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  1. Hello, I was wondering if the parts that are radially attached inside the Mk1 Structural Fuselage are dragless and protected from reentry heat. I've noticed that with angle snap off, you can radially attach parts inside the fuselage, but when doing a reentry, things inside were showing temp gauges and some of them were destroyed. Do I need to use the fairings for that? Or was it that the fuselage was getting heated up(and resisting it fine) but passing that heat by conduction to the parts inside?
  2. I was playing ksp coming from minmus, but on re-entry, something wired happened. It refused to simulate drag. The spacecraft was at 900 m/s and accelerating at 2 km. Therefore, I couldn't deploy the parachutes.. Anybody else have this problem?
  3. It'll be really helpful to know the Lift&Drag characteristics on altitude and speed, to fly a proplane. Anyone knows something about this?
  4. Hello! I was designing a new prop. plane, which included a structural component(small cubic one) to hold a engine. So it files, but there seems to be one problem: speed. (It can't beat 50~60m/s ) I know that proplanes can't have very fast speed. The problem is, there is similar proplane I made which is much more faster. this one seems to be slower even with bigger thrust. The only differences I saw was: 1. The slower one used structural component to hold engines. 2. The slower one has bigger wings for prop. engine, which might have bigger drag. 3. The slower one has shorter cone, which would be more draggy. So how can I reduce drag in this situation? Are there some great techniques to reduce drag? If there is, please let me know and it'll be greatly appreciated! + Also I'd like to know which structural part with node attachment? This is necessary to offset parts far enough.
  5. Well, after hours of testing, reading, and testing again, I am still having a really hard time understanding the aerodynamics. Previous post: Even though my previous post was ironically the only ground drag issue that came into the equation with trying to make a stable jet, I'm still trying to build a stable jet. Rather, understanding how to make one that is. I know CoM, CoT, and CoL, but I don't understand their results. There are numerous claims that if the CoL is behind the CoM, then the rocket will be stable. KSP wiki: http://wiki.kerbalspaceprogram.com/wiki/Center_of_lift#Flight_characteristics foamyesque: But my mind is vehemently refusing to accept this. Don't you guys mean the "center of drag"? I feel like this is very similar to the CoL, but is still different. You could have a ship with two wings in the front and then a bunch of random parts on the back, and would fly with the drag-inducing parts in the back like an arrow with feathers. Yet, the CoL would be right between the two wings, because they are the only things providing lift. I've had planes where the CoL is significantly behind the CoM, but it still wants to flip at high speeds, or at least doesn't want to just go straight. And this flows into my second question. You know, let's make a list. Welcome to the buffet of questions for all your answering needs: Is the CoL the same thing as the "Center of Drag"? If not, is there a good way to find how far the CoD (center of drag) is behind the CoM? I've been shooting my crafts way up in the atmosphere and then letting them fall to see if the CoD is behind the CoM. Kinda time-consuming. If all parts create lift (KSP wiki quote below), why don't they change the CoL in-game? KSP wiki: http://wiki.kerbalspaceprogram.com/wiki/Lift#Dynamics The wings are symmetrical. Do they still produce vertical lift in ksp if they are not given any angle of attack? Are there specific wings that do/don't produce vertical lift at 0° angle of attack? I'm really sorry I'm asking the same question that everyone always asks, but this is a little different. Thank you so much for taking the time - Spemble
  6. With 1.2, drag is (even more) king and nosecones dictate that to a large degree. Since the Mk.3 Cockpit is the best command pod for reaction wheels, crew capacity, etc, I try to use it as often as possible. Thus: What nosecone is the least draggy while still being somewhat sane, functional, possibly even nice-looking? This is the best I could come up with: 1.25m Fairing clipped slightly into the Mk.3 pod. 2600 Max Temp (seems to be the highest of anything besides the pod itself)
  7. I have this spaceplane built in the previous versions, which doubles as a reasonable lander And it used to make it to orbit with plenty of dV to spare. I've just loaded it in 1.2.1 though and the rapiers can't keep up the thrust when they are breaking the sound barrier: They'll hold up to about match 1, but between match 1 and match 1.1 they will consistently keep loosing thrust, even if I level out or even descend slowly, which keeps me stuck below match 1.2. I've tried placing precoolers in front of the engines, but they don't change performance. I've replaced the front of the spaceplane with the MK2 (not inline) cockpit and while there is a thrust loss, it isn't nearly as pronounced and I can more easily break the sound barrier, so I guess the issue is related to the changes in drag. Am I right? (And it's a pity, because that's a nice position to put the docking port). I also installed Interstellar (and removed the rapiers MM patch as it caused them to overheat) but I don't think Interstellar should be the curprit
  8. For ModuleLiftingSurface, especially in the wing parts, i know the stock deflectionLiftCoeff is calculated by the area*0.284. But how is the dragAtMaxAoA and dragAtMinAoA calculated? the drag at max AoA for wings seems to never go over 1, so does this mean it's a multiplier of some sort? Also if you look at stock's big delta wing, and the aeroplane main wing, both have different surface area, but have the same dragAtMaxAoA=0.6 and dragAtMinAoA=0.0, why? If anyone know how these values work, please let me know! Thanks!
