B-58 style escape pod (even unpowered, but with chutes).

The Dragon capsule that was lost in the F9 explosion could have survived just with a chute, and the software to trigger it under the right conditions.

I don't see #dearmoon attracting many artists when the thing has barely flown (though maybe that crowd tends to the sort of suicidal depression that might make it a good vacation choice).

I'd think that if they want people in sooner than several years from now (assuming it flies fairly soon, then flies at a ridiculously high flight rate for the entirety of those several years), it needs something.

 

Edited by tater
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My understanding of the outer space treaty means that host nations are responsible for approving rocket launches.  I'd imagine this means NASA would still be the responsible body to approve or deny launches and I can't really see them allowing a crewed mission to fly without robust failure modes, even if they are not a customer.

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1 minute ago, James Kerman said:

My understanding of the outer space treaty means that host nations are responsible for approving rocket launches.  I'd imagine this means NASA would still be the responsible body to approve or deny launches and I can't really see them allowing a crewed mission to fly without robust failure modes, even if they are not a customer.

In the US this is currently the FAA, I believe. NASA has its own crew requirements, but outside of that, I think crew is not a legal issue. If they flew past a certain number, they might start getting treated like an airline, then it probably gets onto really unknown ground. Airlines have no escape pods, lol, but they also have vastly more safety data about them, and even an all engine failure is not a 100% LOC incident (Hudson ditching).

I actually think that it might well be possible to make this super safe, I just don't see it looking safe enough to find customers for crew without a LES.

This is a marketing issue as much as an engineering one. The use case for decent numbers of crew flights is... tourism. I honestly think this is the only case where we'd need many crew launches.

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4 hours ago, tater said:

This I simply don't get. An integral crew compartment in the nose with chutes is dangerous how? The explosive bolts go off accidentally (has that ever happened on any rocket yet?)? The LES propellants explode (have any RCS systems spontaneously blown up yet?)?

A hatch and personal chutes pose no threat. But once you talk about an entire cabin being peeled free of the integrated launch vehicle, things start to get messy.  

Do you use pyro bolts, frangible bolts, or pneumatics? They are, after all, different tech. Pyros have a nonzero chance of going off prematurely; frangibles have a chance of not separating at all. Pneumatics can go either way.

RCS systems usually use COPVs, and I seem to recall a certain COPV-induced LOV event. Any new volatile system adds a new failure mode.

4 hours ago, tater said:

I can see it making little difference, but I can't see it making it less safe than nothing, there are people alive today because of LES systems, and more dead for lack of them. Zero dead because of them.

Again, not denying the utility of LES on most vehicles, but this particular claim is simply untrue. During Soyuz 7K-OK No.1, the LES fired without warning nearly half am hour after a launch abort, igniting the second stage and killing a ground worker. Not nominal, I grant, but that's kind of the point.

Seat belts have malfunctioned and killed people, and LES has malfunctioned and killed people. Not a reason to eschew any of the above out of hand, but it's still a valid question. At some point the math says no.

4 hours ago, tater said:

Combat aircraft (vs support aircraft) have ejection seats because they are more likely to sustain damage that requires ejecting. None the less, combat aircraft have used this feature in regular flight many times, not just airshows. Helos don't have this functionality because the rotor blades are in the way,...

Which is an easily-solved problem. The Ka-50 has a full-envelope 0-0 ejection system and it's been flying operationally for two and a half decades. Use pyros to blow the rotor, allowing rotor inertia to shred the blades and fling them in all directions, then kick the canopy up to deflect any debris before ejecting normally. Works like a charm.

Of course, the risk lies in adding another system with new things to go wrong. Which is why the Chinook doesn't have it.

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The big question is: is it worth it?

Is the complicationa or potential faliure modes worth a LES?

Early launches with NASA may have LES, but once we get to airliner type safety, no.

Especially for tourism, where the chance of an accidental firing of LES or a "Im curious to see what happens to the LES" "accident" is high.

A early launch with NASA crew may have a LES of ejection seats (launching 3 guys on a 100 people spaceship is fun, you get more space)

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15 minutes ago, DDE said:

*If

Do you really think SpaceX will stop iterating and improving until rockets get to airliner reliability? Not saying the 2024 mars rocket will have that reliability, but by 2599,  if spaceX hasn't gone the way of Rocosmos, their rocket flights will be safer than a 21th century airliner flight.

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49 minutes ago, Rakaydos said:

Do you really think SpaceX will stop iterating and improving until rockets get to airliner reliability? Not saying the 2024 mars rocket will have that reliability, but by 2599,  if spaceX hasn't gone the way of Rocosmos, their rocket flights will be safer than a 21th century airliner flight.

