Streetwind

Great, you can use Google But what is your favorite of the lot, and why?

Educate us, then, as to how we best provide the 15 charge/sec that each ion engine requires?

What space enthusiast doesn't love a little tech ****? Let's talk about rocket engines. Shiny, powerful, high-tech rocket engines, marvels of engineering. Can be large or small, old or new, from any nation around the globe - as long as they represent mankind's best. I only ask to limit this thread to engines that have actually flown. I know of many interesting concepts such as nuclear thermal rockets, massive linear aerospikes and other near-future propulsion ideas... but I want to talk about what we have achieved so far, not what we might achieve in the future. I'll start off with the following, an engine many of you might be familiar with: Rocketdyne RS-25 First flight: April 1981 Max thrust: 1,900 kN (ASL) - 2,300 kN (Vac) Rated Isp: 363s (ASL) - 453s (Vac) Fuel type: LH2/LO2 cryogenic bipropellant Perks: - Self-igniting and restartable - 10° wide gimbal action - Fully reusable Cons: - Expensive and time-consuming refurbishing process almost nullified advantages of reusability - Storing liquid H2 in space is challenging - Only moderate thrust, not suitable as a liftoff engine; needs SRB assistance to get off the pad Why it is remarkable: - Main engine of the U.S. space shuttle - Outstanding fuel efficiency; burned from liftoff all the way to orbit - Exceptional maneuverabilty afforded by wide gimbal - Fairly reliable; despite recurring pre-launch issues, only one of 135 shuttle flights saw a single (out of three) engines fail in-flight - Even 35 years after introduction, the upcoming Space Launch System (SLS) will rely on (expendable variants of) this engine - Green engine: LH2/LO2 combustion produces only water vapor What engines do you guys think should be counted amongst mankind's greatest, and why?

The one thing I really don't like about the Outerra engine is the way it renders a planet from orbit. Check out some videos if you want to know what I mean. If you're expecting the wonderful blue sphere of earth, you're going to be disappointed. All you'll get is a glaringly bright milky-white ball. Think "distance fog" in normal game engines, except the entire atmosphere is made of it. You can see absolutely nothing of the surface from space. No clouds, no land features, no colors.... just overbrightened white fog. The rest, admittedly, looks great. For a game set on the ground, it'll be great. For a spaceflight sim... not so much.

The thing is, the sun mission can be flown only once, while Mun landings can be done 15 times. And to get the full science value, you need to have completed most of the tech tree already. You're not getting 1000 science in a starter craft that flung itself out there to collect a crew report and EVA report.

When it got time to put kethane scanning probes into orbit, I experimented with ion thrusters... but in the end, I went with conventional engines again. My ion probe weighed 0.6 tons, with 0.5 kN thrust. My conventional probe weighed 0.8 tons, with 1.5 kN thrust. That's almost three times the thrust/weight ratio even when fully fueled, and increasingly more as it expended fuel. The conventional probe could do everything the ion probe could do as well - travel all the way to Mun and Minmus, place itself into a polar orbit, circularize at the desired height and so on. And it did so in a much, much more convenient and comfortable way. Admittedly, the ion driven probe had more than 90% fuel left after completing its maneuver, while the convenional probes had barely enough left to maybe deorbit themselves at the end of their useful lifetime. But well, what am I going to do with all that leftover fuel? The probe is not going anywhere else anymore. You really need to fly very long distances if you want to make ion engines worthwhile, and those really long distances are going to take a really long time. There's not really much of a way around it.

That's unfortunate. Here's hoping that it somehow survives till February 8th...

Who says you have to match Minmus' inclination? You can make your orbit level with the plane of the solar system. Then at worst, Minmus' own orbital motion gives you a small nudge upwards or downwards at the ascending or descending node, respectively. That can probably be corrected with RCS alone in a midflight course correction. soon after leaving Kerbin's SoI. And if you happen to start at the highest or lowest point above/below the plane, then you fly completely level by default - just a little bit above or below the plane. I don't see that as a bigger issue than trying to hit a planet in an inclined orbit from Kerbin's level one. It's just the reverse process (and maybe starting from Minmus can even let you hit that planet more easily).

