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Rough is correct, for reasons mentioned above. Terminal velocity is dependent not only on the characteristics of the atmosphere, but on the characteristics of the craft, and can change dramatically over the course of the flight (as a case-in-point, this is how parachutes work, though I admit that I do not know whether this is how their simulation works in the game). I can give you an explanation. That chart was an attempt to provide information that would be useful to players who had to work with few mods, few stock indicators, and a weird atmospheric model. None of those things is still true. It comes from this challenge: If you're not familiar with the Goddard problem, the short version is that it is an efficiency problem. The slightly longer version is that it is the question of how best to control a rocket to get the most altitude out of its propellant while taking into account the drag and atmospheric characteristics. It's of practical use because more efficient control means getting more out of a given load of propellant, but because of the reasons mentioned above, it's very specific to a particular rocket in a particular atmosphere. It's also only useful for a particular trajectory: straight up. Reaching maximum altitude is rather useless when the goal is to achieve orbit: the principles are different and the optimum solutions have almost nothing to do with one another. That being said, KSP is great for simulating these kinds of problems because it offers true reproducibility. It's also terrible for getting practical results from simulating these kinds of problems because it's not simulating other real concerns such as unavoidable variations in manufacturing the rocket, changing atmospheric conditions, or a fully-accurate aerodynamic model, among other things. However, at the time that it was made, that chart did provide some useful information. I'll provide details in the spoiler, mainly because it discusses completely outdated game mechanics and I don't want to create confusion. That being said, I think that this is actually a very interesting piece of KSP history, because this is from 2012 and people were still trying to figure out the mechanics of the game (and for a lot of them, spaceflight in general). Have a look at these cutting-edge graphics: Note the lack of lights, gear, and abort action groups. Also note that SAS was in the staging and had a finite capacity. Note the lack of info panels and KSPedia. Suffice it to say that there once was a time when people got to orbit by launching straight up and out of the atmosphere, then turning over and burning horizontally to make orbit ... hopefully before falling back into the atmosphere. At the time of this challenge, the atmospheric model was something like ten times more dense than what it ought to have been. Eventually, people settled on a hybrid approach to ascend in something (very) roughly approximating a gravity turn. What you see here is some of the experimentation that the players performed on their own to try to figure out those optimal ascent and control profiles. The terminal velocity table came from that. It worked at the time, so it made it into the wiki. After version 1.0 and the new model, someone noticed that a table of terminal velocities and altitudes no longer made sense for general use. It's not a matter of updating the table with new values for Eve: general values simply don't exist. An atmospheric density table would be nice, but density varies with temperature, which varies a lot with latitude and time of day, as well as altitude, so a table probably doesn't make much sense compared to an equation, or at least an algorithm. More pragmatically useful would be a list of good landing locations that combine high-altitude plateaus for launch with proximity to multiple biomes for research. Eve's rotation period is nearly four (Kerbin) days, so there isn't much to be gained from landing at the equator (55 m/s of eastwards rotational velocity instead of Kerbin's 175 m/s), but landing four kilometres above sea level is useful to avoid both the density and the heat of Eve's lower atmosphere. There is the idea that, given Eve's greater and more constraining challenges, the kinds of rockets needed to ascend from Eve's surface will be much more generally similar than the many and varied vehicles that come from Kerbin. In such a situation, you can make simplifying assumptions about the nature of these rockets to get a generally applicable range of solutions to the optimal ascent problem. However, those solutions are still dependent on the type of rocket, not on the planet itself, and so still wouldn't really fit on the wiki. But if you wanted to make a tutorial thread, however, then that would be a fantastic idea.

