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Hey there! So I bought the DLC and apart from all of the other bugs and issues mentioned in many other threads, I have come to notice something: I'm not actually having any fun playing the Stock missions, and generally the stock game. I would dare to call myself a KSP veteran, having started out a few years back. Building rockets that can go to the place you want to go is quite a hit and miss, until you discover the concept of Delta-V and TWR. After my discovery, I started calculating them with pen, paper and a calculator. Then I switched to Excel, but that still got tedious real fast. Luckily I discovered MechJeb (and later KER) that calculated the TWR and the stages for me. I got used to them, and building rockets became second nature to me. When Making History was released, I thought to myself: "OK, let's play these missions as they were intended: with just the Stock game, no mods". I finally got to the third part of the mission (building Jebnik 1), and I come to realize: Wait, how the hell am I supposed to know if this is going to space or not??? I don't have a dV readout, I can't even do trial and error, because there is no Revert to VAB after I've launched the thing. My options are: Build the most "Kerbal Rocket" and create a giant behemoth that by my *guess* will probably make it to space Do trial and error by cheating Get it right by copying an existing design from the forum Go back to my days of calculator usage, calculate the dV of 3 stages by hand None of these is fun for me. Option 1) just isn't my style, and it's not even a guarantee that it will work. Option 2) feels cheaty, and also doesn't work very well. 3) is plain lame, and I'm just too old to do 4), I have moved past this years ago, and it's way too much work for a game meant for recreation. So what now? I'm usually a critic of statements like "this mod should be stock", but I'm coming to realize that the game really, really needs a Delta-V and TWR readout. What are your thoughts about this? How do you deal with building rockets without KER/MechJeb? ps.: inb4 "Just install KER/MechJeb": I know I can do that, and probably will. But in this thread I want to talk about the *Stock* experience that the game provides and that the developers intended.

I have this monstrosity I've constructed a couple of times now. First by four Kerbal-X rocket launches, and later by three cargo SSTO trips. Since this first iteration, I've removed the Mk1 inline cockpit and added three more Liquid Fuel tanks. I also removed a little bit of mass here and there, used smaller parts where I could, and lightened the load as much as I could while still being reasonably comfortable to a six-kerbal crew. Aside from KER, I have DMagic's EVA Struts in use. If I just cheat this monster into orbit, I get slightly more than 3500 m/s according to KER's estimate. Enough for Duna and back. If I launch it as intended, the first module containing the Mk1 crew cabin and engines will have in excess of 7200 m/s. But then I start piling on modules, and the estimated delta-v doesn't seem to change once it's fully assembled. I have one of these out at Duna in a career play-through that has slightly less than half of its fuel, and has landed the rover package on Duna's surface. Yet KER thinks I still have 3700 m/s. First off, the Iktomi II, in Duna orbit, has 257 parts, 56.57 tonnes, and 1866 / 4800 Liquid Fuel. This is the ship that already dropped off its rover kit. Supposedly I have over 3700 m/s. Assuming one unit LF = 5 kg, that's 9.330 t fuel, making dry mass 47.34 t and dV = 1397 m/s. Enough to get home, barely, if I'm careful with Ike and Mun assists, or I could dump a lot of hardware first. Second, the Defrahnz, in Kerbin orbit, is prepared for departure to Eve. This has 306 parts, 75.92 tonnes, and is fully fueled at 4800 / 4800 Liquid Fuel. Supposedly I have just over 7400 m/s, but in reality with 24 t fuel I have only 2980 m/s. At least this craft could reach Gilly and land on RCS alone, and refuel. Is KER not taking into account the added mass of modules as I assemble this thing? Have I missed a setting somewhere?

