Changing the Aircraft .cfg file "on the fly"
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Thread: Changing the Aircraft .cfg file "on the fly"

  1. #1

    Changing the Aircraft .cfg file "on the fly"

    I've an FSX FM question for the old hands here: is it possible to arrange a total or partial swap-out of the aircraft .cfg file, while the sim is running? For example, let's talk about tail wheel steering. The [contact_points] area of the .cfg file lets us specify whether we've a fully castoring or a steerable tail wheel, but it's a case of one or the other. I'd like to model an aircraft which has a combination of both - tail wheel steering up to +/- 30 degrees, and a fully castoring tail wheel if forced beyond that point. The only way I can imagine simulating this properly would be to either swap back and forth between two .cfg files, which differ only in the tail wheel line in [contact_points], or to overwrite that particular line somehow, as needed. Can this be done?

    blue six

  2. #2
    You can certainly make changes to the aircraft.cfg while FS is running, but to get them to appear, you have to reload the aircraft either via the normal menu selection, or by the key combination 'Reload User Aircraft' (in my case, FS9, CTRL+SHIFT+R).

    So I don't think you would be able to do what you want to do with with the tailwheel.

    Maybe an xml gauge might be the answer. One that limits the tailwheel to 30 degrees of travel either way, then once exceeded, breaks away into fully castoring, like on the P-40.

    Cheers

    Paul

  3. #3
    Using a castoring wheel is not an issue if you use the tailwheel lock for all ground ops except tight maneuvers. The lock really helps with taxiing. If you have rudder pedals, of course, it is easier but judicious use of the tailwheel lock makes life on the ground a bit easier.
    Milton Shupe
    FS9/FSX Modeler Hack

    My Uploads at SOH - Here
    Video Tutorials - Gmax for Beginners

  4. #4
    Thanks for your replies, Milton and Bradburger. For Bradburger, you got it right in one guess, it's the P-40 I'm looking at. What I'm really after is more than just improving the ground handling in the sim; it's a matter of persuading the sim to properly replicate both visually and in its dynamic response, a "hybrid" tail wheel steering mechanism - one which is switchable between conventional steering, linked to rudder movement, and free castoring. My sense from both your replies is that this is perhaps just not achievable, even using xml gauges. If I'm mistaken, please let me know.

    blue six

  5. #5
    I just stumbled upon a lengthy and unrelated discussion over at the AVSIM FSX forum, related to ground handling, here: http://forum.avsim.net/topic/392772-...ound-friction/

    Although this item is focused on ground friction, fore/aft and lateral, the methodology discussed (dynamically patching the runtime copy of an FSX file) perhaps could work for us. In the case being explored at AVSIM, the hook is being made into FSX file sim1.dll, which apparently contains values for wheel to ground sliding and rolling friction for various surfaces and weather conditions. Conceivably, something similar could be done for aircraft .cfg file values, one would think, with the switchover trigger conditions defined in a LUA module perhaps?

    Any thoughts from the more experienced hands on this?

    blue six

  6. #6
    From What i can gather the Pee fourty may have been oneof the few WWII era military fighters to have some sort of tailwheel steering. My guesses that it was not effective on an aircraft of this weight qnd power and was abandoned on just about all other aircraft. Nose draggers, even through the B29 had castoring nose wheels. Not till the B50 did that series have nose steeering.

    Look in the cfg file to see if there is a differwntial braking entry. This proportions braking in response to rudder deflection for thlse without pedals. Many years of designing and testing, plus many more years flying real taildraggers convinces me that a castoring tw is even for small GA planes a more realistic simulation of how you steer these things on the groind.

    T

  7. #7
    Quote Originally Posted by fliger747 View Post
    Many years of designing and testing, plus many more years flying real taildraggers convinces me that a castoring tw is even for small GA planes a more realistic simulation of how you steer these things on the groind.