Build it like any other rocket, though you may want to preserve the aircraft shape by linking it to the launch stack by the belly rather than the rear, like the space shuttle. The only real problem is that the lifting surfaces the aircraft needs will strongly draw the rocket "upwards," and you'll need to account for that. Give the ship lots of control authority and maybe rotate it so that this trend works in your favor and helps make the gravity turn. Or you can use the really messy fix of making the craft symmetrical by copying the plane part on each side.

yes, of course it is. the terrier quadruple its deltaV in vacuum - though i don't understand how you can have 2 stages both based on terrier engines with similar twr there, unless it's some mod to rescale (i checked, only the terrier has that atmosphere Isp). anyway, this leaves you with 2300 + 2300 + 1200 = 5800 m/s. you should actually go to orbit and have half fuel left in the second stage. if you don't, then there are two possibilities. maybe the rocket is a lot more draggy than you think - just because it looks aerodinamic, it doesn't mean it is. aerodinamic is glitchy. or maybe you are not doing your gravity turn correctly

There's a lot of factors at play here, the biggest of which is probably your gravity turn profile. The time you spend in the lowest parts of the atmosphere should be short either way, and the amount of time you wait till beginning the turn can make a big impact on dV margins. I think either Matt Lowne or Stratzenblitz came up with this technique for getting consistent turns, but a good way to repeat the same gravity turn profile consistently is to turn to five degrees on your navball right after launch then set SAS to prograde at a certain altitude (or speed, I cant remember but the latter may be better for low TWR launchers). Experiment with when you begin the turn and see what works most efficiently. Addendum: It was Stratzenblitz (3 parts to Duna, Ike and Minmus) and they began the gravity turn at 80m/s. That was for their particular vessel though and it resulted in the vessel intentionally overheating so you may benefit from experimenting with the technique.

I have been working on this EVE SSTO for a couple of days. Exploring how aerodynamics work in EVE atmosphere has been a lot of trial and errors. So far, I can get to 12km above sea level using propellers, and from there I switch to the rocket engines. The best I got is about 77km (AP). I have successfully built several SSTOs for Kerbin and Laythe, but EVE is just on a completely different difficulty level. How can I perfect this prototype into an actual EVE SSTO? More dv? Alternative engine setup? Aerodynamics? Better gravity turn? Drag seems to be a major problem the mk2 cargo bay can generate a lot of drag, but switching to service bay also generate quite the amount of drag too. (Don't worry about the change in the center of mass, I have altered how fuel gets drained from each parts. The center of mass doesn't change until the last fuel tank starts draining.) Nov 28 Update: I done did it! Thanks to all your tips, I made it to the low Eve orbit. Scroll down to see the pics and download link

pitching or yawing is only a matter of how your rocket is rotated on its axis. completely irrelevant. just aim for 90 degrees. it's not different from orbiting kerbin. what do you do when orbiting kerbin? as soon as atmosphere is no longer a concern, you aim 90 degrees. unless you want a polar or retrograde orbit, but let's not make confusion. on mun is the same, except that there is no atmosphere and so you can go for a much steeper gravity turn. also, with the lower gravity you need a lot less speed to orbit. incidentally, as long as you pick up horizontal speed, any direction will give you an orbit. 90 degrees is just more convenient for inclination

