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Everything posted by KerikBalm
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I'd say learn docking first.... orbital rendevous interplanetary missions are just so much cooler and more fun (at least for me) - although it can become much more difficult if your interplanetary transfer was done poorly, and you arrive in something more like a polar orbit instead of equatorial... that makes the orbital rendevous for the return mission so much harder (the timing is harder, and the launch windows for the rendevous are much less frequent)
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the ion engine is way too OP
KerikBalm replied to lammatt's topic in KSP1 Suggestions & Development Discussion
"You either enable time warp thrust, or you buff up the engine," I want time warp thrust. A "Physics-lite" warp - no calculating structural loads, moments of inertia, etc etc.... just the normal on rails physics + F=MA calculations (note that on rails warp already supports draining resources, such as electric charge). Buffing the engine makes it the least realistic engine in the game FWIW I used the ion engine before the buff, as a "utility" module, not main propulsion, IRL hall effect thrusters are often used for station keeping and fine tuning orbits. That is what I used Ion engines for - orbital adjustments, getting into exact kerbostationary orbits, fine tuning my interplanetary trajectories, etc . (although, I don't use mechjeb, which I hear allows you to get pretty precise burns and trajectories). It wasn't too bad as primary propulsion for a tiny probe core+ 1 ion tank. And you are still very very wrong about hohmann transfers with real life Ion Engines for most purposes. * There is no such thing as capture kicks for interplanetary trajectories - you either complete your burn, or go sailing off into heliocentric orbit. * Perapsis kicks only work until you get to escape velocity. You can't perapsis kick out to jupiter's orbit with an ion engine. You can perapsis kick to get out of Earth orbit, and then you're in a heliocentric orbit, and you can perapsis kick (from the perapsis of your heliocentric orbit) to get your apopasis out ot Jupiter orbit - but that is not a hohman transfer, not even close. * once you get your apoapsis out to jupiter orbit's, you still won't be able to do a single orbital insertion burn, and it will keep flinging you off, or you'll end up diving into its atmosphere. Even using aerobraking is probably not possible, because it won't have the thrust to circularize at the apoapsis. You don't need to do a 100% brachistichrone trajectory (indeed, as you get closer to the halfway time point, you get less and less value for additional expended propellant - but with such extremely low TWRs, the trajectory will much more resemble a brachistichrone than a hohman. LV-Ns are realistic enough. Ion engines could give us a very different but still realistic spaceflight experience, if we had on rails thrusting. That is what I want. I want that other type of trajectory available to us. I don't want a super-duper-lulz-look-at-my-dV-that-I-get-to-use-to-do-standard-hohman-transfers-like-I-did-with-the-LV-N-but-I-Sit-at-the-computer-longer engine -
Those staged burns would be called "perapsis kicks", and each one would have to be done exactly at perapsis to avoid changing the perapsis (of course, they don't need to be exact to get it to work, close enough is good enough) Regarding #4, one person replied: "4) The most efficient way is a suicide burn. Just drop down and burn at the very last moment, so that you lost all your velocity when you reach the ground." What you want to avoid here, is gravity drag. Imagine hovering using your rocket - zero change in velocity, all your fuel used. Every second you spend fighting gravity, is lost dV equal to the gravity's strength. So you want to burn pointing at the planet as little as possible - ie at apoapsis to lower your perapsis to just above the surface, at perapsis to kill your horizontal velocity, and then right before touch down to kill your vertical velocity (or do this in one continuous retrograde burn). You don't even need mechjeb. What I do, is set up a perapsis just below the surface. Then I eyeball a manuever node somewhere low but before the trajectory intersects the surface, and drag the retrograde pointer until the post maneuver elispe looks more like a straight line (ie, a very very very high eccentricity, so it is like two mostly straight, parallel lines segments, joined at the end). If the estimated burn time is 1 minute, I start burning at 30 seconds from the maneuver node - (note, I make sure the estmate dburn time is more or less accurate with a brief full throttle pulse prior to the main burn). Since the maneuver is meant to kill my horizontal velocity, and it assumes a constant acceleration, a 1 minute burn, 30 seconds before the node, will stop you before the node, because by the time your burn finishes, your average velocity has been half of what it was at the start of the burn (ie, due to your deceleration it took a minute to get there, not the 30 seconds it would have taken before the burn) - but since you use up fuel, your acceleration actually increases throughout the burn, for an additional safety margin. Lastly, its the velocity relative to the surface that you want to reduce to zero, but I set up the manuever node to get the "orbit" velocity to zero, and of course, I picked a node above the surface. Combined, these mechjeb-less suicide burns give me plenty of margin for error
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0.23.5 transfer windows changed?
