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ferram4

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Everything posted by ferram4

  1. ferram4
    Spheres produce less drag than cylinders in cross flow. You've got cylinders in axial flow there, which causes the difference. As for the stuff added in the edit, the raycasting done by deadly reentry is directly along the surface velocity vector, and it only goes from the center of the part. That means that if you get the center behind the shield no heat will be added to it. As for the part popping off, odds are that the part's density is either higher or lower than most other parts in the game; in the first case, the joint won't be strong enough to handle the weight. In the second case the added stiffness will cause issues when floating point errors start to crop up.
  2. ferram4
    Well, odds are it should make more drag; it's not like spheres are really all that aerodynamic. That said, there are still some things wrong because FAR doesn't know how to handle parts that can't be approximated as conical frustums, and I'm not planning on adding support for more complicated shapes because it risks adding very nasty issues if someone else comes up with a more convoluted shape. FAR also doesn't account for local changes in dynamic pressure yet, which would make using them as airbrakes behind a heat shield impossible. I'll look into adding a bit of code to override using attachNodes for drag, and then the only solution would be manually setting the drag parameters.
  3. ferram4
    1. It's pretty much storage of the rocket and the fact that you don't need to launch the rocket immediately after it's fueled or enough LOX will boiloff to reduce the dV enough to harm the mission. There is the nice advantage that it's denser than all the other fuel types, which means that the tanks can be smaller. I don't know of any other reasons for using it. 2. Actually, I've launched a few GEO sats using kick stages way, and with the right timing you can get within 1 m/s of your target velocity. It really does just come down to figuring out where to make the fixed dV burn; for some sats I ended up not using all the dV in the stage before it, while with others I just made the payload as heavy as possible. Unfortunately, none of the maneuver node editors seem to include a "set the maneuver node to burn x dV, just change the angle and time" function, which would make it a lot easier. All that said, the payload makes the necessary corrections after burnout, and done properly there aren't that many corrections needed.
  4. ferram4
    That's an issue with older versions of FAR; make sure you're running v0.12.5.2.
  5. ferram4
    Alright, looking from the bottom going up, and only considering the shape of the nozzle, ignoring the hoops: From the lip at the end of the nozzle to 3rd hoop from the bottom it looks good; a nice curved shape. From the 3rd hoop to the 7th hoop it looks like the engine nozzle it built out of one single cone with straight sides. From hoop 7 up looks like another. There looks like there might be a change in the angle at hoop 9, but I'm not sure without a protractor handy. The problem is that the sudden change in angle at hoop 7 makes heavily accents the straight lines above and below it. Don't take any of this the wrong way, it's a great start.
  6. ferram4
    The actual optimum way would be to use parachutes to slow it down, but you'd need to go to stupid_chris' RealChutes to get one that doesn't immediately disappear when you hit the ground. Another thing to try would be to disable the brakes on the front wheel so that it can't wheelbarrow on you.
  7. ferram4
    The pictures I come up with when searching for "RS-27A" look like the hoops are evenly spaced and like they have the same thicknesses. Most engines that have those on them seem to have even spacing between the hoops, so I don't see why this one would be any different.
  8. ferram4
    A very nice start, but some criticisms from what I can see: The structural hoops on the nozzle don't appear to be evenly spaced, it's particularly notable between the 1 and 2 compared to 2 and 3 (counting from the bottom and not counting the lip at the end); check the distance between them and even it out. Around hoop 5 it looks like the engine bell is curved the wrong way; the line between hoops 4 and 6 is probably straight, but since the nozzle it broken up visually by the hoops you need the angle to change, even if just a little to make it look right. It also looks like the hoops are inconsistent in their thicknesses; it looks off. It's a very good start, keep at it! It just looks like it needs a ruler put next to a lot of the elements to make them consistent.
  9. ferram4
    Then in that case the issue is that you're trying to stay in the air too long. What altitude are you trying to fly at when it flips? Honestly, for a very low L/D craft like that I'd expect it to land somewhere around 100 - 150 m/s. Come down closer to the space center and don't try to glide as much, since it's not designed for gliding.
