Terwin
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Posts posted by Terwin
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On 3/15/2024 at 4:44 PM, Spacescifi said:
My point is you cannot have the same TWR as external pulse propulsion using rocketry.
For all the mass required for rocketry (most of it being propellant), and the engine waste heat being a factor, you won't be able to ever have the TWR of nuke or antimatter external pulse propulsion, unless you try something dangerous like NSWR.
I would appreciate you explaining the physics of this to me, because everything I know about rocketry says that antimatter pulse is stupidly wasteful and inefficient compared to thermal antimatter rocketry, for both ISP and TWR.
Are you assuming that pulse propulsion does not need reaction mass? Nuclear pulse requires a tungsten plug to work as the reaction mass that hits the pusher-plate, and antimatter pulse would also require a large amount of reaction mass to throw against the pusher-plate, much of which would miss and be wasted, along with > 90% of the energy in the antimatter explosion, much like nuclear pulse. The only difference is that a nuculear pulse is ~ 1,000,000 times as energy dense as chemical reactions, letting you get 100 times the push with only 0.1% of the efficiency. (antimatter pulse does *not* have this advantage over antimatter thermal, because they both have the same energy density)
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16 hours ago, Spacescifi said:
I meant efficiency with the thrust to weight ratio. Detonating a nuclear or antimatter bomb requires less mass/weight than exhausting enough propellant to gain the equivalent amount of thrust if you just detonated the bomb.
By the time you reach the TWR of the bomb with a rocket your engine will either melt or you have some type of nuclear saltwater rocket shenanigans going on that are teetering at the edge of blowing up your vessel in a catastrophic explosion the whole time.
Um, no.
Consider a regeneratively cooled rocket nozzle.
It is able to withstand great temperatures and a lot of well-controlled pressure coming in an easy to predict way.
Now design something that can withstand highly variable temperatures and pressures with the ability to change rapidly, both in intensity and direction, with much tighter weight restrictions because it can only harness a fraction of the energy it is being battered with, as most of it is pushing the wrong way. Note: temperatures and pressures can get much higher than the nozzle interacts with.
You are suggesting that it is easier to design and build a mobile structure to resist tornadoes than it is to build a stationary, reinforced wind-break that only needs to survive 1% of the wind-speed of a tornado, from one direction.
For the same energy release, a rocket is always better than external combustion. Always.
Thermal antimatter will always be more efficient in both TWR and ISP than any sort of external combustion antimatter.
* If your materials can withstand a temperature of X, then running your thermal antimatter at (x-safety margin) will always equal or beat being far enough away form an explosion so that it cools down to (x-safety margin) as you will, at best, get the same result, but only by benefitting from a small fraction of your fuel and reaction mass.
* Anything you can do to get a better result from your am-pusher plate, can also be done to get the same benefits(or more) in a thermal rocket.
* A rocket gets to benefit from roughly 100% of the pressure from the heated reaction mass, while any sort of pusher-plate will, at best, get less than half of the pressure from an external combustion event(because to get any more, it would need to be inside your reaction chamber, even 50% would require half of the event be inside of a chamber of some sort, but much of that would be laterally focused and thus lost), usually only a small fraction of 1% because being any closer means your vessel gets vaporized by the explosion if you make it large enough to be a useful external reaction.
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It seems reasonable that SpaceX may include starlinks as payload on attempts 4+
They may wait until 5, but loading 4 seems plausible
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On 3/12/2024 at 5:13 PM, Spacescifi said:
Arguably one of the most efficient engines using antimatter would be a variation on mini magnetic Orion external pulse propulsion, just subbing the nuke for a photon torpedo lol.
External combustion is the *least* efficient option.
Not even modern trains use external combustion any more.
External combustion is only viable if there is no other option.