KerikBalm replied to KerikBalm's topic in KSP1 Gameplay Questions and Tutorials
So year numbers also change as well? The old day 59 is now... 283? Seems about right.... I time warped to when the alignment looked mostly right, and then launched on the IP trajectory (some radial burning required...) I seem to recall it was day 200 something -
Is it just me, or are the old transfer windows all wrong in the latest version. Previoulsy, following this table: http://www.eiden.fi/ksp/phaseangle-Kerbin-Duna.txt I've sent missions to duna between days 57-60, with no problems. Now after downloading .23.5 , when I start a new game, and timewarp to day 59, Duna is still way ahead of me... Has there been a change in the starting position of the planets? Maybe the clock now reads Kerbin days instead of 24 hour Earth days? Or maybe I'm screwing up in some other way.
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Well, I'm ambivalent about this... On the one hand, we have small parts that were OP'd- ie the 48-7s. A cluster of those weighing as much as a mainsail was pretty OP relative to a mainsail. Bigger shouldn't be better, but it also shouldn't be worse. It shouldn't be a matter of balancing your rocket performance, agaisnt your computer performance, because it hates the 200+ engine 48-7s cluster you used.... Larger parts that make it easier to build a rocket without a high part count are good. In this aspect I like the Liquid fuel booster - same weight as a mainsail+ orange tank, half the part count, more stiffness (as the engine/tank interface could often be wobbly itself). The problem is, it is equal in weight and fuel capacity to a mainsail+ orange tank, but its trust is much higher, and on top of that, its ISP is higher too. Yes, I know, you can't stack anything below it.... as if it was ever a good idea to have a mainsail in an upper stage. If that is a problem, you can just use the larger engine, its only half a ton heavier, but produces much more thrust (you can use less of them) at much higher ISP. Mainsails are obsolete. Its taken away part of the challenge. Sure- we could just not use them - but then we are making a decision about what is acceptable, and what is not acceptable to use. Instead of just optimizing designs within "stock" - no mods, now its a matter of declaring certain stock parts forbidden, and a question of where to draw the line. No mods -> No SLS parts -> no 48-7s? no ions? no nukes? No aerospikes? no fuel lines/asparagus? No reaction wheels? By adding parts that obsolete parts... you've made the game full of obsolete parts, or you've removed the simplicity from the "all stock parts" playstyle, to various shaded of grey (as far as what parts are or are not OP'd). Some may have liked squad drawing that line, with their stock parts - but now that line drawn by squad is meaningless, when its so clear that the new parts are OPd relative to the old parts. But then again... these parts are not outside the realms of realism as far as their stats are concerned.... the problem is simply at these scales, the lack of realism of the 1/10th scale system becomes apparent
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the ion engine is way too OP
KerikBalm replied to lammatt's topic in KSP1 Suggestions & Development Discussion
Nope.... hohmann burns aren't possible with real ion engines at the given power levels*, so instead they do brachistochrone trajectories. You shouldn't be trying to do something that isn't possible. Because of the way ion engines work in KSP, we're always doing hohmanns, and never doing brachistichrones... its a shame. *sure, in theory you could perapsiss kick for your outbound, but that would take far too long, and you wouldn't be able to do a burn for capture at the destination... you'd go whizzing by, and fail your hohman transfer. With the OP'd "ion" engines in KSP, yea, you should do Hohmann's to maximize efficiency. But the point is that a real simulation of flight with an ion engine would have you doing a brachistichrone trajectory, not a hohmann transfer. -
how do you use radial solid boosters
KerikBalm replied to kiwiak's topic in KSP1 Gameplay Questions and Tutorials
Don't you mean a payload pretending to be an engine? -
the ion engine is way too OP
KerikBalm replied to lammatt's topic in KSP1 Suggestions & Development Discussion
The point is that you shouldn't be doing hohman burns at all with ion engines. What we need is an engine that works during time warp/affects "on rails" calculations. As it is now, the ion engine acts like a perfectly efficient ion thruster in the 40 MEGAwatt power range, (or more realistically, an ion thruster at 50% efficiency, with a power consumption of 80 megawatts). Good luck getting 10's of megawatts of power output from solar alone... -
