GoSlash27 Posted July 7, 2014 Share Posted July 7, 2014 The gauntlet has been thrown down. The challenge is to create an SSTO from Eve to LEO. -Stock parts only.-The craft must work in a stock KSP installation, so you can use mods to design it, but cannot use them to make it work.-No using loopholes in the physics engine to make it work. No kraken drives, no infinigliding, no GOAP drives, no nuthin' we haven't thought of yet (lookin' at you, whackjob! )- You can, however, take advantage of the stock "zero physics" parts. I have a feeling you're gonna need them... We're thinkin' of declaring stock Eve SSTOs impossible. Here's your chance to prove us wrong!Good luck!-Slashy Link to comment Share on other sites More sharing options...
Tsevion Posted July 8, 2014 Share Posted July 8, 2014 I don't think it's mathematically possible. You need to scrounge up 9km/s of delta-v or more, while maintaining a TWR of at least 1 on Eve. I don't think any combination of stock parts can do that in 1 stage. My only theory on how you might be able to do it is some sort of ion powered glider, but I don't think it's possible to make the transition from lift based flight to the orbital regime with just ion power. Link to comment Share on other sites More sharing options...
robopilot99 Posted July 8, 2014 Share Posted July 8, 2014 Maybe I made some ion powered gliders that worked on Kerbin. I think it could be done with sufficient abuse of massless parts Link to comment Share on other sites More sharing options...
Tsevion Posted July 8, 2014 Share Posted July 8, 2014 Yeah, the problem I see is that every Kerbin ion glider I've seen needs at TWR of a minimum of 0.4 or so to break from the atmosphere into orbital flight. And on Eve, an ion engine on it's own has a TWR of 0.47, meaning your craft would have to be 85% ion engine by mass... which doesn't really leave enough extra mass to carry the xenon you still need. Also, I'm not sure I've actually seen a Kerbin ion glider SSTO at all, they usually use stages or drop tanks. Link to comment Share on other sites More sharing options...
GoSlash27 Posted July 8, 2014 Author Share Posted July 8, 2014 I don't think it's mathematically possible either, but I can't prove it. I know that a vertical lift rocket is out of the question, but an ion glider is technically plausible right now. I'm working on an ion glider that looks to be true SSTO from Kerbin if it pans out. If not... I can't say for sure that an Eve SSTO is impossible, but I sure as heck don't know how to do it. Link to comment Share on other sites More sharing options...
Tsevion Posted July 8, 2014 Share Posted July 8, 2014 One of the biggest problems with ion gliders is actually removing the infiniglide issue. Almost every ion glider I've seen is actually leveraging infiniglide to some degree (I'm NOT saying this is intended by the craft designers, or likely even noticed)... on craft that weigh as little as the typical ion glider ANY control surface is going to have a non-negligible impact on performance. Frustratingly the only ways I've found to avoid infiniglide polluting my results is to either have no control surfaces (which makes flying rather tricky), or to use FAR... which is definitely not stock anymore. Link to comment Share on other sites More sharing options...
KandoKris Posted July 8, 2014 Share Posted July 8, 2014 SSTO from Eve from sea level.........Surly u jest Link to comment Share on other sites More sharing options...
JDCollie Posted July 8, 2014 Share Posted July 8, 2014 SSTO from Eve from sea level.........Surly u jestWell, the OP didn't call this a "challenge" for nothing Link to comment Share on other sites More sharing options...
The Jedi Master Posted July 8, 2014 Share Posted July 8, 2014 (edited) Doing the one thing in KSP that every player has decreed absolutely, positively impossible?Challenge accepted.- - - Updated - - -<--Always wanted one of these! Though I wonder where they come from... Edited July 8, 2014 by The Jedi Master Bit of a derp happened Link to comment Share on other sites More sharing options...
