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Staging Optimally A spreadsheet planner and conversation place. We've all been there. After all the hours building a launcher to put X tons in obit, you want to make sure that payload can do just as much as kerbally possible! But it's hard to know exactly how many stages to put in the thing, and how large to make each. If your stages are too small, you're wasting deltaV pushing around extra decouplers and engines, but if your stages are too big, you're wasting deltaV pushing around empty fuel tanks! So where's the magic happy balance inbetween? Now you can find out*! *Software provider does not assume liability for engineers trying to saw engines in half to achieve "The most optimum ratio!!" At the moment, there are 2 programs which can find the optimum relative sizes of stages for your rocket: One option is @IncongruousGoat's C# & .NET automatic version available here: Github Link! It'll suggest engines for you: The other option is a GoogleDoc spreadsheet program, which you can also use as a planner. More info on that follows: Instructions: 1. Open the doc, and make your own sheet by clicking the "down" arrow by the "Template" tab at the bottom, and click the duplicate button. Rename your sheet and you're set to play around! 2. Write in the names of each stage your rocket will have, and the TWR they'll need as well as their engine specs (see the ksp wiki for a quick reference). 3. Then for the stage's scale, type in a guess of 1 (scale is just a convenient measure of size). Down below you'll see a huge field full of information for how changing this scale for each stage will change the final rocket's efficiency. Simply make the best changes, and soon enough you'll have the very optimum of rockets! Notes: The template has a rocket already loaded in so you have something to work from. Here's a picture! The underlying math doesn't care how big your rocket is, or what order the stages are in, but if you give it your payload mass and stage order, it'll read out how big each stage should be and how many engines it should have. The optimum efficiency tends to be fairly broad, so there's typically plenty of wiggle room to choose a slightly-sub-optimal scale to get a whole number of engines. You can also tweak the TWR requirements if you really want to see a whole number of engines at an optimum . IRL just round the sucker It handles asparagus staging and drop tanks, because I figure'd it'd be fun! It doesn't handle weird fuel tanks that don't have a 1/9 ratio, but I can add that in if it's desired? This system does scoot mass around between stages to let more efficient stages cover for less efficient ones. You'll notice if you have a particularly inefficient engine (thud), the optimizer will tell you the most efficient scale for that stage is so small it has a negative deltaV. This means that it would be better deltaV-wise to not even give those engines fuel tanks... that's sad, thud. Sorry. Whatever, I'm using them anyway! If you don't want to optimize a certain stage, you don't need to. The solver will optimize all the rest around it. Final Thoughts: Please let me know if it winds up being confusing in any way. I'd like to make it convenient and intuitive, but I have a peculiar design aesthetic by nature. I encourage community additions and am happy to share the math behind the calculator. There's also ongoing development thread for the underlying math here, and I'll be making a tutorial thread on how the system works in a few weeks. Huge thanks to co-conspirators @Abastro and @IncongruousGoat who helped with the math development! If this stuff happens to be your jam, please kick them a like in posts here and here. Thanks! Oh, once again, I'm flagging the good banana mod banana @Vanamonde in case another board is better. I'm planning to make a separate tutorial thread for the actual how-to stuff, but if tutorials is the best place, I can always roll the two threads into one? In any case, let's see where we end up. Brace for warp drive!