Umm, no.... "Deploy them as early as possible of course." This can cause problems if you are still significantly faster than terminal velocity - like rip your ship apart problems. Doing a full deplot of main chutes at 2500 vs 500 meters won't change your touchdown speed. I can't think of a scenario where 500m is not enough time for your main chutes to decelerate your ship, where an earlier opening would have helped rather than ripped the craft apart. Full deploy your drogues if your G meter reads less than 1 G while you are within 5km of the surface Full deploy your mains when your meter drops below 1 G again following the drogue deployment. "Even in the deepest valley of Duna with 20+ parachutes, you'll "land" at 10+ m/s. You always have to use your engines at least a little bit." Not true, I've done many completely unpowered descents. In some cases everything was fine, in other cases, my kerbals had to repair the landing legs. I've also dropped lightweight 1 way probes with no engines at all. However... if your craft does have engines, it may actually be better to use them, than to add more chuts and landing struts - its often better to spend 5-10 m/s of lander dV on touchdown, than to haul the extra mass of the chutes and struts to Duna. I never really considered using wings on Duna, as you can't use air breathing engines... but recently I was making an Eve mission, where I was going to deliver the ascent vehicle, and a science rover separately - and I figured... I should add wings to the science rover to make landing near the ascent vehicle easier. And... the wings would jsut get in the way when roving around, so I added decouplers, and attached the wings to those. Now it occurs to me, that using wings on Duna could remove the need for drogue chutes. Lacking the ability to use jets, any ascent would be a vertical climb and gravity turn as if there were no wings, so I don't think I'd bother with making a spaceplane design (not to mention a horizontal landing would require very careful landing site selection). So next I'm going to try out using wings on decouplers... as I figure it: My lander will be coming in pointing retrograde, with the landing chutes at the top, so I design my wings to be aerodynamically stable with the lander flying "backward" (I'll use and inverted small probe core, so I can click "control from here", and fly it without the reversed controls) - I should be able to pitch up and slow it down/flare, then pop the chutes and then quickly decouple the wings. It should be even easier than my Eve rover, as I was trying to land that thing still facing horizontal, and my parachtues weren't at the retrograde end.
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Standard parachutes semi-deploy at almost exactly 9km on Duna. Drogues semi-deploy at almost exactly 10km on Duna. Of course you want them semi deployed ASAP to slow you down more before full deployment - drogues again help a bit here because their semi-deploy drag is 4x higher than the other chutes. The first chutes that open should be on the heaviest parts of your craft - ie if you have a full fuel tank, you should have some chuts on it, not on a part that is attached to it (as this will likely rip that part off your fuel tank). Even drogue opening can be a shock if you come in fast and deploy at 5km. I'd say full deploy on the drogues at 2.5 km, full deploy on the rest can come at pretty much any point after your drogue(s) open(s). If not using drogues, then stagger the openings, again starting with the chutes attached to the most massive parts first. This game really needs the radial drogue chutes to be stock parts....
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Meh, you don't need to find all the anomalies or visit all the biomes before moving on to Duna. IMO, it gets a bit tedious to just do the same basic mission over again, just different landing sites - although trying to get to the canyons is cool- as is sending a rover near the intersection of 3 biomes, and roving around to get full science from all 3 (I think I did one in a crater, by a canyon entrance- get crater science, go into canyon, get canyon science, go back to crater, ascend torim, get highland science, return to ascent vehicle and transfer data). Once you've gone to minmus and landed and returned from the mun, why not go out further? As already mentioned, you can also go to eve, but anything that does more than dip into just the top of the upper atmosphere is going to become a 1 way mission real fast.... An eve orbiter/gilly explorer is quite feasible to do next. But IIRC, the Duna launch window opens before the Eve launch window, so I'm sticking with my Duna recommendation.
