GoSlash27

I have found that transfer DVs are pretty much right out of the window for anything that's not in the same orbital plane. It ends up taking whatever it takes *shrug*... Kerbin surface to LKO takes about 4300 to 4500 and Mun is right on the money at 870. Anything else... It varies so widely that a DV map is almost useless. Generally it takes way less because I can "cheat" by using the other bodies to accelerate or decelerate me, but sometimes it ends up taking way more than the map suggests. Perhaps it will firm up as I gain experience? Best, -Slashy

Not so as I understand it. It would be impossible for a rocket to establish a circular orbit while only heading toward prograde. And with no air resistance, there's no reason to. As the rocket approaches the apoapsis, the nose has already fallen below the horizon. It's the increase in velocity that makes the rate of pitch *seem* to be zero; the horizon is falling away from you at the same rate that your nose is rotating. I'm not sure I can explain this without diagrams...

For torque moment, I'm talking about the weight distribution around the center of mass. Like an ice skater with her arms spread out vs. pulled in close. tall rockets rotate slower than short rockets, so you need to balance that to make the rocket tip over at a proper rate. For prograde elevation, I'm talking about the elevation above( or below) the horizon where "forward" is. Or in simpler terms where you're going. If your apoapsis is already correct, then you can maintain it there by pointing your nose at the opposite side of the horizon from where you're headed the same number of degrees. This allows you to continue to accelerate to circularize your orbit without cutting/ restarting the engines. Best, -Slashy

Sorta, I suppose. I use a standard lifter for everything which imposes a 5t weight limit on what I launch. Since all of my space station components/ interplanetary movers/ landers/ rovers/ etc. are all weight restricted and modular, it's kind of inevitable that it would all end up standardized. I do have some rules that I've self- imposed (mainly safety rules for the Kerbals) that aren't necessary, but one of my aims is to place Kerbals on every accessible body in the system without killing or stranding them. Other than that, it's little stuff. Nuclear engines have unique rules, stuff like that.

Oops! Didn't read the last page before opening my yap. Nevermind... I recommend ditching those SRBs. They are worse than useless because you can't throttle them or turn them off, so they're liable to wreck any burn you use them on. If you want quick acceleration, I recommend toroidal aerospikes. good thrust to weight for an engine that delivers 390 Isp.

The math is super- easy. Well... in your case it's complicated by your mixing engines, but other than that, it's a simple equation. just tally up the mass of your ship when fully fueled and when empty. divide the first total by the second. Then take the natural log of that number. Now multiply by your Isp* and 9.81. That's exactly how much delta v you can generate. 2 points of advice: 1) Those engines are not ideal for cruising in vacuum and they will severely hamper your range. Like putting a top fuel dragster motor in your Geo Metro. You should really be running the LV-N. 2) be careful using delta V maps, as they can be misleading. If your target planet has an inclined orbit or you attempt the trip at the wrong time, it can cost you a lot more than the map suggests. Also those numbers don't include all the correction burns, which can add up to a lot. But as Allmhuran pointed out, if you can get to Eve, you can get just about anywhere... *IF* you're really sharp with your maneuver nodes and aren't particular about how long it takes. Best of luck! -Slashy 2) * figuring your delta v when using dissimilar engines is tougher. You have to scale the Isp of each engine by it's relative thrust to the total, so the stronger engines will have more of an impact than the weaker ones. In your case, 4 skippers have almost exactly the same thrust as a KR-2L, so you're close enough to split the difference. call it 365.

I think the main question is "how to create a rocket that will do a true gravity assist turn in KSP". Basically firing up a rocket, tipping it off vertical, and (look ma no hands); a perfect orbit. Although IRL rockets still need minor corrections... The answer is simulation, which in KSP means trial and error. Especially since #1 the aerodynamic model in KSP is hosed and #2 you can't get the precise dimensions and centers of gravity, which you need for the maths. build a rocket that will generate the proper delta v for the payload and the mission. I can tell you how to do that if you're interested. Then simply throttle it up and let it rip with the SAS off. Hopefully if your torque moment is long enough it'll fly straight up. At 7Km, kick it prograde a few degrees and see what happens. If it falls over too fast, then you need to either lengthen the torque moment, increase the thrust, or adjust the altitude and/or angle of your initial pitchover. do the opposite for a rocket that doesn't tip fast enough. Each stage must be balanced to naturally tip at just the right rate, so it's liable to take you a long time to get it just so. AFA what a gravity turn will end up looking like, there are a few goalposts to shoot for: -pitchover at 7Km -22.5* off vertical at 15Km -45*at 25 Km maintain that rate of pitch down until you achieve the desired apoapsis. then... - pitch= -|prograde elevation| when apoapsis = desired apoapsis from there, the orbit should circularize itself by simply accelerating at a rate sufficient to keep the apoapsis 30 seconds ahead. This is how I run all my launch vehicles and it's very economical for dV, but I cheat by using SAS and guiding it manually. SAS is so cheap from a mass ratio standpoint that I don't see a reason to build a rocket that doesn't use it. Good luck!, -Slashy