    T
    Thanks for your reply, fliger747. Your point is well made and understood. That said, for the sake of fidelity with the real world aircraft, I'd be happier to find a more direct means of simulating the P-40's combination of tail wheel steering and free castoring. Differential braking plus free castoring is a solid, 90% workaround, but the real thing would look and feel more like what you can see in this video clip. See mins 5:55 to 6:50 in particular. Tail wheel steering is initially engaged and in use during taxi; at approx 6:25 differential braking is used to force the tail wheel beyond its steering limits and into free castoring mode, and at about 6:45 the steering splines are re-engaged. Simulating this would be the 100% solution.

    http://www.youtube.com/watch?v=iD6t9...=youtu.be&hd=1

    blue six

  8. #8
    No one has said it cannot be done, and almost anything CAN be done using XML. In fact, I think over at Cal_Classic someone designed xml nose steering for an airliner to to restrict deflection after a given speed. It's all doable. You might post your question there, or at FSDeveloper. I always wanted the feature for the Dash 7 whose steering deflection is limited to 7 degrees after a certain speed, but never pursued it.
    Milton Shupe
    FS9/FSX Modeler Hack

    My Uploads at SOH - Here
    Video Tutorials - Gmax for Beginners

  9. #9
    Thanks Milton, I'll pursue my quest elsewhere - if something comes of it, I'll close the loop back here.

    blue six

  10. #10
    If you can do it, that would certainly be an advance. Mt real life supercub for instance has a rubbery steering effect to a ceratin degree, about 45 deg and then the tw breaks loose and castors. Not dooable with stock Fsx.

    T

  11. #11
    Quote Originally Posted by fliger747 View Post
    If you can do it, that would certainly be an advance. Mt real life supercub for instance has a rubbery steering effect to a ceratin degree, about 45 deg and then the tw breaks loose and castors. Not dooable with stock Fsx.

    T
    Exactly the sort of behavior I'm looking for. It would also be useful to be able to replicate the P-51's combination of free castoring with the stick forward of neutral and tail wheel "lock" with limited direct steering, with stick back. Ideally, in a manner that's transparent to the user. I'm afraid it will take someone much more clever than me to solve this one...

    blue six

  12. #12
    The P51 setup has already been done, which is not too dificult as it is either locked or castorin, not steerable.

    t

  13. #13
    Quote Originally Posted by fliger747 View Post
    The P51 setup has already been done, which is not too dificult as it is either locked or castorin, not steerable.

    t
    I currently use Gnoopey's XML tailwheel lock for my P-51's in FS9 and it works quite well. Although it actually locks the tailwheel rather than make it steerable when the stick is pulled back, it actually seems to give the impression it has tailwheel steering.

    (I'm using the modified sim1.dll btw which has modified ground friction coefficients much like has been done for the FSX one).

    For the P-40 FMs I've done, at the moment I just use a fully castoring tailwheel, and with just the right amount of prop plast on the rudder, it works quite well.

    Here's a video of Bruce Thorsen's P-40B I did when testing Fraps.



    Although it's doesn't feature much taxying, when it does, you can see it's quite controlable using bursts of power and differential braking. But if you're not careful, you can easily ground loop it!

    I guess it would be nice to have the tailwheel work like the real thing, so as Milton suggests, XML might well be the answer.

    Cheers

    Paul

  14. #14
    Actually the tail-wheel lock associated with the yoke pullback came from our Howard 500 gauge by Scott Thomas. And he may have had help from Nick on that, not sure.
    Milton Shupe
    FS9/FSX Modeler Hack

    My Uploads at SOH - Here
    Video Tutorials - Gmax for Beginners

  15. #15
    Quote Originally Posted by Milton Shupe View Post
    Actually the tail-wheel lock associated with the yoke pullback came from our Howard 500 gauge by Scott Thomas. And he may have had help from Nick on that, not sure.
    You may well be right Milton.

    The gauge is called _GY_P-47, and came with Gnoopey's P-47 that was released a long time ago.

    Looking at the XML file it says the following: -

    <name>tail lock 1.0

    <copyright>(c)2004 Nick Pike</copyright>


    Cheers

    Paul

  16. #16
    No sim is perfect, we do pretty well considering, even the multi million sims I get to (have to) fly like last night aren't perfect.


    Cheers. T

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