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Design Tip: Displaying Contact Points Visually

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I want to share a method I use to visualize the contact points on an a/c. I added a fx light to the [LIGHTS] section of my aircraft.cfg using the coordinates for the contact point or wing apex point relative to the reference datum.Like thislight.7=3, -0.672, 0.00, 2.24, fx_navwhi // wing apex long lightlight.8=3, -11.00, 0.00, -2.10, fx_navwhi // wing apex vert lightNow, I can see if the wing apex is really where I want it or at least close.Steve

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Good Idea!I use the same trick with a blue nav light to locate the vclight(s)correctly in virtual cockpits....JR

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hehe - getting ideas from FSDS2 ????Inspector Polygonne...(sorry, couldn't resist)

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That's a good idea. When making my wing, kept thinking that MaxScript might be a nice way to produce a wing from the NACA number, but I've got enough on my plate without learning another scripting language.Steve

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Wow Finn,Is that your script? When can I play with it?Please let us know when and where, if you could.odog

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Well I have FSDS2, but haven't installed it yet so I haven't been reverse engineering! Having said that I've always missed having some sim specific stuff in gMax like you have in FSDSv1 - well I was browsing through the gMax docs and it has stuff in it precisely for storing game specific data (look under scripted plugins and custom properties for those interested); what I've done is inspired by that rather than FSDS. There's been mention of doing something like this since the first FS gamepack was released with FS2002Pro so I'm suprised no-one has (as far as I know) made a move on doing it so far.Anyhow, the basics of the script is (I think) finished - just need to add some sensible defaults and some error trapping so you should see a first release version very soon. Look for it at gMax Support, Netwings and FreeFlightDesign.Have funFinnBTW I like the idea of visible lights to judge position of things in the sim as well as in gMax, I might add that idea to a future version.

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Of course I was pulling your leg on the "FSDS2" connection. FSDS2 can output to a text file a list of all parts tagged "reference" such as gear.center, gear.left, scrape.point(s), etc., along with their coordinates in z,x,y order. When producing the FS2002 and CFS2 aircraft, it will enter the gear points into the cfg file.All in all, the best thing that both gmax and FSDS2 have is the flightsim user support willing to help out each other and create those add-ons - your script for example - that make flightsim modelling easier for all of us.Thanks again.

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>Of course I was pulling your leg on the "FSDS2" connection. >FSDS2 can output to a text file a list of all parts tagged >"reference" such as gear.center, gear.left, scrape.point(s), >etc., along with their coordinates in z,x,y order. When >producing the FS2002 and CFS2 aircraft, it will enter the >gear points into the cfg file. >>All in all, the best thing that both gmax and FSDS2 have is >the flightsim user support willing to help out each other >and create those add-ons - your script for example - that >make flightsim modelling easier for all of us. >>Thanks again. Ah yes, of course I realise you weren't serious - but one needs to be careful about these things in case someone else down the line decides to bill the script as being based on FSDS2! My gMax script works in a similar way to what you describe, but it has properties for all the entries in the cfg file so you can set it all up in gMax with a minimum of fiddling after copying and pasting the points. I'm putting in the possibility to set the wheel radius and compression entries visually as well. Still some fiddling to do, but the first public version should be out at the weekend.Agreed on point 2!Have funFinn

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>My gMax script works in a similar way to what you >describe, but it has properties for all the entries in the >cfg file so you can set it all up in gMax with a minimum of >fiddling after copying and pasting the points. I'm putting >in the possibility to set the wheel radius and compression >entries visually as well. Still some fiddling to do, but the >first public version should be out at the weekend. Finn, that's marvelous! That sure will cut down on the current trial-n-error method we're currently forced to endure!Thanks!

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Good Idea Steve. I wanted to take advantage of this topic to ask some questions.What is the wing apex?Where is the correct position?Where is the correct position for contact points in the wheels LG?The center of the wheelWhere is the correct position for scrape points?How many points do I need?Thanks in advanceJose

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The Wing Apex (WA) is very confusing until you read some articles on aerodynamics and FS air file modeling. I thought it was just the highest point on the wing, but it is more complicated than that.An aircraft wing has lift force acting over its entire surface. To model the flight characteristics of an aircraft wing you need to simulate this lift force. Calculating values for a great number of points over the wing surface would be prohibitively inefficient. So what FS does is model lift at one single point representing force on the whole wing.Thus WA is a fairly important figure to get right! But where to put it. That is a good question without any stock answer. I suggest you start out by placing WA just back from the leading edge of the wing on the aircraft centerline. You can place it 1/4 of the root chord width back from the leading edge. But you may be forced by inaccuracies in the FS flight model to adjust it from ideal. You may need to set it back or forward relative to the actual wing to get correct performance.Most of this if "book knowledge" because I am very new to this.Hmm, good question on the wheels. I forget where I measured the contact point for the wheels to, but I assume it is to the bottom edge of the tire.I measured all my contact points in GMAX using box shapes as makeshift rulers. It was just easier for me to click and drag a box, the adjust it from the reference datum point down to the bottom of the tire, etc. than to use the GMAX so called ruler.The scrape points. You should have one for the nose, one for the tail, and one for each wing tip.

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