Shadownailshot Posted August 31, 2012 Share Posted August 31, 2012 You realize to get to moho, if you go directly from a 200km parking orbit around Kerbin, you need ~12,500m/s ejection velocity out of kerbin's orbit? I wouldn't be worried about getting there unless you have an obscenely large rocket. Link to comment Share on other sites More sharing options...
SteevyT Posted August 31, 2012 Share Posted August 31, 2012 You realize to get to moho, if you go directly from a 200km parking orbit around Kerbin, you need ~12,500m/s ejection velocity out of kerbin's orbit? I wouldn't be worried about getting there unless you have an obscenely large rocket.Well, I push my current computer down to about 2 frames per second. And I'm building a computer many, many times more powerful than my current one soon, so I don't know what kind of monstrosities I'll be able to build then. Just as an example of some stuff I try to build and launch. Link to comment Share on other sites More sharing options...
Awaras Posted August 31, 2012 Share Posted August 31, 2012 You realize to get to moho, if you go directly from a 200km parking orbit around Kerbin, you need ~12,500m/s ejection velocity out of kerbin's orbit? I wouldn't be worried about getting there unless you have an obscenely large rocket.How do you mean 12500m/s? I think you would need a lot less than that... Link to comment Share on other sites More sharing options...
Shadownailshot Posted August 31, 2012 Share Posted August 31, 2012 Well, I push my current computer down to about 2 frames per second. And I'm building a computer many, many times more powerful than my current one soon, so I don't know what kind of monstrosities I'll be able to build then. Just as an example of some stuff I try to build and launch.My computer would fart, shart, and then explode if I were to build a single rocket capable of going to Moho. That rocket you're picturing would knock me down to about 1/2 or less frames per second. I want to build a new computer that makes my current one look as powerful as a pocket calculator, but that requires all of the money I don't have. Link to comment Share on other sites More sharing options...
olex Posted August 31, 2012 Share Posted August 31, 2012 How do you mean 12500m/s? I think you would need a lot less than that...Guessing the orbital altitude of Moho to be ~1Gm from Kerbol, my calculator (link in signature) puts the ejection velocity required for the Hohmann transfer to Moho at ~6600m/s from a 100km parking orbit around Kerbin. So not quite >12km/s, but still three times as fast as you would normally be going around Kerbin... that will require a really capable rocket. Link to comment Share on other sites More sharing options...
Awaras Posted August 31, 2012 Share Posted August 31, 2012 Guessing the orbital altitude of Moho to be ~1Gm from Kerbol, my calculator (link in signature) puts the ejection velocity required for the Hohmann transfer to Moho at ~6600m/s from a 100km parking orbit around Kerbin. So not quite >12km/s, but still three times as fast as you would normally be going around Kerbin... that will require a really capable rocket.Yeah, 6600m/s sounds a lot more reasonable... I have been testing possible designs for 0.17 and have been able to send ships into circular orbits less than half that of Kerbin (and also 2-3 times larger than Kerbin's), so it is doable. Link to comment Share on other sites More sharing options...
Shadownailshot Posted August 31, 2012 Share Posted August 31, 2012 Ohhh I was thinking the other way around. Link to comment Share on other sites More sharing options...
MrMoog Posted August 31, 2012 Share Posted August 31, 2012 Guessing the orbital altitude of Moho to be ~1Gm from Kerbol, my calculator (link in signature) puts the ejection velocity required for the Hohmann transfer to Moho at ~6600m/s from a 100km parking orbit around Kerbin. So not quite >12km/s, but still three times as fast as you would normally be going around Kerbin... that will require a really capable rocket.I still think there may be something off with the delta-v calculation in your calculator. It says that you need > 50 000m/s delta-v to get to Jool.I don't know what distance you used but I did some inter-planetary testing of my own and from a 100km Kerbin orbit, I was able to reach a "planet" that is 3 times further than Kerbin, 40.5Gm away, with something like 3-4000 m/s delta-v. 50 000 seems too much, considering that your speed stays between 2000 around Kerbin, to 9 500 m/s around Kerbol. Link to comment Share on other sites More sharing options...
Shadownailshot Posted August 31, 2012 Share Posted August 31, 2012 I still think there may be something off with the delta-v calculation in your calculator. It says that you need > 50 000m/s delta-v to get to Jool.I don't know what distance you used but I did some inter-planetary testing of my own and from a 100km Kerbin orbit, I was able to reach a "planet" that is 3 times further than Kerbin, 40.5Gm away, with something like 3-4000 m/s delta-v. 50 000 seems too much, considering that your speed stays between 2000 around Kerbin, to 9 500 m/s around Kerbol.Where does it say that? Even from Moho to Jool it only says ~13,500m/s ejection velocity. I don't see what you're talking about.If you're going from Jool to Kerbin it says you need 50,000 m/s ejection velocity, which you can probably obtain using gravity slingshots off of the moons and Jool, which would greatly reduce the amount of dv necessary for the ejection velocity. I'm still not sure how to calculate dv, but I don't really care either, because I can usually eye it out, and I usually add more fuel than necessary and reach my destination with leftovers. Link to comment Share on other sites More sharing options...
