Is it possible to export .MDL files? I'm throwing this question out there if anyone is interested.  I'm trying to build a simple rotorcraft model for a flight simulator.  It has 10 engines and is a called a deca-rotor.  I have a cheesy model built up in .blend format and have been able to export to .3ds.

I am ultimately interested to export to .mdl for the flight simulator?  Can anyone help me make this conversion?  Thanks in advance.

After some research I see there is a mdl importer GitHub repo for bringing models into .blend but I am interested in the export path.  Thanks and hopefully this is not a duplicate issue.
There is a game development framework called Urho which utilizes 3D models as .mdl files for the model and .png for the texture, you don't need to download the whole framework but they have a plugin for blender that lets you export a model in those formats.

See http://urho3d.wikia.com/wiki/Blender_to_Urho3D_Guide

Simple Installation: https://github.com/reattiva/Urho3D-Blender

^^^ go to that page and  click the green button where it says 'clone or download' then click Download Zip

Once you have the zip file, open Blender, go to File -> User Preferences -> Addons.

At the bottom click  Install From File... and give it the zip file.

Then click the checkbox to enable, and to see the export option:

The addon is located in the "Properties" panel, at the end of the "Render" page (camera icon)

Note: In Urho, the textures are mapped to the models via xml material files, this is due to the Xamarin (mobile .NET) architecture of Urho projects. If all you need however, is the .mdl then this is the solution for you :)