  10. ferram4
    How does it flip out? Is it in yaw or in pitch? If it's in yaw (or something involving roll) you need more yaw stability, since that thing looks like it has very little yaw stability, especially at high Mach numbers. You might want to try angling the vertical stabilizers a bit so that they each start with ~5 degrees of angle of attack with respect to the flow to help. If it's in pitch, I'd actually use larger control surfaces on the main wing for pitch and get rid of the canards. You've got too much weight near the back of the rocket with those RAPIERs back there, and the long body will add quite a bit of lift at the front without the canards.
  11. ferram4
    Alright, I've uploaded the v2.0x2 experimental which should tighten things up a bit more while also allowing a slightly smoother physics initialization. Due to what it does when it initializes physics, watch for weird things happening on crafts the are landed on other bodies, especially a few degrees off the equator, since there might be bugs in the Coriolis force calculations. Hopefully things will be much less wobbly this time around. @Castun: Okay, I'm going to need a bit more information: what mods are you running, what versions are they, and what is the simplest craft that can cause this error? Does it occur if you save and launch a lone pod? The error is being caused in a relatively large function and I'd like some more info so I can narrow it down further. @LameLefty: Would you be so kind as to try the new experimental with that craft and see how it handles? Also, would you be kind enough to post the save file with a list of required mods for that craft? I need a good, potentially wobbly test subject to balance out my RSS giant launch vehicle tests.
  12. ferram4
    @a.g.: I think I might have to abandon the inertia tensor fix. I can't make it work with the stuff intended for Real Solar System, and this mod was originally intended to fix the wobbliness with those rockets, so it has to be able to handle 500+ tonne tanks. I've gotten things working a little bit better in my current dev version, but I want to be able to attach 2000 t boosters to a 3 t radial decoupler and have the connection hold together. Even if you think it's silly, that's my priority. Worst-case scenario, we have different configs for RSS and stock KSP. @Castun: I need a copy of the output_log.txt; without that I have no idea where things are breaking. Especially since I've never had that issue myself.
  13. ferram4
    @Surefoot: The best solution is to make sure that the stretchies are all the same mass, if possible; a bunch of 1:1 ratio joints with a few 8:1 joints at the end will hurt things a lot less than a bunch of 4:1 joints the whole way, since that will allow less flexing between each joint, but it will add up. If you can manage to build your stage out of one single stretchy, with engines at the bottom and a decoupler at the top it should be fine though, since the extra decoupler stiffening will be able to help there to remove a lot of the wobble. If you can't use a single stretchy, then you do the 1:1 ratio as much as you can. Keep in mind that the 5:1 is my own rule-of-thumb, not a hard limit; noticeable effects happen with 2:1 if you know what to look for, and things can be managed up to ~20:1 if you are able to build enough extra joints between the parts with struts. Higher can be handled if you add joints to parts on either side of the problem joints, which is how the decoupler stiffening handles the 300 t tanks connected to 0.5 t decouplers in RSS; it connects that tank to the engine and fuel tank on the other side of the decoupler and the combination resists the forces.
  14. ferram4
    The inertia tensor fix helps dealing with stretchies, but a lot of the issues with them are simply design issues caused by the player. There is a more proper fix, but it does wobble a bit more than the quickfix, although hopefully I'll be able to tighten things up for the full release. If you're insisting on making something out of lots of tanks when you don't need to for aesthetics, then it'll wobble a lot more, and there's really not much I can do about that. Ultimately, this is just a problem with stretchy tanks that cannot be solved: there is no way to stop a player from building a vehicle that breaks the physics simulation, since it gives you so much control over the mass of various parts. For reference, things start to get weird in physics simulations when two connected rigid bodies have a mass ratio greater than ~5:1. Stretchy tanks easily encourage mass ratios of 50:1, 100:1, or (in a case that I'm currently trying to stabilize) 550:1 between parts. Basically, stretchy tanks will always be capable of being noodle-like if you try to make them act like noodles. I've always kind of had a love-hate relationship with them, and after dealing with this I can see why SQUAD doesn't want procedural parts.
  15. ferram4
    Honestly, the way utilization gets handled with the current stretchy tanks it seems less like there are a pair of capsule tanks in there and more like super-sized versions of Cluster's Last Stand are hiding in there based on the utilization. I'm honestly not sure if the math is right, since I only barely glanced at the code, all I know is that my attempt at a Saturn V/4-260 looks awfully squat. Also, the KJR pre-release doesn't like it very much; the solids pop off on the pad, but that's another matter entirely.
