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Codraroll

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Everything posted by Codraroll

  1. Not sure how much more could be brought to the topic, but perhaps I can try a summary? @jimmymcgoochie said it, but I think it bears repeating: I think this is a really important crux of the whole matter. Moving stuff to/from surface to orbit is a specialized task, moving stuff between planets is another specialized task, and trying to make the same craft do both makes it kinda bad at either job. Barring magic technology, of course, but ... nah, possibly even then. SSTOP (Single stage to Other Planets) is like building a container ship that takes cargo between two inland cities without navigable waterways. It would be a quite crappy land craft, and the modifications required for it to even work on land would make it a bad seafaring ship as well. And for the sake of the analogy, the shipbuilder insists on staying within the realm of surface travel even when everybody shouts "just use aircraft!" at the top of their lungs. That is not saying SSTO isn't necessarily useful, it could definitely be as long as it only hauls as much mass as it has to. It must be specialized to go to orbit, nothing more. Of course, SSTO shouldn't be an end goal in itself, efficient transport to orbit should. As far as current engineering limitations are concerned, that means multiple reusable stages à la Starship or a space elevator, but if you can handwave a good reason why the ship can haul its entire first stage to space without losing performance, go for it. Cargo and passengers should then be transferred to another craft that is specialized for transport to other planets, but that doesn't need all the complicated stuff required to navigate an atmosphere, land on a surface, and take off afterwards. Of course, if you want Star Wars-level craft that can take off from one planet carrying hundreds of tons of cargo and fly it to another planet, then exchange its load and fly home with a different set of cargo, possibly without refueling on its way ... then you can of course do so, but you have to accept that it's as much of a stretch of reality as the Force is. [snip] The answer is always "Yes, in sci-fi you can pretend it works, but in real life this and this and this and this and this and this would make it a terrible idea", and the only form of acknowledgement seems to be "Oh, so it's a good idea if we just ____", with "____" being something that was never brought up among the counterpoints at all. The insistence on discussing these topics in the context of real life physics, but constantly failing to acknowledge the limitations of real life physics, gets a bit exhausting over time. Especially when the threads usually revolve around the same few topics too.
  2. All of them notable for using the ground effect principle, though. That's a fine principle with lots of interesting applications, but I'd say it's a little optimistic to use it for travelling to space.
  3. How big do you envision this ramp to be? And how steep? I guess the idea is something like the barrel of an artillery gun, where the vessel builds up speed along a straight portion and exits it fast enough that the ballistic trajectory takes it into space. However, this would require the ramp to be several kilometers tall and hundreds of kilometers long. And capable of withstanding a live load of 8000 tons ... needless to say, that is foolery. Alternately, it could work like a skateboard ramp, where speed is built up horizontally, then the ramp curves to direct the trajectory upwards. This would run into the same effect as rollercoaster trains do in loops: G-forces perpendicular to the direction of travel, which again necessitates an absolutely colossal ramp. And of course, there's the whole thing with gaining speed while in the thickest part of the atmosphere. How do you envision a runway landing without wings? No wings means you'll be on a ballistic trajectory. And that means gaining a vertical velocity component of 9.8 m/s2, courtesy of gravity. If you plan to use RCS thrusters to cancel out this, you need those thrusters to be powerful enough to lift the whole thing vertically, which means packing a VTOL engine on board anyway. If cargo is brought to its destination planet using a shuttle, the ship can be stocked at its orbital shipyard of origin using a shuttle, and you will never need the whole thing to land in an atmosphere anyway. Again, I ask, what is the point of making the heavy ship an SSTO? In atmosphere? Aerodynamic forces are not your friends in that situation. And engineering the ship to withstand them (and perform a flip in atmosphere) means adding lots of mass and a large amount of other design constraints you can easily be without. Again, just build the dang thing in orbit. Consider the necessary length of the runway and the ludicrous amount of infrastructure you're proposing for this ordeal. Any engineering assessment would conclude, in the first thirty seconds, "just ditch the SSTO concept to solve the problem instead". Why do you insist on examining the physics from a realism standpoint if you're going to make exceptions for something as ludicrous as a heavy SSTO in the first place? Physics says, in flaming letters a thousand feet high, that IT'S A BAD IDEA. And you seem intent on trying to find new ways to ask "But is it a good idea if we just ... ?". The answer will still be the same. Again I would point out the similarity to trying to improve horseback riding as a means of transport, by making powered rollerskates for the horse.