Oafman Posted July 8, 2014 Share Posted July 8, 2014 SSTO from Eve from sea level.........Surly u jestThe OP doesn't stipulate sea level. But I think it's impossible even from the highest mountain, and will be hugely impressed if I'm proved wrong Link to comment Share on other sites More sharing options...
MegaFlop10 Posted July 8, 2014 Share Posted July 8, 2014 I know that a vertical lift rocket is out of the question,Challenge Accepted. Link to comment Share on other sites More sharing options...
Pds314 Posted July 8, 2014 Share Posted July 8, 2014 I don't think you understand. It isn't just out-of-the-question. It is a fundamentally impossible idea.Even using space TWRs, the only possible configuration I can find that gets over 6500 m/s is 1.5 Giant 3.75 m tanks and a KR-2L. Keep in mind that this assumes that the payload is just an OKTO2.Realistically, you want to put at least a lander can up there, and the atmospheric efficiency of that engine would make it much worse than aerospikes. Practically speaking, either aerospikes or the quad engine booster are best, but nothing with aerospikes can beat 5400 m/s. Link to comment Share on other sites More sharing options...
Starwaster Posted July 8, 2014 Share Posted July 8, 2014 Winner of the challenge has to do it again.... with Real Solar System and FAR installed! Link to comment Share on other sites More sharing options...
No one Posted July 8, 2014 Share Posted July 8, 2014 Do the following things count as "Loopholes in the physics engine":Symmetries above 8x (Obtainable in stock via a glitch)Taking advantage of the obscenely high Isp of Jet Engines via using lots and lots of air intakes, filling them up on Kerbin, bringing them to Eve, and then taking off with Jet Engines? Link to comment Share on other sites More sharing options...
Red Iron Crown Posted July 8, 2014 Share Posted July 8, 2014 I don't think you understand. It isn't just out-of-the-question. It is a fundamentally impossible idea.Even using space TWRs, the only possible configuration I can find that gets over 6500 m/s is 1.5 Giant 3.75 m tanks and a KR-2L. Keep in mind that this assumes that the payload is just an OKTO2.Realistically, you want to put at least a lander can up there, and the atmospheric efficiency of that engine would make it much worse than aerospikes. Practically speaking, either aerospikes or the quad engine booster are best, but nothing with aerospikes can beat 5400 m/s.It is entirely possible to get to orbit from a planet with an atmosphere without ever having your TWR exceed 1. Not saying it's possible on Eve, but it hasn't been mathematically proven.I messed around with a rocket/ion hybrid last night after reading about GoSlash's attempts in the other thread. The idea being: Use the ions to take off and ascend until the glider reaches the equilibrium of lift/weight and thrust/drag. Pitch up and light the rocket (just a 48-7S and a few Oscar-Bs), use it to get suborbital but out of atmo. Then use the ions again to circularize.I'm not sure this approach will work; the more rocket that gets lugged up, the lower the speed/altitude that's achievable with ions. I only tried a couple of iterations of the design, it is incredibly tedious doing the slow, slow climb. That and I'm not all that good at designing planes that fly well. Link to comment Share on other sites More sharing options...
Pds314 Posted July 8, 2014 Share Posted July 8, 2014 (edited) It is entirely possible to get to orbit from a planet with an atmosphere without ever having your TWR exceed 1. Not saying it's possible on Eve, but it hasn't been mathematically proven.Technically yes, but you'd run into more air on your way up and so having a TWR of say, 0.5 will increase the delta-v requirements from 7800 at the top of the tallest mountains to even more obscene amounts, similar to taking off from sea level with a rocket.Basically, rocket planes with lots of fuel are always less efficient than regular rockets with as much fuel.In any case, the best possible mass ratio in KSP is 9.0, and at that point, your ship is a pile of fuel tanks. At 390 ISP, you'd have slightly under 8400 delta-v I seriously doubt that, with the added wings, engines to take off, etc, you'd manage to only gain 600 m/s in dv requirement. Edited July 8, 2014 by Pds314 Link to comment Share on other sites More sharing options...