The single best tip I've come up with on my own: e^(ÃŽâ€V/9.81Isp) = Rwd 9(Rwd-1)(Me+Mp) ________________ = Mft (9-Rwd) where Me is the mass of your engine(s), Mp is the mass of your payload, and Mft is the mass of your necessary fuel tanks (loaded) So given the ÃŽâ€V you need to make, the payload you need to haul, and the engines you intend to use, this will tell you exactly how many fuel tanks you need to do the job. This works for all small and large radius liquid tanks. If you end up with a negative number, you can't do the job with that engine. It's still up to you to verify that your engines are adequate to lift it. Use in good health! -Slashy

The only way I see that as a possibility is if it's out of Kerbin's SOI. It would have to be in the exact same kerboocentric orbit as Kerbin itself and just ahead or behind to minimize the distance. It won't get eclipsed by Kerbin, but it will get blocked by the Mun once a month.(edit) Unless, of course, you have 2 of them on opposite sides...(/edit) Beyond that... maintaining zero angular velocity with respect to Kerbin means that it's angular velocity with respect to Kerbol is exactly the same as Kerbin's; same orbit. Best, -Slashy

How'sabout this? Burn retrograde until your orbit just barely closes off. Then ride that orbit to apoapsis on the opposite side. Once there, you should be going so slowly that you can retroburn your orbit to a dead stop for fairly cheap. Then burn East until you establish an aerobraking periapsis on Jool and proceed. It won't be perfectly in the ecliptic plane, but it should be close enough to catch a moon. Just a thought... -Slashy

-When you accidentally deorbit yourself while attempting a rendezvous. -When you lose control of a ship because you forgot to deploy the solar panels -When you lose control of a ship because you forgot to *include* solar panels in the first place / I have done all of these...

I went through an entire dress rehearsal with my Eve 14 lander. Everything works and it seems to make the delta V, but getting this thing from Kerbin to Eve is gonna be a headache. 52 tons. Not light compared to most of the stuff here, but it's equipped for every phase of the mission. retro burn, parachute descent, stable landing platform, refueling capability while on the surface, and boarding access. This pic is kinda neat. One of my rovers busted a wheel, so I sent another to assist it in getting to the lander for refueling.

Eve seems to be the big challenge to crack, but I think I've made a breakthrough today. It's not just designing a booster to get off Eve, but also one that can be lifted from Kerbin and be deposited on the surface of Eve. I *think* I can do all that with 52t total if I sort out a couple engineering wrinkles. 8,960 delta V atmospheric with at least 1.1G (eve) throughout the launch. It'll take a lot of testing before I'm comfortable risking a little green butt in it, so it'll be a while before I submit my entry. Wish me luck... -Slashy

That's exactly what I needed! Thanks and regards, -Slashy

This seems to be a question that would've been answered by now, but if so I can't find it. Does anybody know the mathematical model that KSP uses for lift and drag? is it similar to real life? Cl*d*v^2=L? Does drag work the same way as lift?

You're right! There was a typo in the equation. I'll fix it after I post this. As a very simple example, say we want to design a rocket to deliver a 10 ton payload directly from LKO to the mun. We will use the LV-909 engine due to it's efficient Isp. our required delta v is 1070, but we'll add 10% as a safety margin to cover pilot error and rendezvous. call it 1200. Our engine makes 390 seconds of ISP in vacuum and weighs .5t. We will be docking, so we will need to add RCS and 4 thrusters as well as a brain and reaction wheel. 1.55 tons. Plus a docking port to decouple the load, so 1.6 tons plus the mass of our engine is 2.1 tons. Add our payload and it's 12.1 tons. Our Rwd is e^(deltaV/(9.81*Isp) 2.72^(1200/(9.81*390) 0r 1.368 Almost all liquid fuel rocket tanks have a ratio of .125 for tank to fuel, so Rtf is .125 So now we would fill in the blanks. F=M(Rwd-1)/(1+Rtf) F=(12.6)(1.368-1)/(1+.125) F=(12.6)(.368)/(1.125) F= 4.12 We need to carry 4.12 tons of fuel and F(Rtf) or (4.12) (.125) = .515 tons of tank. Closest we can get to that is an FL- T800 plus another 120k of fuel. That's a round 8 + an Oscar B. So that's 4.5 + .136 + .079 = 4.715t loaded and .5+ .025 + .015 =.054t dry Our mass including the fuel is 12.6 + 4.715 = 17.315 and the mass with this stage dry is 12.6+.054 = 12.654. plugging these numbers into the original rocket equation as a sanity check deltaV= 9.81*390* ln(17.315/12.654) = 1,199.8 deltaV, as expected. So we can use these numbers to plan the preceding stage. best, -Slashy