  9. What are the aerodynamic properties of this part? Does the big flat part cause drag if you put engines on it? Or does it count as a smooth mk3-to-3x1.25m adapter?
  10. So pretty much every lunar rocket I've been building in 1.2 has some variation of "small 2.5m tank, Terrier, decoupler, larger 2.5m tank." I had a general sense that I might be taking some kind of drag penalty for the change in form factor, but was not exactly sure how it worked or how large the effect was. So, following @Gaarst and @Yakuzi's excellent work on nose cone drag, I whipped up a little experiment. This was my rig: The nosecone, capsule (I edited mass down to 3 tons so I would actually use it in my new career) and top 2.5m fuel tank represent the payload, and will be providing the drag occlusion, if any. The middle piece was my independent variable. I tried four combinations: (1) Terrier alone, as shown here, (2) Terrier with 2.5m interstage fairing, (3) a 2.5m probe core instead of Terrier (selected because it is the same mass as the Terrier, but in the 2.5 form factor), and (4) the 2.5m probe core with 2.5m fairing base. On #4, I could not actually build a fairing, I just wanted to check the fairing base itself didn't cause weirdness. I also drained fuel from the upper tank to balance out the added weight of the fairing when it was used (within a couple kilograms, at least). Just to keep extra variables out, I also disabled the reaction wheel on the probe core when it was used. The bottom 2.5m tank and Reliant provided the thrust. On each test, I set the SAS to hold radial out, and fired the Reliant with only the bottom fuel tank available. I then saw how high each rocket would go after burning through the bottom tank. #1, the plain Terrier, only made it a little over 9,000 meters, #2, the Terrier with fairing, made it over 11,000 meters. #3, the probe core, made it over 13,000 meters! #4, the probe core with fairing base, ended up very close to #3. So the fairing base appears to have no special aerodynamic effects. Results: It looks like parts in front do not fully occlude trailing parts if there is a smaller-size part in between. The lower tank may be getting some drag occlusion, but definitely not as much as if the stack was uniformly 2.5m wide. So all else being equal, it's better to avoid the "hourglass" shape. Using an interstage fairing considerably improved drag, though surprisingly, the net effect was not as good as a pure 2.5m setup. Thus, besides their weight and cost, fairings don't appear to be a perfect option occlusion. It's also worth mentioning that, even when I did NOT reduce payload weight to compensate for the fairing, it still made the Terrier package go higher. This suggests that interstage fairings are probably a good idea, at least as long as the fairing base is staged low enough you're not hauling it to Tylo and back or something. In career mode, though, the fairing might or might not be worth the cost. One final note: this test did not attempt to measure drag occlusion when the rocket is not facing directly prograde. But I would expect the penalty for changing sizes to be even worse in that case, since there's not even perfect occlusion from a geometric standpoint. tl;dr: going back and forth between form factors is bad for drag. If you have to do it, consider an interstage fairing.
  11. Speaking about drag occlusion generated by different parts, are 3.75m parts occluded by Mk3 parts? Thank you. Cheers.
  12. Hello! Got a problem today on fresh reinstall of KSP 1.1.3 (1289), which I was able to solve myself - but I think I must publish so that someone encountering it will spare himself the time. Symptoms: Parachutes refuse to work. Any parachutes. Attached to any capsule. Anywhere. Be it stock KerbalX, or MK1 dropped from height. The Aerodynamics overlay shows them not working at all. It became so crazy, that I designed a high altitude rocket-plane just to show how crazy the situation is. http://imgur.com/a/kLRh2 Here is a scenario to reproduce the problem, nothing extraordinary: 1) Installed KSP - did not start it yet! (important) 2) Installed Module Manager (2.6.25, current), Kerbal Engineer Redux (1.1.1, current) and Docking Port Alignment Indicator (6.4, current) 3) Started KSP I have tried to remove: - Unity3d settings directory in /home/ - physics.cfg and settings.cfg I have tried to restart the game and sandbox mode. I have played around with vsync on/off and physics settings. To no avail. Solution! 1) Remove the game completely 2) Install it again 3) Run KSP before adding any other mods 4) After at least one run - add the mods. Now the parachutes suddenly WORK. It looks like one of these three mods corrupts parachutes data or does something that leads to that - if KSP never run before.
