GoSlash27

Well... my version is a bit modified, but it's called "hyperbolic excess velocity" @OhioBob has an excellent write-up here: http://www.braeunig.us/space/orbmech.htm#hyperbolic Be sure to throw a quarter in his tip jar. *edit* Stressing the importance of what TheDestroyer said upstream, if you attempt to do the burn in two stages (1 to escape Kerbin and 1 to transfer to Duna), then it really *will* work out to what you calculated initially. Best, -Slashy

Catbus, What @TheDestroyer111 said. You've got the correct values, but you're putting them together incorrectly. To model a transfer burn from low orbit requires excess hyperbolic velocity. Sounds daunting, but it's actually pretty easy. DV=sqrt(Vxs^2+Vesc^2)-Vorb where DV= the delta-v of the burn Vxs= excess hyperbolic velocity; the DV that would've been required had you started your transfer in Kerbin's orbit about the sun (vis-viva as you outlined above) Vesc= escape velocity from your current orbit around Kerbin Vorb= your current orbital velocity. So in your case, your 950.7 isn't the escape velocity, but rather DV required to reach escape velocity. Your actual escape velocity is 2,295*sqrt(2)= 3,246. Vxs= 918 Vesc= 3,246 Vorb=2,295 DV=sqrt(918^2+3,246^2)-2,295= 1,078 m/sec to Duna. If you subtract out the DV required to escape Kerbin (950.7), that leaves 128m/sec, which shows all is in agreement between your models and the map (the map rounds up to the nearest 10). As a side note, I think it's awesome that you are doing this. Best, -Slashy

That's the part I'm not getting. What purpose would these multiple landings at the same spot serve? This makes sense. You could even use it as a sort of biome hopper... but that's liable to be a bit slow and risky. Thanks, -Slashy

^ And to be fair, we did get some pretty good hardware and experience from the program. Best, -Slashy

Fair 'nuff, but none of these strike me as "practical" goals. Well.. the *first* one does. I can see a reusable taxi if it can hit several biomes, but this doesn't do that. A surface base could be served just as well (and more easily and flexibly) by a disposable lifter and "grand tour" missions are, by nature, impractical. Not crapping on the concept, mind you. I've pursued many "impractical" goals myself. I'm just trying to understand the nature of it. Best, -Slashy

^This. Especially since the pitfalls were all known during development, not just in retrospect. The shuttle fell victim to "mission creep" during the design process and the goal morphed from cheap space exploration to keeping the contract from getting cancelled. We wound up with something at the end of the process that wasn't what was originally intended. And FWIW (in deference to B.M.), no offense... but most of the things I design in KSP wind up being exactly what I had intended them to be. Whether what I had intended winds up panning out or not... a bit of a crap- shoot Best, -Slashy

This has always been present in my experience. "Prograde" doesn't stay in one place when in orbit, so SAS is constantly correcting. I have always parked my ships radial when in orbit to avoid this problem. It also males it easier to keep my solar panels exposed to sunlight. Best, -Slashy

@Brainlord Mesomorph, just one quick question before you go: What's the point? I'll open up this question to anyone who's interested. It seems to me that a 100% reusable Eve lander is of dubious value if it can only land in one place. Why would you ever need to land on and return from the same place more than once? Is it just an engineering exercise to prove that it can be done, or does it have some utility that I'm not seeing? Thanks, -Slashy

Cynical, and absolutely true! It was also very good at convincing the Soviets that they "needed" a shuttle when they couldn't afford one. -Slashy

solarbearman, You should check out the cheap 'n cheerful rocket challenge. Lots of good ideas on how to make more economical disposables. Best, -Slashy

In the design I posted, the fuel in orbit is the cargo. 1 orange tank minus the tank. Of course... if you wish to carry something else instead of fuel, you would put it in a cargo bay or whatever, but the same design philosophy would apply. Also, this design (like all of my designs) has the CoM stable. The forward fuel tank is locked to provide ballast. This design would work just as well with (say) a Mk3 cockpit. All of this is getting away from my point: You don't need to spam wings because you don't need to spam engines. If your design is aerodynamically clean and you use the proper amount of wing incidence, you can do the job with very little thrust. Best, -Slashy

Yeah, I agree with most of the points in the video. It doesn't mention the fact that recovering and refurbishing the SRBs was *much* more expensive than building new ones, but they continued doing it for purely political reasons. The STS system could've worked out, but when it got axed, NASA came up with a compromise design that wasn't particularly good at anything it did. IMO they should've trashed the proposal and gone with disposables. Not well. I've built replica shuttles for every KSP version since .24 or so, and they're not competitive with space planes and struggle to keep up with disposables. They also take more time and effort to develop and are more difficult to fly. Nevertheless... they *are* fun. Best, -Slashy

