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ferram4

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Everything posted by ferram4

  1. ferram4
    I'm looking into that, I'll probably have something for tomorrow. It's not exactly a straightforward thing.
  2. ferram4
    Really, it depends on the exact shape of the graph; if you're talking about a negative, but small slope for a bit followed by a sudden drop, that is the effect of stall causing the plane to pitch down; congratulations, you've built a plane that automatically recovers from stalling! If the yellow line just falls off a cliff immediately, with the entire thing being a line with a steep negative slope that means that your plane is way to stable and you probably won't have the pitch authority to maneuver. You'll need to move the CoL forward a bit.
  3. ferram4
    For your specific questions: A plane is stable if the Center of Lift is behind the Center of Mass; those indicators can be found in the bottom left of the editor. Another method of determining stability is to use the static analysis or dynamic analysis tabs in the FAR editor GUI: If you do a static angle of attack sweep analysis, the moment coefficient (Cm, yellow line) will slope downwards for a stable plane; it will slope upwards for an unstable plane. If you do a dynamic longitudinal analysis the oscillations in the graph will converge to zero if the plane is stable; if it is unstable the graphs will explode. Honestly, the static analysis is easier than the dynamic analysis and is more accurate than the CoL method, though the CoL is better for doing very fast initial design iterations. As for seeing if it has enough lift, figure that there should be slightly more surface area from the wings than from the fuselage. That should be about enough for the first iterations. Just make sure that your main landing gear are just behind the center of mass so that the plane can rotate on the runway and take off properly; no matter how much wing you add, if you can't angle it to make lift you'll have a bad time. Hope that helps, if you have any more questions, feel free to ask.
  4. ferram4
    @SkyHook: If the lift from wings is affecting your vehicle, that means that the CoL is too far towards the top of your shuttle-rocket assembly; essentially it's the same problem as a plane that backflips the second it gets off the runway. Put the wings further back or the fuel tanks further forward and it should fix things. @Netris: You're probably more accurate than you think; the main problem is that KSP rockets have very small gimballing ranges, which makes trying to handle the moving CoM a serious pain; I've often found that the best way to design a STS- or Buran-style shuttle is to design it so that the shuttle wants to pitch the wrong way at first, since generally that gives you some leeway when the main boosters and tank start to empty out. I don't know if the Bobcat's Buran is FAR compatible though; the wings need special work done to be recognized by FAR. And as everyone else has said, post pictures if you want help; it makes diagnosing problems easier.
  5. ferram4
    Version 0.9.3 is out, fixing (with 99% certainty) the CoL indicator bug. A bug where the FAR Control Sys wouldn't be applied automatically was fixed, as well as a change to the way exposed attach nodes apply drag to make things make more sense. @Laphtiya: FAR is compatible with KW; I use it myself sometimes. I'd advise posting a picture of your vehicle if you want more help since that'll provide more information about what you're doing. Here's my Apollo-style Mun rocket if you want to give it a shot: http://www./download.php?rqqlm3wx11fets7
  6. ferram4
    The CoL problem is only a problem in the editor; in-game the physics are accurate and will function properly. Don't treat the indicator as absolutely correct, instead use it as a guideline. Your planes being difficult or impossible to fly is due to poor plane design, not a bug in a visual overlay.
  7. ferram4
    There shouldn't be any reason for you to add it. Unless I messed up.
  8. ferram4
    A multi-stage spaceplane generally has to deal with a larger Center of Mass shift than SSTOs do, so that's one reason to use them. Overall, from a fuel perspective, SSTOs are never more efficient than multi-staged vehicles. From a parts perspective, SSTOs are infinitely more efficient than multi-staged vehicles. Likely, from a cost perspective (when career mode is added) SSTOs will be a great deal more efficient than multi-staged vehicles. Finally, how does being able to turn engines on and off as needed in groups have anything to do with staging? You're not losing any parts, so it's not staging in any sense. That's like saying that a car with nitrous installed is a multi-stage vehicle.
  9. ferram4
    It automatically adds the flight control module to the part when the vessel loads... it searches the parts in your vehicle and adds the module to every single command pod. There's really nothing to explain here. Try clearing out everything for a command pod and see if the GUI loads properly.