Red Iron Crown Posted July 8, 2014 Share Posted July 8, 2014 Technically yes, but you'd run into more air on your way up and so having a TWR of say, 0.5 will increase the delta-v requirements from 7800 at the top of the tallest mountains to even more obscene amounts, similar to taking off from sea level with a rocket.Basically, rocket planes with lots of fuel are always less efficient than regular rockets with as much fuel.That's why ions are the only thing remotely close to being capable of doing this, and only since 0.23.5 with the higher thrust ions and massless electrical parts. It's fairly trivial to make an ion glider with >12km/s of dV; my first rocket/ion hybrid design had over 11km/s without really optimizing much. TWR is definitely the kicker, though. The ion only ascent is very slow and tops out, the ship then needs enough rocket to kick it into a higher apoapsis trajectory which the ions then try to make orbital. Very tricky, and certainly skirting the edge of impossibility if it's not actually so.I suspect it's impossible, but it's a bit of fun to see how close I can get. Link to comment Share on other sites More sharing options...
Pds314 Posted July 8, 2014 Share Posted July 8, 2014 It might just be possible with an ion/chemical rocket hybrid, but even then, I doubt it is practical. You probably have to take an extremely shallow ascent profile, increasing the need for xenon, increasing the need for ion engines. Increasing the need for something to provide power. Link to comment Share on other sites More sharing options...
Pds314 Posted July 8, 2014 Share Posted July 8, 2014 Also, if I understand it correctly, the stock drag model makes flying anything with a low TWR inherently very inefficient, causing an arms race between wing area and drag Link to comment Share on other sites More sharing options...
Pds314 Posted July 8, 2014 Share Posted July 8, 2014 Not saying it is completely impossible, but even an ion glider would be pushed to it's limits. Link to comment Share on other sites More sharing options...
Red Iron Crown Posted July 8, 2014 Share Posted July 8, 2014 That's the idea, to push the limits to see if it's possible. I agree that it's not a practical ship for carrying any kind of payload, just a one-trick-pony for the Eve-SSTO stunt.Power is not really an issue, with massless batteries and solar panels you can just spam OX-STAT panels and Z-400 batteries until sufficient capacity is added. Link to comment Share on other sites More sharing options...
GoSlash27 Posted July 8, 2014 Author Share Posted July 8, 2014 ^ This. I'm not yet in Kerbin orbit, but I'm very close. The trick seems to be not in getting enough DV, but in making the glider as efficient as possible from a drag standpoint. Lift seems to be a whole lot less critical than drag, and this would be even more true on Eve. I would say that there would be 2 categories here: Unmanned and manned. Link to comment Share on other sites More sharing options...
KvickFlygarn87 Posted July 8, 2014 Share Posted July 8, 2014 The challenge is to create an SSTO from Eve to LEO.Single stage to orbit from eve to low Earth orbit? Those are two separate universes, pal Link to comment Share on other sites More sharing options...
Red Iron Crown Posted July 8, 2014 Share Posted July 8, 2014 Low Eve Orbit. Link to comment Share on other sites More sharing options...
Tsevion Posted July 8, 2014 Share Posted July 8, 2014 (edited) I played around with a pure ion glider last night, and a pure ion glider definitely can't do it. I made a minimal ion glider (smallest probe, single ion, single xenon tank (empty), and a pair of Delta-Deluxe Winglets), and turned on infinite fuel. It topped out at 51km doing around 840 m/s, it also took like an hour to get up to that... which is a lot more than a single xenon tank worth of delta-V. And even that craft is technically abusing infiniglide slightly. The only possible non-cheating method left that I can't eliminate completely is a hybrid ion glider / chemical rocket... but I think it's quite unlikely you can actually lift anything with an ion glider that could then give the boost needed to allow the ions to achieve orbit.Edit: For clarity, this was on Eve, not Kerbin. Edited July 9, 2014 by Tsevion Link to comment Share on other sites More sharing options...
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