Thermal antimatter is entirely doable as a rocket, so external antimatter reactions can never be within an order of magnitude of the most efficient option. Not unless we learn something that would re-write every physics textbook from jr high on up
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I am guessing that the faa only cares if the hazard is increased by a given action, or if something done without informing them
The fact that a booster splashing down in an exclusion zone might only be destroyed by water turbulence instead of a hard splash-down(or disintegrating as it falls), does not seem like it would be of interest unless it might stay afloat for an extended period.(Probably why they need a guy with a rifle on-hand for starship, In case it does not sink on its own)
The faa might not even care to be informed of the type of splash-down, so long as it is in the designated area.(Such as landing on an unmanned barge as opposed to slamming into the waves, letting the owner risk non-human assets as much as they want, so long as it goes where they were told it would go)
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On 3/8/2024 at 8:22 PM, Spacescifi said:
1. You are mixing it with several tons of propellant.
I remember reading that if you used antimatter as the energy source for your rocket, you could use the same reaction mass tank(possibly water?) regardless of your destination, you just use a higher energy mix by adding a higher proportion of antimatter to energies your reaction mass before you shoot it through the nozzle.
And no, antimatter is not your reaction mass, it serves the same function as the nuclear reactor in a Nerva engine, just (presumably) lighter
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I thought that was just having a conductive path through the silver of the fillings that was the right length to pick up radio waves of the right frequency (possibly conducting it to the nerve for lots of fun)
So both radio and solar storms would just add an electric charge to part of the tooth.
Solar storms received by radios sound like louder static if I recall correctly.
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5 hours ago, darthgently said:
I don't think there is a technical solution, though many will try only to achieve Kafkaesque results. There is really only a character based solution
Sort of like the Spanish inquisition?
If you disagree with our morals we 'put you to the question '?
How do you have a character based solution to self-published phone recordings of a newsworthy event when the citizen journalist has no history, just luck?
Also, how do you identity which of the conflicting accounts should be considered truthful or criminal when they primarily differ in definition and framing?
How about the same source video cut and framed by two different providers, giving widely different understanding of the situation based on framing?
We know that governments will eagerly abuse such authority, and any other organization will likely start out corrupted and favor one set of views over others
Multiple independent organizations gives us the current splintered view of 'truth' based on your source.
I see lots of issues, but not a lot of solutions, especially considering our current status and lack of agreement on things as simple and basic as gender.
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Adding insulation on the inside is probably cheaper and can be just as effective, if not more effective if you need it.
Structural components are very expensive and require maintenance, but insulation is cheap and only requires care if it gets wet in most cases.
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Even assuming that they are not some sort of insect that communicates through pheromones, and they have the capacity to perceive your attempts to communicate as such, why would you depend on the intellectual and computational capacity of a presumably more primitive society to decide and understand your message which presumably has a finite and thus limited body to work on (and no doubt includes ideas for which they do not even have words)
As opposed to having as much time and computational capacity as you can cram on your ship to decide the more primitive words and ideas of the culture you intend to contact?
Someone very lazy could do as you describe, but it would not make a very good impression, and may only be worked on by crazies if everyone else thinks it is a hoax
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This is a reaction less drive, so inverting it seems like it would reverse the direction of thrust.
Then again this is a magic drive, so if you want it to, inverting the thrust could cause daisies to sprout from the control console.
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I can easily see smart-speaker systems besting humans at a range of tasks.
Setting up alarms and calendar reminders would be a fairly low bar, but remember the tropes about people not able to set the clock on their VCR.
Other tasks, such as adding an item to a specific list in a proprietary system(such as whatever app Google is currently using to story my shopping list) could even stymie relatively bright people if it has a poor UI.
Adding appointments to other peoples calendars could be particularly difficult depending on your security set-up.
My wife has a masters and regularly uses our smart-speakers as a calculator.(if I am in the room, I often supply the answer first though)
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3 minutes ago, Shpaget said:
If you know now that the ship didn't (will not) arrive to the future, you still have backwards time travel of information, which is exactly the same thing as the problem you're avoiding.
If time-ports can be blocked by things other than destruction of the pad, it becomes easy to ask questions of the future by just arranging for temporary blocks based on the answer of the question. If only destruction of the timeport will block it, it is still possible, just more expensive
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Multi-star civilizations without ftl puts you in a state akin to the British empire, with colonies that took months to communicate back and forth.
The colonies and delays are just bigger
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On 2/9/2024 at 7:50 PM, mikegarrison said:
That's not responding to what I said. Or perhaps I misunderstood you.
