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Found 47 results

  1. A while ago there was this excellent discussion on air intakes and drag in KSP: This is still an important topic (would be even more so if the dev's could give us some larger airbreathing/jet engines, so spaceplanes are actually useful without massive engine-spam!) and I wanted to continue to draw attention to the idea, discuss it, and see if anything has changed. Also, there were some nuances to Right's graph (re-posted below for convenience) that I don't think really got any proper discussion- and couldn't be discussed there now without nero'ing a very old thread... Note, for instance, the shape of the Shock Cone Intake performance curve (or lack thereof). I think many players sub-optimally assumed the most efficient Spaceplane ascents involve keeping all your engines lit throughout your entire ascent. However I have increasingly found this is NOT the case-especially with the 2 stage spaceplane designs I have been experimenting with lately (a smaller Spaceplane optimized for high-altitude, high-speed operation rides piggyback atop a larger plane that breaks off. Awesome in Sandbox/Science, but requires a mod like Flight Manager for Reusable Stages so you can fly the lower stage back to actually be useful in Career...) Often it is better to have some engines- particularly Ramjet engines- you only ignite at higher altitudes and speeds, keeping your demand for IntakeAir (and Thrust production) relatively flat as you ascend... (this is even MORE true with modded parts like the Air-Augmented rockets from, I think, Mk2 Expansion: which, realistically for a ducted rocket, perform better at high speeds not only in terms of Thrust, but ISP...) If you have engines you only ignite at high altitude+speed (or simply don't throttle all the way up until you reach high speed/altitude due to heating issues, aerodynamic stability- particularly with dynamically unstable designs that become less stable at higher speeds, or not having your wings rip off due to aero forces in FAR!) then the Shock Intake curve suddenly looks a lot more appealing: note these curves are for constant altitude- the Shock curve ends up being flattened (in terms of rate of IntakeAir production) by reduced air density at higher altitude... Other things notable: - The Divertless Radial Supersonic Intakes appear to have the smallest performance-drop of any intake other than the Shock Intakes between Mach 3 and higher speeds (the slope of their curve is much more gradual, even controlling for their lower peak), making them often the second-best choice for high-speed planes (as well as great for fine-tuning *precisely* how much intake you have, so you don't have any more than needed...) - Engine Pre-coolers have, surprisingly (and unrealistically, given the whole POINT of using them in real life would be high speed+altitude performance) a steeper curve relative to the amplitude of their peak than the Adjustable Ramp Intake (aka the stock RAM-effect intakes). This makes them more poorly suited for high speed/altitude operations, at least as intakes (again, this is unrealistic- and the dev's ought to rebalance these to make them more useful). That being said, form-drag (from frontal cross-section mainly) becomes much more punishing at higher speeds, at least in FAR, so they actually do work well at high speed planes- but for all the wrong reasons (in real life, Pre-Coolers aren't even intakes at all, but allow you to cool/compress airflow before it reaches the engines so they "think" they're actually operating at lower speeds/altitudes. This would be easily simulated in KSP by simply having them decrease the airflow speed and altitude any engines they are connected too "see"- and indeed this is EXACTLY how they used to or still do work in KSP-Interstellar, which included special code to make pre-coolers work realistically: at least in older versions for sure...) In real life, they would produce a lot of intake Drag (as you slow the airflow more) and provide no direct intake functionality- yet be CRITICAL for a horizontal-takeoff spaceplane ascent... - On the topic of pre-coolers, again: there has been some mention that they are highly heat-conductive (wicking heat away from engines), yet this is somehow a BAD thing (as it causes them to absorb more heat from the atmosphere). It seems to me most players don't understand the Stock heat conduction system well, or how to use this properly. The best parts to attach pre-coolers to (on the other side of the engine) are large, heavy parts with a lot of cross-sectional area (so these parts in turn can pass the heat they absorb from the pre-coolers to other parts). This is entirely because the Stock heat model assumes an entire part is all at a constant temperature, to make the calculations manageable. Anyways, this makes good parts to attach Pre-Coolers to things like the long Mk2-Mk1 adapter, the Mk2 Bicoupler, the flat (rear) end of Mk3 parts, or especially large cross-section mod parts with inline 1.25 meter nodes (like the "Stail" to 2.5 meter adapter with shoulders in OPT Aerospace, or the Mk4 Adapters in Mk4 Expansion...) The parts they are attached to should, ideally, in turn be attached to even larger parts (like a Mk2-3 adapter in front of a Mk2 Bicoupler). The key is to wick heat away from the pre-coolers as quickly as possible so they can wick more heat away from the engines in turn. Not that engine overheating is THAT big of a problem in Stock (except for with the NERVA nuclear rockets- a part intake air precoolers would be USELESS for in real life, unless you were air-augmenting them... Or modded nuclear turbojets, like those in Mk2 Expansion- where at least the use of pre-coolers is realistic) - The Small Circular Intake has a relatively flat curve that LOOKS like it would be well-suited to high-speed operations: but in reality they tend to explode at high speeds, as they have terrible heat-tolerances...
