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Does anyone know why Mechjeb would decide to stop displaying Delta-V in VAB? A screen shot for if it would help: 
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Apr 21, 2014 18:05
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I remember one Moho return mission being characterized by not having enough fuel to get to Kerbin, but juuuuuust enough to get into an Eve orbit. Cue refueling tanker sent to Eve.
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Apr 21, 2014 18:49
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I've been to Moho twice. Once with a small unmanned rover that used asparagus nukes for a one-way trip. Once with a gigantic manned monstrosity that was able to successfully enter orbit but ran out of fuel on the way back after changing my inclination to Kerbin's and needed a resupply.
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Apr 21, 2014 18:58
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MohawkSatan posted:Does anyone know why Mechjeb would decide to stop displaying Delta-V in VAB? I had this problem - downloaded the latest build of mechjeb and it fixed it. Seemed to be related to the parts added by the latest update (the NASA boosters and whatnots)
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Apr 21, 2014 19:12
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I'm having issues with Kerbal Alarm Clock. I downloaded it today to try it out, and it was working fine for the first 10 minutes or so. Then it abruptly stopped responding. I can still click all the buttons on the UI, they just don't do anything. Is there some known issue here I should be aware of?
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Apr 21, 2014 19:36
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Use Eve to help. If you can handle the finicky nature of gravity assists.
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Apr 21, 2014 20:42
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Thwomp posted:Since no one has replied yet, I will! Thanks. Just to be clear, I can and already did go to Moho (F5'd at LKO at the correct - according to Protractor - phase angle so I can do some "simulations" before committing) in my giant 15km/s rocket; the problem is that I dislike wasteful maneuvers and orbiting the sun for a year until maybe you get an encounter but somewhere you messed up and now you have to kill 10km/s. When maneuvering I aim for elegance and economy, which means an encounter straight from LKO or using other bodies to assist in the journey. But is a Moho encounter from LKO even possible? And how do you plan for gravity assists? Who the hell knows! The game offers no help whatsoever in the matter, while actually making things more frustrating with its terrible maneuvering system.
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Apr 21, 2014 21:04
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Protractor states up front that it'll only get you part of the way, even with "easy" planets like Duna and Eve. It's even more of a guess with Moho or really any body that has an inclination. It's almost a given that you'll end up doing some kind of correction burn(s) on your way to these locations. Even NASA's probes make course corrections while enroute. It's just part of space travel. You'll never be so perfect as to burn just the right amount at just the right time while also countering for fuel expended and your starting inclination.
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Apr 21, 2014 21:09
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seravid posted:But is a Moho encounter from LKO even possible? Sure, if you launch at the right time to arrive at Moho while it's crossing Kerbin's plane.
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Apr 21, 2014 21:12
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Thwomp posted:Protractor states up front that it'll only get you part of the way, even with "easy" planets like Duna and Eve. I meant I wanted to avoid major on-the-fly maneuvers. I have nothing against correction burns, of course. haveblue posted:Sure, if you launch at the right time to arrive at Moho while it's crossing Kerbin's plane. And when's that? 
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Apr 21, 2014 21:42
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seravid posted:And when's that? Ask Protractor
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Apr 21, 2014 21:48
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seravid posted:I meant I wanted to avoid major on-the-fly maneuvers. I have nothing against correction burns, of course. At the Kerbin/Moho ascending/descending nodes (you can figure this out visually; it's where the orbits cross if you're looking at both of them edge-on). You can use this planner to look for low delta-v transfer windows that account for inclination: http://alexmoon.github.io/ksp/ As for gravity assists, don't bother. As far as I know, there aren't even planners that make that easy. haveblue posted:Ask Protractor Does Protractor account for inclinations? I didn't think it did.
