wumpus
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Posts posted by wumpus
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On 10/26/2023 at 3:50 PM, kerbiloid said:
And now about the Novgorodian wooden computer AI.
+1
99% could write.1% could read what they've written.
I'm shocked that any would bother. Perhaps it was more useful than I thought. The other question is if anybody progressed past a reading level of a "first year after learning to read" that a modern child would have. With no books and little else to practice with, they couldn't have been any good at reading or writing. I'd be impressed if 1% could read what somebody else "literate in only the vulgar" could write.
On 10/27/2023 at 11:09 AM, darthgently said:I'd like to see a KSP educational variant that used Oregon Trail as a guide. If I had any request for colony mode, that would be it.
Possible mission failure messages:
"Your crew has died from fatal lithobraking".
"Billyjimbob Kerman died from gravity on surface of Eve from lack of exercise in centrifuge during transit"
"Your craft has been crushed by Jool"
Once upon a time there was KerbalEdu, a KSP edition for education. As far as I know, this is the only edition of KSP with included DRM. The wiki link has a webpage for it, but I'm not getting any response. It's dead, Jim. I think it died before the release of KSP 1.0, and certainly wouldn't have survived the K2 buyout. I don't think it was ever all that successful, and probably had too much trouble trying to retrofit all the Edu mods to work with the then-evolving KSP code tree.
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On 10/26/2023 at 4:53 PM, Codraroll said:
There's also the question of whether the Soviet Union had the money for that effort at that stage. The old "if only they had received more funding" exercise tends to assume the funding was feasible in the first place, with all the other expenses that were racking up and the inefficiency of the processes that gathered revenue. With the inefficiency of the Soviet economy, and all the military programs that competed for what little money there was, the space program might never have had any real chance. See also: present day.
Ahh, the lesson that every authoritarian state only ever seems to learn in hindsight. The tendency to dismantle the mechanisms that can unmask a lie and correct the course of the national politics, really tends to be the downfall of Dear Leaders everywhere. Yet somehow, after their successor re-erects those mechanisms and the country starts prospering again, a new Dear Leader thinks he can secure his tenure forever by dismantling them again. The outcome is usually the opposite. See also: present day.
Another point is that post Apollo funding for NASA withered and died. Skylab was launched (and crewed) with Apollo hardware, and after that they sat around and designed a millstone to tie themselves to called "STS/Shuttle" (this lead to great political success with Congress easily budgeting for sunk costs, but often seen as a technical loss).
If Soviet rocketry had spent the money needed, how long could they maintain it? And when the Kremlin/military was no longer interested, would they still be capable of creating all those space stations, crewing said space stations, and developing the Energia engines?
I think this also ignores all the things that could have gone wrong for NASA: mostly involving the death of the crew (especially after burning the crew of Apollo 1 to death) of Apollo 11 and subsequent unwillingness to continue trying. NASA seemed to be blessed with sufficient contingency plans to allow major failures of any one project to be sidelined and replaced with another project (my favorite: the AJ260 boosters that were more powerful than the shuttle SRBs. If they couldn't make the biggest stable combustion chamber ever for the F1s, the AJ260 could do even more).
I will admit that I'm blanking for many more ways for NASA to fail: it would probably require political games such as keeping von Braum out of the system (like with Vanguard). The great thing about the Apollo project (including Gemini) was that it was effectively an entire new bureaucracy, built from the ground up to do one thing, and said thing had a sufficiently hard deadline to allow them to ignore meddling politicians. There are plenty of ways for Artemis to fail that really wouldn't have applied to Apollo, and even Artemis was designed first and foremost to be resistant to being canceled by Congress (all technical decisions were secondary).
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4 hours ago, darthgently said:
To be fair, the part of fungi that rise up are the fruiting body and are elevated to disperse spores, not to feed
I suspect that the easiest way to test this is to find large mushrooms in the forest and weigh one down with increasing weight until it crushes, and then pluck another and weigh the stem. It should be relatively easy to find the amount of mass a mushroom stem can support.
If you really want trees, you are going to have to assume some sort fungus that evolves a hard cellulose internal structure without crossing over into being a tree (presumably lack of photosynthesis would be the obvious issue). Best guess of the shape for a giant mushroom with an elevation to disperse spores would be a cone/pyramidal shape (use above experiment to calculate the angle/shape) with most of the mass spread out near the ground/underground. Of course then you have to figure out where the energy source comes from if it can't photosynthesize and blocks anything below it from photosynthesizing as well. Perhaps something along a river, draining nutritious silt?
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4 hours ago, mikegarrison said:
SpaceX chose to locate in the middle of a wildlife sanctuary.