You would need an autopilot mod, such as Mechjeb, or Gravity Turn

your burn is too long and you start it too late. if the burn goes too long, you will reach apoapsis and then start going down. and since you are taking a very steep ascent, you go down fast. you need to ensure to finish your burn at apoapsis, hence you should start the circularization burn earlier. you should also make a much stronger gravity turn, because the way you are doing it, orbiting is a lot more difficult. you should be at least at 1500 m/s when coasting to apoapsis, possibly more. if you still make a mistake and end up with a low periapsis in front of you - your periapsis is in front of you, like in figure 4 and 5 - you can burn radial (away from the planet) and fix things. if you keep burning prograde, what happens is that you also raise apoapsis, which is why your apoapsis went way up in your last successful attempt. in general, if you burn prograde at periapsis, you raise apoapsis. if you burn at apoapsis, you raise periapsis. but if you burn in any other place - which is what you are doing, because your trajectory is so steep that you are only near apoapsis for a very short time and your burn is longer - you are going to raise both apoapsis and periapsis. so what happens to you is that you pass apoapsis while still burning, you move forward, and from then on your burn is used to raise both periapsis and apoapsis. and the further you go from apoapsis, the more your burn is used to raise apoapsis instead of periapsis. eventually you get to the point where you have a 500 km apoapsis and still a 40 km periapsis. and by now you're so close to periapsis that burning prograde does little good. this is why, in contradiction with what suggested by @James Kerman, i recommend finishing the circularization burn slightly before apoapsis (his advice still applies to most maneuvers). it's a lot easier to recover from errors like that. i set up for a 65 km apoapsis, and then burn prograde a minute or two before that. burning before apoapsis will also raise apoapsis, so i will finish out of the atmosphere once the maneuver is done. the advantage of this is that burning before apoapsis is going to retard your apoapsis. you look at the corner of the screen where is your time to apoapsis, and you will see that at some point, the countdown will revert and the time to apoapsis will start going up. at this point i stop the burn. wait a bit, then burn again. apoapsis is getting closer, closer.... the moment it starts getting further, i stop the burn and wait a bit more. until i enter orbit 10 seconds from apoapsis or so. very self-correcting. another way is to use a radial component. to orbit you burn prograde, which means parallel to the planetary surface. but you can also burn radial, which means perpendicular to the planet surface, in this case pointing upwards. it has the effect of raising orbit in front of you, but lowering it behind you. so, you are at apoapsis, and now you'll fall down towards periapsis; but if you burn a bit above prograde, you can raise orbit in front of you as fast as you are falling, therefore staying at apoapsis indefinitely. and it's not even expensive, it's only a small deviation over prograde; in fact, i think it's one of the most effective ways, though the main difference is for a proper gravity turn (again, i reinstate, you could save at least 500 m/s by making a better gravity turn). anyway, the way to do that is to press alt-f12, go to physics, then aerodinamics, then display aerodinamic window in user interface. it will open a window will a lot of aerodinamic data, which will be of little use to you because you're in near vacuum anyway, but one of those data is ascent speed. before apoapsis, you are moving up, so ascent speed is positive. after apoapsis you go down, ascent speed negative. when you reach apoapsis and ascent speed goes down in the negative, point your nose a bit above prograde, and ascent speed will start increase again. gradually it will become positive again, as apoapsis is again before you. you can go back to burning prograde at this point, or perhaps you can even burn downward if needed to compensate for too much ascent speed. anyway, by pointing your nose just above prograde and making small corrections, you can stay at the same altitude during all the circularization burn. this is also a very self-correcting technique. in fact, making the circularizaton with a maneuver node is a very uncomfortable way of circularizing. i have no idea why some people prefer it, cosine losses are going to mess you up. i always use one of the two self-correcting techniques i described above. p.s. your rocket has extremely high values of twr, especially for the upper stages. you could be a lot more efficient by using smaller engines, you'd cut down on your dry mass a lot. of course, with lower twr ascent is more difficult, so you should improve on that before lowering twr.

Taking a gravity turn angle of sixty I still ran into the same problem.

Looks like you are on a very steep ascent, this means you are moving quite slowly when you get to apo. I think you need to be more aggressive with your gravity turn to stretch out your arc. This will give you a higher velocity at apo and make it easier to circularise.

Are you attempting to get into orbit with a single burn from launch? If so that is quite hard and I think what is happening is that your node is going to need an element of anti-radial to swing your orbit circular and doing this means you are spending lots of time and DV in the atmosphere which drags down your periapsis. Because Kerbin is a fairly small celestial body I normally break launch into orbit into 3 parts; 1) Launch and begin your gravity turn to get a ballistic arc until you are a bit over your target apoapsis (the reason for this is also to account for atmospheric drag) and stop burning. 2) Make a node a few seconds before apoapsis and then just add prograde until you get your required periapsis. 3) That burn (we call it circularisation) should then put you into your desired orbit.

I asking about accent profile as a hole actually the content of the post was incomplete I should have been more specific When to start gravity turn and what is optimal speed at a given range of altitude

Testing results: MOAR POWER worked great - I doubled the thrust on each design and now they reach orbit with plenty to spare using a standard gravity turn via MechJeb. Thank you all for your help!