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Apr 21, 2014 21:57
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There is a slingshot planner but it uses loving Matlab
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Apr 21, 2014 22:04
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I really want to have a list of days and which planet you can intercept. I am playing stock and really I don't want to put a protractor to my screen 
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Apr 21, 2014 22:12
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Axe-man posted:I really want to have a list of days and which planet you can intercept. I am playing stock and really I don't want to put a protractor to my screen Don't know a list of days, but there are web tools you can play with: http://alexmoon.github.io/ksp/ http://ksp.olex.biz/ First one calculates optimal launch windows for each body in the game, letting you start from a specific in-game date. The graph indicates how many days into the future the best window is (the dark blue blob). The second is somewhat similar, but diagrams the phase angles and ejection angle. You can bring up the system map and just kind of eyeball it to get close.
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Apr 21, 2014 22:18
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I don't even bother worrying about launch windows anymore. Everything is going to take hundreds of days anyway, and at present fuel efficiency is only a minor concern (unlimited resources means as much fuel as I can manage to put up there). Pop into a 500k+ orbit, figure out whether you need to eject on the day or night side, and the rest is just manipulating your maneuver node until you hit the planet you want. Maybe once career mode has more structure and I have to worry about limited resources, but until then I just wing it.
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Apr 21, 2014 22:25
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zxqv8 posted:I don't even bother worrying about launch windows anymore. Everything is going to take hundreds of days anyway, and at present fuel efficiency is only a minor concern (unlimited resources means as much fuel as I can manage to put up there). Pop into a 500k+ orbit, figure out whether you need to eject on the day or night side, and the rest is just manipulating your maneuver node until you hit the planet you want. It just comes into effect when I build an awesome eve lander and can't work a landing so I biome hunt the mun or minimus and I have this awesomely designed thing for it that just doesn't work cause of that. I need a eve land and return craft too :o!
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Apr 21, 2014 22:38
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Hey so I am very confused - apparently Kerbin has 9.81m/s/s surface gravity, same as earth. So why does it only take ~4500dV to orbit (vs RSS Earth and also real-life's ~9000dV)?? Is it just the larger radius means you need a larger orbit? Raising your orbit though shouldn't ever take more than I dunno 800dV to get it all the way to the bloody moon though, so what the hell is going on? Just when I think I "get" orbital mechanics I find something to make me feel stupid again...
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Apr 21, 2014 23:04
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Also apparently the real engines do not actually have much higher Isp than stock? I thought KSP Isps were lower to balance out the smaller gravity well?
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Apr 21, 2014 23:07
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Mr. Wynand posted:Hey so I am very confused - apparently Kerbin has 9.81m/s/s surface gravity, same as earth. So why does it only take ~4500dV to orbit (vs RSS Earth and also real-life's ~9000dV)?? Is it just the larger radius means you need a larger orbit? Raising your orbit though shouldn't ever take more than I dunno 800dV to get it all the way to the bloody moon though, so what the hell is going on? More or less, yes. If Kerbin had a similar atomosphere to Earth, you'd need less, actually. But its so thick in the troposphere-equivalent that it pads it out some. Everything in the Kerbol system is scaled down from the Solar System to both simplify and make things more fun.
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Apr 21, 2014 23:07
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OAquinas posted:More or less, yes. If Kerbin had a similar atomosphere to Earth, you'd need less, actually. But its so thick in the troposphere-equivalent that it pads it out some. Ok but... if I took off from stock Kerbin and then went into an orbit that had the same radius (from the centre) as an orbit 100km above the surface of RSS Earth - are you saying it would take the same amount of dV? Because again, I could have sworn you can get into munar orbits for well below 1600 dV on top of LKO, which is surely way farther out then KSS Earth's LEO. This doesn't make sense to me. Even the atmosphere is (mostly) the same height, so it's not even that you have to burn against drag for longer...