I severely doubt anyone, be it SpaceX or the God-Emperor of Mankind, can bring the reliability of spaceflight down to airliner level. Ever. The hazards and energies involved are to a ridiculous degree greater than aircraft travel. Furthermore, it’s likely that the economic “sweet spot” for safety of human spaceflight is way, way, way below that of airliner travel because the tiny handful of humans that would ever venture off of Earth would be far more accepting of risk, so it’s economically irrational to ain for a lower chance than, say, 5% for a LOC event for an Earth-Mars flight.

And don’t even try throwing historical parallels at me.

Edited by DDE
Flipped some scales
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37 minutes ago, DDE said:

I severely doubt anyone, be it SpaceX or the God-Emperor of Mankind, can bring the reliability of spaceflight down to airliner level. Ever. The hazards and energies involved are to a ridiculous degree greater than aircraft travel. Furthermore, it’s likely that the economic “sweet spot” for safety of human spaceflight is way, way, way below that of airliner travel because the tiny handful of humans that would ever venture off of Earth would be far more accepting of risk, so it’s economically irrational to ain for a lower chance than, say, 5% for a LOC event for an Earth-Mars flight.

And don’t even try throwing historical parallels at me.

What about p2p? Cislunar? Orbital hotels?

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18 minutes ago, Xd the great said:

What about p2p? Cislunar? Orbital hotels?

Point-to-point: it's going to be very hard to compete with airliners, which offer a much more gentle ride, are likely to continue to have much better all-weather capability, and have a very, very, very long track record of reliability. Even the Concorde was a commercial flop, and that shaved about 50% of the time off something like a 747 while being far easier to handle.

Cislunar: See DDE's point about "the tiny handful of humans that would ever venture off the one planet to have an oxygenated atmosphere, plenty of tourist destinations, a nice handy ozone layer, etc, etc".

Orbital hotels: See DDE's point.

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1 hour ago, Rakaydos said:

Do you really think SpaceX will stop iterating and improving until rockets get to airliner reliability? Not saying the 2024 mars rocket will have that reliability, but by 2599,  if spaceX hasn't gone the way of Rocosmos, their rocket flights will be safer than a 21th century airliner flight.

Airliner reliability seems like an impossibly high standard, honestly. We have LOV incidents every few million take offs (what's the current rate per flight?)?

That's the actual rate, too, not some calculated rate.

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43 minutes ago, tater said:

Airliner reliability seems like an impossibly high standard, honestly. We have LOV incidents every few million take offs (what's the current rate per flight?)?

That's the actual rate, too, not some calculated rate.

I think 1 in 10000 is tolerable, how many spaceflights per day does Elon envision, 10? 20?

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1 hour ago, Xd the great said:

What about p2p? Cislunar? Orbital hotels?

A very slim chance of military logistics use, a fair chance of use but by government agencies alone (and likey those more risk-tolerant than NASA), and straight-up nope, respectively.

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1 hour ago, Xd the great said:

What about p2p? Cislunar? Orbital hotels?

P2P is balistic so slower and reentry is less of an problem, launch and landing is the same. 
Energy levels and stresses on rockets are extreme. They might get it down to helicopter safety levels. 

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1 hour ago, Starman4308 said:

Cislunar: See DDE's point about "the tiny handful of humans that would ever venture off the one planet to have an oxygenated atmosphere, plenty of tourist destinations, a nice handy ozone layer, etc, etc".

Orbital hotels: See DDE's point.

I'm likely an outlier, but I really think that travel/tourism is a huge thing if safety can ever get to some reasonable level. At first it's "extreme tourism," akin to the people who pay a lot of money to climb Everest, or who invest a lot of cash in extreme sports like base jumping.

As safety improves, the pool of people willing to do it increases. Many people flew when flying was still pretty dangerous. It would be interesting to see airline safety data per flight over time. What was it like in the 1920s, 30s, etc.

Edited by tater
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1 hour ago, tater said:

Airliner reliability seems like an impossibly high standard, honestly. We have LOV incidents every few million take offs (what's the current rate per flight?)?

That's the actual rate, too, not some calculated rate.

Note that I specified 21st century accident rates for a 26th century rocket. Airliner reliability will no doubt improve as well.

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23 minutes ago, tater said:

Many people flew when flying was still pretty dangerous.

And this is where we get to the really awakwsrd part. Most of those people flew from point A to point B.