I'd prefer at least 200 or 300 m/s for docking then. As for low TWR, what it means is that: 1. if I try to launch vertically with a standard gravity turn, it takes a lot of time to build up vertical speed - during all that time gravity is pulling down and costing delta-v. 2. If I use my plane ascent profile, I lose slightly more delta-V to drag. However, I cans till get going quickly as the wings help provide lift to keep the SSTO in the air, while the engines provide half vertical and half horizontal thrust. 3. TWR is really only an issue during the earliest parts of the ascent, as when the craft burns off its fuel it becomes much lighter. As for wing placement, the center of lift is where it should be on a good plane. It's slightly below the center of mass so the wings can sort of shield the fuselage, but the plane flies well. The plane is balanced so that the center of mass does not shift when fuel drains, like a jet SSTO, and there is enough wing area to not be too much of a brick. A fighter jet it is not, however.

I'm going to assume that when you say "SSTO", you actually mean "spaceplane" instead. Because it's trivially easy to make a standard rocket go single stage to orbit with plenty of dV left over. Your plane has 4000m/s of vacuum dV, which should be plenty, given that it should only take about 3400m/s to reach low Kerbin orbit with a standard gravity turn trajectory. Hence, your choice of trajectory is to blame for losing about 600 m/s worth of dV along the way. Getting more TWR and climbing a little longer can certainly help improve this. But keep in mind that one major contributor is your launching off of the runway. That's just never going to be as fuel efficient as a start from the vertical pad. Also, if getting more TWR means that you lose maximum dV in return, you may find that you gain little to nothing along the way. Your maximum possible upside from trajectory optimization is less than 600 m/s; if you stick to the runway start, it's probably in the realm of 400 at most. Switching from a Dart to a Swivel will drop your dV by about 300 m/s, depending on how much the extra weight is going to impact your plane. So you might gain about 100 m/s tops when reaching orbit. Workable, but not ideal. (Of course, all of this is guesstimated, so your results may vary ) Another thing you can do is take a page out of the Space Shuttle's book, and make do with flying like a brick. As in: bring less wing, or bring more tank. This makes your landing approach harder, but it'll give you more dV to work with in orbit. You're at less than a 12x multiplier of your Isp in terms of dV, so you aren't that deep in the diminishing returns of your mass fraction just yet. If you can get back to like 4000m/s while mounting a Swivel, without increasing your wing surface, that should allow for more fuel leftover in orbit.

That's probably going to be fine. It looks like you have a terrier like my example above. If you switch the dV reading to vacuum, you'll see the dV of your upper stage with the capsule shoot up. You also might want to fire your core engine at launch and just leave the throttle down so you have some real pitch and yaw authority. Would make doing your gravity turn easier.

When you ask for help with a rocket design, it really does help to include pictures of said rocket- or even better, a video, or better yet the craft file- or else all we can do is guess at the problem. There's a big difference between a vertically and horizontally launched SSTO, between an SSTO rocket and an SSTO spaceplane and things like engine and payload placement can create vessels that handle in dramatically different ways. What speed do you reach before you start your gravity turn, what altitude are you at and how far do you pitch over? Starting your turn earlier (50-100m/s) and pitching only slightly (5-10 degrees) minimises the forces applied to the craft from aerodynamic drag and is less likely to cause the rocket to start flipping and tear itself apart, whereas waiting until you've built up a lot of speed and then aggressively turning causes a lot more stress on the craft and is more likely to cause things to break apart. Try to stay close to the prograde marker on the navball to minimise drag, throttle your engines back once your time to apoapsis reaches about 40-50 seconds and keep burning until you reach the desired apoapsis, then do a circularisation burn- if you do a gravity turn right, the final burn to enter orbit should be pretty small. SSTO rockets are hard. You need to build something with the thrust to lift off the ground, the delta-V to make it all the way to orbit and still carry a useful payload, then preferably return it to the surface in one piece. Atmosphere-optimised booster engines are inefficient in space, while vacuum-optimised engines don't work well (or at all) in the thick air near sea level; aerodynamic features are critical at low altitude, but dead weight in space; carrying extra weight reduces delta-V, requiring more fuel, meaning more weight, meaning more thrust is needed, meaning more engines, meaning yet more weight, and so on. It takes a lot of effort to make a functional SSTO rocket, never mind a good one, and there's a lot of trial and error involved. Don't give up

