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So, when I'm doing a gravity turn. I always have SAS on, I know how to get into orbit and do a gravity turn. Though, recently when I've been doing a gravity turn. My pro grade pitches slightly up, note that i'm not giving any input for it to be doing that. Not sure why, and like I said. I've done this so many times before, and i've done it really good. Though now that I do a gravity turn, I have this problem. I usually use stock KSP rockets as I'm not very creative. And if its built by the KSP team, its impossible to be a design flaw. The only thing I add onto the stock ksp rockets is the mechjeb case which I usually place at the command pod. I'm not quite sure as to why this might be happening. I'll be sure to answer any questions you guys have!

If the navball switching from surface to orbit causes a large change in pitch when you’re following the prograde marker, you’re pitching too little and/or too slowly. Try pitching over a bit more steeply or at a lower speed/altitude; I tend to pitch 5-10 degrees at 50m/s depending on the TWR, with a higher TWR necessitating a faster pitch. Try to keep your time to apoapsis between 30 and 50 seconds, pitching up/down or adjusting throttle as necessary. On the topic of TWR, it’s usually best to go for 1.4 to 1.8 on the launchpad- too low and gravity losses eat into your delta-V, too high and you’ll get more drag losses plus the extra weight of those high thrust engines reduced your delta-V too. There are a few mods that can automate gravity turns and launches- GravityTurn is a pretty simple one to use but often requires multiple attempts to get the curve right, while MechJeb does many things besides just launches and can be very useful, but the options can be a bit bewildering. It might help to use one of them and watch what they do then copy them yourself to understand how to make a good gravity turn.

First the easy part: if you are already outside the atmosphere - in orbit or on a body without atmosphere - then higher TWR is in theory better. In reality you a) have problems with the precise execution of maneuvers if the TWR is too high and b) you are more interested in dV anyhow, so you usually are quite willing to sacrifice some TWR for more dV. For the low TWR case of orbital maneuvers see @Streetwind's comment about cosine losses during long burns. For landing and take-off in vacuum the TWR can be as high as you want (with the caveats listed above). In the imaginary case of of an infinite TWR (on a perfectly spherical body) you would just burn horizontal directly at take-off, and do a kind of Hohmann transfer from the surface to the orbit. Which kind of answers your implicit question: no, having an extended coasting phase before circularizing is not necessarily a bad thing. For the launch from Kerbin (or Eve for that matter) see @Streetwind's answer. Experience has shown that a TWR of 1.3 to 1.7 on the launchpad is usually a good value. A low TWR will lead to more gravity losses, because you need to steer a steeper trajectory to avoid falling back to the ground. If you have a high TWR (especially once you are outside most of the atmosphere) then you'll want a flatter trajectory to reduce the gravity losses in order to reduce gravity losses and to avoid raising your AP more than necessary. That gives rise to the "keep time-to-AP constant" strategy of launching. But you also don't want too high TWR at launch because that will either cause too high aerodynamic losses (if you do a "regular" gravity turn), or too high gravity losses (if you first go more or less straight up to get out of the atmosphere). I'm sure there is a way to develop a mathematical expression that will give you an optimized TWR for launches from Kerbin, but I don't know if anyone ever bothered to make one. (I know that you would have to pay me real money to do that. )

Ah, okay. Sorry 'bout that. Moving back to Gameplay Questions. So, aiming for a particular inclination exactly is kinda tricky. If you're willing to do a little bit of trigonometry you can work it out more exactly, but generally what I do is just eyeball it, which I find gets me within a couple degrees with a bit of practice; and then I can just manually adjust the inclination once I'm in orbit, which isn't too expensive if it's just a small adjustment. The easiest way, for me at least-- both for the inclination and for getting the longitude of ascending node-- is to eyeball it in map view, but with the view set to Kerbin centric (instead of the default ship-centric view). A common use case for this is when I've taken a contract to put a satellite into a particular orbit, and the orbit is inclined by a fair amount, like 30 degrees or whatever. In such situations, here's what I typically do: Get the target inclination. It's generally specified in the contract wording. Or, alternatively, I can just switch control to a satellite I have in LKO in a perfectly equatorial orbit (I always have at least one), and then check out what the AN/DN says in map view. In the VAB, design my satellite that's going to be heading to the target orbit. (Side note: For launching into equatorial orbit, I always design my craft facing east, rather than the game's default of north, because that makes way more sense to me-- I do my gravity turn by pitching down, rather than yawing right. I used to do this by manually rotating the root part by 90 degrees in the VAB each time, but eventually that got too tedious so I made a mod, VABReorienter, that makes that the default for me. The remainder of this discussion assumes that the craft is facing east to start with, for launching to zero-inclination orbits.) For a zero-inclination launch, I normally face east. Since this is going to be an inclined orbit, after I finish building my craft, I use the rotate tool to rotate the root part (and therefore the whole ship) left or right a bit to match the desired inclination. For example, if I'm going to be launching at the ascending node and the target orbit has an inclination of 30 degrees, then I would rotate my craft to the left (i.e. north) by "a bit more" than 30 degrees. Why it's "a bit more" than the target inclination: This is because Kerbin is rotating, so even when you're at zero velocity relative to the ground, you're already moving eastward at around 174 m/s. So therefore you launch a little bit farther to the north (for launching at the AN) or south (for launching at the DN) than the target inclination. Just eyeball a smidge different, like 3 or 4 degrees. Close enough. Okay, now my rocket is facing the correct direction to launch into the desired inclination, or pretty close to it, anyway. Now launch it to the pad but do not yet take off. You want to get the longitude of ascending node correct. The way to do this is to launch your ship when it's directly under the AN or DN. How to do this: While you're sitting on the pad, switch to map view. By default, the map view is centered on your ship. Change this by double-clicking on Kerbin, so that the view is centered on Kerbin, instead. Rotate the camera to latitude zero, i.e. so you're precisely over the equator looking "horizontally" at Kerbin. Now rotate the longitude of the camera until you're looking precisely edge-on at the target orbit. From this viewpoint, it's collapsed to a straight line passing through Kerbin's center. Note also that at this viewpoint, you'll see the pointy tips of the AN/DN markers just about touching each other, right at Kerbin's center. Now, without moving the camera, start to time warp. You'll need to warp forward a few minutes or hours until your spacecraft (sitting on the launch pad) is directly over Kerbin's center in the camera view, i.e. directly between the AN/DN markers. Congratulations! Your ship is now sitting directly under the AN or DN of the desired orbit. Now's the time to launch. Launch the craft and immediately begin your gravity turn by pitching down, same as usual. Climb to LKO and circularize as you would usually do. You'll have pretty close to the desired inclination, but likely you'll be off by a degree or two. So, after you're well underway (e.g. when you're going mostly horizontally and you've reached the point in your gravity turn when you're pointed, say, 30 degrees or less above horizontal), you can look at the map view and check your AN/DN with respect to the target orbit, and adjust your aim slightly to the left or right for the remainder of the burn in order to correct it. Anyway, that's what I do-- it's not mathematically perfectly accurate, but it gets pretty close and requires only a very small fine-tuning correction burn to make it exactly accurate once in orbit.

