GoSlash27

Pretty much this. The rovers and lander pod (or whatever other payload pod they're working with) are designed to attach when parked next to each other and jacked up on the landing gear. The payload doesn't necessarily have to be a landing pod as shown here, but can be (for example) habitat modules, power stations, fuel cans, etc. The idea is that you're not going to drop payloads from orbit down to the millimeter where they're supposed to be, so you need to 1) land them on the surface, 2) traverse them across broken terrain to the build site (possibly fording/ traversing hazards), and 3) assemble them together in place once you've arrived. I designed the rovers to incorporate all these functions and more into a single assembly to ease the logistical process of building outposts off- planet. But this is all getting away from the point I'm trying to illustrate; a lander doesn't have to be very big to work even on Tylo. If you design the payload small, then every stage that precedes it will be smaller. It's an exponential progression backwards down the chain. Best, -Slashy

Starman, I actually bring the rovers along; they *are* my boosters. The idea here is that the rovers working in pairs can bring payloads to the surface, traverse terrain to a site, assemble whatever they brought in place, then refuel and take payload back to orbit with them. It's a "surface rendezvous" scheme intended for constructing elaborate habitats on other bodies. A simple exploration lander/ lifter could be built lighter and simpler than what I've shown here. This is just presented to illustrate how small and light these systems can be if you're designing for it. Best, -Slashy

I tested on Kerbin and Eve to find the correlation between altitude and Isp using LV-N atomic rockets. The results are surprising... Kerbin Altitude/ Isp 0 /229 1.7Km/ 390 (equivalent to Aerospike) 5Km/ 588 (closer to vacuum Isp than atmospheric) 10Km/722 (90% of vacuum Isp) 15Km/772 (over 95% of vacuum Isp) 20Km/789 (nearly 99% of vacuum Isp) Eve altitude/ Isp <11 Km/ 220 14 Km/ 390 (equivalent to aerospike) 16 Km/ 510 (midway between atm and vac figures) 25 Km/720 (90% of vacuum figure) 30 Km/760 (95% of vacuum figure) 41 Km/792 (99% of vacuum figure) The moral of the story: Anywhere other than Eve, the Isp(atm) figure may be safely ignored altogether. On Eve, anything other than the vertical boost phase may be safely calculated using the vacuum figure. Once you get to the gravity turn, you're virtually in vacuum as far as the engines are concerned. Best, -Slashy

I understand what you're trying to do here, but these are seriously huge landers for such a little job! Tylo is the most difficult job in the Jool system, so let me show you my lander arrangement for that just for comparison. These 2 rovers hold enough fuel and have enough thrust to put themselves and the lander in orbit in a single stage. Not saying you need to do it the way I do it, but it shows how little vehicle is actually required for this job. Smaller landers mean smaller mass movers and much, much smaller boosters. Best, -Slashy

Asparagus staging is *very* efficient. Not just in terms of fuel, but in terms of payload fraction, which translates to dramatically smaller launchers with lower price tags for the same payload. It is not, however, more efficient than turbojet/rocket hybrid or RAPIER SSTO lifters. I could probably build a jet asparagus booster even smaller and lighter than my SSTO, but why stage when you don't need to? Best, -Slashy

MabDeno, You've earned your spot atop the unmanned leaderboard. Congratulations! I got my best results by maintaining my horizontal velocity at a percentage of terminal velocity with the percentage matching my thrust to weight ratio. Best, -Slashy

Oh, it's possible. I did it a few months back with an unsuccessful ssto. Clarifying: I did a suborbital circumnavigation with an "even harder mode" glider without running out of daylight. "Hard mode" is actually fairly easy; I put one of those in orbit with enough DV to land on Eve. Best, -Slashy

These are some examples from the way-back machine of how small and light you can make an asparagus booster and still have it work: In this case, the mass- mover has just enough fuel to complete it's own insertion burn. Here, the stack of rovers is empty and the booster does everything including rendezvous and docking. Here, the payload is all dead weight and fully loaded. A supply pod destined for transfer to a space station. I don't use asparagus staging much these days, but this shows what even simple arrangements are capable of. Best, -Slashy

DSC, The entire launch assembly needs to be redesigned to take advantage of the new engines. You don't need all the tankage in the upper stages you did before, which lowers payload demand on the lower stages, thus cascading the weight (and thus monetary) savings back down the launch vehicle. As for why you're running into the t/w bottleneck, it's partially what I mentioned above and partially a by-product of asparagus staging. Thrust is reduced at each staging event more than payload is reduced. The trick is to balance the fuel load distribution among the stages such that the t/w after staging is where you need it to be at that portion of the launch profile. 1.2-1.5 at initial boost, approximately 1 at the gravity turn, and .75 or even less at insertion is adequate to get the job done. There's no reason why all your asparagus boosters need to be clones of each other (or even use the same engines, necessarily). Best, -Slashy