  4. Once again, I see this curious fixation on a really unrealistic/unreasonable solution, and trying to invent a problem it can solve. Like the modern revival of the Zeppelin, it's an answer on a futile search for the right question. The base concept has massive drawbacks, yet you keep inventing new complications to justify it, rather than doing something about the fundamental approach. Which, again, is fine for sci-fi if that's what you want, story first and all that, but you seem to want to evaluate the concept in terms of realism, in which case reality keeps throwing more hurdles in your way the more you try to walk around them. Every "but what if we do it like this?" will give several handfuls more problems on top of the ones you already have. And yet, here we are at "but what if we do it like this?" thread number countless +1, still seemingly without willingness to adjust the base concept. The big conceptual question is: "Why single-stage?" What is the benefit of bringing this thing in one piece to and from the surface if it already needs to be compatible with a shuttle for personnel and cargo? The technology required to launch this thing would be overwhelmingly more advanced than an orbital shipyard anyway. And if it's only going to be used as an orbit-to-orbit cruiser, why must it ever land? Just service the thing in orbit. Second, you seem to have realized one drawback of SSTOs, which is that they demand a very low mass fraction of cargo for the rocket equation to be forgiving in any way. But you don't seem to have taken into account that they also need to carry everything required to withstand aerodynamic forces as they travel through the atmosphere, both when ascending and re-entering. In this case, you seem to base the concept on horizontal velocity at low altitudes, which means oodles of drag, and you need the design to provide aerodynamic lift to get airborne at TWR < 1, which means large control surfaces, which once again add mass like crazy. And as you know from making aircraft in KSP, achieving the right balance for stable flight is no easy task either. And it has to survive reentry, even. Then there's the "fun" job of carrying something that weighs 8000 tons on wheels, at takeoff speed. Never mind landing. And making the runway capable of withstanding "fusion pulse detonations" strong enough to push 8000 tons of mass up to takeoff speed. Lose some horizontal velocity, you mean. When re-entering the atmosphere at orbital speeds, your problem is excess horizontal velocity, in spades. Unless you somehow make a vertical re-entry profile, of course, in which case other problems will present themselves (and barely get past "hello" before you get to the crater phase of the confrontation). And these are just the problems I can think of off the top of my head. They are not small and trivial problems with easy workarounds. The base concept has enormous flaws if examined through the lens of realism (as you seem to insist on doing). To be blunt, I am honestly a bit flabbergasted that this idea could be thought through by someone with a basic (KSP-level) grasp of engineering without the problems being immediately apparent as deal-breakers.
  5. Huh, I guess some experience with rocketry would be nice to have, in a position so exposed to their receiving end. Seems to me that they're looking to send somebody "high up" for the prestige of the position, but not somebody indispensable, in case things go sour for the person in question. Gotta wonder if Rogozin wants the position (having spouted the government line so much he might actually believe himself to be safe) or if he simply doesn't have the clout to negotiate his way out of it.
  6. Doesn't sound like they are too happy with his performance, then. Receiving a post in an active warzone is hardly a promotion over a cushy administration position of a prestigious state agency. It's almost as if they want to set him up for a fall, to put it like that ... "Comrade, seeing your success leading the space agency, we are promoting you to a special operator role. Here is your flintlock pistol, your flag, and your fluorescent orange jumpsuit. Now sprint across the open fields over there and destroy the enemy brigade entrenched there. We will await your glorious return."
  7. "And the rocket's somewhat-orangey glare, fuel bursting in air, Gave proof through the afternoon that some issues were still there ..."
  8. Lots of systems have to work perfectly for the rocket to even get off the pad and into the air. Whatever issue occurred happened mid-flight, but it was clearly just severe enough to shorten the flight time rather than RUD-ing the rocket. I'd say it was a good enough first try. [snip]
  9. Why the heck is the Presidential administration the entity that will release the pictures, and not NASA itself?
  10. That, plus buses are heavy. In a collision between two cars, there might easily be multiple fatalities because they bring each other to a standstill or roll-over. While a bus colliding with a car will slow down quite bumpily, but its passengers are not likely to die in the collision. Buses colliding with other heavy vehicles is rare too. Overall, it's just very uncommon for a bus accident to have multiple fatalities.
  11. Nice to have in case the Yetis refuse to submit to the tyrannical authoritarianism of the unelected Beijing regime, I suppose.
  12. It should also be noted that the Sprint missiles didn't achieve their awesome acceleration because they had a "magic" rocket booster. It was more because they placed a dinky little payload atop a honking great booster, and the missile didn't consist of much else to weigh the setup down. If you (somehow) attached a bigger payload to a Sprint missile, the results would be a lot more mundane.
  13. What is wrong with the way we explain things? Time and time again, various members have made it clear that SSTOs are pretty hopeless endeavours and cannot be combined with Orion in any way, shape or form. Yet barely two days pass, and then your conclusion reverts to "I guess an Orion SSTO is the best answer" again, as if nothing had been said to the opposite. Why doesn't it sink in? Is anything unclear about the explanations? To reiterate: 1) An SSTO needs to be as light as possible for the rocket equation to allow the endeavour. 2) An Orion drive is a monstrously heavy thing. It does not play nice with the rocket equation. 3) The Orion drive has various insane drawbacks that make it a stupidly bad idea overall, and any attempts to improve it will make it obsolete instead. Is it 1), 2), or 3) you have a problem with?
  14. Which is why you would never launch something of such ridiculous weight in one piece. What mission types could possibly require that?
