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wumpus
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Everything posted by wumpus
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While I do like this thread, I have to question why all the drawings only work if prograde is straight up and the rocket has an angle of inclination. Your rocket can flip out quite well while following the prograde vector (and thus have drag straight backwards, while gravity is some other direction (effectively straight down)).
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What is your biggest science pet peeve in movies?
wumpus replied to todofwar's topic in Science & Spaceflight
That is a special case of the law of conservation of characters. In any work, there are only a small number of characters in the universe (specifically limited to the space and effort needed to describe them in the work). If you need a violent act, simply bring in a red shirt to die, as you can't afford to lose one of your characters. Also if something important happens late in the work, no matter how far away you, no matter how unlikely, one of the existing characters will be involved on hand to describe it. Conservation of character isn't going to leave thanks to a brain developed for dealing with either* a relatively small band of hunter gatherers or perhaps a traditional village. The other issue is that characterization is *hard* and takes up most of a writer/filmakers job. Filling out a world with the hundreds or thousands that would be involved in a typical plot is impossible, so we have a limited number of characters developed and used. * there are a surprising number of human adaptations since paleolithic times making the assumption that the brain finished adaptation during paleolithic times less likely. -
Is it possible to launch something to space stealthily?
wumpus replied to ARS's topic in Science & Spaceflight
Quick answer: no. Longer answer: the only example of somebody gaining control of another's spacecraft was the ISEE-3. This was "taken over" with full awareness of the original owners. The difficulty of convincing the original owners that there billion dollar satellite was space junk (presumably arranging an anti-satellite satellite that is assumed to be space junk explode with the "correct amount" of energy for the collision and then jam the satellite until the owner gives up. Then take over the satellite. Actually going up and physically stealing the satellite (especially if attempting to return it) looks silly even in a James Bond movie. Stealth is impossible with the mass necessary. The key elements in such theft would require the thief to have (and use) extraordinary resources and the victim to have little or no extra resources (even with the aid of insurance: note that there have been cases of poorly maneuvered GTO satellites setting a course around the Moon to position themselves in the correct place. Don't expect anyone to give up without a fight). Presumably the victim organisation would be out of business and dissolved without the satellite. Don't be too surprised if others attempt to contact the satellite when they notice it barely changed course after the "collision". In any event, "destroy and replace" is relatively trivial (just slowly maneuver a "dead" satellite into a collision course) and launch your own copy of the thing into space. Vastly more simple, same result. So nobody is going to try the Rube Goldberg system of "stealing a satellite". -
I didn't consider throttling down the jet engine to roughly zero thrust, if the drag of the 747 is higher than the rocket, it might separate. The idea of "launch at idle" seems weird in a battle of thrust vs. gravity. I still wouldn't like anything threatening the tail of my aircraft, I don't think I'm landing without it. I also don't see Stratolaunch rushing to push this idea, which would certainly make more sense than trying to launch 3 pegasus craft in one flight. The SR-71 (M-21 Drone) isn't a very good example. The plane was destroyed and the launch control officer was killed during a test flight of the drone and the whole idea was scrapped. Presumably it moved to the B-52 (and much lower launch speeds), but it didn't seem to last long there either. It is pretty much a clear example of "separation is hard". I'd be curious if the original stratolaunch plan of "welding together two 747s" wouldn't be easier than extra long landing gear or heroic efforts for a top-mounted launch. Presumably stratolaunch's switch to a "full custom" plane shows just how difficult the "weld two 747s together" idea really is.
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While in general I'm less impressed by this justification, I'd like to point out that the Mun has 17 biomes, and while I'm sure hittting two of them in one landing (typically in and just out of a crater) is fairly easy, getting much more than that will likely require refueling. This requires a lot more dedication to landing skill than I have, but I've opened up at least half the map by doing similar on Minmus (9 biomes, one refueling trip). Visiting 17+9 biomes means you can build a rather comfortable rocket to Duna and beyond. Just understand that all your early launch windows will have passed and you will have to figure out from there.