30 km is still mostly out of the atmosphere. The pressure there is about 400 Pascals, or less than half of a percent of sea level. There is still drag (it's certainly enough air for aerobraking, for example) but it's not going to materially interfere with your ascent. Yes, you can. Real-life rockets and the Space Shuttle didn't have the throttle range that KSP rockets have, so they would actually pitch down (meaning add a little radial in) to circularise. That wastes fuel but the difference in cost between adding more fuel capacity versus designing a deep-throttle-capable SSME is such that anyone who approved that line of development would have earned all of Senator Proxmire's Golden Fleece awards. I understand that the SSME of itself is capable of throttling down to something under twenty percent, but the pumps have trouble ... suffice it to say that while the capability would be nice, sometimes, the real-life answer really is, 'More boosters!' In any event, you have the basic idea: horizontal velocity is yours to keep, but vertical velocity is not. The entire point of a gravity turn is to trade vertical velocity for horizontal as your speed and altitude increase, within the limits of your thrust-to-weight ratio. A perfect gravity turn is one that exchanges vertical for horizontal velocity as soon as you no longer need it, and does so continuously throughout the ascent. This can result in some interesting-looking gravity turns. For example, Minmus gravity is such that many landers have a surface TWR of around eight or ten, or even more. With such extreme thrust and no atmosphere, the perfect gravity turn on Minmus is to thrust up just long enough to clear the ground and then turn hard over to horizontal: you'll ascend to orbit easily because you have too much engine power to do otherwise. On the other hand, for your Kerbin ascent, you are seeing the opposite end of the spectrum. You need a TWR greater than one to get off the ground; that's non-negotiable. However, staying off the ground is a new problem, and once you begin to ascend, the situation begins to change. As your trajectory begins to look more and more like an orbit, your TWR needs begin to reflect that. Since orbital thrust is only required to be nonzero (although greater thrust means shorter burns), it means that the required TWR begins to drop. Practically, that means that you need enough thrust to counter whatever drag you still experience, and you need enough thrust over that to keep the surface of Kerbin receding faster than you fall, which simultaneously counters gravity losses and gains altitude. Especially when you're in the upper atmosphere where drag is low, and doubly especially when you have a lot of horizontal speed such that the gravity losses are low, that required TWR will be less than one. If you ever decide to try spaceplanes, you'll start to see this much more clearly. Wings to provide lift alleviate the need to thrust vertically, which means that the engines can focus on providing horizontal thrust alone. The main challenges are to reduce drag, and to balance the interests of building up enough horizontal speed while low enough in the atmosphere for the wings and jets to work but also high enough that you won't burn up from the increased drag of the lower atmosphere, but meeting these challenges does not require a TWR of greater than one.

A rocket shouldn't tip over in a true gravity turn because the gravity turn, in theory, applies the thrust through the centre of the mass. Its one gradual smooth turn once its been initiated. However with the WASD controls applying 0%-100%-0%-100% of turn, its a limitation of KSP. But its worth remembering it ought to be smooth. As a VERY rough guide, I've had success with trying to "hit": 30deg at 15,000m 45deg at 25,000m 60deg at 35,000m

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

What you are doing is efficient with KSP physics, but not "realistic" in terms of how real rockets fly. You are doing a very aggressive turn and that causes you to gain "too much" velocity (compared to real rockets) while still in thick atmosphere. Consider experimenting with less TWR, don't turn as sharply, mostly follow prograde on the way up with some keyboard input to steepen the gravity turn.