For just about every journeys there are questions that need to be made. Just about all of us have taken off from Kerbin with 10k dV in the Moho's orbital direction and finding out, when we go close to Moho that we did not have enough fuel left to circularize (or some other nice oversight like pointing the solar panel in the direction of the sun for 6 months). Can we sit down with a spreadsheet and make decisions that factor the choices that are presented. I decided to basically write these posts because of the eccentricity thread in order to illustrate what the real value of eccentricity is when all is said and done. To make the answer short, energy is much more important, but eccentricity gives us on the fly information. For example if you are circularizing from an eccentric orbit close to Pe or Apo (whichever is the burn point) and your delta-e/t is too low compared to time to pe/apo, this informs you that you need to increase thrust or should have carried a more powerful engine. Another situation is during reentry from distal targets, the delta-e/t tells you how rapidly or effective your entry-theta was. If your ship is overheating and your e is not likely to approach zero at some point during reentry then you probably should have used a bigger shield(or kept some retro fuel) and choosen a steeper entry angle (lower no-ATM Pe). The eccentricity argument has an effective range of 0.0005 to 1.0000 below or above which are meaningless in the game. In this case an eccentricty of 0.5 = 0.4995 to 0.5005. This differs from other stats such as dV which are accurate over a 100,000 fold range in the game, altitudes are accurate to >10 decimal places. IOW, the values used to derive e are much more precise than e itself. Does it make a difference, yes and no, theoretically if you had a TWR = infinity, an exactly angle to prograde for a perfect burn (with perfect thruster control) there is no wasted dV and you end up intersecting the minimum orbit of the target planet. In reality the dV calculated at best puts the craft in a range were RCS thrusters in the departure orbit can be used to get within about 5000 meters of the perfect arrival orbit (on a good day). However knowing energy makes some logical sense of what is going on, for example by the Oberth effect works, why burn from low orbit, why use kicks on lowTWR craft in low orbits (versus spiralling away from the celestial). When we are using e for on-the-fly decision making accuracy is not really an issue, however in the formulation of travel strategies we do want to use as accurate as possible starting information. So what about everything else? The procedure is this. Step one. For a target planet orbital ap _and_ pe (meaning two parallel analyses), assign a departure and arrival altitudes relative to kerbol, transform to radius, derive a. Step two. Assign u/a (Escape energy) and u/2a (SKE at a) Step three. Assign SPE changes from kerbin-to-a and from a-to-target. Step four. Assign deltaSPE changes (changes in Kinetic energy) from a to kerbin or target. Step five. Calculate SKE at kerbin or target. Step six. determine dV required to achieve kerbin or target orbits without entering kerbin or targets SOI. Step seven. determine the SKE at planets SOI entry or exit based on step six. Step eight. Add this to planets minimum orbit radius escape energy, this give energy to reach minimum orbit around the planet and free fall to planet. Step nine. Convert this to dV required to free fall from minimum stable orbit Step ten. Subtract the circular orbital velocity from freefall at minimum orbit dV requirement. Step eleven. Add the two dV (kerbin and target planet) together and get total dV. At 6 specific points in the 11 step process unique energy parameters were used to derive decision making information. The table below compares the Total dV (m/s) cost of intersecting orbits (values rounded for clarity) and also compares to inclination dV performed in circumkerbol orbit. Planet Target Intrcpt δV inclination at Apo at Pe dV at a Moho 4724 4001 723.1 1818 (Depart from Kerbin at the Kerbin-Moho inclination node closest to Moho's Apo, inclination nodes are priorities) Eve 2911 2913 002 400 (Eve's orbital inclination nodes are priority) Duna 1928 3009 1081 78 (Depart from Kerbin close to Duna's Pe) Dres 2819 4837 2081 466 (Depart from kerbin closest to Dres's Pe, inclination nodes should be also considered) Jool 5202 5686 484.0 79 (more analysis of satellites requires) Eeloo 3416 3449 32.7 386 (Eeloo's orbital inclination nodes are the priority). As we can see above the analysis is devoid of any consideration of the e parameter, although it is easily obtained from the information we have. How can we get those pesky inclination nodes. One way is to place a satellite in a Kerbinesce orbit at theta = 2/3 pi and 4/3 pi relative to kerbin (in the same orbit as Kerbin but at maximum distance. Then target a planet, the nodes will show up also relative to kerbin. Such satellites can have a dual function since one can also place a deep space array on the satellite. That allows communication to objects that current orbit is on the other side of Kerbol. [Another set of energy and dV calculations that involve the equation The square of the orbital period of a planet is proportional to the cube of the semi-major axis of its orbit. in which we create an orbit a which is 2/3 or 4/3 the period of kerbin by generating a periapsis or apoapsis (respectively) whose average with kerbin orbit gives us a]. Disclaimers. Above assumes two sets of reciprocal process, launch/ascent & descent/land and transfer commence and complete that have a boundary at the minimum stable orbit of both planets. 