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How Would you Steal Someone Else's Satellite from Orbit?
wumpus replied to Jonfliesgoats's topic in Science & Spaceflight
You don't. There was no serious expectation that the US could steal Salyut 7, even if Reagan was on board and thought it was a nifty idea and the mission could justify the extreme mass of the shuttle orbiter. The requirements: Have a Shuttle, Buran, or similar vessel with an absolutely ridiculous cargo bay capable of returning your satellite. Something so big it would eat most of your mass budget for nearly all cargoes going up. Also make sure that your vessel can match orbits and inclination of the target satellite (even more important if using a Buran). Have absolutely detailed and correct engineering drawings (including any expected alterations due to launch accelerations and long term zero-g/UV exposure). Build a harness to store the after capture and during re-entry. Gain control of the satellite, presumably by electronic measures. Note that this was actually done with the ISEE-3 (international cometary expedition-3), but that was a scientific instrument. Don't expect something like the Salyut 7 to be something easily controlled, nor the original owners ignoring your actions. Do the bog-standard kerbal/NASA intercept mission to rendezvous with the satellite. Break out the Canadarm and pull the bird in (your Buran is equipped with a Canadarm, is it not?). If pulling a shuttle out of retirement, make sure the canadarm is fully attached (and there is enough room for both arm and bird). Method 2 (even sillier): Have Bidgelow Aerospace build a "birdbag" that would be effectively be an inflatable fairing plus heat shield and parachutes. Use the same drawings used by the fairing maker (and fairing) to build any harness necessary for building the thing (note that this already isn't possible with Salyut 7 [or the ISS] since they were assembled after multiple flights. You would need to dissemble the the satellite in orbit (which was never intended) and hope it still fit in the fairing). Gain control of the satellite, do your rendezvous. Attempt to stuff the satellite into the birdbag while wearing a full space suit. Film the entire process and upload with Yakety Sax sound track. Put the video on your own website and hope advertising alone covers the bills. If the above is somehow successful, de-orbit the birdbag and collect the pieces of your new satellite. Overall: I can't stress how critical "gain control of the satellite" and "know the exact measures of the satellite" are. Both are certain to make hostile collection of a satellite impossible, no matter how difficult the rest of the steps are. -
Except that Maya and Mercury both use propellers. In this proposal you have a rocket on top of an jet, which will want to flip the combined craft when the rocket is ignited while they are coupled and the rocket will slam into the tail if they are decoupled without igniting the rocket. To be honest, refueling inflight is pretty kerbal already. But refueling inflight with LOH just doesn't sound too likely. I'm still shocked that they didn't take more care that the Maya's tail was shorter than the Mercury. Presumably too many other things could go wrong to bother dealing with all the issues involved in shortening the tail.
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Is it possible to launch something to space stealthily?
wumpus replied to ARS's topic in Science & Spaceflight
Most of this was overreaction from reading an otherwise excellent SF book and knowing just how bad the orbital mechanics were (which unfortunately were often key plot points). But the idea of checking exactly what IR is coming off space junk has probably occurred to every well financed spy agency. "Conspiracy theory kooks" aren't going to get the intelligence nor are they likely to be targeted (at least by a satellite). Using "space junk" might not work well against an intelligence agency's "traditional enemies", but it might be extremely effective against poorly funded groups who at least know to hide when "official" satellites go across. Hiding from well financed agencies might well be impossible. One possible suggestion would be to have a "NASA [change scientific agency to match country launching it] moon impactor" study, preferably impacting (actually landing) on the far side of the moon. Wait plenty of time, then launch again (back on the far side) for a [hopefully] undetectable launch. The difficulty here is that you are a long way from Earth, and would have to burn in visible places to get close to Earth, and would be fairly likely tracked coming in the atmosphere. Possibly some sort of ion propulsion (which simply would not be detectable by anything) might bring you into GTO in several months. Actually, I'd probably do the same thing only instead of impacting, I'd split the thing in two (preferably on the far side, but it shouldn't matter) and have the "spy half" come back via ions and have the "science half" keep working. I'd be rather interested to know just how long it takes to pick up something that looks for all the world like "space