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ferram4

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Everything posted by ferram4

  1. ferram4
    It's difficult to model properly. I admit, it would be funny to see people build planes that can just barely fly along the runway, but they get to the end and drop like a brick because the runway falls away from them, but every attempt at modeling ground effect either resulted in physics glitches, or what appeared to be very inconsistent amounts of lift that didn't vary properly with wingspan or wing loading. The only way that resulted in anything that made any sense also resulted in only tiny increases in lift. So basically, it seems to be more trouble than it's worth, at least for now.
  2. ferram4
    Every time I've tried to model ground effect it ends up being unnoticeable in any form other than the extra performance cost. The B9 huge wings twitching seems to be more related to the flap code; I think I'm going to have to rewrite it again. That said, it isn't showing any infinigliding; large wings with small payloads results in a very high L/D ratio, which means that it will fly for a very long time before coming down.
  3. ferram4
    It's 35,786 km. Make sure that your semimajor axis is 42,164 km and that your orbital period is as close to 23 hours, 56 minutes, 4.0916 seconds as possible.
  4. ferram4
    I saw your conclusions, and think that you should probably set them up with different leaderboards for procedural fairings and other fairings. That would allow you to separate the differences in payload fraction with size and the ability to be able to stuff most anything into a procedural fairing.
  5. ferram4
    I meant that perhaps it would be possible for DR to shut off all the reentry effects just before leaving the flight scene, as a kluge-like workaround, if the reentry effects are the issue.
  6. ferram4
    Nathan, would it be possible for you to work around the click bug by having DR zero out all the reentry flames just before it applies the "exploding" to the root part of a vessel or in the reentry heat's OnDestroy method? If it is reentry-flame linked then that may be able to fix it.
  7. ferram4
    @LORDPrometheus: No, rockets only flip if their center of mass is too low, which puts it behind the aerodynamic center. I really don't understand where this idea that the center of mass has to be low for rockets comes from; haven't any of you people played with darts before? @awdAvenger: Sure, it should make a lot of drag. It's a sudden decrease in cross-sectional area; in the configuration that it's in, that part will cause an area of very, very low pressure to form behind it, which is what drag is primarily caused by for shapes like that. Frankly, for that design the short Rockomax adapter isn't the worst; it's the other adapters above it that are further from the CoM that will cause it to flip over. Second "isShielded" is for parts in cargo bays / payload fairings. I should probably make that clearer. @ANWRocketMan: Yeah, that's been fixed for such low speeds in v0.11. Granted, you can still get things like that to happen at higher speeds, but that's because at high speeds everything makes a decent amount of lift.
  8. ferram4
    @Maxwell Fern: Based on what I've seen, the ablative shields do ablate proportionally to the heat being applied to them. The heat transferred to the shield increases greatly as it drops through the atmosphere, so greater ablation happens lower in the atmosphere. Further, ablation should coincide with the heat shield's temperature dropping, since the material that has ablated away is pulling large amounts of heat away from the shield. @Sparker: "Active heatshield" means that the part will not absorb all of the reentry heat applied to it; normally if some type of ablative material isn't listed there that means that it's a heat-soak type of system, which simply reflects / absorbs as much heat as it can without transferring it to the underlying part.
  9. ferram4
    @nothke: Any situation where it seems like stalling is night and day is probably the control surfaces stalling, since they tend to stall more severely due to their greater angles of attack with respect to the airflow. If you managed to stall a plane and get it at 90 degrees with respect to the air, its main lifting surfaces will only be stalled if that's 90 degrees in pitch; if it's 90 degrees in yaw, but 0 degrees in pitch the wing will still make quite a bit of lift, but due to how the stall works it will be very uneven; the solution to this is a larger vertical tail. The situation with the plane losing lift even though no stall is detected is not actually due to stalling; the plane is too stable and the elevators cannot pitch it up enough to produce the necessary lift. Your plane is basically lawn-darting. @KerbMav: No, FAR users don't have to deal with that. Personally, I'm of the opinion that that bug has never existed and is simply the result of players blaming the mechanics for their own failures. Out of ignorance / pride. @DasBananenbrot: Well, there's no picture there, so I'll have to investigate on my end. It might be that the NovaPunch parachute is messed up in some way.