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Well, with 23.5, there are near kerbin asteroids ot rendevous with, but I haven't tried that yet, it may be quite hard, I'm not sure. The next step is ussually Duna - it doesn't take much more dV to reach than it takes to get to Minmus (but you need to wait for the transfer window, and the transfer is quite long - in game time ofc, time warp makes it trivial). It has very little inclination, relatively low gravity/escape velocity - and best of all, it has an atmosphere- which helps a lot for capture (ie orbital insertion, so you don't just go whizzing past Duna) and landing. Yet the atmosphere is thin enough that it doesn't cost you all that much dV on ascent. Its pretty much the opposite of mar's atmosphere - mars has too little atmosphere to ignore (spacecraft can burn up if they come in too steep), but too little to be of much use (even with parachutes, a spacecraft will be going far too fast, and needs relatively powerful retrorockets). Duna's atmosphere allows you to land with just parachutes, assuming you brought enough, and land in the lowest depressions (where the atmosphere is thickest) - but you don't need to worry too much about it on ascent (although you should still ascend at terminal velocity). For most incoming trajectories , you want a perapsis between 10.5k and 12.5 to aerocapture into Duna orbit (it should give you an apopasis outside the atmosphere, and you burn there to raise your perapsis outside the atmosphere, or for a lander - do nothing and let the orbit degrade for no additional fuel use). Due to the added dV of taking off from Duna again, you should do it "apollo style", and use a lander that will launch and rendevous with the inter-planetary stage (or at least leave some fuel in orbit). - No sense in deorbiting the fuel you need to get from Duna back to kerbin, only to have to haul it back into orbit again. So in Kerbin orbit, perhaps you should practice orbital rendevous
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The total amount of data you can get from each body is not reduced by transmitting data. But that doesn't mean the next return will be as much as the first return would have been without transmission. Ie, suppose you get 100 science for a return, or 20 for a transmit, and its possible to get 140 science total from repeated returns. You land, and transmit 20 science. There is now 120 science remaining to be gained. You do a return mission, this one gets you roughly 86 science, not 100 science. 86+20 >100 Of course, if you did 2 returns, instead of 1 transmit, and then 1 return, it would be something like 100 for the first return, and 29 science for the 2nd return - for a total of 129. Either way, you can keep sending missions to do returns, but the science gained will diminish each time. Its sort of like an infinite sum... 1+1/2 +1/4+1/8+1/16+1/32...... ... sums up to 2 science. Each return will give you a % of the remaining science to be gained. A transmission detracts from the remaining science to be gained, but the total amount is not lowered
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There is no stealth in space. Blackbody radiation will be a dead give away
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[1.3.1] Ferram Aerospace Research: v0.15.9.1 "Liepmann" 4/2/18
KerikBalm replied to ferram4's topic in KSP1 Mod Releases
So... I'm contemplating installing this mod, but I see this statement: "wing pieces at wingtip make less lift and more drag than ones at wing root" This makes no sense to me? Making high aspect ratio wings will perform worse than low aspect ratio wings? 0.o ?- 14,073 replies
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- aerodynamics
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Help getting to Minmus!
KerikBalm replied to Eyekonn's topic in KSP1 Gameplay Questions and Tutorials
Or just match its inclination before even starting the transfer maneuver.... This doesn't work for other planets, but it does work for minmus. Set Minmus as a target, place a maneuver node at the "ascending" or "descending node", at that manuver node, set a burn normal or antinormal (ie pointing "up"/north, or "down"/south) until the ascending/descending node reads 0.0/ NaN/ starts to move (the more precisely placed your maneuer node is, then the closer the point where the asc/desc nodes start to move is to when you'd have perfectly matched inclination, if you placed it perfectly, then the nodes will suddenly swap as you make your burn a bit longer) *execute the burn*, possibly repeat if your inclination is still off by more than say... 0.5 degrees (ie look at where the asc/desc nodes are post burn, do another correction burn at that point) *transfer to minmus as you would to mun with a simple appropriately time prograde burn, and retrograde capture burn. -
A 1kg iron weight falls as fast as a 1000kg iron weight, all you need to do is see if these fall up or down.
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Since gravitational attraction is a property of mass, and anti-matter still has mass, why wouldn't there be a gravitational attraction. Antimatter is essentially the same set of particles, with opposite charges, right (perhaps this is oversimplified), but I can't imagine why there would be gravitational repulsion, unless we were talking negative mass-mass. Furthermore, can't such things be measured already?
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Super Fancy Orbital Mechanics
KerikBalm replied to Alpheratz's topic in KSP1 Gameplay Questions and Tutorials
The concept of getting gravity assists from the point of launch seems weird to me... it seems like a losing proposition, can you actually get more dV out of it than the dV needed to set up the maneuver? -
Thats why some shows get around it by having people view "one possible future" You know, parallel universes, exponentially increasing in number with each interaction (either at the quantum level, or a less well defined level based upon the decisions of conscious individuals). Thus many possible futures exist for any given time... of course in such shows its typically only 2 (despite the disclaimer), the one that will happen if the "vision" is ignored, and the one that will happen if the "vision" is followed. Or its only 1 - the one that happens while trying to avoid it (as in Oedipus Rex)
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Could a Gyroscopic inertial thruster ever work?