2 points: #1 the target doesn't fly along a straight path and neither do you. you each fly a circle from apogee to descending node to perigee to ascending node and the circles add together. If you were flying a uniform distance from the target with no delta v, it would seem as if you were orbiting the target or vice- versa. Therefore you will always have a slow drift in azimuth and elevation that reduces as you approach the target. #2 KSP seems to have a point at 200M where it "fixes" an exact point for objects. You can always expect an instant error to occur when you cross that distance. At 201M the game figures "the object is roughly there" but at 200 it suddenly says "this is precisely where it is" and the 2 positions are different. Just roll with it... HTHs, -Slashy

An SSTO from Kerbin to LKO doesn't get you much of anything. You can always build more rockets and you never have a fuel shortage. But consider the logistical problem of dealing with other planets where you can't do that.Every liter of fuel you burn and every piece of equipment you jettison had to be shipped in from Kerbin, landed on the surface, and possibly assembled on the surface. An SSTO simplifies that job and makes possible what would otherwise be impossible. Regards, -Slashy

I launched it on a parabolic trajectory over to the (spoiler alert) -> island with the abandoned airfield Then I did a retro burn (no chutes) and a landing in hover mode. After that, I ATV'd it all the way to the top of the mountain without using the jets. / flying cars, yo!

http://forum.kerbalspaceprogram.com/threads/80803-Helpful-rewording-of-the-rocket-equation

delta V = 9.81* Isp * ln (Wf/Wd) where Isp = your engine's Isp ln = natural log function Wf= weight of your rocket including fuel Wd= weight of your rocket without fuel. I also worked out an equation to calculate how much rocket you need to generate a known amount of delta v with a known payload. I'll post a link to it...

All- terrain! Also, done with 100% vanilla parts.

Testing and debugging the M3V. It's a combination SSTO lander/ rock crawler/ delivery truck. The idea is I can use a pair of them to deliver hitchhiker cans to the surface, truck them around to wherever I want, link them together, then return to orbit for the crew in lander modules. Each M3V is composed of 2 modules weighing 5 tons or less (my entire space program is designed around 5 ton payloads to LKO) and the tank/thruster assembly is modular so I can scale it to a particular moon. Almost ready for unkerballed testing on Minmus.

Yeah, I think it was either a one time thing or else a case of ham-fisting my approach. I've plugged 4 modules onto my station since then and haven't had any problem. I'm gonna tag this thread "answered". Thanks all!, -Slashy

Shotput/ Courier craft file I guess this one goes under "rockets with payloads". This is my generic 5 ton lifter. Slap whatever you want on top of it with a docking ring (5 ton weight budget) and it'll deliver it to orbit at 80 Km. Shotput launch sequence: Ensure destination's docking port is aligned n/s Orient map view and wait for launch window (target approx 60* short of KSC) Switch to sequence view, run up engines to full, engage SAS Launch Jettison 1st stage when dry begin tipover to prograde heading (generally 090) at 7Km altitude Jettison 2nd stage when dry launch profile keep an eye on 3rd stage and apoapsis. Jettison 3rd stage when dry. Interrupt burn when apoapsis reaches 80Km. 68* pitch at 15Km altitude 45* at 25Km altitude 23* at 35Km altitude 0* at 45Km altitude Stage 4 prograde until dry or until periapsis is about to become established >0. If periapsis >0, burn stage 4 to de-orbit. Jettison stage 4. Courier mission sequence Accelerate prograde to establish 80Km orbit. Deploy solar panels Target destination execute burn to match ascention execute burn to rendezvous (prograde if target is behind you and retrograde no less than 70Km periapsis if target is ahead) begin intercept at apoapsis end intercept at safe distance from target (0.0 closure rate) orient n/s target destination dock and engage RCS. maneuver to docking orient and maneuver payload/ destination as necessary for desired orbit and attitude. decouple from payload maneuver to safe distance disable RCS deorbit burn until periapsis =0. If dry, use RCS. Orient prograde and jettison booster Orient retrograde retract solar panels deploy chute after reentry burn SAS off disable reaction wheel and guidance recover vehicle I'm thinking I can tweak the design a bit to reuse every scrap. I'll re-post it once I've upgraded it enough to warrant. Happy building! -Slashy Edit... Shotput/ Courier 2.0 (shown with 5 ton supply canister payload) Testing Shotput/ Courier 2.0. Changes include: -parachute recovery of all stages for refurbishment and reuse -Moved RCS thrusters to guidance package for recovery -added protective casings to solar panels -added landing struts to guidance package for terrain landings. If it tests out, I'll update with the vehicle file.