junk" slowly changing from lunar orbit to GTO or similar. I'm guessing it would be "detected" many times and thrown out as noise when it doesn't show up in the "right" position when checked again. To be honest, the "rocket science" of a hidden EINT satellite isn't the real problem. The big problems are that EINT satellites aren't exactly controversial, you could simply launch on from Vandenburg and mention it is a NSA flight without measurable protest. The other is that satellite data is pretty much the "cheap cargo" of communications. Of course, if Soviet/Chinese/OpFor_of_the_month could be interested in listening to Iridium calls, and have to cover it as well as they could to keep from blowing the secret that they could break whatever encryption was used (I would go so far to say that no launch is sufficiently stealthy to cover such a huge secret: just look at the care the UK took to hide that they broke enigma, and the fog of war was much thicker in those days). -
In one of the nuclear power threads someone mentions that you could run a small town (or more) off the electric output of a nuclear sub. This isn't exactly hyperbole, the US has actually brought submarines into harbors after disaster strikes (with loss of power) and plugged the local grid into the sub (presumably after carefully making sure how much is still online). I can only imagine how many downed power plants a carrier can replace (probably against US policy to put a carrier in that much danger, they are probably limited to attack subs, the only ships with nuclear power but not nuclear weapons). Hospital ships come in handy as well. I don't think such things really lend themselves to aircraft.
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What is your biggest science pet peeve in movies?
wumpus replied to todofwar's topic in Science & Spaceflight
Robert A. Heinlein was in the middle of writing Stranger in a Strange Land when Ike suspended nuclear testing (wiki claims some group demanded unilateral ending of testing and that was enough. My memory was that RAH said that Ike agreed to a joint suspension, and the the USSR broke it first with even dirtier bombs). In any event it was ~1958 and Viet Nam would not make for strong booksales. Starship Troopers was specifically made as pro-military anti-USSR propaganda. To RAH's surprise and delight, while it remained controversial it kept selling, and selling, and selling. RAH was an Annapolis grad and presumably career naval officer who was kicked out on a medical disability before Pearl Harbor. Sometime afterwards, Joe Haldeman was drafted into Viet Nam (they wouldn't let an atheist claim conscientious objection, not sure if that stuck him with the medic MOS). I think at one point he was the only survivor in his squad and has enough shrapnel still in him that he set off airport security well before 9/11. Joe rewrote Starship Troopers in 1974 as the Forever War, which was a complete remake specifically as Viet Nam. From what I've heard, the movie of the same name might as well be based on Forever War. [My favorite exam question from college: describe RAH's [Glory Road was on the reading list] influence on Forever War. Sure, there was the "derive Newton's gravity equation assuming circular orbits", but the first one let me point out how much of Starship Trooper's serial numbers were still showing before contrasting Glory Road to Forever War.] -
The American Plan to Sieze Salyut 7
wumpus replied to Jonfliesgoats's topic in Science & Spaceflight
From the information in the wiki (needed a boost from Kosmos 1686, uncontrolled reentry), it might not have had any. I would assume that the moment the Shuttle left KSC, Soviet planners would know exactly where it was going and realized if it was heading to Salyut 7 (especially after Reagan tipped his hand by suggesting a joint effort there (which would certainly allow NASA to publicly work on all sorts of Salyut 7 plans)). Unless they had real drawings (and backfitted to what was made: I've certainly seen too many cases where the engineering drawings aren't *exactly* what was shipped. I wouldn't be surprised if USSR design involved "manufacturing fixes the bosses don't need to know about") and could build the appropriate harness, the end results would be "throw the thing in the back of the truck and drive home". Good enough for many things, but probably not space stations. And since by that point the cold war had involved into a complex dance of bird for tat, I can only imagine what the Soviet response would be. Perhaps blowing up one or more satellites and creating a big old mess of space junk. -
Note that for Mun landings, this is probably overkill. You could always leave a fuel tank + octo probe + solar panels +docking port in Munar orbit for that bit of fuel, but that's about it. On the other hand, for some reason I built a craft with an LV-N engine for Minums (or the Mun). It was too much, so I brought it all the way back to Kerbin and left it in orbit. I then proceeded to use it as a "local shuttle" to Minmus and Mun. It was an extremely handy two-part ship (where the lander often brought fuel and staged after docking).