  2. I'm trying to make small craft for Laythe. So i decided to make it with external command seat. But when I tried to ascend my kerbal ate plenty of dV by a huge drag. In fact my kerbanaut is covered up with another part from the airflow and should not be the most draggy thing on the craft. So, I know that if I put seat to small service bay it's some kind of solution, but cargobay is quite heavy and has some drag too. Is there any other ways to reduce kerbal drag by some covering?
  3. Hi All! I've been trying a little more with SSTO spaceplanes recently. I've done some in the past, mostly small ones with stock parts, but in this heavily modded career game I wanted to try big, so I built this one using moslty OPT parts, which I wanted to use for a space camp mission (bring 15 tourists to orbit). It actually has a pretty decent TWR, not a lot of DeltaV probably, but I haven't tuned it yet...mostly because I can't get it past 370 m/s or so. In the picture attached you can even see that I'm pitching down, but even pitching down, my speed was DECREASING... So. I'm showing the aero overlay, by doing some googling, I saw people seem to suggest drag from clipping parts might be a thing. I can't honestly think of anything else, given the large wingspan and high TWR. Is drag what I'm looking at? If so, how do I fix it? Thanks in advance!
  4. I currently have a whole bunch of mods installed and have recently updated to 1.7.0 and my parachutes no longer work. When I deploy my chutes and set the full deploy altitude to max it seems fine at first. But when fully deployed they act like they’re not even there. The parachutes do nothing and I end up hitting the ground at ~160 m/s. Ps I don’t have realchutes installed. Any ideas?
  5. Does anyone know how to work out the safe opening conditions for parachutes? I found this interesting post from @Gaarston calculating terminal velocity with chutes but can't find anything on the safe limits. Presumably the safe limit is based on a maximum force, which will come from drag, so as the Cd and Area will be fixed for a given parachute type it'll be directly proportional to Dynamic pressure, Q. However I can't find any info on it. Using kOS to track Q of a fairly speedy capsule (3 mk1 capsules and a Stayputnik) as it re-entered, I found the Q peaked at about 36kPa when I stopped getting flame effects, it then dropped to about 14kPa, with the radial chutes turning white at around 18kPa, then Q started to rise again with the chutes turning orange at 31kPA and red at 35kPa. I've not entirely got my head around Q having 2 peaks though, I was expecting it to build to a peak and then drop off as it's directly proportional to drag, I guess there's some mach effects there increasing the effective area. The info on the radial chutes in the VAB says they have a tolerance of 4000kPa, which presumably isn't dynamic pressure as that would equate to about 2500m/s at sea level. I'm not even sure that could be a maximum dynamic pressure they can withstand when stowed as they'd presumably overheat and explode well before that. I did find an entry of "Breaking Force = 100" in the radial parachutes cfg file, but no idea what that could be as they're taking way more force than 100N, and I'd need to have a bit of a wade through the topic linked above to try and work out what the Cd and Area are to be able to calculate an actual force at my experimentally derived dynamic pressure to see if it's linked to that, but 100kN sounds too low to me. I might try sticking an accelerometer on a capsule to measure the force when the chute deploys to see if it relates to 100 anything. Anyone got any ideas?