I am not disputing there is more information to be gained from Voyager 1. I was responding to the idea that it would be useful to learn new techniques for maintaining contact with 1970s probes. (The last part of the post I quoted.)
Novel and extreme situations help us confirm and extend our understanding of the technologies involved.
As a theoretical example:
If a new technique is found for extracting useful data from a signal that would previously have been considered too close to the noise floor, then that technique might also be useful for reducing the required broadcast power for wireless networks or tools.
Without the incentive of maintaining a connection to an old but still active historic probe in deep space, that technique might never have been found.
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I was under the impression that stage 2 pushed hard enough on stage 1 that it experienced rearward acceleration, likely causing the contents of both tanks to slosh forward.
Also, I thought that the still burning stage 1 engines were supposed to prevent that, but stage 2 effects on stage 1 were higher than anticipated.
Presumably they have a plan for taming rotational slosh as well, but I do not know if that was sufficient either.(still working out the tolerances and all with that being the first launch to get to that part of the flight)
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Seems like just increasing the separation thrust of SH to keep it from reversing should be sufficient. Some slosh/waves from the turn should be less of an issue so long as the fuel is always against the rear and intakes.
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I thought that the propeller was in the nose for those early planes, making that unavailable for the cockpit
Also, at least on top you have the body of the plane for ablative skid armor for landings where the gear is insufficient. (Also makes ditching from a water landing easier)
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18 minutes ago, Terwin said:
If only a small number of actual launches have performed that procedure before the launch, how could it possibly be a standard procedure?
Perhaps you meant that it is standard procedure for rocket development?
To that I would counter that it is only standard procedure for developing an expendable rocket.
Falcon 9 was expendable with an eye for reuse, Starship is being designed as a fully reusable rocket, and not many of those have gotten far enough to be able to do a static fire,
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2 hours ago, Exoscientist said:
Consider, that is the standard industry practice. It is not just SpaceX and Nasa doing in that way in the past. Every company in the industry does it that way. Every company could just test single engines on test stands if they wanted to. That would be much cheaper. Instead they follow the accepted practice of doing full flight analog testing prior to test flights.
That the Soviet N-1 experienced not just engine shutdowns but engine explosions on every test flight and the SuperHeavy/Starship also experienced the same thing, including the engine explosions, suggests this is not a better approach to getting reliable engines.
Robert Clark
As best as I can tell, only a small percentage of rocket launches, especially in the last few decades, have had a full stack, full flight-like duration static fire before launch as you describe. (none of the launches with solid boosters would count for example, and you showed that Falcon 9's don't do that before each launch, etc)
If only a small number of actual launches have performed that procedure before the launch, how could it possibly be a standard procedure?
14 minutes ago, Exoscientist said:On the static stand you can gradually build up to full thrust and full flight duration. If you see out of nominal state for one or more engines, you can shut the test down, examine the engines not operating properly and compare to the ones that are. Then try again gradually building up to full flight conditions. In contrast if one or more engines fail in flight, even if it didn’t explode but had to be shutdown, usually you have to destroy it by FTS for fear it will stray too far out of the safety zone.
Robert Clark
That makes sense if you have unlimited funds and very little hardware, but SpaceX is very hardware rich, and is trying to do this on a commercial budged(as opposed to cost-plus).
Come to think of it, the type of static-fire you describe seems almost like a 'standard procedure' to squeeze maximum funds out of the government on a cost-plus contract with minimal costs to the provider. Maximizing the opportunities to add delays(and costs) to the project by minimizing the number of problems you uncover with each test(by shutting it down as soon as you find a discrepancy).
As opposed to launch testing, which generally covers more scenarios per test, but has a material cost to the rocket company(hardware instead of just (billable) time and fuel).
I guess that is the real difference, SpaceX is following a fast, cost-effective approach, as opposed to a 'maximize the cost-plus contract' approach.
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4 hours ago, j169 said:
Is it in any way possible to remove things (like harvesters) from a wolf depot, I searched everywhere and couldn't find an answer.