  13. I'm creating scaled-up versions of the ROUND-8 Toroidal Fuel Tank, and need a hand with drag cubes. The stock part has a custom DRAG_CUBE defined as follows: // AREA DRAG COEFF DEPTH cube = Default, 0.2859113, 0.6272321, 0.6734665, // X+ FACE 0.2859113, 0.6268581, 0.9227022, // X- FACE 1.21, 0.96, 0.2872447, // Y+ FACE 1.21, 0.96, 0.245615, // Y- FACE 0.2958315, 0.6112254, 0.6440083, // Z+ FACE 0.2958315, 0.6160544, 1.104762, // Z- FACE 0, 0.02261333, -2.695719E-09, // BOUNDS CENTER 1.152236, 0.3307782, 1.135139 // BOUNDS EXTENTS // X Y Z In one case, I'm scaling the part by a factor of 2.2 along the X/Z axes, and 4.15 along Y axis. I'll also be moving the Y-coordinate of both attachment nodes up to 0.43 so the tank wraps nicely around the exhaust manifold of a Poodle engine when mounted above it (yes, there will unfortunately be a bit of clipping, but hopefully we don't need to get into that here). MODEL { model = Squad/Parts/FuelTank/fuelTankToroidal/model position = 0, 0, 0 scale = 2.2, 4.15, 2.2 } To visualize it, red is the stock part, and blue is my scaled up version (note some of the values may be approximate): I'm trying to figure out how I should adjust the drag cubes to sensibly represent the increased drag of the bigger part. I read the following links: Drag cubes introduced Explanation and "OMG" Experiments Image showing XYZ face orientation Drag cube scaler/calculator and its announcement But still have some basic questions on how they work: In general, how "tightly" should the values correlate to my part geometry? e.g. Should I be doing calculations based on the dimensions of my part? Or is the system just an imaginary way of visualizing multipliers which should be tweaked using best judgement? (Since drag cubes also affect buoyancy, I'm assuming they need to be fairly tightly coupled to part geometry, and if you start going willy-nillie to tailor the drag you'll end up with unwanted side effects in the water... unless you decouple the drag/buoyancy cubes via buoyancyUseCubeNamed) I infer AREA should roughly correspond to the surface area my part presents to the given face. Should it be calculated from a projection of my part onto that face (or maybe from an outline of the cross-section made at DEPTH)? e.g. The stock toroid projected onto the Y+ face (i.e. viewed from above) looks like this (numbers approximate): So the area is roughly 0.74m2 (or 1.04m2 if you ignore the hole in the middle). That's a bit smaller than the 1.21m2 area in the stock DRAG_CUBE above (I guess for whatever reason Squad used a slightly bigger outer diameter of 1.24m). But what I'm really wondering is why did they ignore the hole in the middle? Does that mean I won't get the benefit of reduced drag from the air rushing through the middle? (It's a valid question - I could build a craft where that hole isn't occluded) How does DEPTH work? Is it to tell the game something akin to where "tip" drag ends and "surface" drag begins? @NathanKell said it should be "depth of widest point from the frontmost point at that angle". I assume that means if you have, for example, a part that looks like a pencil pointing upward, then the DEPTH of the Y+ face should be equal to the length of the pencil's tapered tip, like so: The widest point of the stock toroid tank is at its equator. So I'd expect DEPTH for its Y+/Y- faces to be roughly half the height of the part - but they're both nearly the FULL height. Similarly, X-/Z- are only slightly less than the full outer diameter (while I'd expect them to be much smaller, about equal to the outer radius), and I'm totally confounded as to why they're so different from their X+ and Z+ counterparts. The mesh looks reasonably symmetrical. Does it have something to do with the little gauge dial on one side? If so, why's that bugger have such a big effect, and why doesn't the effect come into play when the wind's coming from the opposite direction? Any advice for determining the drag coefficient? Is it intended to be adjusted to represent the "pointiness" of my part in the given direction (and perhaps the "slipperiness" of the material composing its surface)? Do I have a fair bit of leeway to adjust it (without causing unintended side-effects e.g. to buoyancy)? What are the extents of the drag cubes (last tuple) used for? e.g. Does it come into play when the game compensates for occlusion of stacked parts? Any general guidelines would be helpful. e.g. At one point @NathanKell said that for "a stackmounted hollow part" like a cargo bay, the Y+ and Y- area values should be adjusted to match the non-hollow version of that part. That's a very easy-to-use piece of advice that seems to make sense intuitively :-). Another one was "If the part is not hollow in terms of mesh, but should be (in terms of it being an intake with a flat black section that's supposed to represent a hole), you play with the drag coefficient (second number in the triplet) in the intake's incoming axis." Although I'm wondering, could you not simply "fake" a hole in the drag cube (regardless of whether it's in the mesh) by subtracting the opening's area from the face it points toward (i.e. poke a hole like I want to do with the toroid above, but only for the face the intake faces)? Have the part-level tags dragModelType, maximum_drag, minimum_drag and angularDrag been deprecated?