Tangentially related - I've seen some people suggest that a refueling station at Minmus would be a good idea. After all, if you are at Minmus then the dV required to leave Kerbin's SoI is miniscule because you already expended most of it getting to Minmus. And the low gravity means that adjusting your heading, inclination and other such things are extremely cheap. Finally, you can also take advantage of Minmus' own speed relative to Kerbin (either on the outer pass for accelerating towards the outer planets, or on the inner pass for decelerating towards the inner ones). Getting the fuel to the Minmus depot would be trivial in the presence of Kethane since mining it directly on Minmus and lifting it to orbit there is effortless in the low gravity. On the other hand, I see lots of advice to burn directly from Kerbin orbit into an interplanetary transfer, because of the Oberth effect. Since that effect is directly related to gravity, Minmus would have very little of it. The question is then, does that make Minmus a better or worse departure point? Oberth effect versus intrinsic orbital energy and refueling at the edge of the SoI... what wins?

Or a radial attachment port.

Makes me wonder what kind of thrust you can achieve with a 4 kg thruster. After all, the KSP ion thruster weighs much much more - 250 kg. It produces 500 newton worth of thrust. Of course, ingame parts are scaled down to match the tiny Kerbals on their tiny planet in their tiny solar system...

Unsure if you've heard of it before or not - but there's a japanese manga and animated series named "Planetes" (from the ancient Greek word for "wanderer", from which the word "planet" is derived, as an object wandering across the sky). It features a relatively hard sci-fi scenario set in 2075. Pretty much exactly what you're aiming at. It was critically acclaimed but remains rather obscure due to not being a "typical" anime (you won't find fanservicy magical girls or superpowered fighting tournaments in there). It starts off with addressing the issue of space debris, but later delves deeper into the sociopolitical climate of the time (large international treaty organizations and massive private megacompanies as the center of space development), as well as philosophical questions as to what the heck humanity is doing up there anyway, and why.

This isn't for anything specific. This is a general purpose improvement to autopilot functionality. The idea is that all rockets or vehicles designed for powered landings will be capable of doing this in the future.

Not really. We already have very powerful propulsion systems that can take us anywhere in the solar system with ease. The issue is that these propulsion systems need fuel, and that fuel needs to be lifted out of earth's gravity well, and that is prohibitively expensive. With cheap trips to orbit, large orbitally built and fueled exploration craft advance from "are you insane" to "we might actually have a budget for this". Just think of how much further away Minmus is from the Mun than the Mun is from Kerbin. Yet the delta-V required for a Mun transfer is 5360, and the delta-V required for a Minmus transfer is about 5420. The difference is utterly negligible next to Kerbin's massive gravity well. And the same is true in real life - as soon as you break free of the Earth, relatively tiny amounts of fuel used in small engines can get you almost anywhere. The fuel cost difference between a Moon rocket and a Mars rocket is a few percent on the launchpad. The reason we haven't sent humans to Mars is not propulsion technology, it's money, time and health concerns. Sure, one could argument that with a new kind of propulsion system, you could use a much faster transfer on the same small amount of fuel. But it's not a hard requirement. Lower the cost to orbit, and you can simply lift that much more fuel up there and use conventional engines on the same faster transfer. In my opinion, space exploration stands and falls with our ability to conquer Earth's gravity well in a consistent and efficient fashion.

Something to add to the already plentiful answers to the question of "why should I use part X over parts Y and Z if the end result is identical?": Keep in mind that, while you are playing career mode, that is actually a very new thing that was only just added and isn't nearly complete. For the longest time, KSP only had sandbox mode. And in a sandbox where you always have access to everything, you do not need redundant parts. If there was something that's clearly worse than all other options, why bother implementing it? For this reason, all the parts that exist do so not because they are upgrades, but because they fill a different niche that no other part can fill. Small tanks exist because sometimes a large tabk is too much. Large tanks exist so you don't have to stack dozens of small ones. As a result, in career mode you will find that 95% of what you research actually won't be an upgrade to anything, but either a sidegrade (something that is just as good, but looks different/fills a different niche) or an aesthetic option (some of the highest tech nodes contain freeform building toys like structural beams and panels). You can and will still use much of what you had right at the start in your rockets even after completing the tech tree - because sometimes, those things are just the thing you happen to need at the moment. Nose-mounted parachutes, radial and inline decouplers and the excellent LV-T30 never get old.

The confusing thing about orbits is that the concepts of "faster" and "slower" are upside down. If you increase your speed, then the orbit gets wider. And a wider orbit takes longer to go around the planet. That means the faster you fly, the slower you are for rendezvous purposes. If you want a ship that is behind you to catch up with you for a rendezvous, you need to accelerate to widen your orbit. If you want to catch up to something that's ahead of you, you need to decelerate for a tighter curve around the planet. This works until you have visual contact with your target, at most two or three kilometers apart. Then you can start gently steering your ship directly towards your target, because at that point variation in your orbits is negligible and the mere act of steering towards the target helps further lessening the difference.