  10. ferram4
    @Climberfx: It works perfectly fine; it stays at about 20 degrees off of retrograde until it drops below Mach 1, at which point it goes retrograde. I made some changes to the lifting characteristics of blunt objects this update, that might have fixed it. @pwnedbyscope: The CoL issue is a known bug (see my post regarding the latest update) and is acknowledged in the readme. The second issue is likely that your CoL is too far behind the CoM. Put the wings a little further forward than they currently are and everything should work out fine. @Van Disaster: It might be getting partial flameouts; the engine doesn't completely go out, but its thrust does decrease as air runs out. I've noticed this myself.
  11. ferram4
    There are a bunch of extra non-stock parts on that ship; remove them or give me a list of the mods you're using or I won't be able to test it.
  12. ferram4
    @zzz: Post the plane so I can try it out. I think everything should work correctly. @Climberfx: Remove MechJeb and I'll take a look at it.
  13. ferram4
    @Climberfx: But my point still stands; this is a jet engine we're talking about, not a rocket engine that can ingest air to augment its oxidizer supplies; the two are completely different. And I suspect you're doing something very wrong if you can't get your rocket to orient itself the way you want; you're just refusing to design around the aerodynamics that are there and are instead insisting that the aerodynamics change to make your design work. @zzz: See if adding struts to keep the wings straight helps fix the problem. @vrga: I didn't look into fixing that this time around; hopefully next update. @masiboss: The shouting-style text wasn't necessary, you know. If you really want to switch between FAR-on and FAR-off, just have two separate versions of KSP; adding an option in-game would allow people to cheat around difficult aerodynamics. @MAKC: I've never actually understood the desire for this; it's not like they use electricity or something. Yeah, it can look stupid, but this is KSP; everything looks a little derpy.
  14. ferram4
    Okay everyone, version 0.9.2 is out, hopefully fixing the debris lag bug and some of the twitchy wing problems. Center of lift is also more accurate now, though the off-center issue persists. And all command pods automatically get the control system added. @kizza42: Try this version, see if it works; if it doesn't please post a picture and the problematic craft so I can find the problem. @DresCroffgrin: Part of the reason that Cd would be decreasing as S increases would be the Dragon Pod itself not having a large drag coefficient; something is very, very wrong here since an S of 350 corresponds to about the surface area of an entire rocket. Try having it come in oriented the other way and see what happens; the part might just be backwards.
  15. ferram4
    @Climberfx: I'm not returning the TurboJet engines to their previous performance; there is no engine on Earth that can possibly come anywhere near that kind of broken performance and they should run out of steam long before they reach 1600 m/s (which is about the fastest you can go on those engines). It still makes more thrust than it really should and is far more efficient than it should be. I'm not changing a currently still OP part back to more-OP. And the "fix" you made on the command pod has it suffering from stock drag and FAR drag. With FAR installed all parts end up having those drag values set to zero, though most of them have it done in-game and not in the part.cfg; this is because if I don't do that then stock drag still acts on the part. Your "fix" is, frankly, a terrible idea and will cause unexpected and unrealistic aerodynamic problems to occur. @Laphtiya: You need to account for the aerodynamics of your rocket design with FAR installed; if your rocket is unstable a quick fix is to put fins at the bottom. Consider delaying serious staging events until you're out of the lower atmosphere and try to keep the rocket from overspeeding, since that will allow aerodynamic forces to overpower your control authority. Make sure to start your gravity turn much lower than you're used to and keep the rocket pointed fairly close to prograde so that you stay in control. Those suggestions tend to fix approximately 99% of all the problems people have with transitioning to FAR. If you need more inspiration, take a look at real life rockets and design yours to look more like those than the abominations that most people build. @vrga: Possibilities: 1. You need more struts; essentially, your plane is so flexible that it's undergoing aeroelastic flutter prior to takeoff; that's a very rare thing, but a possibility. 2. You're overspeeding on the runway; you might need to push your CoL or main landing gear forward to make rotating and taking off easier. 3. Your landing gear aren't perfectly straight; check to make sure they are and then strut to prevent hopping around on the runway. If you need more help, post a picture, since that's far more useful than a description.
  16. ferram4
    I'd just increase the surface area parameter for the Dragon proportionally to be honest; it's the most reliable way of increasing drag. Considering it is larger than the Mk1-2, this seems to be proper, though reducing the mass of the Dragon might be appropriate, considering it has an empty mass of 4.9 tonnes plus however much monopropellant it's carrying; I'll bet that monopropellant on board is part of the problem. I'd reduce the mass a bit and increase the surface area to make things work out. Also, the Dragon's behavior with respect to heating might be explained by it's larger mass if Deadly Reentry accounts for a greater mass of material that needs to be brought up to temperature.