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I've taken a multi-month vacation after dealing with the extra time of landing orange tanks. I was aware that it didn't change the game at all (there was plenty of money for each stage), I just wanted to keep costs minimal. The catch was that taking all the time to shepherd the first stages to KSC meant I didn't have any time to go to Duna, so it was a poor choice. If I get that itch again, I suspect I'll go for stage recovery mods.
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There's a reason I prefer Minmus first: easy landings. Low gravity plus flat surfaces means an ideal training zone.
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How to NOT lose control with asparagus staging?
wumpus replied to nyugnep's topic in KSP1 Gameplay Questions and Tutorials
I'd recommend at least trying putting one fuel tank from the center and moving it to the sides. You will be carrying extra mass [the engines] and the drag, but typically you expect to burn less each stage (there is no exact formula, but twice the fuel in each stage (or equal delta-v per stage) is a good place to start). Looks like I (and probably a few other returning old hands) have a lot of unlearning to do). Then again I just took a contract to haul a 2.5m heatshield to 2km/s in the atmosphere with only 1.25m parts available. Not recommended (the solution was to arrange the boosters around the heatshield and have the drag below the CoM). -
This isn't even "dropping stuff". It is launching the thing from on *top* of the aircraft. Missing the tail of the aircraft is a critical feature of ejection seats (and I think the first US/UK seat (the Germans had been building them for awhile), still badly injured the pilot when he hit the tail. So do you do a "fire in the hole" launch when you fire "clear the tail" stage to separate? (getting the CoM/CoP right for both the combined and individual aircraft appears unlikely). Apparently there is no effort to try to keep the H2 second stage topped off. Any guesses as to how much will be left when it stages? The rocket gets refueled with RP-1 in flight. This is reasonably plausible as draining a tanker of JP-whatever and replacing it with RP-1 is probably a non-issue (you might fill the thing up with an alcohol cleaner or not, I suspect it won't need any real cleaning). This takes things out of the hands of commercial flight, but I'm sure NASA/Air Force/Navy can handle it. The rocket also gets refueled with LOX. Right. At this point I'm really surprised at the lack of LOH refueling, as that is probably a bigger issue and roughly equally difficult. Somebody is trying to take kerbal designs and use them in real life [hello Eric D. Waters/Dennis M. Creech/Alan D. Philips!, one of you is on here, I'm sure] . Redo it after you install the "real fuels" mod. Also using the staging to fire both decoupler and seperatron together is cheating. You need to hit the space bar twice in succession to fire them. Ideally you should have some randomly decide on the order and cover up that bit of screen with tape when you launch. And whatever you do, don't build a real rocket off results from KSP, even with RO.
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Is it possible to launch something to space stealthily?