You phrased it very politely, but this is more than semantics, this is knowledge. Thank you, this was exactly the sort of information I was looking for. That makes sense. Sometimes I have some trouble with roll and yaw during the unassisted gravity turn. This comment made me wonder if I could use the advanced tweakables to disable pitch control from the SAS when I start my gravity turn to let gravity take over but still allow it to maintain yaw and roll constant. Nonetheless, there is something beautiful about a rocket than can ride a smooth gravity turn all the way to orbit without any controls inputs required (other than throttle). Makes you feel like you got the design just right. I read through your drag post. Very thorough and interesting. Some of it is a bit beyond my ken but I did notice one interesting component of your analysis that may be relevant to this problem. If I understood your post correctly, it looks like the drag forces on trailing parts decline significantly at Mach 1. Looking at my screenshot, it looks like my "flip out" happens right as I approach the sound barrier. The fairing solving the problem does suggest that the underlying problem was drag at the front of the spacecraft. Perhaps at subsonic speeds the trailing part drag is sufficiently balanced with the leading part drag that the lift from the fins and the force of gravity on the COM are able to maintain straight flight, but when it passes through Mach 1, the relative increase in drag at the front of the craft as the rear drag decreases is enough to throw the forces out of balance and push it out of straight flight. Thanks! I'll give that a try with my next post. I have few more nagging challenges I may pick your collective rocket scientist brains on.

The most efficient kind of ascent path is typically what's known as a gravity turn. This involves gaining a certain amount of straight-upward velocity, and then tilting the rocket a certain number of degrees in the desired direction (usually east, and often north or south for polar orbits), waiting for the prograde marker to descend to match the rocket's new "forward" direction, and from that point on following the prograde marker in a smooth curve that minimizes drag. If you have a level 1+ pilot or a good enough probe core, you can turn on SAS and simply set it to the "follow prograde" mode. And as mentioned by many others everywhere, there is no single, optimal ascent for every rocket. Finding the best gravity turn path for your unique rocket takes trial and error, even when a plugin is doing it (the Gravity Turn launch autopilot is an excellent assistant and/or learning aid if you want to watch how it tries different paths and see what the results are, just be sure that you have the option to 'revert to launch' before using it). With experience, you'll get more of a feel for what's likely to work well for a given rocket. It depends mainly on two factors: TWR (Thrust to Weight Ratio) and staging. Drag can also be an issue if it's very high (large fairings or a great deal of parts sticking out without a fairing, for instance). TWR determines how fast your rocket accelerates. If it's not above 1.0, you can't even get off the ground. I prefer to keep the starting TWR in the 1.2 to 1.5 range, and though going higher is an option it could also mean that you have built too much rocket for your payload and might be able to save some money by using a weaker engine. TWR will increase over time as each stage expends fuel, reducing its mass and thus its weight while the amount of thrust (typically) remains constant, resulting in a greater acceleration being felt, peaking right before the fuel runs out. Staging affects your ascent by typically causing your TWR to change suddenly, usually decreasing quite a bit as your spent first stage's powerful engines and rising TWR are traded for a more efficient but weaker upper stage engine. If your second stage (or third, etc) doesn't have enough TWR you could potentially find yourself falling right back into the atmosphere if your prograde is too low to the horizon and you haven't gained enough horizontal speed yet, especially if the engine is simply too underpowered for the amount of payload it's trying to push. I'd recommend keeping this above 1.0, but keep in mind that sometimes you need to make sure it's showing you the vacuum stats (rather than atmospheric / sea-level) in order to see the right TWR and delta-V figures, as some vacuum-optimized engines (like the Poodle and Terrier) have abysmal sea-level thrust and efficiency (ISP). How does all this affect your ascent path? If your starting TWR is high, especially if your second stage's is as well, you typically want to make more of a turn away from vertical, and start sooner. If your TWR is low, you want to start later and turn less. Expressing when to start the turn is also often done in terms of your rocket's current speed, such as "start turn at 100m/s" rather than by giving a time or altitude. They're all interrelated along with TWR anyway, and since a high-thrust rocket will gain speed faster than one with lower thrust, using starting speed figures can make it easier to make comparisons and take what you've learned with one rocket and apply it to another. Finally, it's typically best to throttle back when your time to apoapsis reaches about 50 seconds (in the stock game you have to go to the map view and point at the apoapsis marker to see this, you can right click it to make it stay visible without having to track it with your mouse). Try to maintain that time at 50 seconds so that more of your rocket's thrust is applied later in the ascent when the rocket is aiming closer to the horizon. The benefits of this are twofold: You waste less thrust on going up, and you delay causing your apoapsis to reach your intended orbital altitude. The sooner that happens, the larger a circularization burn you'll need to finish gaining horizontal velocity. For "getting into orbit" purposes, a larger circularization burn is bad. That's because having to apply more of your horizontal thrust at apoapsis, compared to at a lower altitude, reduces the efficiency of that thrust, costing you more fuel, according to the Oberth Effect. (Basically, you spend more delta-V for the same effect when you do it at a higher altitude.) It's a bit counter-intuitive, so to put it another way: Applying less thrust during the middle stages of the ascent (when you're aiming more upward) allows you to apply more total horizontal thrust prior to reaching your desired apoapsis height, which saves you from having to apply significantly more thrust at the end of your ascent where that thrust is less effective. The net effect is that you spend less fuel to reach orbit if you throttle back as needed to avoid pushing your time to apoapsis over about 50 seconds until as late as possible in your ascent (often into the 25-50% range, although TWR affects it too).

