GoSlash27

JAFO, Sorry, no. If you peruse my threads in the tutorial section, I give information on how to build one. I don't want to release mine and then worry about keeping it updated for others. Best, -Slashy An *hour*?? Yeah, no thanks. I can plan out an entire mission and iterate all those alternatives in a lot less time. Doing it manually in the VAB gives a lot more flexibility, but it's not any more precise and takes a whole lot more time. Plus, you can only use it when actually playing KSP, whereas I can design entire missions on my lunch break. To each his own... Best, -Slashy

*facepalm* Yeah, you're right.... Nevermind Best, -Slashy

foamyesque, After running a sanity check on my numbers, you're correct; there's something off in my spreadsheet. I'll have to dig into it to figure out what's wrong. After running a sanity check on your numbers, you're also off in the other direction 7 tanks falls short of the DV budget. 9.81*340*ln(60t/32t)= 2096.7 m/sec. As for the other stuff, excess thrust is not "wasted" if it results in a lighter and cheaper stage. Mass matters and cost matters. Unused thrust doesn't. And sure... you can spend hours noodling around with KER in the VAB to try to mix and match and come up with a solution... but having a spreadsheet to do it for me means that I don't have to. I can have a highly efficient design with 100% confidence in it's performance in less time than it takes to type this sentence. I don't need mods, the VAB, or even an internet connection to do it. Best, -Slashy

foamyesque, No, Sir. Just payload, engines, fuel, and tanks. Best, -Slashy

Precisely this. It is the height of arrogance to suggest that somebody else is playing a single player game "wrong". We should also keep in mind that people sharing *their* preference isn't an attack on anyone else's preference. Best, -Slashy

Leafbaron, I have no idea what any of those terms mean. Your description of "constraint model" sounds about like what I'm doing. I plug in constraints (either direct entry or pulldown) that tell the spreadsheet the job I want the stage to do. Payload, DV, minimum t/w, starting and ending % atmospheric density, and reference body. It then applies the reverse rocket equation to each engine in order to derive the stage design. It displays all pertinent information about the designs for all engines in a table, highlighting the best/worst options using color and bold/ underlining. Hope that explains it adequately, -Slashy

foamyesque, Your guesstimate is pretty close, but the Poodle is actually the 3rd lightest option. #1: 2 Poodles. 62.105t, $9,000 #2 3 Aerospikes. 62.487t, $20,850 #3 7 Terriers. 62.838t, $12,030 #4 1 Vector. 65.140t, $27,750 #5 1 Skipper. 65.850t $12,500 That's what I mean... unless you have a spreadsheet to check all the engines, you're never really sure if you've found the best option. Best, -Slashy

foamyesque, The entire point of having a spreadsheet is that you don't have to handmath. As for whether you "can" or not, go ahead and try it. Without firing up KSP, what's the lightest upper stage for a 25t payload with 2,100 m/sec DV and minimum t/w of 0.7? My spreadsheet tells me that directly with a few clicks and I can use it anywhere at any time. MJ and KER won't tell you that. Even if you have them running and you're in the VAB, you can't be sure you've hit upon the "best" combo through trial and error no matter how long you try. This is the power of the dark side. Plus, we have cookies Best, -Slashy

Harry Rhodan, Heck yeah! I spreadcheat every chance I get. I worked out the math and programmed it myself, so I see no reason why I shouldn't let the computer handle the drudgery part for me. Under normal circumstances, I can mathematically zero in on an optimal design before I build and plan missions/ stages without having access to KSP (something MJ and KER users can't do), but this situation is an added bonus: I'm never left guesstimating when KSP updates. Yay science! -Slashy

Never used it. I'm 100% manual. Best, -Slashy

What @Plusck said. And even if you could do what you're proposing, you won't be able to do it with RAPIERs and nukes, since neither engine is efficient enough to be effective in Eve's thick atmosphere. Additionally, even if you had a ship that was almost completely fuel, you'll still be stuck in orbit with no way to refuel by the time you get there. Hate to say it, but I'm afraid you'll have to go back to the drawing board on this. Best, -Slashy

Like this, same as always -Slashy

The Terrier and Poodle are more mass efficient for trips under 2km/sec and a whole lot cheaper as well. Best, -Slashy

Bloojay, My post was accurate at the time it was written, and remained accurate almost a half a year afterwards, so no correction necessary Best, -Slashy

I generally keep my t/w for orbital maneuvers at a minimum of .5. This allows for plenty- quick burns, yet still allows for efficient stage design. Best, -Slashy