wumpus replied to ARS's topic in Science & Spaceflight
I have to wonder if you read this again how many mistakes you would find. The thing would have to launch from Vandenburg (which helps secrecy a lot, there are a ton of controls of what goes in and out even on non-secret missions), and complete orbital insertion (of a polar orbit). That's a fairly odd orbit to park in if you have a "staging failure" to launch a probe into escape velocity. I was going to wonder if anybody noticed it was "hot". Then I realized that the energy absorbed by solar panels (or TNG if the "cover mission" went past Jupiter) would cause the thing to heat up with the exact same energy regardless of the function of the craft. If you decided to calibrate your IR sensors by comparing live birds to space junk you might be a little confused until you discovered the secret, but unless you did some precise measurements of the frequencies of the black body radiation emitted from the satellite, you'd never see a difference. I wouldn't be surprised if spy agencies make such careful analysis of space junk, but I doubt ISIS has any agents in places that would tell them about such "hidden satellites". Picking up the downlink would be relatively trivial if sent to Ft. Meade (just put a "home dish" in Columbia, MD). A little harder in Utah. Harder still for somebody listening to a Russian downlink to Siberia, and virtually impossible for NSA birds in GTO (especially if they sway back and forth to view northern sights). I also thought there would be a bureaucracy issue (for pretty much the reason I laughed at the idea of NSA code in Windows. Any US spook would run screaming from the idea of "we'll just have a bunch of H1-B temps code this up, then pull the code from an insecure server for the final build..." all to put [more] security holes in code they can hack at will). My guess is that they could just have a Congressman insist on his pet company (which happens to be a small woman/veteran/indian owned company that is really a NSA front, so the immediately source a company that can handle everything [but insist on *one* specific part that can be easily replaced with the guts of an ELINT sat]). This is so common in US contracting that nobody would notice (and only require a *tiny* front that wouldn't require a history at all. And the "staging failure" makes a great reason to go out of business). Yes, I've sat in too many meetings listening to government types drone on about "funding vehicles", can you tell? Is the "staging failure" the thing just didn't work when in the right orbit? Because "staging failure" sounds like "rocket failure" to me, which would be a bit odd. But just failing (possibly working for a short period of time, some NASA missions are pretty short) would work pretty well. And cover the tracks of the front agency well (which is probably more important in fiction, giving closure to those characters). [Most of this post was thanks to some whoppers in Solar Express by L.E.Modesitt Jr. He included a casual mention of "extending a partial space elevator" (which I would have easily caught *before* KSP) and [I think, I mostly assumed that anything after that was wrong] went downhill from there. The non-orbital dynamics stuff was of course good. 2015 (probably written a year or two before) was not the time to release lousy orbital dynamics in SF. -
You are assuming that this single possible cause of loss or rocket and cargo is absolutely a bigger threat than all other possible dangers to the craft. The issues is that they have 2 catastrophic failures in 30 rockets put on the pad (even worse if limited to full thrust). Best guess is that they need a larger ongoing safety check and not plan on any passengers in Dragon any time soon. update: Note that it looks like the Dragon could escape either of these disasters. So a lot of this thinking is rooted in my "the shuttle is how you get into space" attitude (I did watch one or two Saturn liftoffs. But by the time I could understand the details everything was shuttle...). Of course, reverting after your spaceship explodes doesn't help either.
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There's also the issue that Unity (4 or 5) does all physics calculations in single point (32 bit) math. For most games this is irrelevant: this works out to something like 9 significant digits and since maximum possible graphics resolution is about 4000x4000, it never comes up. KSP, on the other hand, uses that math to cover everything from the forces acting on each strut to the movement of the planets. You might hear people mention "the Kraken eating their ships". Unless it was a post from several years back, it wasn't "the" Kraken. Back then the origin used was either Kerbin (since KSP started there and only gradually added the rest of the solar system [and most likely due to how the bug manifested]) or Kerbol (which would make things easier once you added the rest of the planets). In any event, what would happen was that thanks to the minute errors of the floating point numbers (because most of the ship's 9 digits were all the same, there was little room left to calculate ship's physics) things would either overlap or otherwise produce ship-destroying actions. The Kraken had fed. In the end, KSP now puts the ship at the origin of the floating point coordinates, so the ship parts get full resolution of their calculations. Far off planetary masses hardly need any more resolution, and any ship further away than a few kilometers or so (the "physics bubble") are simply assumed to maintain their orbits (the "on rails" effect). I'm sure all this makes life hard for the "real gravity mod" people, but Squad certainly preferred doing it to writing all the physics code from scratch, and doing it all in doubles. To be honest, the bugs drive me away and the kerbals keep calling me back. Simple trips to orbit are great, long drawn trips involving multiple launches that are blocked by bugs (like the system absolutely refusing to give me a maneuver node when I approach Duna) drive me back away.