  6. Is there a general rule of thumb as to the optimum altitude/velocity/pressure (Q, I think) to jettison fairings-- where the aerodynamic drag reduction is no longer worth the weight/gravity loss? I don't really need the exact equations-- just a general "feel" for the right timing/altitude. Thinking of firing off a series of sounding rockets to test, but I imagine someone else has done a lot more thinking about it already...
  7. I've noticed a HUGE difference in my Mk2 spaceplanes, but I wanted to make sure it wasn't something I was doing, so I made two identical craft in 1.3.1 and 1.4.1 and launched them with a launch testing script I adapted from the kOS tutorials. The difference is huge and makes pretty much all of my Mk2 based spaceplanes no longer viable. I hope this gets fixed. I loved some of those. Craft file here: https://github.com/quade-ksp/KSP_Craft/blob/master/Testing.craft kOS launch test script here: https://github.com/quade-ksp/KSP_Craft/blob/master/launch_test.ks Video here:
  8. Right now im still learning the mechanics of KOS, and while doing this i was trying to use air drag to calculate throttle during ascent. But when i started searching online i coulnd't find any proper scripts to do this, apart from the ones before 1.0. Everyone was saying that you couldnt calculate it now because we don't know the Cd value of ships anymore. But you can actually calculate it on the fly using: Thrust vector + Gravity Vector + Drag vector = total force on ship(Vector). After puzzling for a while with vectors i managed to come up with this script which returns the drag as the vector AirResVec: Important notes!!: Doesn't work while landed because the script will think the drag is keeping the craft from falling instead of the ground its standing on(edit: now fixed by adding a failsafe that will return 0 drag if the ship is either landed, not launched yet or splashed down) There is a slight delay when changing the throttle which will cause the air drag vector to freak out for a split second You need an accelerometer on the craft to calculate the (wait for it...) acceleration.(edit: these two issues are now fixed by using the KO's built-in ship:velocity instead of ksp's accelerometer which averages the acceleration from the last 0.4 seconds which caused glitches) I hope this helps the community since the script wasnt available when i needed it. BTW. here is a pictures of the vectors in action:
  9. As the title states, I am using a mechanics bay to shield some science instruments. I've also used a regular cargo bay from 1.25 and the mk2 line for planes. The items contained within them, when aero debugging is turned on, are not listed as shielded, and as expected for random objects hitting the atmosphere at mach x, the drag is insane. Anyone else experienced this? Its killing my plane game.
  10. I'm making some really big truss segments, but the procedural drag cube treats each part like it's clad in plastic. When falling through the atmosphere, it basically drifts down like a feather. I could just make the parts super heavy, but they're supposed to be made of lightweight materials. Anyone had a similar problem in the past? I could use the help
  11. KSP Version: 1.3.1.1891 (Windows 7 x64), fresh install, fresh sandbox savegame. I keep this particular KSP install for such testing only. Mods / Add-Ons: All Stock Description: if there is a long enough part inside a cargohold that consists of two shorter ones, then drag is applied to the payload. (I think its because the game thinks that payload part is clipping through the cargobay. Although visually it is only clipping through its front or its back as it is longer than the cargobay.) I also think the problem is known. But I'm not sure. Also I'd like to know if it's gonna be fixed or not. The reason I'm reporting this is because there are many modded parts that are longer than the longest cargobay available. Fuel tanks for example. It also limits how one should attach their payload inside cargobays. UPD: not every part bugs. Incomplete list of parts which I've tested (yes = causes the bug): - FL-T800 Fuel Tank: yes - Modular Girder Segment XL: no - M-Beam 200 I-Beam: no - Mk1 Cockpit: yes - Orange Tank: yes - RT-10 Hammer Solid Fuel Booster: yes (omg i've ignited it inside my cargobay.. omg.. oh nevermind it didnt explode) As a lil' bonus I've also tested the situation when a small part is placed between two cargobays. It didn't bug at all (tested with 2x FL-T200 Fuel Tank). Steps to Replicate: 1) Create a plane with two connected short cargobays so they make a longer one together. 