KerikBalm replied to FREEFALL1984's topic in Science & Spaceflight
Let me sumarize: Hurr durr, I don't understand what I'm watching video 5 Video 5 shows an offset gyro rotating about a plausible CG. The purpose of the experiment is to show that it rotates about the CG, the only misunderstanding is on your end. You claim to do the experiment, but offer no proof. So I'll just claim to have done the experiment 1000x more than you, and generated data disproving your position -
Tiny, easy-to-fly interplanetary spaceplane
KerikBalm replied to godefroi's topic in KSP1 Gameplay Questions and Tutorials
Its too hard and inefficient for me... I just build SSTO lifters. Its easy enough to build a SSTO spaceplane that can lift large payloads (my most recent was 83 tons) My "fully reusable Zero Debris" to duna missions involve: * Large spaceplane lifts an LV-N powered interplanetary transfer stage and a SSTO Duna lander. * Large spaceplane lands, Interplanetary stage goes to Duna * Lander + IP stage begins aerobraking as one unit * Lander separates and lands while, Interplanetary craft circularizes into low Duna orbit. * Lander launches, docks with IP stage, and refuels * Lander remains in orbit for future use, IP stage returns to kerbin * IP stage aerobrakes and circularizes. * Large Spaceplane refuels the interplanetary stage Everything is reusable, but trying to move them all together as one craft is... IMO wasteful and inefficient I could bring the Duna lander back with the IP stage.. but what is the point? Much more elegant IMO, to leave a fully fueled lander ready for use by the next mission (so the next mission can simply bring a fuel tank to set up a fuel depot, rather than another lander) For sure, I can get my spaceplanes to the mun, or to Duna... getting them back is another story... No spaceplane I send to laythe returns. Every SSTO lander I make, I leave in orbit (preferably fully fueled, or at least fuelled enough to de orbit and then get back to orbit) rather than carying it back (I'm assuming spaceplanes are the most mass efficient SSTOs for use on Laythe, I also like that they launch themselves, and I only need to launch additional fuel for them/something to push them to laythe [some have enough fuel left over to reach orbit from laythe's surface, and thus for a single mission just need a boost, not a refuel]) -
I'd also say it happens at engine cutoff, and ends upon reentry. I suppose for suborbital flights, it could possibly be more gradual, if the engine cuts off while there is still noticable atmospheric drag(of course this would result in going from positive Gs to slight negative Gs, and theb back to zero as the craft ascends through the atmophere and out into space) - but that wouldn't happen on an orbital flight, so engine cutoff would occur last.
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For sure, most of those hydrocarbons involved biological processes. Hence the key word "all". The question is if you can get relatively long chain hydrocarbons abiotically, and if any such abiotic hydrocarbons are still present on Earth. For example: http://www.osti.gov/scitech/biblio/7052010 There are abiotic hydrocarbons on Earth - in the specific case above, that abiotic methane is only 0.02%... but it is there. I will agree the consensus is that a biological origin is the predominant origin. But on a lifeless world, where the much faster biotic process is absent, could an abiotic process still produce significant amounts of high MW hydrocarbons? As I said, Titan may be a nice test case to see what sort of complexity you can get in hydrocarbons without biological processes. Of course, #1) It will be very hard to see anything that is not on the surface or just a short distance below it #2) Due to its lower mass, the pressures will not be as great #3) Its much lower temperatures will also affect this. #4) There's a chance that biological processes are at work on Titan, and that would be so cool that nobody should mind that our test case is inapplicable Yea, I was being too imprecise, I'm mainly just talking about generic "hydrocarbons" Well, I'm not sure why you mention this. #1, I didn't mean to imply that the microbes would be synthesizing compounds at the same place that the petrol is being formed. I shouldn't have specified deep underground at all - however, in the case of a "lush world" bs a world where the surface is sterile (as is likely the case on mars), you could have a deep biosphere responsible for the presence of the petrol, but the world would be far from "lush" #2, cyanobacteria, and not forrests may concentrate and synthesize the hydrocarbons - so accepting a biological origin, hydrocarbon deposits do not mean a world once covered in forrests, it could be "slime" covered. (again, a not so "lush" world) #3, the abiotic origin hypothesese have the petroleum form, then migrate upward, where bacteria then feed on it and alter it. Its then a question if the hydrocarbon originated from within the earth, or from buried biomass. No bacteria would be involved at the origin. Additionally: http://www.pnas.org/content/99/17/10976.full Clearly a) Abiotic hydrocarbons exist (Methane, Ethane, as on titan) At sufficient pressure, abiotic hydrocarbons can form alkanes up to at least decane, and also forms alkenes and various other variations. Evidence for a biological origin does not exclude a parallel abiotic process. The biological process may be much faster and dominate, and it may also "reprocess" the abiotically produced hydrocarbons, obscuring the origin. The biomarkers are clear, but abiotic origins are still plausible, and thus for the purposes of this discussion, if Eve had hydrocarbon lakes, we could not conclude a history of life (particularly given that Eve's gravity would result in even higher subsurface pressures)