MrMoog Posted August 31, 2012 Share Posted August 31, 2012 (edited) Where does it say that? Even from Moho to Jool it only says ~13,500m/s ejection velocity. I don't see what you're talking about.If you're going from Jool to Kerbin it says you need 50,000 m/s ejection velocity, which you can probably obtain using gravity slingshots off of the moons and Jool, which would greatly reduce the amount of dv necessary for the ejection velocity. I'm still not sure how to calculate dv, but I don't really care either, because I can usually eye it out, and I usually add more fuel than necessary and reach my destination with leftovers.Wow, my bad. I was looking at Jool -> Kerbin, and not Kerbin -> Jool, which is makes more sense at ~3700m/s. The travel back from Jool will be quite a challenge though! By the way, it's a very nifty tool you've made there. It will be very useful to optimize our travels, and to get from Gilly to Laythe in one burn!EDIT: It's a good idea to have some fuel left, because you still need to circularize the orbit when you reach the planet, except if you plan a direct landing, which might be very risk... I mean very kerbal! Edited August 31, 2012 by MrMoog Link to comment Share on other sites More sharing options...
Shadownailshot Posted August 31, 2012 Share Posted August 31, 2012 Wow, my bad. I was looking at Jool -> Kerbin, and not Kerbin -> Jool, which is makes more sense at ~3700m/s. The travel back from Jool will be quite a challenge though! By the way, it's a very nifty tool you've made there. It will be very usefull to optimize our travels, and to get from Gilly to Laythe in one burn!Unfortunately the calculator is not yet set up for that, nor do I think KSP has advanced enough navigation systems for that. I would have said "well the nav systems are great," before (don't get me wrong, I love the conics system and I think it's genius and a beauty), but after playing orbiter (I just got it) I realize that there are quite a few tools that KSP is lacking, although I don't think it should have them. In some cases they can make gameplay harder. Also, it wouldn't be very Kerbal to use an advanced nav computer, now would it? If I can see it, I can fly to it! How that tickle your fuzzy green dude? Link to comment Share on other sites More sharing options...
MedwedianPresident Posted August 31, 2012 Share Posted August 31, 2012 About maths, 99.9999999% of all KSP Players use MechJeb. Link to comment Share on other sites More sharing options...
dragonfree97 Posted August 31, 2012 Share Posted August 31, 2012 About maths, 99.9999999% of all KSP Players use MechJeb.Maths fact of the day: Approximately 57% of statistics are made up on the spot. Link to comment Share on other sites More sharing options...
Shadownailshot Posted August 31, 2012 Share Posted August 31, 2012 About maths, 99.9999999% of all KSP Players use MechJeb.I'm one of the 00.0000001% then I guess. Link to comment Share on other sites More sharing options...
SLAMS Posted August 31, 2012 Share Posted August 31, 2012 <- All Manual pilot, whats the fun if you can't attempt to fly your wacky creations yourself.Interplanetary stuff is going to be difficult(harder than mun/minimus), but its supposed to be hard. Kinda like endgame for KSP.I understand why some people use mechjeb but with a little practice(less than you think) you can out perform it on your own and the achievement will be that much sweeter. Link to comment Share on other sites More sharing options...
SLAMS Posted August 31, 2012 Share Posted August 31, 2012 Can mechjeb perform a pin point rendezvous? Last I knew it could only get you in the relative area. Those of you who go on about (you know what) won't be able to do it at all if you can't pilot without mechjeb... Link to comment Share on other sites More sharing options...
thorfinn Posted August 31, 2012 Share Posted August 31, 2012 (edited) Wow, my bad. I was looking at Jool -> Kerbin, and not Kerbin -> Jool, which is makes more sense at ~3700m/s. The travel back from Jool will be quite a challenge though! The calculator wants to compute the total delta-V needed, including what is needed to escape the gravity well. If you don't change the default settings, it computes that escape velocity from an impossible 100km orbit of Jool (Impossible because the "surface" of Jool will be defined as the 1-atmosphere isobar, or maybe even a higher pressure: 100 km higher will still be deep in the atmosphere). Orbiting tightly around a gas giant means being at the bottom of a very tall gravity well.Also, the calculator operates under the assumption that Jool will have 1841 times the mass of Kerbin, which is almost certainly an overestimate: Jupiter is ~317 Earth masses, as a comparison.Inputting a higher orbit gives more sensible results, even though there is a bug somewhere because the ejection angle goes NaN. Edited August 31, 2012 by thorfinn Link to comment Share on other sites More sharing options...