Now many people wanted to launch. But not me, I wanted to show how I play ksp career normal.after accepting the easy contracts, go to vab from there just pop a mystery goo canister on a random command pod Launch that, I'm serious, launch that. observe the GU, it should give you 3 science. Then take a crew report and a eva report. Then recover vessel. Now that we completed a contract, we should get almost 9 science, accept the "escape the atmosphere" one. Go for engineering 101 in the R&D facility. Keep the GU unit on - we still haven't take all the science yet. Now plug in the new thermometer we've got. Launch it. Log the temperature with the thermometer and the GU unit. Recover it. Then go for basic rocketry. Log the GU unit again for 0.2 science. Do the same in the runway (GU, thermometer, eva report and crew report). Remember to observe the goo unit twice! Now that we've got all science in the pads, lets launch! Keep the science things and add a RT-10. Put a TD-12 decoupler (TR-18A before 1.4). Then put another RT-10. Put a Mk16 parachute on the top. Then remove half of the solid propellant on a random one. I'll suggest the bottom. Remember to pluck 2 thermometers and gu units! Should be something like this. But just a quick note here: Overheating and velocity. Remove a bit of propellant (75 should be good). Your rocket would be accelerating something like 100m/s which means overheating. Throttle the upper stage down to something like 50%. The first stage burns up fast and doesn't hit MAX q so a TWR of almost 4 should be fine. Launch it. Turn on SAS and full throttle (T and Z), press space to takeoff. Store the data. Once the speed reaches 75m/s, do your gravity turn. Once the bottom one finish igniting, stage it, then ignite the upper one. Once it finished burning, check your Ap. If it is under 70km, it means that it is glitched, revert the flight. Once the red glow finishes, do the science experiments. Once we reach 70km, take a crew report, it should give you 5 science, log one of the thermometer, and observe a goo unit. Since we don't have a heat shield, we're going to use the upper stage as a heat shield as it is more heat resistance than the pod. Point retrograde. *Please note that if it flips automatically just put 8 modular girder segments on the bottom (of course above the chamber) to lower the CoM, however for that you need to increase the fuel to maximum and a small third stage with 2 FL-T100 tanks and a swivel but will need to replace the modular girders to the third stage. Shut the engine down after reaching 75km. Only need around 4 for it as it have gimbal. Remove the EVA jetpack and the parachute - It's useless and can safe weight, remove the monopropellant in the pod to save more Deploy the parachute when you can. Recover when landing. Now with 84.3 science, we'll "upgrade our gear". Go for General rocketry, survivability and general construction. We do need stability but now we have a heat shield we can fly straight up. Accept a ton of tourism contracts. Make sure it is divisible by 4. 12 is a good number to start. It's okay to decline a few unwanted ones. Usually 2. Note: Only accept significant ones. With over 200k in funds, upgrade mission control. Now, download the Expendable Falcon 0, also known as the suborbital maker/tour suborbital. but it is relatively advanced and cannot be launched. 1. Replace the tanks with 5 FL-T200 tanks. 2. Replace the wings with the Basic Fins 3. Remove the service bay Now fill the cabins in with tourists and keep on launching, we need to launch 12 before the next step and also take a crew report in the upper atmosphere for 4.5 science with only around 11 science (11.8), we need to get more. One of them is to do part tests. They're easy. Only accept trivial, Testing contracts (No hauling), contracts that is staged not run test buttons, location is landed or launch site. Accept 4, if not enough, use ALT+F12 debug menu. Start of with a KV-1 pod (as it contains a decoupler), then attach all the things u need on the bottom, 1 each. For solid rocket boosters remove all the propellant and for liquid engines don't put any fuel tanks then press w to flip it around Should be like that (for me) put everything together in staging sequence launch it, hit space and recover the pod there you go! now you got 4 science, some reputation and funds! Next, we are going to use a presmat barometer in survivability. We didn't use this before because of space problems, but now we don't need the goo unit and the thermometer on the pad, pluck a presmat barometer on a pod and log the pressure for 3.6 science and recover it. Now go for stability - we need wings for sure. Now we need a vehicle that will explore kerbin underneath the atmosphere. We want to fly with the stage, not ditch it. First, of course, we're modifying our suborbital vehicle. We're going to use this. It's totally designed to sleek high speed landings so we only need 2 chutes. The modular girder segments have a great tolerance impact of 80m/s. Immediately after liftoff, log one of the presmat barometer and pitch right. Once you are out of the launch pad area, shut your engines and deploy the parachutes. Once you are on the ground, log a presmat barometer, a goo unit and a therometer. Then recover the vessel. The next place we want to go is grasslands. first, upgrade the astronaut complex. Open the spaceplane hangar and load the vessel. Before launching, log pressure. We do need a bit of experience so go to the lands nearby to do a eva report and a crew report Then recover vessel. Now what are we doing with those science? this is what we want. Meaning, the stayputink. Also the science Jr is good for science so we will go for that. This is our ocean capsule. Take the modular girder segments out - we'll throw that away. We are going to the ocean Immediately after launching, take a crew report and a EVA report, we can do those later after launching tourists ditch the stage to save weight. Once landed, do the science experiments. With almost 50 science, we are going for basic science For now accept <=7 contracts, one is orbit kerbin, 3-6 significant contrats to ship tourists to space - we'll take a bit of money later upgrade the launchpad put a science jr underneath a pod and conduct material study should be something like this recover it launch it again recover it again launch it again recover it again after3 times, you should get a total of about 13.9 science, now its time to use this for space missions in between put a td-12 decoupler, and a mk16 chute 1. cheaper 2. less weight remove the jetpack though, we don't need it keep the personal chute though unless you're sure jeb won't accidentally get out and crash put four av-t1 winglets for stability. on top put 6 goo units, 2 presmat barometer and a thermometer immediately after liftoff observe 2 goo units and a thermometer when you're at ~40km observe 2 goo units, a presmat barometer when you're above 70km observe 2 goo units, conduct a material study, a presmat barometer and a EVA report remember to point it straight up! before seperation right click on the science Jr while holding on the ladder of the capsule, collect the data and bring it inside the capsule, ditch the bottom stage point retrograde when it reaches 300m/s deploy your parachute Touchdown and recovery now we have 86.5 science go for advanced rocketry - we need better tanks and engines Now we can ship our 12 eager tourists to space with the almost original falcon 0 - just replace the av-r8's with av-t1's. But there's a problem. CoM Add modular girder segments like before But... is that really safe??? Isn't that dangerous as one would not be cared? There's a much easier way Remove the decoupler and the service bay, make sure all chutes deploy for landing. Like before, use SAS to point retrograde and deploy the chutes when all parachutes fully deploy safely and pointing retrograde, EVA your kerbal to do a eva report, above grasslands it should land softly at around 2-5m/s, depending on the remaining delta v go for flight control, the new pod is great, we also need AV-R8's, the reaction wheel uses only electricity which is completely free and doesn't have mass it's like this upgrade the VAB and launch 16 more tourists Launch all 16 with this falcon 0 If the rocket kept on tipping try adding 3 landing struts start retracted and click on "G" to deploy it, because we upgraded VAB for a bit of science we'll take 2 trivial part tests like before finish them accept 12 tourism contracts upgrade tracking station We're now finishing this tutorial We're getting into orbit! The rusty, old, stupid Orbital 0 is too noob, it's in my kerbalx account named orbital craft, it's expensive and unefficient For me this is great. Test it. I kept on updating it to make it better Remember to conduct a material study in the upper atmosphere! Mechjeb flies this great, REMEMBER to do the gravity turn in 52m/s!!!! Note: I flew this quite a few times, mechjeb flies this into orbit with over 800m/s of excess delta v The new one is better, 0nly around 100m/s of excess delta v Btw, we want to land on highlands which is west of grasslands, try targeting for the ocean close to ksc Take a crew report and EVA report after landing on highlands, we should now have 36.3 science! Great! This tutorial is finished! Read it! It took me weeks to do this!