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My assumption was that the practices were established in a mad rush to catch up to Sputnik and Gagarin, and later expanded to reach the Moon. After that it was "we've always done it this way, and if a failure happens when a change happens, whoever changed it will be blamed regardless of whether that caused it". My understanding was that the DC-X project made some strides in towards reducing launch costs and *nobody* else has really tried. Spacex has certainly had to walk back any "gas and go" statements about how falcon 9 would be reused, but that doesn't mean that they shouldn't be looking for ways to make launches cheaper. Formula 1 is a rather interesting case. Certainly any wearable item (tires, clutch, brakes) will be replaced. I'd even expect things like struts, springs and shocks to be replaced as well (they may not be pushed hard compared to normal items, but their weight is likely reduced to the point they can only survive a single race). There's also the issue that the entire car will only exist for relatively few races (a few seasons, then FIA will change the rules again and everybody builds a new car). Presumably spacex new some items would wear out before 10 launches (never mind Musk's "thousands of launches" Mars justifications), and they are replaceable and scheduled to be replaced. I also would be fairly surprised if they didn't discover that some few parts wore more than expected and need replaced. Probably enough that at least one will be hard to get to. That reminds me. Next time I fly I'll pick an airline that does maintenance in the US (at least for US domestic flights). There's more than a few ways to invent your own cheaper system.
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Apparently that fraction is at least 3/10s. I suspect that they can get it down if they create their own [unlike NASA] countdown procedures. I suspect that Spacex might be wishing they hired a few more DC-X alumni (mostly hired by Blue Origin). While DC-X might not have gotten very far in terms of going into space and especially any SSTO plans, it certainly blazed a trail of low workforce launches.
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One thing that seems to be forgotten is that the Karman line (what you need to cross to get into space) is defined the height such that the velocity needed for lift is equal to the velocity needed for orbit. So any lift-based flight that gets into space achieves orbital velocity. Space planes simply don't go into orbit on Earth. They are Kerbin-only. If you want to use a spaceplane to get into orbit, a good idea of minimum thrust would be the X-43 (mach 9.6 flight). It was released at mach 9.6, managed to maintain that speed, then started to slow down. https://hapb-www.larc.nasa.gov/Public/Documents/AIAA-2006-1-317.pdf Obviously, you would need an additional (rocket) stage, but getting anywhere near mach 9.6 on air means you barely need any rocket to get there (the second stage of Falcon 9 starts from about mach 6: you might get away with getting something Dragon-sized with something half the size of the falcon 9 first stage). But while the X-43 program showed that atmospheric (and atmosphere-breathing) flight was possible at mach 9.6, it didn't begin to provide a roadmap on how to get there. It certainly didn't show much about how to accelerate to scramjet speed (other than using a relatively huge rocket), nor to haul a first stage from such speeds to a significant fraction of orbital velocity. If you want to use a spaceplane to get into space, you will still need a second stage. And it would probably look remarkably like spaceship 1 or spaceship 2.
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I can't believe I left out the most kerbal thing ever! Explosive Staging! Explosive staging is when you put a solid rocket booster (almost always a RT-10 hammer, but presumably nowadays you would use an RT-5 flea) under another rocket without a decoupler, and light the above engine in such a way that the SRB exploded to remove its own mass (and anything connected to it). The two motivations to this concept was that you don't get decouplers when you start the game (and "career mode" then was what we now call "science mode". No limitations on parts or mass (which might exist in science mode for all I know)), the other was that a RT-10 hammer was pretty useful, but costs 400 funds (may have been cheaper) while the decoupler also costs 400 funds, often instantly obsoleting the RT-10. On the other hand, if build a final liquid stage, a RT-10 under that, and three RT-10s under that (all with no decouplers), you could go into orbit with the first mission, merely by exploding each stage as needed [that design is from very poor memory, and I'm not even sure where the old rockets are saved. But I launched plenty of those rockets into orbit, both to refine the design and to determine which kerbals had the "bada55" tag (Jeb loves the flight, Bill and Bob not so much). This was taken to