There’s a pronounced shortage of desireable Points B in space. Thus we end up in a vicious cycle with BO’s thrillseeker-optimized suborbital trips breathing down our neck.

Edited by DDE
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38 minutes ago, DDE said:

And this is where we get to the really awakwsrd part. Most of those people flew from point A to point B.

There’s a pronounced shortage of desireable Points B in space. Thus we end up in a vicious cycle with BO’s thrillseeker-optimized suborbital trips breathing down our neck.

This is entirely true. All real estate off Earth must be 100% manufactured. there is simply no place to go unless it is built first---unless the spacecraft itself counts (land, walk around, come back, or fly someplace, grok the view, fly back).

I'm just trying to think of a use case for people in space at all, and it comes up empty except for "because it's cool."

Teleoperation can only get better over time.

Autonomous systems can only get better over time (smaller, more capable, indeed more capable than people at narrow tasks).

There is literally no reason to send people anyplace except for the desire to do so.

Shotwell seems all-in for P2P, so maybe they actually think that it's possible, and can be safe. If they could do this, it's a game changer, but it seems incredibly unlikely to me. I'd fly on New Shepard tomorrow, for example, I think it has a really low chance of killing anyone. I can't imagine thinking flying on Starship would feel as safe in even a decade, frankly.

Edited by tater
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Spoiler
17 hours ago, tater said:

Unless they fly hundreds of times with no incidents before they consider putting people on it, I can only imagine NASA would demand some abort modes.

Hundreds-schmundreds... Who cares about that NASA when they have a BFS "Moonraker".

moonraker-ii.jpg?w=1038&h=540&crop=1

"Dear Moon" is their secret orbital base.

 

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4 hours ago, tater said:

We have LOV incidents every few million take offs (what's the current rate per flight?)?

http://planecrashinfo.com/cause.htm

Odds of being involved in a fatal accident
Odds of being on an airline flight which results in at least one fatality Odds of being killed on a single airline flight
78 major world airlines
1 in 3.4 million 
78 major world airlines
1 in 4.7 million
Top 39 airlines with the best accident rates 
 1 in 10.0 million 
Top 39 airlines with the best accident rates 
 1 in 19.8 million 
Bottom 39 with the worst accident rates 
 1 in 1.5 million
Bottom 39 with the worst accident rates 
 1 in 2.0 million

**********

LES engines of the early Buran 
(Two small rockets aside)
http://www.buran.ru/htm/os-120.htm

Spoiler

os-120-6.gif

 

Clipper LES
(The octorocket below the ship. If no sheep happened, should be used to give additional delta-V and at last reach the orbit).

http://www.buran.ru/htm/cliper04.htm

Spoiler

clipe_ro.gif

 

Probably, such wannabe-LES are the best the BFS can have.

****************

18 hours ago, Starman4308 said:

Second, there are unknown risks in reuse. Equipment wears out, and needs to be replaced. Metal fatigue accumulates. Foreign objects get left inside on accident. There are micro-fractures in Merlin engine turbines: what if those become worse over time? While the bathtub model does suggest a lot of failures occur at the beginning of equipment lifespan, it also suggests a lot of failures occur at the end of lifespan, and nobody yet knows where the end of that bathtub is.

At least, the "acoustic defectoscopy".

If give a knock to an intact glass, it sounds different from a scratched or a cracked one.
As you don't need to know, where is the defect, you need just to know if the part sounds like an intact one, you can be knocking and hearing every part of the reusable ship, and when a part sounds enough different (numerically), replace it.

You anyway can't be sure if a just made part is intact. You can just do the same with it, so you anyway have to believe in music.

****************

18 hours ago, James Kerman said:

My understanding of the outer space treaty means that host nations are responsible for approving rocket launches.  I'd imagine this means NASA would still be the responsible body to approve or deny launches and I can't really see them allowing a crewed mission to fly without robust failure modes, even if they are not a customer.

Idea.

Spoiler

This works for the sea ships, why shouldn't for the space ones.
images?q=tbn:ANd9GcTqHuB8_JqBg2gjLwVMRGE

 

18 hours ago, tater said:

The use case for decent numbers of crew flights is... tourism. I honestly think this is the only case where we'd need many crew launches.

No problem. If automate the plants, the cars, and the offices, a lot of people will be glad to do it for food. 

Edited by kerbiloid
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3 hours ago, Xd the great said:

I think 1 in 10000 is tolerable, how many spaceflights per day does Elon envision, 10? 20?

The number Musk envisions is irrelevant. The number that will actually happen is the more important figure, and it's not going to hit even one per day anytime soon.

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