You mean spinning or flipping? If it's spinning (like, you know, a spinner) then it's probably something wrong with the fins, picture would be nice. If it's flipping, then I would blame your approach to gravity turn (or more like gravity slap really, looking at how you describe it). Low speed, late turn is a thing of the past, over five years now. It may still work while the rocket is long, with first stage still attached but then it often goes sideways, literally. It's now more like a 1.2twr on the pad, 28° at 5km, 45° at 10k, 70° at 20km and almost horizontally at 40km. Don't go too far from prograde marker, turn on aero overlay and don't let the red arrow (drag) appear anywhere else than at the bottom of the rocket.

You crack me up, you really do The reason why it's called a "gravity turn" is because the rocket is NOT directionally stable. This lack of directional stability means gravity is causing the rocket is falling over like a tree felled by a lumberjack. If the rocket was directionally stable, it would instead keep going in a straight line. Because of this, a true "gravity turn" requires no control input at all after the 1st little nudge to start the rocket tipping over slowly. The rocket is just tuned in the design phase (TWR, CoM position/movement, and aerodynamically) to reach the desired altitude and speed by the time it's rotated 90^. The long, skinny shape of the rocket, plus any tail feathers, acts as a brake on the rotational speed, so the rocket takes longer to reach the horizontal position when moving forward than it would if it just fell over on the pad. However, the aerodynamics do not, and cannot, stop the rotation caused by gravity. Ergo, the rocket is NOT directionally stable. Any ascent that requires control inputs throughout the ascent to make the rocket curve over is NOT, strictly speaking a "gravity turn", even if the trajectory looks exactly the same. In this case, the rocket IS directionally stable, going in a straight line despite gravity trying to tip it over. This is especially true if you have SAS on in default mode without picking the prograde lock. Maintaining directional stability is its whole job in this mode. The rocket thus periodically needs control inputs that upset its stability briefly in the desired direction, to make it curve on over. These control inputs use various systems to have their effect on the rocket's orientation. Torque, control surface deflection, or directional thrust (gimbal, RCS, or Vernor). In this case, fixed tail fins again act as a brake on rotation, so you need more force to make the same turn than you would with movable fins. That extra force costs dV, either from gimbal cosine losses, fuel burned by Vernors, or lugging an extra launch-only RCS system. This has nothing at all do to with "piloting errors". It's a function of the rocket design. If you make a stable rocket, you will have to divert force to make it turn, and you are not doing a gravity turn. If you make an unstable rocket (only with carefully limited instability), then you don't need control inputs and ARE doing a gravity turn.