  14. I hope I'm in the right place to post this, but I've noticed a major increase in the applied drag after the recent update. I did some testing in the current 1.1.2, 1.1.1 and 1.1 versions of the game and noticed that 1.1 had significantly less drag applied than subsequent ones. According to what I could conclude, 1.1.2 applies almost 20% more drag, which is never mentioned in any of the release notes. (1.1.2 just introduced some optimization). This practically grounded 90% of my spaceplanes, so I'm curious if anyone else noticed this? Here are some screenshots with flight data GUI for both 1.1 and 1.1.2. (notice that 1.0.5 aero was more similar to 1.1). Flight stats in 1.1 And the same situation in 1.1.2
  15. Hi, I'm a new poster but have been (trying to) play KSP for a long time now. After a lengthy break, I've picked it up again at v1.1.2 to discover quite a lot has changed. I had a program back in the day for modelling ascents of various ships into orbit and have been trying to update the code to model the new drag cube system. However, when opening my GameData\Squad\Parts folder, none of the .cfg files for any of the parts seem to have the DRAG_CUBE { cube= } parameters as described in numerous discussions on the new aerodynamics system (see link) Am I missing the most recent files, or am I simply looking in the wrong place? Any help is much appreciated, Cheers
  16. I was wondering if it might be an idea to add a wind tunnel to the KSP? Aerodynamics testing is pretty important, but it'd be nice if we didn't have to resort to the debug menu. Tier 1: You only see how much lift something generates. Positive or negative Tier 2: You get the torque overlay. Tier 3: You get the drag overlay. An ideas? Lift is already visible in the SPH and VAB, but I think not the exact amount? Taking a build to the wind tunnel could give you more info on the amount and surface areas, so it wouldn't be completely useless.
  17. Is there a mod that adds orbital decay effects by : Atmospheric drag, Tidal forces...? like this : https://en.wikipedia.org/wiki/Orbital_decay
  18. In flight, you can open up a nice aero forces display by opening the ALT F12 debug menu, going to the physics tab, then the aerodynamics sub-tab, then checking the "display aero data gui" checkbox. I've noticed however, that the lift:drag ratio numbers seem very poor compared with real-life airplanes. The best I can get is 8 or 9 to one, at 2 degrees AoA, at low speed and altitude. At 0.82 mach and 10km, similar to how commercial airliners fly, best seems to be 2.8 AoA and maybe 5 to one lift / drag ratio. Real commercial airliners are pushing 20:1 at such a point, in fact i'd bet the newest of them, the 787, is over 20 at an "economy cruise" setting. Supersonic , things get worse. At 1.3 Mach, I try climbing higher to use thinner air to compensate for the extra drag. Best results seem to occur at 3.5 AoA and altitudes of 14km or more, I might get close to 4:1. Concorde did 7.5 to 1 at mach 2 and 60,000ft. As we get deeper into the supersonic regime, numbers ebb steadily lower. Above 20km I'll start my final climb to orbit at something like Mach 4 and shutdown engines (needing only to circularise) at Mach 6.6. During this period optimal AoA seems to shift from 4 degrees to 8 or so. At best, I might see L/D display of 2.8, whilst pitching up to high alpha because my craft is overheating can pull it down to 1.6. Reading a little further on wiki, it appears max lift:drag does taper off with increasing mach no matter how high the altitude and thin the air, especially for conventional supersonic/transonic swept designs. However waveriders that rely on compression lift can do better, with designs like the Hypersoar project making 10:1 at mach 6. I guess this is all to compensate for the overpowered nature of jet engines themselves, compared with real life. I still find it a bit weird however, that if my L/D is so poor, why my spaceplanes are so reluctant to actually land. I've long since given up targeting the runway and am quite happy to settle for anywhere on the KSP peninsula or in the shallow seas nearby, usually after flying back and forth across it several times. I guess as we head below 100 m/s our L/D is getting up that of a Cessna light aircraft and we're usually coming in a tad "hot" , also the drag from landing gear, flaps, and jet intakes (with engines off!) is less than it should be .