1. There is a simpler mechanic, single step "star trek" mechanic, in which your ship has so much power that you travel from departure x,y,z, vx, vy, vz to arrival x, y, z, vx, vy, vz before either of which have significantly changed position (arrival point and departure points are oriented to each other). Given that human life could never survive the dV/dt and the dV & TWR required do not exist this scenario can be disregarded and physically impossible and should not be considered. Deep space probes such as New Horizons need not depart into a circular orbit. That if they reach an angle to prograde of theta>090' while still in upper atmosphere while at the same time burning the dV required for a highly eccentric orbit does not require circularization and may use less dV. In such a burn the base assumption is that the best delta-SKE on hill sphere exit is obtained from the lowest altitude burn even if that burn starts at a suborbital trajectory with pe always below safe circular orbit altitude. To convert this to KSP the ascent angle is say inclination is at >15' and you are at alt=45 you simply can burn to Eeloo Apo intersect as you are crossing some theta~90 and have a large plume of overheated gas momentarily burning through the fairings before they are deployed. 2. KSP provides perfect examples, kerbin is in a zero inclination, zero eccentricity orbit about kerbol and as it so happens it common departure planet or arrival planet for most of the transfers. The argument of periapsis differs for all other planets so you are not going to be able to match a Apo/Pe angle of a planetary departure with 180 degree Pe/Apo of a planetary arrival except from Kerbin because kerbins orbit a=Pe=Apo. This has some relevance for the Eeloo, Jool transfer which is damn cheap relative to traveling back to kerbin and traveling to Jool (given some dV spent on plane matching). 3. The smallest-sweep area stable orbit about a planet may be unpreferential. Jool being the example. This infers there is complex decision making involved in getting to a system moon in which the planet is not the target. mechanical thermodynamics can be used to burn less than the amount needed to circularize at the planets rMin, that dV would be used to circularize at an apo that intersects the moons orbit. In the case of Jool, all three inner planets have a=pe=apo, so this is not too much of a problem. In these instances you want to compare intersecting the moons orbit directly (using a different planetary Rx,orbit) versus a hohmann transfer to 200k Jool-altitude and a partial circularization burn to intersect the target orbit and circularize. 4. If we make the assumption that inclination nodes are approximate to r = a (semi-major axis), that the dV required for inclination burn (see table) is low enough not to be a priority. In these cases we can, if we desire burn at a bearing above or below the departure planets equitorial plane on depart to send the inclination node to r = a and get rid of some inclination. In comparing the table below the difference between an Kerbin-Moho transfer Pe-target and Apo-target is delta-dV = 724 but the inclination change dV averages at 1814. Therefore its simply intelligent to set a priority on changing planes over departing theta = Moho's apo theta (fortunately Moho-apo is relatively close to the inclination node). The cost of changing inclination at kerbol is reduced by 100s of dV. The same logic is also true for Eve, and Eeloo. For the other planets a departure window closest to the target planets periapsis is a better choice than choosing a departure window closest to an inclination node. 5. Entry burns particularly on planets like Jool need transfers that seldomly overlap with their pe or Apo, consequently there is a triangulation between time to get good window for efficient inclination change, or close to Jool theta. In other instances like Moho, which is so small oberth effect is minimal, free burn times at pe near a kerbin inclination node is going to occur separately than the moho circularization burn. 6. Depending of kerbol relative altitude of the target the true burn altitude is different from the planets altitude. Our burn starts 670,000 meters closer but a maximum efficiency burns leaves kerbin's SOI at the moment of crafts circumkerbol Apo or Pe (depending on an interior or exterior target). We always want the exit trajectory to be parallel to kerbins path of travel even if the line is not identical with Kerbin, otherwise predicting intercept could be off and correcting dV would be required. This occurs both on kerbin exit and on target arrival. For example a the flat part of the escape curve to moho should generally be at a final angle to prograde ever so slightly more than 180 at kerbin SOI otherwise the Apo for the circumkerbol orbit will occur in the future. This means that the numbers for apo and pe differ slightly relative to the calculation. If the target was exactly one SOI in front or behind Kerbin, the difference would be zero, on an interstellar trajectory that the difference is nominal, from Kerbin 670,000 radius is 0.99995 that of the calculated. On such a trajectory 670000 = 85000000 sin theta, translates to an angle to prograde of is 180.45'.