Also, bear in mind that dV is a complicated beastie. Circumstances matter. In particular, it matters a lot whether you're talking about launching from the surface of a planet (especially a heavy-gravity planet like Kerbin) to get to orbit, versus doing orbital maneuvering. The reason why it matters (and the reason why the answer to "what's best?" is a complex "it depends" rather than a simple one) is because of gravity losses, which affect planetary launches but not orbital maneuvering. Explanation in wall of text below, but what it boils down to is this, if you're trying to maximize your dV: For maneuvering in space, you generally want the lowest possible TWR you can get away with. For lifting off the launchpad on Kerbin, you generally want a TWR of around 1.5 off the pad, but less than that for your 2nd and later stages. Okay, on with the details: When you use your engines, what are you doing with them? Specifically, are you using them to fight gravity (e.g. when you're accelerating straight up upon Kerbin launch)? If you're not fighting gravity (e.g. you're in circular LKO and doing a prograde burn)... then your TWR is completely irrelevant to your dV. All that matters is your engine's Isp and the mass fraction (i.e. fuel percentage) of your rocket. (You can see this in the rocket equation for calculating dV: there's nothing there at all about thrust, it's irrelevant.) Therefore, the best dV generally comes with very low TWR, for a couple of reasons: first, the highest-Isp engines generally have very low TWR; second, you typically want as few engines as possible, since they're dead weight that counts against your dV. If you are fighting gravity (e.g. you're ascending straight up after KSC launch), then your TWR matters. This is because every second you're ascending straight up, gravity is sucking 9.8 m/s out of you (on Kerbin, anyway), which is dV that's just flushed down the toilet. This is called "gravity loss" and is a huge hit to your fuel economy when gravity is strong. The only way to get around it is to minimize the time you spend fighting gravity (i.e. quickly get up above the thick part of the atmosphere, so you can tip farther over to the horizontal and spend your fuel in actually accelerating your rocket rather than fighting gravity), and the only way to accomplish that is with a high TWR. So, for a launch from Kerbin, it's a balancing act. On the one hand, you want to minimize gravity losses, in which case you want a high TWR-- the higher the better. On the other hand, the rocket equation still applies to you (engines are still dead weight), so if you go too nuts with an overpowered ship, then you'll be wasting so much mass on engines that it more than offsets the benefit from reduced gravity loss. Furthermore, there's another practical limit: the faster you go while you're in the thick part of the atmosphere, the more energy you waste fighting aerodynamic drag. If you go faster than terminal velocity on ascent, then the loss to drag outweighs the benefit due to decreased gravity loss. This sets a practical upper limit on your speed, which in turn means it's not useful to have too much TWR, you'd just waste the capacity. (Sort of like saying, it's not worthwhile driving a Lamborghini if you're going to be driving around city streets where traffic prevents you from going at high speed.) In other words: for liftoff, you need a happy medium in terms of TWR. Too low, and you waste too much dV on gravity losses. Too high, and you're lugging too much dead weight and wasting too much dV on aerodynamic drag. So, I hear you ask, just what is that happy medium? Answer: It depends on your ship design (specifically, how big it is and how aerodynamic it is), but typically it's in the neighborhood of 1.3 to 1.5. (Personally, I prefer 1.5.) The more aerodynamic the ship is, the higher the TWR it can get away with. Very large ships (i.e. multi-hundred-ton behemoths) can generally get away with a higher launchpad TWR, because they're less affected by aerodynamic drag and it's therefore worth their while to get up to speed faster. Also, bear in mind that you don't want high TWR all the way up. You need it off the launchpad to fight gravity, but pretty soon you're going to be tipping over into your gravity turn, and going less vertical and more horizontal. Once that happens, a smaller fraction of your rocket power will be spent fighting gravity, which means you'll be wanting a lower TWR to get better dV efficiency. So, typically, you want your 1st stage off the launch pad to have a high TWR (e.g. 1.5), then your 2nd stage usually kicks in when you're already tipped over 45 degrees or more and can be considerably lower TWR (e.g. in the 1 to 1.3 range), and your 3rd stage should generally be pretty low (is fine to be under 1).

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'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.

so, when you mentioned that you couldn't get enough fuel for a rocket "bigger than a cockroach", i assumed you were using minimalistic rockets with a small command pod and nothing else. that you were launching 20-30 tons rockets. You are launching stuff with multiple mammoths.... you should be able to put into orbit many tens of tons with each launch. Maybe you are just trying to put too much payload into orbit anyway? do you do the gravity turn manuever? especially with rockets so big, you should start turning eastward at around 50 m/s, and reach 45° inclination around 500 m/s for maximum efficiency. even if you botch it somewhat, though, it's not a big deal, you lose 100-200 m/s maximum. You need to botch it badly to lose more. Another thing to check is the TWR: if it's too low (say, 1.2 or something similar) the rocket will lift very slowly, and you'll lose a lot of fuel hovering there (it's called gravity drag). But, most important, I see that the Trüffelschwein 1 only has 2400 m/s before the fairing is removed. Assuming the fairing contains your payload, of course you can't orbit, it should need 3400 m/s on a well-optimized launch. The 5 flips because you have a huge payload with terrible aerodinamics. It would need a huge fairing, but it's still very draggy. Really, that kind of very large payload is a nightmare. I launched one that big a couple months ago, and it took me a day of trying, and i'm good at this game. So perhaps what I can suggest is, take things more calmly, you are trying to put the cart before the horses. Get good with simple ships first. Try maybe with basic designs like this before you try the really huge stuff. Huge stuff is way more difficult. From what I can see, you started the game and immediately went for the biggest, most showy stuff. It's like someone trying to learn to drive and picking the fastest racing car.