Chose. To.
Maybe if they had done a better job of not setting the place on fire or covering it with debris then they would be given the benefits of more trust.
That was a huge unforced error, although I'm not sure where you can find undeveloped land on any US coastal area that isn't a wildlife refuge. There are better ways of determining just how strong your launchpad needs to be, especially after building in a wildlife refuge. Did they hire Calvin's dad* as the engineer?
I still think that the booster still intact until 40 seconds after the automated "Big Red Button" was pushed is going to make the FAA even more cranky than the former. Granted, I'm not in the industry at all, but 40 seconds of uncontrolled travel of a huge tube of liquid oxygen + fuel sounds bad.
* Calvin's dad is famous for bad answers to science questions. For this example he suggested that to find the maximum load of a bridge you should build it first, test it to destruction, then rebuild it with the known "max load" clearly labeled.
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On 6/30/2023 at 5:01 PM, Kerbart said:
I find it inconceivable that a civilization capable of interstellar travel cannot build Von Neumann machines. Infact, it's more likely a civilization bui,ds them before gaining the abiity to travel between stars. So, if you don't want your neighbors to strip-mine their corner of the galaxy and then start with yours, you work on exterminating them. I'm not saying you'd have to, or that it's ethical, but it is certainly a motivation.
One of my favorite games (largely thanks to working on outdated equipment I had lying around). http://www.deltatao.com/ho/
A 4X game pruned to the very limit. Just start with a planet with the understanding that "this here galaxy only has room for one player's people". Alas it has been removed from Google play, limiting my access to it.
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6 minutes ago, sevenperforce said:
The (perhaps deceptively) attractive element of parallel staging is that you can get better T/W at liftoff without needing more engine mass. Of course, crossfeed makes it much more advantageous.
This seems to be one of those things that KSP <1.0 taught that wasn't quite right. Of course it also taught (and still teaches) that a RL-10 engine is cheap. Aerodyne says otherwise. But you need a lot less thrust on a second stage than you'd put in a sustainer, and that weight comes out of your cargo capacity (much worse than forcing the first stage to lift the dead weight of the second stage engine).
I think the most important consideration is just how confident you are that the second stage will light. If you can get it to light, then you want a two stage rocket. If you aren't so confident, then a sustainer is ideal. Another thing to unlearn from KSP.
And it looks like the highest Chinese launch site gets .8 bar at launch. Helps a little, but might not be worth redesigning a nozzle. You'd be surprised how thin air can be and still be able to breathe (a lot higher than that).
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I think the real issue is how you construct the habitat modules. As far as I know, all such modules have been constructed on Earth, and connected together through some sort of docking (likely permanently) seal.
If you stick to this, rotating around the center of the spacecraft would be limited by the radius that can be launched. An alternative would be two (or more) habitats placed outside the center of the main rotation, and rotated. Presumably you'd need a ladder to get back to the zero-g center and on to a different gravity habitat, at least until you could build a ring around the center.
Expect to have a two "wasted modules" for each connection to from 0-g to 1-g.
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31 minutes ago, sevenperforce said:
I like altitude-compensating nozzles, so I really want to see a better sustainer architecture.
So far we have three main sustainer architectures:
- Wimpy core hydrolox stage with beefy boosters to get T/W over 1 (Ariane 5, SLS, STS, LM-5)
- Beefier core stage with large upper stage and optional small solid boosters (Atlas V, Delta IV M, Ariane 4)
- Two-stage architecture with multi-stick first stage (Delta IV Heavy, Falcon Heavy, Soyuz)
I want something more interesting.
The gotcha is that 3 launcher platforms that solved altitude compensation all failed.
Pegasus (+XL) is basically retired
Stratolaunch isn't interested in orbital launches
Virgin Galactic (the air-launch to orbit company) is bankrupt and nobody is interested in the rocketNot to mention, using a 2 stage rocket gives you ideal vacuum Isp for most of the delta-v needed. Didn't somebody slap a moveable extension onto a sustainer already, or was the proposal tabled before construction/launch? I think China has a launch facility at altitude, but no idea how that will affect nozzles and pressure design.
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On 6/11/2023 at 12:33 AM, steve9728 said:
It's almost time for the annual Dragon Boat Festival again. In fact, apart from the boring straight-line acceleration, there are places where it adds something a little more difficult: for example, stopping sharply and turning into a sharp 90° corner (then do it again back to the finish line), or more than a corner
I know what you want to see, there's even have 20 minutes one
Do they play "the Immigrant Song"? Any chance to run to shore, loot a monastery, and run back? Dragon-prowed ships aren't exclusively Chinese.