By uncontrollable, do you mean that it just tips forward/backward on launch, or it just spins out of control when you are in the atmosphere? If it's the first one, you could try rotating the engines on the actual shuttle piece towards the center of mass, as said by Cantab, but if that doesn't work for some reason or is just too hard to get working, you could simply just mount two shuttles on either side of the big fuel tank like this: This works quite well, but is pretty cursed and might not satisfy you if you're trying to build one similar to or a replica of the American space shuttle. If it is the second thing, it might be caused by there being too much weight at the top of the craft, which you can fix by simply doing a steeper gravity turn, adding more fins to the sides of the orbiter, or maybe both if one doesn't fix it. Again, adding fins might ruin the American-space-shuttle feel your going for, but do remember that the space shuttles were some of the hardest to fly spacecraft ever made, and you might not get the hang of the art of space shuttling on your first few goes. Hope that helped, Jaq

nope, no RO or other tweaks. after reading all the stuff RO does, i decided some of that was too annoying to keep track of. as for other tweaks, I decided to go rss to increase difficulty, balance tweaks would defeat the purpose. The rocket is the one here As it is, it keeps crashing the pc because it's too big and complex. I know that with one less stack of boosters the pc can handle it, but i missed orbit by some 200 m/s. I'm trying to see if I can optimize the ascent profile to recover those 200 m/s. It's a big asparagus stack, it starts with twr 1.8 and it gradually goes down as more boosters are discarded. Last stage is twr around 1, with 2000 m/s. Everything before that is no less than 1.4 I don't want to use mechjeb or anything. plus, seeing as how mods increase lag and my pc is already crashing, i don't want to add mods just on principle. Normally, I would have gone for a more horizontal profile. Especially with a rocket so big, aerodinamic losses are less than gravity losses - despite the draggy payload. However, a flatter ascent profile means that I will level up early. This can easily be countered by pointing upward of prograde just enough. But that beast is already very draggy - even on a purely vertical ascent, maxQ is around 30% of weight; pointing above prograde while in the lower atmosphere would increase drag immensely. Which is why I was reluctant to do it. Also, I've seen real rockets and they go straight up for several km before starting the gravity turn, so I figured it could be the best way. I will have to try that, though. If nothing else, because I already spent 2 whole afternoons trying to launch that monster and getting the pc crash every single time. Once I even reached the second-to-last stage, wasn't even lagging so hard anymore, and then it still crashed.

I ask those with experience in real solar system how the gravity turn goes. in the stock game, you generally want to turn very fast, starting already around 50 m/s, being down at a 45° angle already at 500 m/s. that because in stock you orbit at 2200 m/s, you want to be horizontal at that speed. in real solar system, at 2200 m/s you still miss over 5 km/s to orbit. I had experiences where I did start angling down early, and I had to pull up later. on the other hand, I am now trying to go straight up until around 15 km altitude, and while this enables a proper gravity turn afterwards, going straight up at 700 m/s doesn't feel right. it can't be optimized, can it? and orbital launches in rss last way too long for me to want to go by trial and error. any good tip on when I should start turning?

I'm attempting to build a massive SSTO rocket but when I attempt to start turning in the air my rocket instantly explodes. I'm using part clipping to get the diameter of the rocket smaller but from what I understood that shouldnt affect the physics of the craft. The flight log says that there was a structural linkage failure between two adapters high up on the rocket in a random spot. If it helps I'm using vector engines attached to an engine plate onto a 5m fuel tank.

Note for future reference, you can launch a ship with the probe core upside down without changing anything so long as you account for that. Turn SAS on and lock to RETOGRADE, not Prograde. Assuming you use that to assist your gravity turns. If not, it's a bit harder but just remember what you're doing as you manually control the craft. Mechjeb and other autopilots will probably fail because they don't have brains and just follow code. I don't know about those as I don't use autopilots to launch.

