You say you develope things for XP9. I was wondering what you use to export / compile models into XP? Also, do you think its possible to export models from Gmax?
I like typing and talking....so bear with me
One area of confusion for x-plane is the flight model vs. the visual model. X-Plane comes with a program called "plane-maker" as you probably know. This program is what is typically known as a "pre-processor" in computer modeling lingo. You define the aircraft characteristics in "plane-maker" It just so happens that this is done be creating a shape that is similar to the real aircraft. The shape is somewhat simplified for real-time calculation purposes. Some of these shapes are used in the real-time calculation of flight performance and some shapes you add in plane-maker are visual only for eye candy reasons.
This paradigm goes back to the very beginnings of x-plane. Therefore, if you wanted an aircraft "onscreen" that looked like the real aircraft, you actually textured the physical model used for the flight model calculations.
The problem with this is that there is a finite number of polygons that can be used for physics calculations. If you increased the number of physics polygons too high, then the sim would slow to a crawl. That means that the finished visual model seen onscreen was ALWAYS low-poly.
The x-plane developers then developed a proprietary 3D format called *.obj. A bad choice of extension obviously because Alias Wavefront also shares the *.obj extension. Folks were trying to export *.obj out of popular 3D programs and couldn't get them into x-plane.
Well the *.obj format is officially supported on two 3D platforms. Blender 3D and AC3D. AC3D is low-cost payware and Blender 3D is free. Blender is ridiculously powerful but tough to learn, this is what I use myself.
With the ability to create visual models in a 3D program like blender, x-plane has the option to render the physics based meshed invisible and allows a proxy 3D object/s to be the visual model. This allows an F-15 to look like a Volkswagen Van. Before Obj 8, that was impossible. Make a plane that looked like a van, it'd fly like a van. But now you can attach high fidelity 3D shapes to the base physics shapes in plane-maker.
So finally to the issue of GMax. The trick is getting the model from GMax to some format that Blender or AC3D imports. There's a few Studio Max scripts out there, but they're not quite mature. Because I started with Blender, I don't have a easy answer for you. There is a developer named "Japo3D" that I believe uses GMax..but it might be studio max. If you can get your models to 3DS format, then getting them into Blender should be a no-brainer. It's a heck of a dance though and one thing that keeps x-plane development down. X-Plane has the base infrastructure and architecture to match anything in the MSFS world visually and animatically, but the tech is relatively new...so what you have is a vast "west" expansion with few pioneers to venture into the abyss and do development to attract others.
I hope to change that, my first product coming out in a week.
Also, can one adjust the inertial movements of aircraft? For instance, the 172 rolls very stiffly. Can it be adjusted to move more fluid like? Another words, is it possible to adjust the planes handling characteristics? or is that all governed by the sim engine?
Definitely one of my pet peeves. Yes it can be adjusted. X-plane will, based on the Cg of things like fuel tanks, center of lift and center of gravity, calculate the moments of inertia about pitch, roll and yaw. You can move the Cg of the wing tanks outward in order to slow and smooth roll movement. Lots of developers will just enter the max fuel value in the "fuel load" dialog and not bother to specify the outboard location of wing tanks. This has a HUGE effect on roll feel. The Cg setting also has a forward / middle/ aft range. Adjusting those values will cause the pitch intertia to change.
And when you finally can't get it quite right...and in the case of my own work, you can select a checkbox to override x-plane's intertia settings entirely and enter your own intertia values for pitch, roll and yaw. This is the ultimate way to gain control of the "feel" of your aircraft. My aircraft has one of the heaviest roll action in it's class and I had to really bump the roll intertia a bit to get it to feel realistic (yes I fly in the real thing.)
The sim uses very well proven algorithms for calculating forces on an aircraft, but you need to have a decent understanding of physics to get the most out of them. If an airplane doesn't "feel" right, it most assuredly can be quickly adjusted in plane-maker. Close x-plane, open plane-maker, change a value, save, close, relaunch x-plane. In the "tweaking" stage, I do this all the time.
For the 172..if you're talking the default one...the first thing I'd do to change the roll performance is play with the location of the fuel tanks in the wings. Move them in or out.
If that doesn't fly, then you can set the moment of interia values manually. This is a bit tricky because x-plane give no hint (in planemaker anyhow) of what these values are. Calculating true moment of inertia is out of the question for such a shape....BUT x-plane outputs a text file log during startup that gives you ALL the fixed parameters that govern the plane...even as far as the pitch of the prop every few inches along the blade.
Well among these values are the moments of intertia that x-plane has calculated. You could copy these values down, then in plane-maker, enter the same values for the pitch and yaw, but then enter a higher value for the roll. Launch x-plane and retest until you get the feel just right.
For dabbler's it's great fun. For more "I want to fly" oriented individuals, this would probably be a chore.
hope that helps...sorry for the long wind! I love talking about this stuff.