Not sure what you mean. My designs are not tail- heavy and the CoM always stays the same whether fully- loaded or empty. I suppose that's a trick too; build it so that the CoM doesn't shift as the fuel drains. Best, -Slashy

^ In addition to what OhioBob said, "low orbit" is whatever you personally decide is appropriate. For bodies with atmospheres, "orbit" doesn't include altitudes where you encounter drag, but you may decide to raise it far above the atmosphere for higher time warp multipliers. For airless bodies, the lower limit is terrain avoidance and again... higher altitudes allow for higher warp. It's your chart, so you decide what constitutes "low orbit". Best, -Slashy

In KSP, wings are wings. They're not particular about how they are mounted or what your wing loading is at high speed. Just maintain the proper longitudinal relationship between the CoM and CoL, and build it so your nose is pointed at your prograde vector. If possible, take advantage of those BigS deltas. They are an aerodynamically cheap way to carry your fuel. Much lower drag than fuselage tanks. Also high temperature tolerance. If you do it right, you need very little engine to get yourself hypersonic at high altitude. Low drag is more important than high thrust. *edit* Use wing incidence to knife your way through Mach 1 instead of spamming engines/ intakes. If you can keep that needle- nose pointed straight ahead when drag is highest instead of pitched up, you'll top out the speed without needing lots of engines. Less engines means more payload. Use a few large panels instead of a bunch of small ones. Big wings don't need struts and struts are the devil. Best, -Slashy

foamyesque, Far be it from me to tell you how to design your ship. I'm sure you're waiting for the "but", but there isn't one. Spacing is hard, especially if it's in a single stage from Eve. Just be aware that flying from your starting point requires more DV than you might expect, so it'd be in your interest to pack extra. Flying from a mountaintop is very difficult, but possible. @astrobond did it back in 1.04. Best, -Slashy

Yeah... FWIW you're going to have that so long as you're flying out of the atmosphere instead of launching ballistically. Flying always raises the total DV budget. Best of luck to you! -Slashy

Actually, it was already established that it was possible, and there's already an Eve SSTO limbo contest. Nevertheless, it's probably a good idea to restart it since it's old. Best, -Slashy

mhoram, Actually, they do. We calculate burns across SoI boundaries using the excess velocity (vis-viva in the solar frame), escape velocity, and orbital velocity. DV=sqrt(Vexcess^2+Vescape^2)-Vorbit Best, -Slashy *edit* as an example... Suppose you want to burn directly from low Kerbin orbit to Duna. First thing you need to do is figure out what a Hohmann transfer would cost from Kerbin to Duna. There's lots of good tutorials on vis-viva, but it goes like this. Kerbin's orbital velocity is 9,297 m/sec. If we were in an elliptical orbit with a periapsis at Kerbin and an apoapsis at Duna, our velocity at periapsis would be 10,216 m/sec. Our hypothetical DV on this burn would be 10,216-9,297= 919 m/sec. Of course, we are not actually doing this burn, but it is the excess velocity required to set up a Duna transfer, so we use it in the above equation. Vxs= 919 m/sec We're chillin' in LKO at 70 km altitude, so Vorb=2,296 m/sec Escape velocity is orbital velocity x sqrt(2) Vesc= 3,247 m/sec So using the equation above... DV= sqrt(3,247^2+919^2)-2,296 DV=1,079 m/sec Best, -Slashy

1) Yeah, you could. 2) It has wings, which are disadvantageous for a mountaintop SSTO. It's sitting at a typical low terrain height. It's refueling. Not hard to connect the dots. Nevertheless, I *asked* if that's what he's doing rather than stating it as fact, and if that's not his intention, I'm sure he'll let us know. Best, -Slashy

Well... he *is* refueling down there for some reason It's his project, so he'd be the one to ask. FWIW I agree with you; I don't think sea level SSTO can be done, but I'll be thrilled if I'm proven wrong. Best, -Slashy

shadragon, Assuming you're in a circular orbit, escape velocity is simply orbital velocity x sqrt(2). Recommended orbital altitudes are given in the DV maps, but feel free to set your own based on terrain, atmosphere, and time warp limitations. Best, -Slashy

Eve sea level?? Ambitious! -Slashy

foamyesque, Not that unusual. High initial t/w is good for minimal DV to orbit, but if you want max payload fraction or minimal cost per tonne, you have to set it lower. Most of my launchers operate in this range. Plus, he's battling tremendous heat. Best, -Slashy

Planet "Bob".