  19. I am trying to build my first lander to get to Duna and this is what I got: My issue is that empty space for the small sized engine under the fuel tank. I am assuming this will cause a good deal of Aero-drag, but upgrading from a Terrier to a Poodle costs me like 600 Dv that I don't want to lose if I don't have to. Any ideas? I ask because I am sure this will come up again in the future
  20. So, I'm back after a long hiatus and v1.0 and all that good stuff. I'm trying career mode and I am getting burned (pun intended) on the new aerodynamic and heat effects. I am trying to do a test contract for the RT-10 booster firing between 40km and 45km and a certain speed window, I did this by stacking three RT-10s with tweaked thrust limiters so the third one ignites while coasting in the target window. Contract satisfied, but then I can't get the capsule safely to splash down because the chutes keep failing. I've tried deploying them as early as possible but it seems like nothing I do will get them to open until 5km altitude and by the time my capsule + heatshield is that low, it's screaming along at nearly 1km/sec and the chutes tear right off. I'm not sure how to slow my capsule down enough to use the chutes safely without being able to deploy them earlier. Thoughts? Thanks!
  21. You play with low resolution? You have heavily modded KSP? You often hit the wrong button during EVA because part's menu is constantly moving? You often get in trouble in the most inappropriate moment when you right-click on part but most portion of its menu hides off-screen so you have to zoom out and rotate camera to actually see it's bottom and all of buttons? If yes then worry no more because Troiden Industries are proud to present you DraggableMenu. With this small mod you won't ever have such problems. Features: Automatically rises menu if it gets off-screen. Freezes menu position when mouse is over it. Allows you to move any menu around your screen by Alt+Click, both in Flight and Editor. How to move menu: Press your ModifierKey(Alt by default) and drag the menu anywhere on your screen and it will stay there(regardless of what buttons you press after) until you close it. Then you can close it the same way you usually close any other menu: either by right-clicking(without Alt pressed) on any part or by right-clicking on empty space between your ship and other windows. This mod is based on famous lifesaving MenuStabilizer written by comrade Alexander Gavrilov aka @a.g. and includes all of its features. Compatibility: It is not recommended to install both MenuStabilizer and DraggableMenu because they will fight for control of same things what can lead to fitful menu movements. Download: SpaceDock Curse GitHub //Coming soon. Installation: Extract the .zip into your KSP directory and overwrite if asked. License: MIT Changelog: Feel free to post your comments, suggestions and of couse bug reports, but don't forget to include your KSP.log.
  22. I know this question has been asked time and again, but I have dug deep and yet to find a clear cut answer to the question: Are pre-coolers capped with an aerodynamic nose (advanced nose or tail connector) less draggy than the same amount of shock cones per intake area? That seems to be the two greatest issues is intake area vs drag on any high speed vehicle. Testing the same vehicle with the same weight, does intake area even count towards drag on the pre-coolers that are streamlined? I guess what I'm asking is how the heck drag is calculated, especially if you can't directly tell from the debug part menu? This is the single most difficult issue preventing an SSTO to the outer planets is the drag on Kerbin.
  23. Has someone got the atmospheric drag function from game files, or an approximate function by fitting? I want to try to simulate flight in mathematical software. It's necessary. Thanks.
  24. (I think this is a general question and not particularly related to any specific craft - but if a specific example would be useful then I can upload one later.) I recall reading that attaching items radially are affected by drag, and that items attached in a stack are not. What happens if you attach an RCS thruster behind a wing (where you would usually attach control surfaces)? Is that radial or stacked, and (more importantly) is it affected by drag? I think that I also recall reading that it doesn't matter how it has been offset and rotated, the item still behaves the same as if it were not offset or rotated. I assume that this means that I can make a RCS thruster look like it is attached on the body just behind the wing, when it is actually attached to the wing just next to the body? Final questing: do RCS thrusters work inside cargo bays? IRL that would not work, but I wonder if the game engine is simplified enough to get away with it.
  25. As part of some nose cone testing (put nose cone on a Hammer SRB with minimal control surfaces and ballast to even out weight differences and see how high they go) I noticed that a shock cone appears to have the same drag regardless of being open or closed (the test vehicle reaches the same height). Has anyone else observed this or is there something screwy with my test? Thanks, Richard
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