extreme lengths, most famously Scott Manley's videos on unlocking the entire science tree with two missions (the first landed on the Mun with beefed up rocket like above. Of course it did involve things like landing a rocket with 4 fuel tanks, an LV-T30 engine, and no landing legs. I suspect that Abysall Lurker did it first, although everybody remembers seeing the Scott Manley video https://www.youtube.com/user/ablu444 (Extreme KSP on old versions). I'll have to go back and look at the old RT-10, it looks like they nerfed the thumper down to the point that RT-10s might even work. But most of the reasons for it are gone, and I'd look more toward all the many things you can do with kickbacks for your SRB needs. Don't expect much from the fleas, but that's all you have for mission 1. [update] I've tested in sandbox mode that you can get into space with nothing but fleas. My "success" so far: Managed to get into space. Could not survive return (capsule only stable upside down. Destroyed parachute and like never came down slower than 300m/s). Managed to get into space and return. Vessel upwards of 40 tons (limit 18T), ~50 parts (limit 30) and probably too tall. 23 fleas arranged in layers of 1,1,1,1,5,5,9. The key to survival was flying with the capsule upside down (so it would be stable coming down right side up, and survive), and attaching to parachutes via modular girders to the sides. Unfortunately this is not terribly aerodynamic going up and requires so many boosters, as well as far too many simple fins so that you can't do it with a first mission. Gave up trying to get to orbit. The catch is that you have to burn a significant amount of delta-v above 70,000m. Lowering the thrust from boosters only helps so much. My old trick of turning the last booster upside down (so it can be fired after waiting for AP) appears to cause too much drag (I *did* manage [please ignore the cheating launch towers holding it to an angle: if that worked, I'm sure I could finagle the means to emulate it legally] to escape the atmosphere with an inverted flea, but it doesn't have the delta-v it needs. Two might work, but that's a lot of fleas to add to the lower stages (curse you, tyrannical rocket equation).
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The tyranny of the rocket equation shows why the only reason for recovering the tip of the rocket is the astronauts themselves. You would want to start your recovery operations with stage 1, then move on to stage 2 (if possible) and so on [Spacex has given up on recovering stage 2 of Falcon 9]. Somebody did run an experiment where an F1 engine (the main engines of the Saturn V) was dunked in saltwater, but it was at a relatively shallow depth for a brief period of time. The Shuttle SRBs fell (with parachutes) hit the water at 23 m/s (~50mph) and wound up with ~10m sticking out of the water (which, if it had engines at the bottom meant they would be ~35m down). The SRBs also have the advantage of naturally floating due to being tube made of solid steel holding a column of air inside. While the Saturn V first stage might float, it certainly wasn't all that strong for any force other than 3G of force along the prograde axis (presumably it could handle the retrograde forces of the parachutes, but don't count on the impact of the water). It wasn't going to handle water impact horizontally, and if it did survive a vertical impact it would go deep enough to crush the fuel tanks/rocket body. Assuming you were only interested in the engines (a reasonable assumption), it would be hard to imagine recovery method that didn't involve them being dunked vastly deeper than that famous test (although maybe you could disconnect them and attach them to some sort of buoyant device quickly enough). All this is pretty hypothetical, and wouldn't be seriously considered in the crash course to get to the Moon (and back) before December 31, 1969. There was a design for a followup of the Saturn V (the Saturn Int-21) and I don't think even it considered reusing any parts. I'd have to wonder how much final payload it would cost (for Apollos 12-17) to put parachutes on the engine end of the first stage (and thus use the entire rocket as a crumple zone for water impact).
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Is there limit on how small fusion/fission reactor can be??
wumpus replied to raxo2222's topic in Science & Spaceflight
I'm missing the point as well. If they weren't afraid of a containment leak, why didn't they just use water as a coolant? Also, wiki mentions "fearing explosion from the recombination of hydrogen and oxygen": I suppose they might recombine somewhere suboptimal, but the net energy has to be lower. I suspect using cooler bits of the fire to "presteam" the water would keep down massive pressure changes from vaporizing water (and this also assumes that the reactor is *so* *hot* that you can afford to give up the phase change energy because the steam will absorb that much energy. I'd be impressed if even a burning reactor could get that hot).