Please ignore boat/ship issues.
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17 hours ago, StrandedonEarth said:
If anything, what sci-fi gets wrong is the relative velocities in space. Any attack or "joust" in space is going to happen at relative velocities of at least 1 Mm/h, if not multiple tens of Mm/h. It's easier to just release a cloud of lead marbles in the path of oncoming wessels. Defense against ships will be easy, just shower them with gravel. The simplest offence is attacking with a rubble pile.
The ultimate outcome of a space battle is that space gets filled with high-speed debris and no-one can use it safely.
16 hours ago, darthgently said:Space defensive weapons need to leave was little debris as possible. More along the lines of focused tactical EMP and such. Offensive uses would obviously best be avoided. But ppl being ppl...
"Space is big. You just won't believe how vastly, hugely, mind-bogglingly big it is. I mean, you may think it's a long way down the road to the chemist's, but that's just peanuts to space." Douglas Adams
You really can't fill up space. You'd have a hard enough time filling up the elliptic. You can have issues with space junk in Earth orbit, and certainly any debris crossing GSO would be bad. But those are just tiny portions of space that humans care about. In general, any debris field will rotate and expand around the Sun until it might not exist. Compare to the asteroid belt. As far as I know, no craft has ever needed to take evasive action in the asteroid belt and that is almost certainly the canonical example of "space debris field". Also look at the "space metro map": the map only cares about delta-v, because you are unlikely to ever use the same route twice between the planets. There really is nowhere for "space pirates" to lay in wait, with the possible exception of a weird orbit that will just happen to line up with an optimal launch window between planets the next orbit or two (and even then, it is a one-shot event. You'll have to move on to be in position for the next good launch window. And if there *are* space pirates, you probably aren't going to wait until the window opens up, especially if it increases the chances of a lost vessel.To answer the original question (why, why do I do this?), it depends. If avoiding RADAR detection is key, then they will look like current atmospheric missiles. If not, expect spherical tanks, possibly with multiple stages of large/medium/small tanks (hint: think of the rocket equation). I've assumed some sort of stealth, but thinking about it a bit more it should be trivial to cover any likely battlefield (like the solar system) with enough sensors to watch for missiles firing their engines.
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I have to wonder if the North American common frog is even the same genus let alone species as the European (or at least English) common frog (or at least "frog commonly near populated areas"). Unless invasive species are at work (easy enough for a frog to hitch a ride), then I wouldn't expect them to sound the same. Similar for Africa (don't think there are liniked frog habitats between Africa and Eurasia) South America, and Australia.
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On 5/5/2023 at 6:33 PM, mikegarrison said:
Well, the thing is, they over-build these probes as much as they can because just launching the mission at all is so expensive. So once they complete their primary mission, they can start using up their margins and redundancies to keep going.
This mission had something like 11 or 12 science instruments, and only 5 of them are still alive (but now that they are far from any planets, not all of the instruments would be useful anyway).
They also knew they only had one shot for the "full tour" for at least a hundred years. So there was even more desire to overbuild. But if they wanted to extend the mission, they could have used americanium instead of plutonium in the RTGs. But that would have reduced margins and/or added mass during the critical moments when near planets. So plutonium was ideal and they went with that (and they were also familiar with plutonium RTGs).
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On 5/1/2023 at 11:19 AM, tater said:
An NSF thread mentions a reddit post where someone at BO says they currently have ~10,000 employees.
<blink>
At $100k a head (more likely 3-4 times that in overhead), that's a billion dollars a year. Doesn't Bezos cover at least a billion/yr in burn rate, and hopefully they are getting some money for the vulcans (but the billions a year presumably necessary?). All that money has to go somewhere. I'm guessing at 10k employees, the average salary has to get pushed down a bit.
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On 5/4/2023 at 12:38 AM, kerbiloid said:
So, the Bangladesh ice hockey rinks should be sqrt(4*78) times smaller, 1.7 x 3.5 m.
Do you have 24 players on each side as well? Could you even see the puck as you kick it around (no room to swing a stick).
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21 hours ago, sevenperforce said:
Conspiracy theories require more evidence than a bare recitation of possibility.
And generally old space is set up to get an easier path. I'm wondering when spacex will hire several senior FAA officials as "VP of FAA relations" (and obviously, doing same with the DoD, NASA, and congressional staffers). That will put them on the path to becoming the new "old space". I suspect they've already started.
21 hours ago, sevenperforce said:Egads!
Whatever will we do?
While we're at it, let's investigate ALL the inaccurate depictions of vehicles in ALL purely promotional or webcast material!