2) Put a long enough part inside - its length must be longer than one of the short cargobays. Example: two connected Mk3 Cargo Bays CRG-50 and an Orange Tank inside. 3) Attach additional parts like a Cockpit, landing gears and an engine (if the payload isnt a fuel tank - then attach a fuel tank too of course). 4) Launch the craft. 5) Make aero forces visible in parts' gui menu through the debug menu. 6) Open the payload right-click menu. 7) Accelerate and watch its drag. Result: The payload's drag isn't zero although it must be as it is fully enclosed. Fixes/Workarounds: - attach the payload differently (if there are multiple crafts or parts as a payload); - use different nodes; - use the largest cargobay available; - don't put larger parts inside Other Notes/Pictures/Log Files: Both Mk3 and Mk2 cargobays have this problem. I believe its an internal technical logic problem, not a bug. Its just how the game calculates drag. But still it is a problem. Craft files: Mk2: https://www.dropbox.com/s/kk4h6y8h4alamx0/Bugged Mk2.craft?dl=0 Mk3: https://www.dropbox.com/s/fe4zaluf436nniq/Bugged Mk3.craft?dl=0 Screenshots (the right part-menu reflects the payload on both screenshots): Thank you Squad for making one of the best games! No sarcasm involved. Bugs happen. (I believe there is no need to include logfiles. Will attach if Im wrong.)
  12. In a plane the Centre of mass is just ahead of the centre of pressure, so it is stable. When elevator movement is given, it does go nose up but it doesnot climb. Instead in it tries to come down. How to make it climb. P.s Rhodes34 airfoil if used inclined at 8deg Basically I want to know what affects the rate of climb and vertical velocity
  13. Just wondering. Can you land using drag alone? Parachutes don't count here.
  14. EDIT - partially solved: although nothing ever shows as "shielded" in the debug menu (under fairings OR in cargo bays), parts properly stowed in STOCK cargo bays are showing no drag once the craft gets going. Looks like an issue of bays added in mods (as far as drag actually being applied to stowed parts). I don't know how to delete a post, but someone who can may want to knock this one out. ____________________________________________________________________________________________________________________________________________________________________ I posted this on the modded forum and got no replies, so I'm trying it here, as I've had the same problem on a brand new install as well. I've searched and cannot find why my cargo bays won't shield anything from drag. I've knocked out all the usual suspects I can find, and here's what I've done: 1. I've used different types of cargo bays, mk 2, all the mk 3s (and some OPT ones before my clean install) 2. NO clipping anywhere. 3. Internal parts attached to nodes inside cargo bay. 4. Tried different parts 5. No external parts attached to cargo bays except inline by external nodes. For testing used fuel tanks of same type as cargo bay attached to either end with one random tester part inside bay attached to internal node, nothing else but landing legs attached to fuel tanks and maybe a drone core attached to a fuel tank to allow actuation of bay doors. I load it up on the runway, look inside bay and parts (using debug menu) are showing NO for "shielded." Open and close bay doors, no difference. I haven't played the game in days because space planes are what I'm doing at this point, and useless cargo bays ruin space planes IMO. Please help?