I remember it wasn't possible, if this is the case, are there plans to change that? I know its difficult to implement but in the case of the drills It would make sense because the easy harvester is basically wasting resources, wich is fine at the start but wasteful later on.
WOLF does not store anything about what is in it a depot, only available and provided resources. As such, it is not possible to 'remove' components in-game, and I believe RoverDude explicitly said that he will not be adding that functionality.
If you want to 'remove a drill', then just edit your save file. The Wolf section for each biome is relatively easy to find and understand, just adjust the available and provided resources the opposite amount that one drill would modify, and the drill is 'gone'.
The simpler drill wasting resources is actually a design choice: save time now or be more productive later.
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MKS uses the stock catch-up system, so if you go back to a base it will 'catch-up' in 6 hour blocks until it is current(using the current level of production for things like solar panels or drills)
If you never go back to a base, then it will never have a chance to 'catch up'.
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39 minutes ago, Exoscientist said:
I’m making a serious charge here. I’m suggesting SpaceX knows the Raptor is unreliable and is obscuring that fact both from the NASA and the American public. For an engine that is supposed to power a craft carrying astronauts and for which billions in American tax dollars have been earmarked it should be essential that it’s reliability be established.
39 minutes ago, Exoscientist said:The Raptor has been in development since 2016 and no such reliability estimates are offered for it for an engine intended to power craft carrying astronauts and even civilian passengers.
Robert Clark
Unless and until SpaceX takes money then fails to deliver on a Starship launch due to engine problems(this would be a commercial payload, as HLS only pays after a milestone is reached) Raptor has not failed.
Raptor is still in development and under the mantra of 'move fast and break things'.
Failures are *EXPECTED* and if they do not fail often enough, then they will take greater risks so that they do.
The two (probably) independent failures on IFT2 is likely a *better* outcome for SpaceX than a nominal flight on a rocket with hidden problems, because they learned more and now have a better understanding of how to make the rocket better.
The earlier you find a problem, the less expensive it is to fix, and SpaceX just found 2 problems(probably) for the cost of 1 in their second launch attempt.
Falcon 1 failed its first 3 attempts (and those were clear failures because they had paying customers onboard), and now the falcon 9 delivers more payload to orbit than all other rockets combined, and the rocket is more likely to be destroyed in transit than during a flight or landing attempt(unless deliberately expended)
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9 hours ago, DDE said:
I'm getting the distinct impression we know painfully little about deep geological processes.
It is almost like a miles thick wall of dirt and stone is difficult to observe through.
Antimatter Propulsion.. From Earth To Mars Only Requires Milligrams?!
in Science & Spaceflight
Posted · Edited by Terwin
Not at all, a rocket is a controlled conflagration(just like a lighter, gas stove, gas water heater, fire place, coal power plant, etc.). There is research into continuous detonation engines, but it is very difficult to maintain the continuous detonation(but would greatly increase ISP)
The reaction mass carries away the heat, and generating the heat to heat up the reaction mass is the entire reason you have the antimatter on board, this is a benefit, not a cost.
Orion has much more of a heat problem than a rocket because the pusher plate absorbs some of the heat and you have no productive way to get rid of that heat, more over, the further you get form the explosion(and the heat) the worse you thrust and isp get.
The best option to manage for the heat for Orion that I have seen is to coat your pusher pate with some sort of liquid, cutting down on how much of your pusher plate gets vaporized with each bomb, but this is only a partial option as running the Orion continuously will still heat up the plate until it finally gets soft enough to get splattered by the next bomb.
Nope, Unless you are using some sub-optimal configuration to avoid destroying your launch mount, you always use the same bomb, the largest you can safely use for propulsion. This maximum safe size may go down as your pusher plate gets eroded, but it will never go up. (moving the bomb further away has the same effect as using a smaller bomb, so using a larger bomb further away just wastes materials)
Sort of, as you will have the non-charged particles wearing away at your nozzle hardware, giving you the life-span limitations of Orion, combined with the massive energy requirements of an ion engine because you need to generate the magnetic fields to push away the charged particles(but much less efficient than an ion engine because the particles are much further way from the field), giving you the combined draw-backs of Orion and ion engines.