The first large engine you get is designed for vacuum use only, so it not surprising that it (or the medium engines) can't lift the larger tanks. You can however strap solid rocket boosters to the outside (not the underside) of the large tank using radial decouplers to get it off the ground. Even better than solid fuel boosters are liquid fuel boosters, which are basically just a medium tank with a medium engine like the LV-T30 underneath. Since a LV-T30 has easily enough thrust to lift its own tank, it can help lift the underpowered center tank. And if you have 4-8 of these boosters all around it, that's a lot of thrust. Your problem is basically solved by "moar boosters!!!"

Basically you have the "data" that you transmit, and then you have the "value" of said data. The latter acts as a multiplier on the former, and the result is science points gained. However, "value" tends towards 0 with increasing amounts of science points generated. Let's imagine a hypothetical experiment worth 100 science points if you return it, and worth 20% of that if you transmit it. The transmission is 50 Mits in size, and if you return it once, you "get all the science" and subsequent returns or transmissions do not give you any extra (there are experiments ingame that you can repeat for extra science even if you got the full amount the first time, but this is not one of them). 50 Mits "data" * some "value" * 100% "yield" for returning = 100 science ----> "value" is 2, for 50 * 2 * 1 = 100. This is what you get for returning the experiment intact. However, let's assume that you transmit it instead. You now calculate 50 * 2 * 0.2 = 20 science. And then you reset and return it (or you have a second copy that you return). What happens is that because you already transmitted some data and got some science, the returned experiment isn't worth as much anymore. There's less new stuff for your scientists to learn that they didn't know about already. In game terms, the "value" goes down. After your transmission, you can still return the full experiment, but your science yield will be merely: 50 * 1.6 * 1 = 80. The return multiplier is still 100%, but the value multiplier decreased from 2 to 1.6 because it was already partially completed. This can easily be seen if you don't have the experiment just once, but for example five times. And you transmit all of them instead of returning it. First transmission: 50 * 2 * 0.2 = 20, for a total of 20 out of 100 completed Second transmission: 50 * 1.6 * 0.2 = 16, for a total of 36 out of 100 completed Third transmission: 50 * 1.28 * 0.2 = 12.8, for a total of 48.8 out of 100 completed Fourth transmission: 50 * 1.024 * 0.2 = 10.24, for a total of 59.04 of 100 compelted Fifth transmission: 50 * 0.8192 * 0.2 = 8.192, for a total of 67.232 of 100 completed

There's a different solution too, you know. You could play sandbox mode. This is not meant condescending in any way. The simple truth is that the two game modes are different and will appeal to different player types. If you are someone who enjoys having all parts at your fingertips and building completely freeform, then career mode is simply not offering the experience you're looking for. You shouldn't force yourself to do it because somebody said that it is the only "right" way to play KSP. There is no one single "right" way. I personally enjoy career mode, but I most definitely don't look down on sandbox players. They're usually the people coming up with super-creative designs that blow my utilitarian rigs out of the water, and that's pretty awesome.

I learned by reading up on physics on wikipedia. Looked up a random term I wanted to know - in this case, delta-v - and just followed links and cross-references from there. Browsed easily 30+ pages, all of which had interesting tidbits that helped me along.

I just built my first station yesterday. And with "built" I mean "I managed to launch two parts and dock them together". Considering that I have never done a rendezvous or docking maneuver before, never launched something bigger than a lander before, am completely improvising everything about the station and that the whole thing happens to be in orbit around Minmus and not Kerbin, I'm considering that enough of an accomplishment for now

Ahhh, I see. So it's a result of the fact that parts cannot properly attach to multiple points at once.

Okay, tried it out. This time the engines survived the two-step staging process, and yes, I did see the shrouds fly away with some force. I still got a violent explosion upon decoupling (even before the shrouds got involved, they only split off once you activate the engines). Two of the three decouplers spontaneously ended their existance. Not sure why, but it seems these engines just don't want to play nice. I just hope the explosions remain confined to the decouplers and don't take out the engines again in future flights.

Alright, thanks for the explanation! I'll give it a try. That's quite annoying, suddenly having one engine out of the entire pack of them behave completely different...

...Welp. Yes, I am using a tricoupler. >_< In that configuration, if parts are thrown out symmetrically to the sides, the shrouds won't hit the engines if properly rotated but they'll always hit each other. Will that also cause issues / should I be avoiding multicouplers altogether with these engines? https://dl.dropboxusercontent.com/u/44754370/screenshot7.png