/s
Atkins law: number 30. (von Tiesenhausen’s Law of Engineering Design) If you want to have a maximum effect on the design of a new engineering system, learn to draw. Engineers always wind up designing the vehicle to look like the initial artist’s concept.
Unfortunately, you only get "looks like", not an exact match. Because even if the artists have a good grasp of rocket science, they haven't done enough iterations on the design to grasp all the details.
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1 hour ago, Piscator said:
As far as I know, the charges worked immediately. It's just that it took the vessel 40 seconds to sufficiently depressurize to finally loose enough rigidity to be torn apart by aero forces.
According to the requirements listed in the Scott Manley video, that isn't enough. You need to burn the fuel/oxidizer as well. It all but requires a big explosion. You might get less grief from the FAA if the engines stopped, but maybe not when you have a large bomb doing flips after the automated destruct system fired.
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6 minutes ago, sevenperforce said:
What overall OML are you thinking about for the air-augmented vehicle? That's always a challenging approach because the aerodynamics become non-trivial.
I've always liked the idea of a crossfed air-augumented booster with all the intakes located on the parallel booster that provides the crossfeed.
To be honest, I'm not even sure air-augmenting methane gives much boost in the way of Isp. I know adding air to kerolox should beat hydrolox (without air), but it isn't clear if methane gets similar boosts.
Originally I assumed some sort of side boosters (more air), but expect that wouldn't be worth it and vertical stacking/staging would vastly easier. Ideally it would be more of a nearly straight rocket (aerodynamically), possibly with a larger radius at the base sucking up all the air.
Scott Manley's analysis of how Starship .001 was doomed harped back on having the center of lift over the center of mass. Two re-entry vehicles would play havok on the center of lift, but hopefully an air-sucking base could provide the necessary stability. I hadn't thought of that until watching his video.
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3 minutes ago, StrandedonEarth said:
While I’m sure SpaceX knows this, it may be tricky to get right. I still haven’t seen confirmation of if the FTS fired late, or fired earlier but didn’t do the job. You’d think they’d have tested that…
You'd also assume that Musk would have tested throwing a ball at cybertruck's glass...
Spacex also loves changing things. I wouldn't be surprised if there's no alert to redo the self destruction tests everytime there is an ECO in the outer stainless steel hull/fuel tank design. That type of thing would probably ruin spacex's entire design methodology.
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50 minutes ago, sevenperforce said:
Two-stage reusable is the sweet spot. The lower stage can boostback to the launch site and the upper stage can loiter on orbit until it's time to initiate a re-entry that will bring it back to the launch site.
That's only clear without full reuse. With full reuse, launch costs will be dominated by fuel costs and integration costs, with integration costs hopefully becoming automated. I've mentioned my "Starship followup" a few times, but why not again.
I'd expect that 3 stages would be considered for a Starship 2.0. It would have been silly for the first model, especially with a limited budget, but not necessarily for a follow on. Ideally, the first stage would be air-augmented (reducing fuel is nearly the entire goal). This should also have a relatively easy return to launch trajectory, with few losses in the "boostback". The second stage depends a lot on information from Starship. I'd assume that return to launch is clear off the table (less fuel needed to ship it back by boat, although this adds to integration costs). Generally speaking, the second stage has a bunch of potentially conflicting criteria:
use vacuum optimized engines, but retroland. Current thinking assumes merlin engines for return
add 4-6km/s delta-v (roughly half what's left after the first stage), obviously this is likely to change a lot
no heat tiles (probably, depends on the cost of applying/maintaining starship's tiles and their safety). Expect this to be what really limits the amount of delta-vI'd also expect the second stage to look a lot more like a squashed cylinder (with an extended radius to keep the heat away) that more or less resembles starship (and does a similar bellyflop re-entry).
The whole point of all this extra mass (presumably only the extra engines needed for stage 2, plus a little needed for an extra set of landing fins is that it should lead to overall lower mass of fuel burned, primarily by using air augmentation for the critical ultra-thirsty early burn (most of the gains) followed by dropping a second chunk of the mass halfway through the main burn.
Most of the justification of 3 stages assumes that Starship (needing full reentry capacity) will be significantly more massive than your typical single use fuel tank (and why it has been hard to design). Splitting the orbital (and beyond) part into two parts, a significantly larger part that has to re-enter at a significantly slower speed) will require less overall mass. It is much like the original trick for Falcon 1 (recover the massive low-delta-v part), only iterated a second time.
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On 3/30/2023 at 11:05 AM, sevenperforce said:
That's the point of afterburning -- temporarily increased thrust at the cost of temporarily decreased efficiency.
