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About Kitspace

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    Sr. Spacecraft Engineer

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  1. Kitspace

    Official FAR Craft Repository

    Thank you for helping me! As I understand it the main change regarding the pitch stability comes from moving the stabilizer higher and further aft. Doing the same thing on my version gives an interesting effect. The craft becomes both more stable and more controllable simultaneously. Can you please post a picture of your static stability page at the landing conditions with full pitch up input? What angle of attack is it capable of? To me taking off and landing at 100 meters per second looks like a lot actually. Could it be that the difficulties you are experiencing with landing are due to the high speed? In terms of the actual lifting force the thing can lift off the runway at 70-80 ms. The only difficulty I found is making it pitch up high enough for that. It can be done with stabilizer incidence angle but then it requires a lot of forward pressure on the stick in order to prevent pitching up in flight. A movable stabilizer would probably solve the problem but it seems to be quite difficult to make a kerbal version of one. Anyways an adjustable stabilizer is used to allow for a bigger range of center of gravity as far as I know. And in this plane the center of gravity does not move a lot if at all. By the way cheers for the flag.
  2. Can anyone please check the config for GEnx? I mean the model from the B9 pack. I can try and do the tweak for it but I am still unsure if the issue is in the mod or is it bug or some kind of incorrect installation issue on my side.
  3. Hello! Any chance to get these videos somewhere now that the links seem to be dead?
  4. Kitspace

    Official FAR Craft Repository

    Of course. The plane requires Tweakscale and B9 Procedural wings as flaps. Here are the craft files. One is the full craft and the other is the identical one with the engines removed. That is because the original engines additionally require the Advanced Jet Engine and the B9 pack. Original No engines
  5. Kitspace

    Official FAR Craft Repository

    Hello again! I would be happy to rearrange the center of mass relative to the wing if not for the main landing gear. Even the way they are now it hesitates a bit before settling on the nose gear when it spawns. Yes, I do have the standard control inputs all zeroed on all of the flaps parts. Also there are no speed brakes indeed. Should probably add them anyways. Every time I build something I hope the craft would be able to descend at least somehow if not that quickly without them. But it seems that all planes are just too aerodynamically perfect when it comes to subsonic drag in FAR. The dihedral on the stabilizer is zero however its angle of incidence is different on some of the pictures. Regarding increasing the area of the stabilizer, would that not be helpful only if the stabilizer itself was movable in flight? I have tried both increasing and decreasing it but it seems that the effect is negligible even if it is twice the original size. Does FAR have a problem with tweakscaled parts? That would explain why it did not work then. I always thought that in real life the control authority is defined as sufficient if the maximum deflection corresponds to flying at the critical angle of attack when landing. I just feel that the sweep of the wing gives it way too much static stability to achieve this. For some reason with kerbal planes in general I often find that the wing has to go further forward than I would expect when comparing to the real life planes. Same with this one. Why would that be the case actually?
  6. Kitspace

    Official FAR Craft Repository

    As I understand it the critical angle of attack in level flight is the measure of stall speed. The fact that a plane does not need its maximum lift coefficient to stay level to me means that it CAN go slower. If it is not yet stalling at that speed then what would keep it from slowing down further? What do you mean by as slow as it will fly? It seems right on the pictures at 8 km. It becomes pretty much uncontrollable at the critical angle of attack and at about maximum Cl and looses lift if pulled harder. From my observations with actual flying all the crafts behave according to the statics page and stall where the graphs show. At least at low altitude it happens at a slower speed than the derivatives page predicts. I sometimes have it claim the craft stalls at angles of attack as low as 5 degrees while it actually stalls at 20. Do you seriously suspect the calculations on that panel are broken?
  7. Is it just me or is the GEnx grossly oversized as it is at the moment? Its diameter is about 5 meters and its intake area as stated in its description is almost double that of CF6. As far as I know in real life the diameter is supposed to be only 2.7 meters. Also are there any configs or mod part packs that would add the really big ones like the GE90? What about the non afterburning versions of the old ones that are in there currently or maybe the JT3? I think generally it would be helpful to know what particular engines the supported mod packs add...
  8. Are there any dependancy mods that are still waiting for an update for the game version 1.3?
  9. Kitspace

    Official FAR Craft Repository

    What I see is exactly the same as on your pictures. According to the statics page on the second screenshot your plane stalls at about 16 degrees AoA with Cl 1.1 However the derivatives page on the first screenshot clearly claims the plane is stalled at Cl as low as 0.754 That is quite a large discrepancy. So there is a speed range for which the derivatives page does not want to work for some reason. What happens if you increase the speed just to the bare minimum at which it shows meaningful numbers?
  10. Kitspace

