Here' what I think is the easiest way to convert FMS aircraft to PRE-Flight. Note that not all FMS models can be converted. Only those with the *.x files my be used. These are the more recent (better) models, fortunately!

The software used is Aerodesigner which comes with PRE-Flight. It's also included in the free demo version. You need at least the demo version to do this.

Only the graphics part of the FMS model can be ported. The physics part is difficult to port so these instructions will just do a graphics port. Anyone who knows a way to do the physics, please post!

1) Install PRE-Flight, if you haven't done so yet.
2) Create a new folder under the Models folder where you installed PRE-Flight. Name it something like the new model you are converting.
3) Copy the *.x and the *.bmp files of the FMS model into the new folder.
4) Choose an existing PRE-Flight model which will closely resemble your FMS model. For example, if the FMS model is a electric micro heli, then choose the PRE-Flight MS Hornet or the MD microelectric or similar.
5) Open the model in PRE-Flight, then pull menu Model, Edit with Aerodesigner.
6) Click on the screen once to stop Aerodesigner showing off. Press Tab until you get a side view.
7) Then click Menu Components, Uncheck All to undisplay all components. Then click Menu Components, 3D Meshes. This displays the purple and gold balls which represent the graphical parts of the model. Don't bother about the other components there unless you know what you are doing!
8) Move the mouse over the purlple balls until you find the 3D Object named "Meshbody" or similar. This is the one that you don't want to delete! Right click on all other purple balls and delete them - these are the animated parts of the model (rotors, ailerons, bomb bay doors, etc.) that you can't use anyway.

Press F4 to F9 to navigate around the screen. Press tab to change view (you probably only need the side view).

9) Right click on the remaining "Meshbody" purple ball and select Properties. Click the browse button
next to the Meshfile entry. Locate the *.x file in your new folder and select. Click OK.
10) Look for the purple ball and the gold ball. If these are obscured by the model, go Menu Graphics, Render Wireframe. If the model is too large or too small, adjust by dragging the gold ball or change the scale in Properties. The side view should show the model facing to the left. If it faces right, go back into properties and change the Y Rotation to 180.
11) Go Menu Components, Contacts. This will show blue balls which is where PRE-Flight expects to find the skids/wheels of the model.
12) Adjust the location of the model by dragging the pruple ball. Press tab if you need different views.
13) Click Menu Model, Edit Info. Change the sort description and other details to suit. Click OK.
14) When satified, click Menu Model, Saveas. Put an appropriate model name and press save.
15) Finally, click Menu Test, Use PRE-Flight.

If all went well your new model should be flying in PRE-Flight! I anybody finds any mistakes or has any additions to this, please post.

You can send the contents of the new folder to your friends if you wish.

I've converted a few planes and helis for my own use but I'm afraid I can't post it due to copyright limitations. You have to convert them yourselves or better yet, ask the authors to convert and post them so that all can benefit!