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Apr 21, 2014 23:20
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Mr. Wynand posted:Ok but... if I took off from stock Kerbin and then went into an orbit that had the same radius (from the centre) as an orbit 100km above the surface of RSS Earth - are you saying it would take the same amount of dV? Because again, I could have sworn you can get into munar orbits for well below 1600 dV on top of LKO, which is surely way farther out then KSS Earth's LEO. This doesn't make sense to me. Even the atmosphere is (mostly) the same height, so it's not even that you have to burn against drag for longer... It's all about energy. The force of gravity at a given height is GMm/(r^2), which leads to everything in orbital mechanics. Kerbin has much less mass than the earth, but a much smaller radius, such that M(kerbin)/(distance from center of kerbin to surface)^2 = M(Earth)/(r of earth)^2. Now, the potential energy, is -GMm/r. That's how much energy it would take to place it there, starting an infinite distance away. Gravity is always attractive, hence the negative sign. The altitude of 100km above Kerbin has r = 700km, compared to 100 km above Earth being about 6470 km. That's a huge, nearly 20% change in R for kerbin, but a less than 2% change in R for earth.Kinetic energy is 1/2 m v^2, and crossing out all the little m's (the mass of your space ship), and equating the changes in energy, you get change in PE = GM/R1-GM/R2 = negative of the change in KE = 1/2 v2^2 -1/2 v1^2. All this means is that the gravitational acceleration on a body decreases much more rapidly with altitude on Kerbin than on Earth, since the actual height above gravitational center is what matters, not height above surface. For example, to halve the force of gravity (local g = 4.9m/s^2), you'd need an altitude of about 248km above Kerbin, about 2638 km above Earth. Unreal_One fucked around with this message at 23:50 on Apr 21, 2014 |
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Apr 21, 2014 23:29
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Ohhhh wait wait so... Kebin and Earth may have the same surface gravity, but since gravity drops off by the inverse square of distance, having the same surface gravity when that surface is at a radius ... checking on wikipedia... oh wow ~5700km (!!) higher means... well a whole a hell of a lot more mass to start with, and you still feel most of it at LEO (compared to barely any of it at LKO +5700km).... Allllrighty I think I get it now. Thank you for help!
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Apr 21, 2014 23:46
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Aaaand looks like the heavy-lift 1st stage engines are actually rather underpowered in stock KSP.
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Apr 21, 2014 23:48
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Fil5000 posted:I had this problem - downloaded the latest build of mechjeb and it fixed it. Seemed to be related to the parts added by the latest update (the NASA boosters and whatnots) There was also a bug where it would not consider stages above the current root node. I don't know if that one has been fixed yet.
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Apr 22, 2014 00:02
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Thwomp posted:Moho is a bitch for the opposite reasons Eve is: low gravity, no atmosphere, and you'll almost always have a high velocity coming in and you've got to nearly kill all of it. Perhaps you should be able to research an anchor. Attach it to one end of the spacecraft, go EVA, throw the anchor towards the planet, have it dig in and slowly dig a trench around the planet to slow the ship.
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Apr 22, 2014 00:44
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zxqv8 posted:I don't even bother worrying about launch windows anymore. Everything is going to take hundreds of days anyway, and at present fuel efficiency is only a minor concern (unlimited resources means as much fuel as I can manage to put up there). Pop into a 500k+ orbit, figure out whether you need to eject on the day or night side, and the rest is just manipulating your maneuver node until you hit the planet you want. I still do, because when going to Jool or Eeloo a Hohmann it's going to take you three to four times as long to get there as the maximum wait for the next window. That, and I can't resist going after the second Kerbal-Alarm-Clock (Model, not Formula) window for Dres after a new Game. It's just so bloody perfect. Dres is just about passing through Kerbin's orbital plane on arrival, so mid-course corrections can be /tiny/. I threw something like ten craft through that window on my Current save, and the largest mid-course correction any of them had to do was ~30 m/s. No matching planes en-route, just pack that all into your capture burn (Which was about 1500m/s, all told) And the return window's in about ten days after your arrival. Duna and Eve are another matter,as their windows are the most infrequent but if you're throwing things to outer planets to begin with, and have Kerbal Alarm Clock to remind you, you'll hit a few on the way out. The first Duna window happens at about day 50-60, by the time that spacecraft reaches Duna, you're a little ways off from the first Eve Window, and when that spacecraft gets there, you're maybe a month or two out from the aforementioned Perfect Dres Window. But then, as is pretty obvious from the above, Kerbal Alarm Clock has pretty much anchored my playstyle since 0.18.