I'm also including t/w ratio. Both must be considered when designing a stage for minimum overall mass and thus operating/ initial cost. If you plot out t/w vs Isp for all the liquid engines, you can see that the engines I cited form the vanguard with the others falling behind them in terms of Isp, t/w, or both. As an aside, I just figured out this morning that Isp (atm) vs Isp(vac) is highly misleading in this game. On Kerbin, by the time you hit 5Km altitude you're already closer to the vacuum value than the atmospheric. At 10k, you may as well use the vacuum number in your calculations. Best, -Slashy

I'm thinkin' the switch from a rubber binder to a plastic is what caused the motor to blow. Are there other theories floating around? Best, -Slashy

Nevermind. I googled his craft and overview. The reason his craft is cheaper is because he's using better engines. Each stage has been optimized to employ the best engines in the game in their most efficient regimes, while your design uses sub-optimal engines and more fuel to get a cleaner overall vehicle and part count. For all the liquid rocket engine choices available in this game, there are only a handful of them that are ideal. They are: O-10 monoprop Rockomax 48-7S Toroidal Aerospike LV-N Atomic Rockomax Mainsail Each of these either delivers superior ISP for the same t/w or superior t/w for the same Isp as compared to every other offering. Anything else can be out- performed by these at the expense of part count, which results in a lighter, more efficient overall vehicle. This usually ends up cheaper on the launchpad. Comparing either of these to my vehicles... it's a whole other level in terms of efficiency. I don't ever design boosters to lift more than 15 tons because there's nothing in this game that can't be accomplished with that payload. I rely on rendezvous schemes to make up the difference, so my launches are dirt- cheap with full recovery and I just make more of 'em. I put payload in orbit for $73 a ton and just assemble it up there using clamp-o-trons. Best, -Slashy

DSC, Not trying to come off as disinterested, but I'd rather not download both files. Can you give an overview of both craft? Overview of engines and stage fuel volumes, etc? -Slashy

I don't believe that the two are mutually exclusive. Even when the government is heading up efforts, the progress of mankind is a by-product of the effort rather than the altruistic goal. Branson's motivation may be profit, but that's not a bad thing. The end result is they learn how to put people in space without killing them or losing money. Or at the very least, how to *not* do it. Living in space is ultimately going to come down to a profit motive in and of itself. People will move out there because it's better for their personal interests than staying here. They're never going to migrate merely for "progress of mankind" and nobody's going to put them up there for that either. My $0.02 -Slashy

Condolences to the crew and their families. While this is a setback to private venture spaceflight, I don't believe it's the end. So long as people are willing to take the risk, these sorts of endeavors will continue. I hope they get to the bottom of the failure quickly and resolve it. -Slashy

Syhrus, Thanks. Didn't mean to put you on the spot, just doing my due dilligence for the other contestants. Since the stage in this case happened while the craft was sitting still on the runway and didn't impart any acceleration, I'll allow it and alter the rules to reflect it. Congratulations, you own the "manned" record for .25! Best, -Slashy

Everybody's covered the high points already; wide aspect ratio, low center of gravity, and arresting lateral velocity. It also helps if you make your landers no heavier than they need to be. A lot of players either over-engineer their DV budget or crutch an inadequate design with "moar boosters". In both cases, it's a bigger vehicle and more prone to tipping. Crunch the numbers first and design it to not tip, and you shouldn't have a problem. Best, -Slashy

I'm an "engineer". I work out a plan to accomplish the mission objectives, then spend a ridiculous amount of time designing the "perfect" vehicle for the mission. Once I've got the vehicle designed to my satisfaction I build it, test fly it to work the bugs out, then finally fly the mission to see how accurately the performance conforms to my expectations. -Slashy

CMN, Remember that this particular challenge was made back in April when we hadn't yet established whether or not this was possible. We (and by "we" I'm including "you") have collectively established the answer to this question since then. Best, -Slashy

I haven't had a need to use asparagus staging lately, but I would if the situation presented itself. The only reason I might need it is early in the tech tree where I don't have turbojets or an Eve launch vehicle. Otherwise, I've found it easier and cheaper to use standardized SSTOs. Best, -Slashy

Syhrus, I have a couple questions about your flight I need to clear up before I put you on the board. Actually, 3... What was "staged" from the aircraft at the beginning of the flight? Was the flat spin up at 22k and you just didn't take a pic until it was back down to 4300? Finally, this was done with stock aero and physics, right? Just gotta make sure, 'cuz the photo evidence is a bit thin. Best, -Slashy

Very cool, minimalist design. Do you have a name for it?

Sorry, but no. Entries must begin their flight from the runway and no parts may be dropped for any reason. Best, -Slashy

I always set my solar arrays at right angles to each other about the longitudinal axis. This assures a constant supply of charge regardless of angle to the sun. Best, -Slashy

I agree with the others; an Eve LV needs to have a low aspect ratio for landing stability, especially in the uneven terrain of higher altitudes. The atmosphere is like soup, so you don't need much in the way of 'chutes to stick the landing. But short and wide has gotten me good results. Good luck! -Slashy