Forgo the gravity turn. Just luanch straight up and turn right.

Which TWR is "right" depends on a lot of factors, including how you like to fly and what sort of payload you have. In general, you never want to go higher than 2.0, and usually no lower than about 1.2. The optimal rocket design changes quite a lot based on the TWR. If you have a very "draggy" payload (which most of your rockets look to be-- you've got a lot of flat surfaces, these are not very aerodynamic), then usually a lower TWR tends to work better, at least for the first several kilometers of ascent. This is because a high TWR causes you to go too fast when you're still too low, so you're wasting all your fuel trying to shove a draggy thing through thick soupy atmosphere. Taking off a bit more slowly, to keep drag down, may help. (Normally, the solution people go for is to make their craft more aerodynamic and then raise the TWR, which is more fuel efficient. But if you have an awkward payload that has to be draggy, you may have better luck starting off a bit slower.) In general, the most efficient (and stable) ascent path is called a gravity turn (that's a good term to search the forums for, if you'd like to read about it). The basic idea of a gravity turn is that you nudge the craft just a little bit eastward, practically right off the pad... and then you just set SAS to hold all the way up. No steering needed, you're just going all the way, as your ship gradually and naturally pitches farther and farther eastward as it climbs. Just how much of an initial "nudge" you should give it is the tricky part, of course. There's no one right answer, because it depends on your TWR and how aerodynamic you are. But there's a fairly straightforward way to find out: Launch to the pad. Take off! Immediately upon lift-off, pitch a small amount eastwards. (Just take a guess, as to how much.) As soon as you do that, set SAS to hold Don't do any further steering. The only time your hands should touch the controls is to jettison empty stages when the time comes. Take a note of what your trajectory is like when you reach an altitude of 10 kilometers. Specifically, how fast are you going? what angle are you pitched at? Ideally, you should probably be pitched roughly 45 degrees at that point, and traveling something like 300-400 m/s. If (at 10 km) you are going too fast, or pointing too vertically: This means you didn't pitch quite enough in step 3. Revert to launch, and repeat, and pitch it a bit more this time. If (at 10 km) you are going too slow, or pointing too horizontally: This means you pitched too much in step 3. Revert to launch, and repeat, and pitch it a bit less this time. Keep repeating steps 2 through 7 until you're going about the right speed and angle when you're at 10 km. At this point, you're in the pipe and probably going to space, as long as your fuel holds out. The above is only a very rough rule of thumb, but I've found that it works pretty well for most people most of the time, and at least is a pretty good starting point for flying your ship. Really don't do that. Very very fuel inefficient, and will waste scads of dV. That's also very inefficient, and likely to cause control problems, as you have no doubt discovered. The moral of the story is: You want your rocket to be traveling at all times. Never point more than just a couple of degrees off while thrusting, if you can help it.

This one got to orbit OK for me out of the box, but it was a very delicate, challenging launch. The thrust at launch is indeed quite low, but that's more of a minor inconvenience than a launch-wrecking problem. The real difficulty was the very low thrust after the side tanks are emptied and detached (the initial TWR of that stage is something like 0.3). To deal with that, I performed a very gradual gravity turn (tilt eastward just enough to notice the prograde marker moving slightly away from vertical, then straight up till at least 200 m/s or so, then lock prograde), which incidentally helps with flipping, then when the prograde marker started to drop too fast toward the horizon, I kept the nose pointing thirty-ish degrees above it until well outside the atmosphere (locking prograde again once the time-to-apoapsis stabilized at about 8s and started ticking back up). This managed to pull the prograde vector up just enough to give me time to get up to orbital speed. That probably isn't too easy to follow if you haven't done something like that before, so I would recommend making the craft easier to launch instead of trying to replicate what I did with this one. My ideal launch profile is to tilt a degree or two eastward off the pad, lock prograde early, reach 45 degrees around 10km, cut thrust when the desired apoapsis is reached, then thrust again to circularize. Try to keep all your stages' initial TWR at or above 1.0 and you'll have an easier time.