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Apr 22, 2014 00:47
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OwlFancier posted:Perhaps you should be able to research an anchor. Attach it to one end of the spacecraft, go EVA, throw the anchor towards the planet, have it dig in and slowly dig a trench around the planet to slow the ship. Picturing the death and destruction from such a system being used on earth is a funny mental picture.
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Apr 22, 2014 00:50
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Maxmaps posted:Picturing the death and destruction from such a system being used on earth is a funny mental picture. I'm imagining someone fine-tuning an orbit to be less than 100 meters above Moho or Dres that they can drop a winch line with KAS into the ground, then the winch catches on something and either the cable breaks, or fun physics happen and there's tons of kerbonaut and spacecraft debris in an impact crater.
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Apr 22, 2014 01:01
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maltesh posted:I still do, because when going to Jool or Eeloo a Hohmann it's going to take you three to four times as long to get there as the maximum wait for the next window. Well, you can plainly tell from my post that I don't bother with the math much  I hadn't paid near enough attention to how the windows line up, because you describe a pretty cool setup for some nifty flight plans.But as for the quote in bold, I am with you entirely. I don't even want to play without it if I can avoid it. Please get it or something similar added as part of the game's basic features, Max!
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Apr 22, 2014 01:01
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Unfortunately any such anchor would probably never make it to the lithosphere, it'd burn up in the atmosphere first.  So I say we try it on the moon instead.
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Apr 22, 2014 01:03
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Maxmaps posted:Picturing the death and destruction from such a system being used on earth is a funny mental picture.  gives no shits.
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Apr 22, 2014 01:05
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Maybe some form of practical lithobreaking could be achieved by slamming something very dense and heavy into your target planetoid at interplanetary transfer velocity ahead of your probe. The impact may kick up a "dinosaur-killer" amount of dust and hey maybe the heat would even boil away some of the local dirt, and bam, you got yourself an atmosphere to get captured in.
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Apr 22, 2014 01:22
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Maxmaps posted:Picturing the death and destruction from such a system being used on earth is a funny mental picture. Confirmed for .24
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Apr 22, 2014 01:22
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Mr. Wynand posted:Maybe some form of practical lithobreaking could be achieved by slamming something very dense and heavy into your target planetoid at interplanetary transfer velocity ahead of your probe. The impact may kick up a "dinosaur-killer" amount of dust and hey maybe the heat would even boil away some of the local dirt, and bam, you got yourself an atmosphere to get captured in. While I admire the sheer of this idea, I'm not sure atmospheres work that way.
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Apr 22, 2014 01:31
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Acquire Currency! posted:Confirmed for .24 Haha, nah, clock's ticking on .24, no time for more features.
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Apr 22, 2014 01:47
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zxqv8 posted:While I admire the sheer Well an atmosphere is just a bunch of gas right, and hard things + heat = a liquid of sorts, and liquid + heat = gas, and orbital velocity + hard things = a very respectable pressure wave + lots and lots of heat... sooo I don't see the problem here.
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Apr 22, 2014 01:52
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It's certainly lithobreaking, but I don't think it would be lithobraking.
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Apr 22, 2014 01:59
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Maxmaps posted:Haha, nah, clock's ticking on .24, no time for more features. .24 confirmed forrrrr tomorrow.
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Apr 22, 2014 02:04
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Acquire Currency! posted:.24 confirmed forrrrr tomorrow. Nah, just not too far. And hey, this time we have full control of everything related to development. 
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Apr 22, 2014 02:11
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