Which is why the gravity turn must be initiated at a relatively low speed, to allow "gravity" to then induce the rest of the "turn". A stable, top-heavy and rear-finned rocket will always make a gravity turn unless you (a) force it not to or (b) make a one-in-a-thousand launch that is actually perfectly straight up. Most people will only have RL experience with emergency flares or fireworks, both of which are top-heavy for a reason and both of which will (a) make a gravity turn and (b) naturally turn into the airflow. That is why you must fire flares slightly downwind - otherwise they turn into the airflow and continue their gravity turn into the ground. Whether bugged or not, fairings in themselves make the top of a rocket light, and this needs careful attention. The OP's rocket is essentially empty space in the top third, followed by a rapidly-draining small tank. With or without the fairing, it would not take kindly to any kind of deviation from prograde. It is also massively overpowered, making any kind of gravity turn difficult because it won't have time to dip towards the horizon if run at full thrust. The main issues with the OP's problem with fliipping are therefore (a) trying to turn too late, going too fast, and too far away from prograde, (b) having far too high a TWR, which rules out a natural gravity turn, (c) possibly using MechJeb which sounds like it enforces the "old and wrong atmosphere" approach to gravity turns, (d) using a lightweight 2.5-to-1.25m adapter that is pointless and merely adds to the length of the fairing, and (e) allowing a smallish fuel tank just under the fairing to drain first. These basic problems with design and ascent profiles are, indeed, exacerbated by the fairing. That added problem is certainly the final straw as far as the OP's design is concerned, but I and many other people manage to use fairings extensively as long as these major design and flightpath problems are eliminated. I'm not saying there is no bug. I'm saying that the bug is merely highlighting problems that were there already, and sorting those will help the OP. Understanding the problems helps understand the mechanics that are at work. And finally, I'm pretty sure that a realistic physics rendering of a realistic fairing, applied to the OP's rocket and in the OP's usage scenario, would give exactly the same problem as the OP is describing. If Claw's bug fix allows the OP to get away with a sharp gravity turn with that rocket, then I would wonder whether "fixing" the bug is actually positive for the game.

@Lankspace: Others have covered theory of construction well enough that I don't need to repeat them. In terms of theory of design, however, I can say that the overall goal is to get something into space such that it doesn't: cost too much, blow up on the way there, fall back down later, and fail the mission. Usually for real-life space programs, cost is the deciding factor. There are a lot of missions that don't fly because they cost too much. For KSP, the practical issue of getting something to space--and making it stay in space--intact is more important. The main difference between the two designs you gave as examples involves drag versus thrust: a rocket with boosters has more of both. Sometimes, that's needed, and the reason for that is because getting off the ground requires you to fly in what would otherwise be the most inefficient way possible. I will assume that you know about how to manoeuvre in space. If not, then please accept that you generally want to change your orbit by thrusting in the prograde/retrograde direction, with normal added if you need to change inclination. Radial burns (at right angles to both prograde and normal but meaning roughly toward or away from the planet) are the least efficient because they don't add much useful velocity to your rocket and don't add any inclination at all. There are a couple of very specific use cases for them but normally only as corrective manoeuvres. When you launch, however, your rocket begins by going straight up--which is to say, radial out. Because of both the atmosphere and the gravity, it is necessary to include a radial-out component in your launch burn. Obviously, radial-out keeps you from falling down to the surface, but it also gets you out of the atmosphere, which otherwise parasitically drains prograde velocity. Spaceplanes get this radial-out component from lift, which is what makes spaceplanes potentially so efficient, but wingless rockets cannot take advantage of that. However, with the right rocket design, you can immediately begin adding prograde velocity at launch in such a way that gravity and drag cancel the radial part at the correct rate to match the declining need for radial velocity--that is to say, you want gravity and drag to work against you so that when you don't have any radial velocity left, you don't need it anymore, either. That's the idea behind a gravity turn. Ultimately, your choice for a rocket design is tied to how well it will fly to orbit. 'Well' can be defined as a matter of cost, weight, thrust, or a combination of these and other factors. One thing to remember is that because of the way gravity works, you will only need to provide a specific value of thrust to counter it, so anything above that value is thrust that you can use for other things, such as going to orbit. Side boosters provide that extra thrust (which means, practically, that you can tip the rocket a bit more on your way to orbit), but that also has you going faster in the atmosphere which increases drag and heat and wastes fuel--there's also such a thing as too much thrust. On the other hand, a long inline rocket will fly very well through the atmosphere--provided that it is pointed in the same direction that it flies. Also, with less thrust generally available, a larger proportion of it must be used to counteract gravity. This requires a longer gravity turn and wastes fuel--there's such a thing as too little thrust, as well. You are always going to 'waste' fuel to fight gravity in any surface launch; the object is to find a design that wastes less of it.

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

Edit: I suspect a problem/limitation to do with IR. Gentlemen, I present you with the largest payload I have attempted to launch into low kerbin orbit to date, and I find myself utterly stumped as to what is keeping me from achieving that goal. It is not a matter of thrust, delta-v or structural integrity, it's simply the fact that the craft refuses to do anything but go straight up. I have tried adding stacks of reaction wheels, removing all reaction wheel torque (including the cockpit torque), Ive even action-grouped boosters to force the craft to turn over and added side-ways firing rockets. The cargo contained one micro reaction wheel, which i have removed to no avail. I cannot make the gravity turn, so i reach my apoapsis with almost no horizontal speed. This is frustrating me to no end. Wings with control surfaces seem to make no difference either. I'm close to giving up. The craft minus the boosters weighs about 120t. COG + COT: http://i.imgur.com/OS53OaX.jpg Payload: http://i.imgur.com/HTY75Ic.jpg The entire thing: http://i.imgur.com/pple1qn.jpg You'd think it would flip over, right? Nope: http://i.imgur.com/nX3a9y1.jpg This last picture leads me to believe the problem lies with the cargo. It is attempting to torque the craft upright, while the engines attempt to turn it over, causing the structure to bend like it does at the end of the cargo bay. Would this be a IR (infernal robotics) issue? The cargo contained one micro ASAS node (since removed) and 1 small and 1 medium size remote control node. Can anyone assist?