  16. ferram4
    Hey Nathan, do you get the feeling that the volume utilization is a little too high with stretchy tanks, particularly when using really wide tanks? My Saturn-IC is about 10m too short at the correct mass, and by attempt at building the Nova GD-B concept ended up with all its tanks being quite a bit shorter than they should have been. A lot of these tanks look like they'd have to have really, really sharp corners to make use of the amount of volume they're taking up. Would it be possible to have volume utilization dynamically vary with tank length and radius, at least for stretchy tanks?
  17. ferram4
    @tryder: That's an out of memory error, which is something else entirely. Look, just delete all your mods and start over. Re-download all of them to make sure they're up-to-date and don't install them unless they're confirmed to work perfectly in KSP 0.23. If you have issues after that, come back.
  18. ferram4
    No, this is a terrible idea, entirely caused by the name of the Center of Lift. In theory the Center of Lift (also called the Aerodynamic Center, which is a better name, IMO) would also include the effect of differences in drag across the vehicle. By implementing this you'll just confuse people. Honestly, this sounds like a good argument for combining drag effects into the current CoL and changing the in-game name of the CoL to AC, since that's where this confusion is stemming from. It would help reduce player's confusion while also not feeding them bad information (the implication that lift is the only thing that matters for stability, not drag, as the CoL name seems to imply).
  19. ferram4
    Alright, I've made the v2.0x1 experimental available for people to play with, integrating a.g.'s inertia tensor fix. There may be some issues with it (hence why it's an experimental) but it does seem to help quite a bit. I suspect that it might need separate configs for Real Solar System (which needs some play between the joints to allow physics to not destroy everything) and stock KSP, where things can be tightened to the limit; if you're thinking that things are too loose, try going into the config.xml and reducing the angLimit and linLimit values to 0 and see if that causes any weirdness. Launch clamps should also be more rigid as well. I also removed the previous stretchy tank quickfix, since it's completely improper and really shouldn't be there. Be aware that stretchy tanks encourage stupidly large mass ratios and that there's not much that I can do if you insist on attaching a 0.5 tonne tank to a 900 tonne tank.
  20. ferram4
    You're using KJR v1.7? What exploded (read: pictures of the craft), at what velocity, where?
  21. ferram4
    Try GameEvents.onGameSceneLoadRequested.Add() with the proper arguments to register a function for the event.
  22. ferram4
    That should still be supported without any changes.
  23. ferram4
    @Traches: It's supposed to be CoL, but the CoL only stays in one place for linear aerodynamics; it can actually shift quite a bit for nonlinear aerodynamics, and body lift + drag happens to be highly nonlinear. It's actually quite hard to build an unstable rocket on purpose; it's a little bit easier than it should be given the mass distribution of rockets (engines are way too heavy) to try and make it easier for people. Given how tall and narrow your payload is it might actually not be possible to make an unstable launcher for it. I'd try building the launcher around the payload rather than under it, since that's something that's encouraged by stock aerodynamics. @tryder: I need an output_log.txt and I need to know the version numbers of all the mods you're using. Honestly, this doesn't look like a problem with FAR, this looks like you're using some other mod that hasn't been updated for KSP 0.23. Odds are if you're still using the old ModularFuelTanks that's part of the problem. Update your mods.
  24. ferram4
    I don't know if it's related to the current attachNode issue, but if a procedural interstage is attached to a lengthened stretchy tank whenever it is loaded in the editor the interstage is shifted so that it's placed as if it were attached to a stretchy tank of default length.
  25. ferram4
    The version number is on the top of the GUI that you minimized, like pretty much every other mod with a GUI out there. Oh, I see the issue. You have a stupid high TWR and you're letting MechJeb try to fly it into orbit. Let me guess, it's fine up until the "gravity turn" when it all falls apart? Or it falls apart after MJ gets a good oscillation going? Get rid of the boosters, get the TWR down to about 1.5, keep it aimed prograde, and start your gravity turn at about 100 m/s (wherever that ends up being). You don't want to try and reach terminal velocity, because your rocket will tend to fly apart if you get near it. If you insist on using the autopilot, change the ascent path settings so that it actually follows a gravity turn (you'll need trial and error I'm afraid) rather than the goofy ascent profile that most people fly in stock.
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