  15. EDIT - partially solved: although nothing ever shows as "shielded" in the debug menu (under fairings OR in cargo bays), parts properly stowed in STOCK cargo bays are showing no drag once the craft gets going. Looks like an issue of bays added in mods (as far as drag actually being applied to stowed parts). I don't know how to delete a post, but someone who can may want to knock this one out. _____________________________________________________________________________________________________________________________________________ I've searched and cannot find why my cargo bays won't shield anything from drag. I've knocked out all the usual suspects I can find, and here's what I've done: 1. I've used different types of cargo bays, both stock and OPT. 2. NO clipping anywhere. 3. Internal parts attached to nodes inside cargo bay. 4. Tried different parts 5. No external parts attached to cargo bays except inline by external nodes. For testing used fuel tanks of same type as cargo bay attached to either end with one random tester part inside bay attached to internal node, nothing else but landing legs attached to fuel tanks and maybe a drone core attached to a fuel tank to allow actuation of bay doors. I load it up on the runway, look inside bay and parts (using debug menu) are showing NO for "shielded." Open and close bay doors, no difference. Used several types of different sized bays, mk3, mk2, OPT J, no difference. *(edit) I finally removed all mods and made a simple tester as described above and had the same results, but I will list my mods here anyways, since I put it in the modded category. xScience (doubtful) CommunityResourcePack (didn't install this? came with another mod?) Firespitter (didn't really want this one either...came with Infernal Robotics I think) InterstellarFuelSwitch Infernal Robotics MechJeb2 MechJeb2 Embedded by Dennis6492 OPT Planetshine (doubtful) TextureReplacerReplaced TweakScale Module Manager 2.8.0 I am running 1.3 with all mods updated and (I thought) working. I'm trying to get some space planes flying around and I use cargo bays extensively, so this issue is killing me. Any help would be very much appreciated!
  16. Hi, im wondering wether i should put all the solar panels for the Magnetoplasmadynamic's needs. Im considering overcovering the spaceplane with flat solar panels or just the typical Gigantors XL Would the plane oversuffer from drag if i overcover it with the flat solar panels?
  17. So I'm making a spaceplace in the 50-60 ton range, and I don't know what I did, but some relatively minor change now causes it to no longer go to space. I can't figure out what happened, but I think something is causing massive drag that shouldn't be, as it now feels sluggish and underpowered, and this is compared to another fairly similar spaceplane that's 15 tons heavier, with the same engines, it it goes to space just fine. Even worse, I just now forgot to retract the landing gear, and it still outperformed the lighter plane. So something's very wrong. I've tried to figure out what's causing the drag, but no luck. I'm not even sure if it's really drag, but it seems to be the most likely culprit. So far, I haven't any way to even see drag values. Supposedly MechJeb shows atmospheric drag, but I can't find that feature. And some other mods I tried were out of date. At any rate, this will only confirm if drag is the issue, not what part is causing it. Any ideas? Any suggestions to see the drag of parts?
  18. I am playing KSP with a bunch of mods. the game was running fine and then i had a game crash. i had to re validate, update my drivers and restart my computer to be able to get KSP to load again. when it did finally load and i tried to launch a plane from my hangar but i was unable to lift off as my speed couldn't go above 13m/s. i know it was working before because i had no problem gaining speed and flying with the exact same plane i was using. i thought it could just be the liquid engines but when i loaded up my rocket fueled plane it had the same effect. i could not gain speed its as if the physics had been changed by a mod or something was affecting the atmosphere. i tried deleting my physics file and re validating but that didn't fix it either. i opened the console config with shift F12 or w/e it is and looked up the default values online and the numbers were the same? any ideas on what could be causing these physic issues? or mods that might tamper with physics? i dont have the real physics mod installed thanks
  19. I've always hated the way drag is shown in stock KSP. I have no idea which parts are causing the most drag, and by how much. All i get are a bunch of long red lines overlapping each other so they are impossible to distinguish from one another. Is there a mod that changes the way drag is shown in the aero forces overlay view? I'm looking for something stock compatible that's not going to actually change drag, but just show it easier. Thanks in advance!
  20. So, I'm not sure if anyone else has noticed this, but ladders have a ridiculous amount of drag. I've had them create as much drag as a Big-S Shuttle Wing on some occasions. Now, is there any nice way to make drag cubes check for other drag cubes existing in the same space, or would this be an absolute nightmare for anyone to code? I don't know a thing about modding on KSP, so I am posting this as a request, but if anyone knows some of the basics on how to do this, I'd be willing to try my hand at it.
  21. 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?
  22. 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?
  23. It'll be really helpful to know the Lift&Drag characteristics on altitude and speed, to fly a proplane. Anyone knows something about this?
  24. 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.
  25. 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