I'm playing a Career mode game with no mods (except MechJeb), and this is the largest rocket I've been able to build. It works well for traveling within the Kerbin system so far, but I want to start going to other planets, but it clearly lacks enough Delta-V to do so (only 7500 m/s). I only have all the 90-Science nodes of the tech tree researched, plus Heavier Rocketry and Command Modules. I would like to increase its Delta-V to (hopefully) 10000 m/s, but am unable to do so. Adding more boosters renders its TWR too small to lift itself. Any ideas? Picture here

Hello Everyone, I've been wondering for a little over an hour about this now, how can you calculate the delta-v from needed to get into orbit of a body once you enter its Sphere of Influence? On many delta-v maps like this one there is a delta-v needed to get into orbit (mun: 310m/s). I understand the Hohmann transfer which gives the other values but I don't know how to get the delta-v needed to get into orbit once you're intercepted by a body. So can anyone help please?

I've been working on an program to calculate combined takeoff and landing delta-v from a wide range of planet sizes (comets through superearths) and atmospheric thicknesses (vacuum through supervenuses). I'm reasonably happy with the takeoff delta-v calculation - a two-burn Hohmann transfer from surface to orbit assuming a vacuum, plus a term to approximate atmospheric drag. It's not perfect - it makes several assumptions including unlimited TWR on the rocket - but it's a decent first approximation. The landing delta-v calculation involves a deorbit burn and then a braking burn. Deorbit is easy enough - just reverse the circularization burn to bring the periapsis back to the surface. But the braking burn is more involved, because I'm looking to land a rocket capable of taking off back to orbit (not just a capsule). We can set certain limits. Braking delta-v can be as low as 0 m/s (super-thick atmosphere and/or tiny comet where descent to the surface is very slow) or as high as 110% of the takeoff delta-v (vacuum descent with unlimited TWR, allowing 10% safety margin). Between these two values - where the atmosphere is thick enough to slow descent but not to a safe landing speed - is where I could use some ideas on how to proceed. The rocket we're landing will vary greatly in mass depending on the surface gravity and thickness of the atmosphere we're dealing with. My initial thinking is to find the terminal velocity at the surface and use that to deduce the braking delta-v. This won't be the same as the terminal velocity on ascent though, because on descent there'll be more drag (rocket travelling rear-end first). Also, any parachutes will have much more of a drag effect on low-mass rockets than heavy ones. Clearly there's a lot going on here. I'm not looking for an exact solution, but a decent approximation. How do we estimate landing delta-v for a rocket - across a range of planet sizes - when there's not enough atmosphere to land safely without a braking burn? Any thoughts are welcome!

Hi, I'm not new to Kerbal Space Program but I still don't know one thing. I don't know how much Delta-V I need to get to a planet or moon. If someone could tell me how to calculate the amount of Delta-V I need I would really really REALLY appreciate it. Thanks for looking at my post

As the title says, I'm attempting a Duna Mission (hoping that there isn't any major inclination) but not sure of the DV requirements. I'd like either an SSTO or Rocket being capable of the transfer burn and the most efficent transfer window (I will figure this out using the Transfer Window Planner Mod). Of course, I will try to build a craft myself first but I'm clueless as exactly how much DV is required. A rocket that I can test which can get me to Duna (Either SSTO or a VAB Consturction) so I get a rough idea from the readouts on KER. Mods I'm using (All Abbrevaitions in the Title): KER KAC KAX Transfer Window Planner Texture Replacer (When I work out how to do Custom Spacesuits, regardless it is still installed) SpaceY and SpaceY Expanded RasterPropMonitor Precise Node (See here, since I can't exactly get mine to show the Window...thats why there is a seperate thread here: Rocket Factory Thank you for the help KSP Community, it is much appreicated and I wish the best of luck and I appreciate the people who are willing to help me! -awfulcraftdesigns, wishing the help he is given...good luck and peace out! Mission Update: (PIcs Coming Soon!)

I'm tossing around the idea of doing an opposition class Duna mission instead of the standard kerbal way of "wait for the launch window then wait a year for the next one". There are two parts to this question: When do I need to depart from Kerbin and later on Duna? How much delta-v would be required to depart, insert into Duna orbit, then return to Kerbin? Thanks in advance!

As shown in the screenshot, KER reads out two readings for stage 3 - 1697m/s, and 5196m/s. Why are those two different? And why are the ones below it the same?

I know there are Delta-v calculations all over this forum, but I thought I'd make a video on my channel trying to break it right down and demonstrate it. I would love to know what you all think. Running stock without plugins like Mechjeb and Kerbal Engineer can make it less simple to determine the distance your vessel can travel. These simple calculations show you how to calculate the Delta-v for your rockets stages quickly and easily with this simple formula. Why do it manually? For the fun of learning, having that deeper understanding on how the math works in rocket science and of course understanding the science/physics principals themselves. Formulas like this are very simple for anyone to do, and are rewarding when trying to get that deeper understanding. Please do follow and subscribe the the channel if you like.