  10. ferram4
    If I understand this correctly, you want an orbit that where the orbit normal vector points as close to the sun as possible so that the satellite never ends up in the Earth's shadow, correct? If so, then a Sun-synchronous orbit is probably what you want to look at. It takes advantage of the non-spherical gravity of Earth to subtly change the orientation of the orbit so that the sun is always in the same place relative to the plane of the orbit.
  11. ferram4
    Obviously, what's happening is that the real chute is still applying drag through the stock model. FAR zeroes out everything that needs to be zeroed out for stock parachutes, but not for real chute. Try adding this to the end of the FerramAerospaceResearch.cfg file in the FerramAerospaceResearch folder: @PART[*]:HAS[@MODULE[RealChuteModule]] { @MODULE[RealChuteModule] { @stowedDrag = 0 } }
  12. ferram4
    @mhoram: Forbidding the use of payload fairings with FAR basically makes designing a properly stable payload above ~50 tonnes almost impossible; a payload fairing is much more aerodynamic than slapping radially-attached fuel tanks with nosecones on either end. You could allow payload fairings but require that they be jettisoned before figuring out the total mass of the payload, effectively balancing out whatever aerodynamic dV benefits that might come from them by reducing the payload fraction. Don't require them, but don't forbid them either. @Frederf: I was meaning to do that, it just slipped my mind. @nothke: The same basic principles apply, CoL behind CoM. The yellow moment curve is really the only one you want to seriously care about (except for very specific point designs, like a U2, where you would care about the behavior of the blue lift curve more). Just make sure that it slopes downward to be sure that your vehicle is stable. Make sure to check at different Mach numbers, since planes that are stable at subsonic velocities can be unstable at transonic (0.8 < M < 1.2) velocities, and can lawn-dart at supersonic velocities if not designed properly. Looking into flight dynamics and aerodynamic stability on Wikipedia should tell you all you need to know to be honest. FAR simply checks all of the meshes and bases its performance on that, with the exception of wing parts, which have specifically defined parameters. The documentation for the wing parameters is in the readme.
  13. ferram4
    First, tall, thin rockets, not pancake-asparagus things that have lots of dV but no aerodynamic ability. Second, small changes in angle of attack; letting your attitude drift outside of the prograde circle can cause problems. No sudden 45 degree pitch-over maneuvers. Third, make sure that your payload is of similar density to your rocket if you're not using fins; this includes empty space. A mostly empty payload fairing will shift the aerodynamic forces further forward on the rocket while not shifting the mass that far forward, so the rocket will become unstable. If you must launch something like that, use fins at the bottom of the rocket to counteract it. Fourth, don't have a crazy TWR. TWR over 1.6 is generally bad enough; if you're the type of person that starts with a TWR of 3 (yes, I have seen that in screenshots) you will have a very bad time. Fifth, consider posting pictures if you're stumped after reading this; there are a lot of people here who will be willing to help if we have something specific to critique and work with.
  14. ferram4
    SAS has always hard locked onto a heading. Perhaps you've been using rockets that SAS is better at being aggressive with.
  15. ferram4
    I sent updated config values to MedievalNerd when he asked about including FAR in a pack with RO and all the other RSS thingies, so he has that data as well. You can figure out the diameter factor, obviously. Incompressible should be set to 0.01, sonic to 0.2.
  16. ferram4
    Only stock jet engines are nerfed. Anything else is left alone.