I agree with the others; you need a vertical stabilizer. Best, -Slashy

John Kermin, For best results, the rocket should be designed from the outset to impart the required DV and t/w to your payload. Attempting to crutch a lifter that's insufficient for the payload will generally result in a bodged design... assuming you get it to work at all. You will have a lot more success if you design from the top down instead of the bottom up. Payload first so you know what you're dealing with, then rocket. Many players create lifters by payload rating, but even then they start with a boilerplate payload and design the lifter under it. A little tip: When launching a ship, I use the ship itself as it's upper stage. It's got tanks 'n engines, so why not put 'em to use? Once in orbit, it's a simple matter to refuel it and send it off to wherever. I hope this helps, and welcome to the fascinating world of rocket science! Best, -Slashy

Back in 1.0, we found that the cheapest option for large disposable lifters was a pseudo- asparagus arrangement. SRBs are used to lift LF&O drop tanks, and are arranged asparagus style to feed a cheap general purpose LF&O core. http://s52.photobucket.com/user/GoSlash27/slideshow/KSP/CnCRocketFactory/Cheep135 For smaller payloads, SRBs serial staged behind vacuum engines was cheapest. @Nefrums created a pseudo- asparagus lifter that cost less than $600/ tonne. Best, -Slashy

Here's a copy of the original craft. http://wikisend.com/download/621292/Mk3SP.craft I checked it in 1.2 to make sure it still works. It does. Not only that, but with the revamped aero, it now hauls an additional 10 tonnes to orbit on the same profile; over 10t of pure payload per engine. I think the problem you're having is in piloting. Getting this design to fly is now much more taxing than it was when I first made it. When it first leaves the runway, it's on the backside of the power curve, already in a stall. Very high wing loading and very low t/w means that it's just *barely* flying. You have to get it out of that high- alpha condition without running out of altitude, so you have to *very carefully* trade altitude for airspeed. Gaining airspeed allows you to maintain level flight at lower alpha. Once you've got it down to 5° alpha in level flight, it's generating more thrust than drag, and you can begin the profile to orbit. After that, it will accelerate to the necessary speed to get you to orbit. The trick to getting it up there without overheating is to allow it to climb into thinner air without overrunning 20km altitude. Don't try to get all of your speed at sea level. Just get 380 m/sec and climb out at 5°. Once you get a temp warning around 1,380 m/sec and 20 km, switch to closed cycle and pull up to get into thinner air. It'll do the rest on its own. Best, -Slashy

I'm also intrigued as to why @Raideur Ng's design doesn't fly. Just looking at it, it *seems* like it should. The original design was intentionally set up to run close to the minimum thrust/ mass so that I could demonstrate the design techniques required to make a successful SSTO without spamming engines. Perhaps there's some glitch that's creating excessive drag in his derivation? Best, -Slashy

I don't know if I've even participated in 10 challenges Of course I enjoyed my own challenges. Not because I'm super- awesome or anything, but simply because I know what I like. A few shout- outs to some of my favorites: The Cheap 'n' cheerful rocket challenge: How cheap and reliable can you make a disposable lifter? K-Prize: Make a SSTO space plane. Kind of mandatory whenever they tweak the physics. Pro SSTO Master Challenge: Make a spaceplane that anyone can operate reliably and safely. Best, -Slashy

As Empirio said, you need a little more info than that. If you have the units of fuel, oxidizer, ship's mass, and Isp of the engine, calculating the DV available is pretty simple. Thankfully, all of that info is available in a vanilla game. First step is to make sure that you won't run out of oxidizer before fuel or vice- versa. Fuel comprises 45% of your propellant mass while oxidizer is 55%. If you don't have them in proper proportion, you must calculate your total propellant mass based on whichever you have less of. Assuming that's in order, add your fuel units to your propellant units. Divide that total by 200. That's your propellant mass in tonnes. Save that value in memory in your calculator. Example: You have 45 units of fuel and 55 units of oxidizer. 45+55= 100. 100/200= .5 tonnes of propellant. Now go to your map view and click the info icon. That will show you your current ship mass. Subtract the propellant mass from ship mass and save the result in memory. That's your dry mass. Now divide your current ship mass by the value in memory; wet mass over dry mass. That gives you your wet-dry ratio. Take the natural log of your wet-dry ratio, multiply it by 9.81, and save it. Now go to your ship view and right click on your engine. It will show the Isp of your engine. Take that Isp and multiply it by the value in memory. That gives you your total DV remaining. It takes longer to explain it than it does to actually calculate it. If you're like me and dead- set against using add- ons, I recommend creating a spreadsheet to do this. It's a calculation you use pretty often during a mission. Best, -Slashy

Sorry, man! -Slashy

Snoke was a baby penguin in an obscure side scroller game for the Commodore 64. He was horribly disfigured when an icicle fell on his head and he turned to the dark side. Best, -Slashy

Sippitous, If everything is different in a similar pattern, they've probably altered G. You should submit a bug report about it; a change there will skew the results of KER, MechJeb, and everyone who's ginned up spreadsheets. You may be in line for the chance to name something. Great find! -Slashy