A lot of people say "gravity turn" but mean - turn around planet, which is wrong. Like, "I do gravity turn, I first turn XX at xxx, then wait till altitude of XX" - this is not a gravity turn, this is a "manual gravity turn". Gravity turn means - Gravity turns your space craft. For the whole time, since Launch <---> up to Orbit burn, you don't touch controls and there is no autopilot, you don't apply any rules after you figured few right points where to add some influence. BUT the possibility of gravity on itself to turn your rocket correctly demands that your rocket is aerodynamically correct. That it has right CoM and CoL placement, right T/W. Rockets which carry exposed equipment, or control surfaces in upper stages are gonna have it real hard though, for example - the stock shuttle is impossible to do gravity turn. The speed distribution in gravity turn is - first vertical speed goes up fast, horizontal pretty slow. Again - it happens by itself, gravity is autopilot. Over the whole trajectory the rocket continuously stalls - all by itself. At around 12km, the rocket falls into 45 degree and Vspeed and Hspeed match. Then Vspeed starts falling, Hspeed boosting. At around 35km the Vspeed is around 200-150 m/s, but Hspeed already at 1600+ m/s... Personally I do engage stability assist only at T minus 30 before orbit burn to align with horizon below (incoming) prograde. Thats at 80 km near apoapsis. If rocket gets unstable at 30km, it either has too bad aerodynamical qualities or too bad CoM/CoL or too weak T/W. This is not necessary bad.. sometimes its demanded by mission.

Back to reviving a... 9 year old thread?!? I start the gravity turn slowly, almost directly after liftoff. When the apoapsis reaches the target altitude, I turn equatorial and sometimes below 0°, until the first stage runs out of fuel. Then I burn prograde (without even using a maneuver node!) until I reach a circular orbit.

The thing which helped me to learn to use gravity turns was actually MechJeb. It has (amongst other things) an ascent autopilot that will do the gravity turn for you. The only time it will fail is if a) your vessel doesn't have enough fuel to reach orbit or b) your vessel is badly designed - not streamlined, no fins, mass not centred above thrust vector, no engine gimballing or reaction wheels, and similar things which you probably will pick up fairly quickly as you progress with learning the game. Here's an example of what your spacecraft should have to safely perform a gravity turn and ascent from Kerbin: As you can see, my Mercury 1 spacecraft is streamlined and has fins at the bottom (fins without control surfaces). The engine at the bottom is modded, but the important thing about it is that it can gimbal (if you're unfamiliar with that term, it means that the engine can direct its thrust to help to turn the rocket). There is a fairing around all parts of the rocket that are not particularly streamlined in order to minimise drag (the less drag you have the safer your gravity turn is). Finally, in addition to the integrated reaction wheel in the command pod, there is also a 1.25m reaction wheel at the top of the booster. It is decoupled when the booster is decoupled, but on the ascent it aids in control of the rocket. Like most of the rockets that I make are designed for, the Mercury 1 transport follows the following set of guidelines for a launch: Engine at full throttle (I actually limit the thrust in the VAB to suit the payload mass but that's somewhat advanced); stability assist turned on Straight up until speed is about 100m/s Rotate so that North line is at the bottom of the navball whilst ascending directly up (this is a personal preference so that I use the s key instead of the d key to perform the gravity turn, it's not a requirement for this craft) Begin gradual turn to East when speed passes 100m/s Turn rocket by about two degrees every second or so at first, until 50 degree angle is reached by 8km altitude (your initial angle is 90 degrees) Aim for 50 degrees by 8km, 45 degrees by 10km (once you reach this point it may be possible to set stability assist to point prograde, which may minimise needed control input until main engine cutoff), 30 degrees by 30km, and under 20 degrees by 40km After 40km set stability assist to point prograde if not done already, and burn either until main engine cutoff or until the apoapsis of 100km is reached (with a good ascent there should be maybe 1% of the fuel for the main engine remaining by the time the desired apoapsis is reached; this remaining fuel is not necessary if the gravity turn was performed properly and can be jettisoned). This should happen when the vessel is pointing about 5 degrees above the horizon and is between 50 and 60km above sea level. At this point the fairing and launch escape tower are jettisoned (in that order because the fairing is attached to the launch escape tower) and then the main booster is separated. The service module engine can be ignited at this point but only if throttle is at zero. Plot and execute maneuver to circularise orbit at apoapsis. There should be a significant amount of fuel remaining in the service module if the ascent was performed well (this vessel in particular is designed for orbital rendezvous with stations or large vessels in orbits up to 500km, hence the excessive delta-v). These instructions are perhaps a little specific, but hopefully should give you some insight into how to perform a gravity turn, and how to design your vessels so that they're capable of performing a gravity turn.

For what I understand the most efficient way to get into a LKO is the gravity turn maneuver. https://en.wikipedia.org/wiki/Gravity_turn " It is a trajectory optimization that uses gravity to steer the vehicle onto its desired trajectory. It offers two main advantages over a trajectory controlled solely through the vehicle's own thrust. First, the thrust is not used to change the spacecraft's direction, so more of it is used to accelerate the vehicle into orbit. Second, and more importantly, during the initial ascent phase the vehicle can maintain low or even zero angle of attack." So probably you have to take off, then you reach 50m/s or so and immediately turn the vehicle 20° or so east direction, SAS prograde and let the gravity steers for you. Speed and inclination strongly depend on your vehicle properties like TWR, mass, air resistance, etc...