And presumably burning through all your LOX during ascent to orbit so you have lower total mass when you want higher efficiency (and don't need a separate high-thrust second stage).
Also, to answer the original question about "creating your own electricity", consider the link:
https://news.mit.edu/2022/thermal-heat-engine-0413
This is wildly better than the traditional method of thermocouples (although I'm sure NASA has considered the "old fashioned non-wide band gap" cells).
The article also suggests using such high-efficiency cells in conjunction with solar concentrators (which would absorb the entire spectrum into heat). Assuming land usage isn't an issue, I'd suggest forgetting about maximizing efficiency and simply using a single layer for low cost (perhaps overdoing it, in this case the cost of the non-solar parts might drive the cost enough to warrant multiple layers, if not maximum efficiency) and building the concentrator large enough to run the cells 24/7. I'm probably missing the costs involved in absorbing and storing solar heat at 2000K-3000K. You might need high efficiency if you are getting your heat from natural gas, but with low cost mirrors (silver plated aluminum is relatively cheap) it comes down to the area available and just how hot you need to make your TPV work.
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16 hours ago, tater said:
I doubt that one is gonna do much better, tbh.
I would have flown on the crew New Shepard the day after their anomaly (different booster and obviously different capsule)—I'd not fly on Spaceship if they paid me.
In the unlikely event that anyone wanted to invest in Virgin Galactic, I think that "push himself to the front of the bankruptcy line" stunt drove everyone away from Virgin Galactic as well. From what I understand, there is no possible way VG can send enough passengers to "space" to make enough profits to cover the investment, even if everyone with the money wanted to buy a ticket. Not sure how many tickets they need to survive (with grumpy investors).
As far as I know, the capsule landed safely after the New Shepard anomaly. Not the best look, but shouldn't change your outlook too much. Space is hard, assuming a craft is "safe" after 22 successful flights and "unsafe" after 23 flights with an anomaly that lead to a safe landing is pretty weird.
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1 hour ago, sevenperforce said:
Nope, they aren’t.
Multiple rocket nozzles are never clustered in place of a larger nozzle.
Multiple rocket CHAMBERS, on the other hand, are often clustered, either in connection to a single turbopump or as a cluster of completely separate engines. There are a variety of reasons for this, mostly related to combustion stability but also for economies of scale and additional thrust. But of course the multiple rocket chambers will need multiple rocket nuzzles.
There would never be any need for multiple rocket nozzles attached to a single combustion chamber.
You might want extra nozzles on an expansion-cycle hydrolox engine, but even then I'd expect additional combustion chambers would be better. Expansion-cycle hydrolox engines are more or less limited to combustion chamber+nozzle sizes similar to RL-10 or higher, but you could get greater performance from more combustion chambers and nozzles. For some reason I remember hearing the nozzle was the limiting factor, but I suspect that the chamber might be as well. No idea if they attempt to cool the chamber.
No idea if a mini-mag has scaling issues. And as mentioned, the reasons for multiple combustion chambers are combustion-specific issues. And if you went multiple nozzles for a hydrolox expander-cycle it would be for thrust *inefficiency* (you want to scavenge the heat from the thrust to power your turbopumps).
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10 hours ago, kerbiloid said:
Make you buy a new version of Windows to be compatible.
Currently that's the CPU "drivers". Microsoft only includes the thread optimizations to balance Intel CPU "P-cores" and "E-cores" on Windows 11. They must have been bored with GPU drivers and start playing with CPU issues to force new editions of Windows.
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1 hour ago, radonek said:
What if you don't pipe that extra fuel directly into engine, but top-off center tank, using it as a buffer?
One reason for using asparagus that I don't see mentioned is that it allows me to use beefier center engine. With center tank full, there is less of a TWR jump through staging, without need to throttle down. I know that bigger engine is not called for at LEO missions, but for heavier cargo at TLI or farther burns…
No idea. Falcon Heavy was the only rocket I ever heard of that was planned to use asparagus staging, although only NASA and Spacex typically publish their iterative design process so there may be plenty others. Ask them why it didn't work.
Boeing's Starliner
in Science & Spaceflight
Posted
Boeing aircraft division will certainly sell the government any of the models of jets it already produces. They might even be willing to have a fixed price contract for minor alterations for specific military use.
The catch is that unless the US Govt wants to buy additional Atlas and/or Delta rockets (and not from ULA), anything Boeing does for NASA is going to involve a ton of NRE (non recurring engineering)
- And yes. I've been on projects with fixed prices and the (DoD) customer insists on customizing the product during design. There's a reason that those fixed budgets are about 10 times what it would cost to make a product for commercial sales. But it doesn't look like even that is good enough for Boeing (space).