  17. ferram4
    Version 0.11 is out, changelog below: 0.11v------------------------------------ Features: Cylinder crossflow drag is now more accurately modeled; cylinders make less drag when the crossflow Mach number is below the critical Mach number (M = 0.4) More updates and fixes to Editor GUI and Center of Lift indicator Reduced stability of command pods and reentering objects to more reasonable levels; lifting reentries are now easier to manage, but sane mass distributions are required for proper stability Optimizations in all constantly-running code and some reductions in memory usage Update to use ModuleManager 1.5, by sarbian Some attach node corrections for stock parts that had incorrect attach sizes, causing poor drag modeling Ability to modify some aerodynamic properties in the config.xml, including: --Area Factor: a multiplier to increase or decrease aerodynamic forces; 1 by default --Attach Node Diameter Factor: how many meters in diameter an attach node size applies to; 1.25 by default --Incompressible Rear Attach Drag: the drag coefficient of a rear-facing attach node at Mach 0 --Sonic Additional Rear Attach Drag: additional drag above incompressible at Mach 1 Includes set up for Kerbal Updater BugFixes: Fixed an issue where cargo bays that started closed would not properly shield parts unless it was opened, then closed
  18. ferram4
    @Reign OfMagic: Then you must be using Kerbal Updater, and this is an issue more suited to its thread rather than this one. Odds are that you're either keeping multiple copies of ModuleManager floating around somewhere (which you shouldn't be doing) or that you just installed FAR and that Kerbal Updater is attempting to make sense of it. @mhoram: No, FAR doesn't depend on anything other than Module Manager, which is packaged with FAR. No, nothing you can change in the VAB, SPH or in-flight changes the physics; the upcoming version will allow some changes in physics through a config.xml though, mostly to allow for more realistic parameters for RSS while keeping the less-accurate but more stability enhancing higher drag values for stock KSP.
  19. ferram4
    Yes; it was called updating KJR to the latest version.
  20. ferram4
    You can't edit the aerodynamics; that would be like letting you edit the gravity of the planets in-game. Most of the settings are to control the strength of a few of the control systems added (that can be turned on using the buttons on the bottom of the main flight window). The main reason to change those is because sometimes vehicles don't respond well with those settings. General info is best found in the long FAR release thread; pretty much every question that could be asked has been asked, and has been answered.
  21. ferram4
    Take a look at how much stuff you're trying to bring down, and then take a look at the size of your heat shield. According to Flight Engineer, you're trying to bring down a vehicle that is 3/4 the mass of a 3-man pod, but using a heat shield with half the diameter, which corresponds to 1/4 the cross-sectional area. So this means that your ballistic coefficient (a nice measure of how much mass your vehicle has compared to its drag) will be 3 times as high as that for the 3-man pod; you want that number to be as low as possible for reentry. It may not be possible to bring that vehicle down, since it's too massive for the amount of drag you've given it, which is realistic behavior. If you're wondering why the landing gear burned off, it's because they weren't designed for reentry heating, and you didn't slap on a heat shield capable of covering them. Another thing is that you've taken a relatively steep trajectory, considering you're at 25km and still moving at 1.9 km/s, with a good portion of it downwards. This basically means that you're not taking advantage of whatever drag you can while the atmosphere is too thin to actually heat up the heat shield dramatically.
  22. ferram4
    Except you're encasing your fuel carrier in a payload fairing; all that empty space between the fairing and the fuel tank reduces the density quite a bit. Make your rocket taller; don't build outwards if you don't have to, add more fins. It's probably just a design issue.
  23. ferram4
    Yeah, that's the entire problem; if you're turning 45 degrees in 7 km while going pretty fast that will cause it to flip out; cylinders in cross-flow make a lot of drag. Another problem is that your payload is probably less dense than the fuel in your boosters; this will place the CoM lower, making the rocket a lot less stable than you think; keep in mind that most "clean" rockets are LH2 + LOX, where the LOX is much denser than the LH2 and the LOX tank is put at the top of the booster, which makes it much more stable than it looks. For reference, the Space Shuttle main tank did this, and it's CoM was 1/3 of the way from the top, rather than slightly below 1/2 as you would expect for that type of shape if it was made of a uniform density material. We can't do that in KSP, so we have to come up with other options, such as the Saturn IB "add all the fins" solution.
  24. ferram4
    Another thing is to make sure that when you finally ditch the heat shield that you also deploy a chute somewhere near the top of the thing you're landing. I had a RSS Duna-Mars rover landing end badly because the rover flipped around due to the weight of the skycrane and the failure of the drogue to deploy in the thin atmosphere.
  25. ferram4
    First, make sure you're using the latest version, since earlier versions have always had problems with large heat shields. Second, make your reentry vehicle as squat as you can, with as much mass as possible near the bottom; this is because if the CoM is too far towards the back no amount of natural stability from the heat shield will save you.
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