  15. Interesting to see a heat graph that middles around 400 kW/m2. For reference, one of these propane burners gives off around 3kW of heat: (Image source) You'd need 133 of them to deliver 400 kW. I don't think there's enough room to pack 133 of those onto one square meter. If the bottle is 5 cm across you could do 20 side-by-side in a meter, but you'd need more than five such rows in the other direction, and I think the burner+bottle is taller than 20 cm, so they wouldn't all fit. Still, they give a pretty impressive mental image of the heating those wing root parts of Starship are going through. Imagine a stack of propane burners packed as tightly side-by-side as possible, and stacked on top of each other, each giving off their blue-hot flames. That's still less energy than the heating faced by certain parts of Starship. Less than half of the maximum, if the graph is any indication.
  16. So, shells loaded from the left. Does that mean an Armata turret would pop up and to the right when hit by ATGMs? Provided it could even make it out of the parade stock warehouse in Moscow without breaking down, of course.
  17. I think you shouldn't rule out the possibility that you misunderstood what he said. Given your reaction (or lack thereof) to the meticulous explanations by sevenperforce and others on these topics, it seems that there are some concepts you should reconsider your conceptions and conclusions about. Indeed. I have seen others try to say the same for quite a while, but it's good to hear it from you too.
  18. Eh, the Russians have been doing the same for decades. The Germans did too. The British before them. Mapping other countries is kind of a thing. I wonder whether the explanation was that they didn't know any better, or that they didn't care. Either way, there's absolutely no way in which this makes "SAST" look any better in the eye of the competent beholder.
  19. Heh, that's one of the cultural things that are different to understand on the other side of the world: the fixation with what we perceive as overly long and detailed slogans. A Western company might put "Seriousness, reliability, safety" as core values somewhere in a document of project values, but rarely more than three individual points, and it'd be seen as overly cheesy to put it on a banner. Writing your goals and aspirations in huge letters on the side of a wall would be quite unthinkable. At least it's even worse in North Korea. "We must work with supreme diligence to execute the plan of the 49th workers' party congress and produce more potatoes to feed the motherland!" or stuff like that seems to decorate every wall over there. If you can say it in a single breath, it's not a proper North Korean slogan.
  20. "We are apparently feeding too much liquid oxygen into the system, and there are fires appearing nearby for reasons we don't quite understand, but really, what could go wrong?"
  21. If I've understood it correctly, it's something like this: He wants a patently unrealistic idea to be a realistic idea. It has repeatedly been explained to him in thorough detail why the idea is unrealistic (I would say "good/bad idea", but everybody keeps stressing that the needs of the plot outweigh everything else, so an unrealistic idea can be a good idea if it makes a good story). But he still insists on applying realism, so we're discussing the real-world merits of the idea rather than its function as a story setpiece. Well, "discussing". It's mostly a many-to-one explanation of where all the hitches are. At times, some of the explanations of why the idea is unrealistic appear to sink in. We've got plenty of people who are good at explaining. Then somebody says something that can be interpreted as an argument for the patently unrealistic idea, or he gets some sort of inspiration on how to slightly alter a minute detail, and spacescifi immediately jumps back to the initial position of "right, then it's a realistic idea after all!", instantly disregarding everything that was carefully explained to him previously. And then we're back to explaining the drawbacks of antimatter Orion SSTOs from scratch yet another time. Try as I might, I do not think I can make a more charitable summary than that. I've seen it play out literally dozens of times by now. It keeps looping back by way of "OK, but if X, then everything you've said doesn't apply after all, right?" There seems to be some fixation on certain ideas and an unwillingness to let them go (or at least, acknowledge their drawbacks) and a continuous re-set to square one. Questions are asked (oh, how they are asked!) but the answers so rarely taken to heed unless they align with the initial notion. As such, it is not really about "efficiency". It's just about the merits of a concept whose merits have repeatedly (Repeatedly! Repeatedly!) been discredited. For the hundredth-and-whatnot time, Orion can work however one wants it to in a sci-fi story. But in real life, there are too many drawbacks and literally any attempt to improve it would make it obsolete instead. And yet, it keeps being insisted that we review the idea that the square peg might fit in the round hole, one more time. That is, at least, how I understand what is going on.
  22. Umm ... literally every single part of this text is badly wrong. Sadly not a fun fact, it would probably be against forum policy to show pictures of what Mariupol, Sievjerodonetsk, Izyum, or Kharkiv looks like nowadays, outside of the carefully crafted camera angles displayed on Russian TV. Mass strikes against civil objects and areas has sadly been a recurring theme from the attacking side in this war.
  23. Here's the caveat, I suppose. According to the rule of thumb of spaceflight, anything announced to happen in two years or more, is just as likely never to happen at all. And up until the moment of launch, delays must be expected (after that, they merely may be expected). Still, three sets of plans independently working towards similar goals is nothing to scoff at. Chances are good at least one will pull through.
  24. In other words, the yard is not in a hurry.
  25. The difference is that NASA actually has money, and the US has a space industry that actively develops new hardware (not just pretends to develop while all the funds are being embezzled).
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