  17. ferram4
    If it was just a straight drop from 200 km then it might be acting properly; everything I'm seeing in the configs is correct, though I'd bump up surface area a little, maybe to ~18 - 19 m2. Try doing the same type of test using a Mk1-2 pod and see if it behaves the same; it's possible that gravity is overpowering aerodynamics that high up in the atmosphere and Deadly Reentry is melting you too soon. Try bringing the Dragon in through a proper orbital reentry (as opposed to a drop) and see if it works properly.
  18. ferram4
    It sounds as if the surface area (S) for the part is the wrong size; make sure you copied that value over. If that's not the case, then make sure that the KerbX parts are using the same units for mass as the stock and stock-compliant parts (such as KSPX, NovaPunch, KW Rocketry, etc.). It's quite possible that they're using mass to kilograms instead of tonnes. If that doesn't work, post a copy of the config file. I honestly don't know how big the pod is, so I can't tell you what the surface area should be.
  19. ferram4
    You want to pitch over somewhere below 10km; to be honest I tend to pitch over at 60 m/s at about 2 - 3km. If you do it right you should have a few moments of panic thinking that your rocket is going to plunge into the sea, and then it will accelerate enough that it'll head into space.
  20. ferram4
    I use a modified version of Lifting-Line theory that accounts for low AR and wing sweep; it may not be absolutely perfect, but it's close enough for a game. The only thing it doesn't model is proper 3-D stalling of low AR wings, but I can approximate the effect enough that it is indistinguishable from the real thing.
  21. ferram4
    You need to move your wing back a little bit; it sounds like your vehicle is unstable in pitch once it drains a fair bit of its liquid fuel. Either get rid of that forward canard and use some other method to handle pitch control or shift your main wing further back. This is especially likely since the CoL is right on the CoM; move the CoL a little behind the CoM and that should fix things.
  22. ferram4
    @Climberfx: Yeah, the spoilers are intended for aircraft only, but I can look into making them angle properly for rockets as well. To be honest, I'd but the ASAS down near the bottom of the rocket to make it more rear-heavy when it runs out of fuel. @AndreyATGB: Most real life rockets make it to supersonic speeds (> 300 m/s) before their first staging event; I think the vast majority go well into supersonic speeds before staging. The fact is that it is far more realistic to be going 300 m/s at 10 km up than 150 m/s; yes, it makes things a little bit easier in the dV department, but it makes things a lot harder in the ascent trajectory department.
  23. ferram4
    @mcbaestro: Because lift is directly proportional to density and velocity squared; as a plane's altitude decreases, air density increase and velocity increases (from gravity). This causes lift to increase until it overpowers gravity, lifting the plane higher; then the cycle works in reverse. As long as you have a vehicle being acted on by gravity and aerodynamic forces, phugoid motion will result. It will oscillate a few hundred meters one way or another, but unless you're flying right near the flameout point that shouldn't be a problem. It's the same physical system; it should behave the same. Also, all planes are slightly asymmetric; this is a KSP issue, and I can't fix it at all; it's been documented as a problem stemming from how joints function.
  24. ferram4
    @mcbmaestro: More struts. The problem is that your plane is flexing in an asymmetric manner (and subtly enough that you can't see it) and that is causing the problem. If your plane actually were symmetric there wouldn't be any rolling tendency. There's also the possibility that your vertical stabilizer / rudder isn't exactly straight, which would cause this problem. Holding altitude in a plane is a little difficult to do, especially if you're gaining / losing speed in the process. If you do get a plane to a proper cruise, don't interfere with minor changes in altitude and velocity; that's completely normal. See phugoid motion for more info. As for the BSOD, I don't know what to tell you. It's probably a memory issue, which hopefully will get fixed in 0.20 with their loading system overhaul, but there's really nothing I can do. @Climberfx: That problem is due to the fact that Mac OS doesn't merge folders by default; instead it overwrites them completely. Go and look up how to merge folders on a Mac and then install the plugin using that method. It will work fine.
  25. ferram4
    First, make sure the cockpit you're using has the FARControlSys module attached to it in the part.cfg; if it does and the GUI won't appear, try deleting the file in PluginData/ferramaerospaceresearch and see if the GUI appears.
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