    Official FAR Craft Repository

    Sorry for the late reply. Did not have the chance to get to my computer sooner. Here are the pictures with the center of mass and controls I do use the procedural parts mods. Some of the controls on this craft are procedural for example. Regarding the computed level flight angle of attack. I am puzzled because with most of my planes it goes blank at a seemingly random value. It does NOT by any means approach the critical angle of attack or the maximum lift coefficient shown on the static stability page. For example the maximum lift coefficient on this plane is about 1.2 while the level flight window goes blank at about of half that and at an angle of attack of just 10 degrees.
  11. Kitspace

    Official FAR Craft Repository

    Hello! I am having some difficulties with one craft that I am trying to design for my kerbal fleet. The plane that does not yet have its name is intended to be a conventional long range cargo transport. It should be capable of relatively quickly moving and deploying various things at different locations around Kerbin such as exploration probes or crew recovery parties for those kerbals who managed to land in the middle of nowhere on the way back from space. A possibility of paradropping items mid flight is also considered. The main thing about it is the balance and stability. The center of gravity seems way way too far forward so that the tips of the main wing and not the stabilizer are responsible for the majority of the static pitch stability. While it may be kinda acceptable in cruise it is absolutely horrible for proper takeoff and landing as the thing lacks the control authority even with ridiculously high stabilizer incidence angles. The problem is that I can not possibly move the wing forward as in its current position the main gear bogies are almost directly below the center of mass. So either I have to drop the airliner style landing gear attachment and snap them into some other place which I do not really want to do or find another way to make the plane less stable. How can I fix this? How is this current arrangement different from the real life designs of the same type? I guess with a highly swept back wing and the gear attached at its root large portions of that wing just have to be behind the center of mass anyways. And that kerbal wing is really not the most sharply swept one even amongst the airliners... The second question is how to make the flaps more effective? Currently as seen on the derivative pages their effect is quite marginal or even negative when the angle is too high. Even when thinking of them as simple hinged non slotted flaps in the real world terms I would expect them to easily deploy to fifty or sixty degrees for landing. Or are they by any chance modeled as some type of slotted or fowler flaps? In the static page on the graph we see that the coefficient of lift never exceeds 2. To me seems quite low for takeoff or landing with flaps. Also the level flight angle of attack value does something that I do not quite understand. When I decrease the speed for which it is calculated it increases to some value but then just suddenly goes zero. It does not approach the stall angle of attack. Does that mean that the plane can not fly slower than that for some other reason even though it is not stalling? Or is it just the prediction algorithm having trouble computing? Any help will be strongly appreciated! Thank you! Pictures
  12. So things are pretty obvious about the two and three but how to achieve realistic results with number one? What exactly does it depend upon that kerbal designs tend to lack?
  13. @ferram4 First of all thank you for your detailed response. Is the over stability also related to the very unhealthy mass of the kerbal cockpits that pull the centre of mass forward? Also if kerbal planes are more stable than real ones should they not oscillate less rather than more when they achieve equilibrium? Yet they seem to oscillate much more than real ones. I have never seen a real life plane make more than one or two slight pitch wobbles before stabilising almost instantly even after very sudden and quick stick movements. Talking about fighters and aerobatic planes here. Why is that?
  14. @ferram4 I do strongly agree with your position on keeping things as realistic as possible at all times. After all that is exactly the thing I love the mod for and I think that is what most of those who use it love it for as well. Therefore I would never suggest changing things towards decrease of realism. What I am trying to do here is to get an understanding of why things behave in the way the do and whether that is the intended behaviour. I never meant to offend you in any way and do apologize if it sounded that way. Is not stall speed defined as the speed at which level flight is no longer possible as the angle of attack required starts to exceed the critical value? You said that kerbal planes tend to be absurdly over stable compared to real ones most of the time. Why does that happen and how to deal with it? What is the realistic balance of stability and control authority then? As I understand most of real life planes do pitch down when the main wing stalls because delaying the stall of the tail plane and the elevator means maintaining pitch control authority for longer. Right? Then does the difficulty of stalling an average kerbal plane only come from the over stability? If kerbal planes do not achieve the critical angle of attack even at maximum control deflection then where does the oscillation come from? For example roll the plane on its side and pull back on the elevator gradually increasing the deflection to maximum and keeping it there as if you want to make a very tight turn. Unless the plane is just heavy and bulky it is very likely to oscillate noticeably and constantly in the pitch channel. Even if you keep the controls steady for a minute this may not stop at at all. How to prevent that happening? Thank you!