Here is my version of a delta V map for 1.05 In order to use this map you add up all of the numbers between you and your destination e.g. to get to Duna from low Kerbin orbit will take 950+ 110+ 370= 1430 m/s of Delta V The map is only an approximation and you can make do with less Delta V but I would recommend having more than the chart suggests. I did not do the calculations for that I used two different charts: One chart was made back in 2013 by @SkyRender and was used for most of the in orbit values. The other chart was @Kowgan who credited the following in his thread: @JellyCubes WAC, CuriousMetaphor, @swashlebucky and AlexMooon. This chart was used for the in atmosphere numbers. I hope you find this useful.

I made a thing. I hope it's useful http://davidhyman.github.io/ksp_bodies_graph/ It's intended as something for quick estimates rather than a full blown mission planner, but I hope it neatly fills the gap between the static dv maps for KSP (of which there are several) and the various calculators for detailed mission planning. I took some inspiration (and data) from @Kowgan, @swashlebucky and @interwound (http://deltavmap.com/) - thank you! Bug reports, corrections and improvements welcome at github: https://github.com/davidhyman/ksp_bodies_graph References: http://deltavmap.com/ swash's delta v map https://github.com/merlinthered/ksp_cheat_sheets

It looks like the Δv needed to reach low Kerbin orbit from KSC went down recently from 4,550 m/s to under 3,600. I've seen references in the forum that suggest that this is due to the new aerodynamics modeling in 1.0.4(?), but can anyone explain why?

So ever since mining and resources came out, Grand Tours have become a lot easier, since ships don't need to take their own fuel everywhere. However, I am attempting an old-school Grand Tour, with a single launch and no refueling. The problem is that I haven't been able to find up-to-date info for a few things. The most important is how much Delta-V something like this needs. I've found maps a few years old, but I haven't seen any 1.0.x info, which, thanks to the new Aero, is very different from the old stuff. My design will be a mothership that carries a few landers with it, which will land and take off before docking to the mothership again. The landers have plenty Delta-V, but I have no idea how much Delta-V I'm going to need for the mothership. Does anyone have any experience with this? Are the Delta-V maps accurate enough, or do gravity assists make huge differences? I guess that's really all I was wondering, so thanks in advance

While there are good Delta-V (ΔV) Maps available, they all rely on departure burns in Low Kerbin Orbit (LKO) and an understanding of Phase and Ejection Angles. Beginners that do not yet feel comfortable with these concepts might try to reach other planets without these advanced maneuvers and ask themself if their ship has enough fuel/ΔV to accomplish the task. While Stock KSP does not display the ships ΔV, Plugins like Kerbal Engineer Redux can help with that. So I put together a ΔV map for the most simple flight path to other planets: Get from the launchpad into a 75km LKO Escape Kerbin's Sphere of Influence Change the inclination to match the one of the target planet Perform the first Hohmann-Transfer burn Fine adjust the trajectory to a low orbit around the target planet Perform a circularization-burn in the low orbit around the target planet Pre V1.0 Version: The ΔV-Values are just a bit larger than the minimal amount needed, so build your rocket with spare fuel. Since most planets are on an eccentric orbit around Kerbol, I gathered data for the minimal and maximal ΔV needed in the columns "Intercept / first Hohmann Burn" and "Circularization @ altitude". I did not include Moons, because the ΔV needed to reach them is smaller than the ΔV needed for the circularization burn at the Low Orbit. Efficiency Here is a comparison with the values of this ΔV-Map for a flight from the launchpad to a low orbit around the target planet. Planet Advanced flightpath Simple flightpath Moho 10040 10550 Eve 6280 6950 Duna 5100 6150 Dres 7260 8800 Jool 8570 10400 Eeloo 8190 9150 So the method described here is a lot less efficient, but at least more easy to accomplish. Reduction of needed ΔV There are several kinds of maneuvers available to lower the amount of needed ΔV. Departure Burn in LKO to utilize the Oberth Effect Aerobraking to reduce the circularization burn to nearly zero m/s at planets with an atmosphere Gravity Assists Version 5, License: The best part for me about putting this map together was, that for the first time I laid my eyes on Jool and it's moons. :-)