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  1. 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?
  2. 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!
  3. 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
  4. 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!)
  5. 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!
  6. 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?
  7. 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.
  8. 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.
  9. 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
  10. 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?
  11. 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
  12. 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. :-)
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