MrMoog Posted August 31, 2012 Share Posted August 31, 2012 I did the other way around. I started all manual to get a hold of the game mechanics, and then installed MechJeb to simplify some repetitive and basic functions, allowing me to build more complex ships with more complex flight plans.Also, the auto-ascent is a must for rockets that get my CPU down to <1 fps on lift off. And I could not live without the information panels anymore.Some people see MechJeb as an easy button for beginners, I see it as an advanced tool for more complex missions. Link to comment Share on other sites More sharing options...
Artlav Posted August 31, 2012 Share Posted August 31, 2012 About maths, 99.9999999% of all KSP Players use MechJeb.You need 1000000000 KSP players to claim such accuracy.Concerning MechJeb, i find even regular SAS/ASAS/avionics a useless waste of mass that sucks the fun out of the flight. Link to comment Share on other sites More sharing options...
MrMoog Posted August 31, 2012 Share Posted August 31, 2012 If you don't change the default settings, it computes that escape velocity from an impossible 100km orbit of Jool (Impossible because the "surface" of Jool will be defined as the 1-atmosphere isobar, or maybe even a higher pressure: 100 km higher will still be deep in the atmosphere).It's 100km above the surface, like mentioned on the tool. Even if you enter 0km, it's still only on the surface. Link to comment Share on other sites More sharing options...
Atimed Posted August 31, 2012 Share Posted August 31, 2012 About maths, 99.9999999% of all KSP Players use MechJeb.You need to get your facts straight, max 60% of all Players use MechJeb..Some (like me) have it just to get some mods up and running..Others use it just for practicality.. Orbital Stats, PE, AP..They might have it but they don't exploit it's autopilot..With minimal effort you can fly more efficient than it.. Link to comment Share on other sites More sharing options...
maltesh Posted August 31, 2012 Share Posted August 31, 2012 Where does it say that? Even from Moho to Jool it only says ~13,500m/s ejection velocity. I don't see what you're talking about.If you're going from Jool to Kerbin it says you need 50,000 m/s ejection velocity, which you can probably obtain using gravity slingshots off of the moons and Jool, which would greatly reduce the amount of dv necessary for the ejection velocity. I'm still not sure how to calculate dv, but I don't really care either, because I can usually eye it out, and I usually add more fuel than necessary and reach my destination with leftovers.50 km/s? No, you probably can't get that much off gravitational slingshots of the moons.Among other things, you'll have to be able to produce a good fraction of that to /reach/ them from your starting point at a 200km altitude circular orbit above the gas giant, and its moons are not going to be massive enough, or moving fast enough to give you much more than a tiny boost.You cannot use an unpowered gravitational slingshot around Jool to gain velocity relative to Jool. If you want to do a powered gravitational slignshot past Jool... that's what you're already doing by directly burning into the 50 km/s hyperbola from your 200 km altitude circular orbit.I suppose the real question is "Why are you in a circular orbit that close to the gas giant without bringing enough fuel, if you planned to return?" Link to comment Share on other sites More sharing options...
olex Posted August 31, 2012 Share Posted August 31, 2012 (edited) Please be aware when using the calculator, that all values for 0.17 planets (except names) are completely and utterly guessed, especially the gravity and SoI data. For all I know, the values I put in for Jool can be orders of magnitude off the ones that 0.17 will use. So in no way should the results of those calculations be used as estimates for now.The only values that are definitely close to the "real" ones are the results for going from Kerbin to the other planets, assuming Kerbin's parameters stay unchanged. The reason is, those calculations only need the orbital radius of the target body, and those radii are definitely estimated closer to their final values than the "internal" parameters of the new bodies. The escape velocities from the new planets can be and most probably are way off.I will update the calculator with correct data for 0.17 planets as soon as it's available. I also welcome bug reports and feature requests in the calculator thread at any time. Edited August 31, 2012 by olex Link to comment Share on other sites More sharing options...
Bekiekutmoar Posted August 31, 2012 Share Posted August 31, 2012 Nah, I'll just do bi-elleptic transfer to reach Moho; less fuel required ... ! Link to comment Share on other sites More sharing options...
maltesh Posted August 31, 2012 Share Posted August 31, 2012 Ah, fair enough. My apologies. Link to comment Share on other sites More sharing options...
Recommended Posts