Here I compiled the keyboard mapping for several versions of X-Plane. I wrote a tiny Perl program that simply formats the keys/X-Plane.txt file distributed with X-Plane into a comprehensible HTML table:

• X-Plane v6.70
• X-Plane v7.00
• X-Plane v7.41
• X-Plane v8.11

(for X-Plane v6.30, take a look here)

1. Open AC3D
2. Now you shall use Side (ZY) view to draw a shape of revolution object to be imported. You may wish to draw it as Polyline:
   
   
   
   Note that the shape polyline has exactly 9 vertices and it is closed.
3. Put your shape a bit off-center. You will be revolving it around Y axis, so just create small gap between shape edge and Y axis:
   
   
   
   Later you will see the meaning of this gap
4. Select your shape as group, and do "Object -> Revolve...". Enter with 180 degrees, Y axis and 11 segments:
   
   
   
   Wow, look, you got half of your object:
   
   
   
   By default it has flat surface but you may wish to set a smooth one like I did.
5. Go to Side (XY) view. Select your object and "Edit -> Duplicate" it. Then flip it on X axis. Now align both halves so they again have a very small gap between them. DO NOT SNAP THEM TOGETHER!. Then do "Object -> Merge". You should get this:
   
   
   
   Note "move to" coordinates. X is 0.53 instead of 0.5! That 0.03 difference on both sides of Y axis makes that desired gap.
   You may be wondering why to have yet another gap here? Well, 18 vertices in each section are supposed to be sorted automatically in counter-clockwise order. If you have overlapping vertices like in this case, algorithm treats vertices with same coordinates as being one vertex and thus messes everything. Sorry.
   
   VERY IMPORTANT: switch to vertex selection mode. You should see exactly 216 vertices. If you do not have 216 vertices you're terrible wrong, start over!!!
6. At this moment you are ready for the most boring part. Split AC3D-generated object to sections that X-Plane would accept. Now a bit of theory. X-Plane treats all aircraft models as 3D objects with 12 sections with 18 vertices each one. If you try to feed it with everything else, surface will be mismapped. Thus you NEED to cut your AC3D object into 12 sections with 18 vertices each one. And 12 * 18 = 216, got it? . OK, to start section splitting you need to remove all surfaces. Sorry again "Surface -> Remove surface only". Now hurry up, "File -> Save" as original.ac.
7. Let the pain begin. >%E~
   Go to Plan (XZ) view. Select 18 vertices:
   
   
   
   
   1. Copy these vertices to clipboard. Delete them.
   2. "File -> Save" original.ac
   3. "File -> New..." and paste 18 vertices from clipboard.
   4. Save as section01.ac
   
   Now reopen original.ac. Select next 18 vertices:
   
   
   
   Do the same steps as for first section, but now save it as section02.ac. Unless you are screaming in anger extract all the 12 sections in this way. Calm down, it's not that boring when you start to do it
8. Understood the meaning of the first gap? If you added none, when you try to select 18 vertices you select 48 each time you reach center, as you select some central vertices from other sections.
9. Supposing you were patient enough, at this moment your original.ac is empty and you have sections 1 to 12 in separate .ac files. Now merge them back. No, I'm not kidding. Merging all sections in sequence from 1 to 12 puts them in the order that X-Plane accepts. OK, I think that there is no need to explain how to "File -> Merge.." 12 section files in one. The result will look the same as original.ac (rest in peace) but internal order would be the right one. You should now "Object -> Merge" & Group 216 vertices (assure that you still have 216!). Call your group "body[45]", it will import to X-Plane as "misc. body 1":
   
   
   
   Rescale this object to any size you want (in feets) and save all the stuff as importable.ac.
10. OK, now go and merge importable.ac in any model of yours using ACFTools:
    

    acftools -e -acf C:\X-Plane\Aircraft\UPHO.acf -txt UPHO.txt
    (prepare UPHO.txt to work with)
    
    acftools -me -ac3d importable.ac -txt UPHO.txt
    
    (merge! don't worry about warnings)
    

    Fine! Next step is to edit UPHO.txt in your favorite text editor (I use Write) to mark that "misc. body 1" was added:
    1. Seek for PARTS_WingBodyGear_part_eq[45] and make it "= 1"
    2. Seek for PARTS_WingBodyGear_body_r[45] and set it to desired radius of your body (or Plane-Maker will mess the things up)
    3. Seek for PARTS_WingBodyGear_body[45][0][0]. This was your section01.ac. Remember the second gap? Remove it setting all the X values for 1^st section to 0. Remember that each section has 18 vertices, so, don't harm neighbor ones!
    4. Seek for PARTS_WingBodyGear_body[45][11][0]. This was your section12.ac. Make the same as for section 1

11. acftools -g -txt UPHO.txt -acf test.acf
    (generate test.acf from edited .txt file)
    

    Finally open test.acf in Plane-Maker and see what the heck you just did =D
    It may be a bit broken, just fix it in Plane-Maker as normal body.

• Convert from ACF (aircraft) & WPN (weapon) formats to TXT format and vice-versa.
  
• Extract AC3D model from TXT file, along with wings and propellers (using the real airfoils!).
• Import AC3D model into TXT file (fuselage, nacelles, wheel fairings & external fuel tanks only)
  

##############################################################################
[ACFTools v0.62a] Set of tools to play with ACF files outside of Plane-Maker
Perl script and modules coded by Stanislaw Pusep 
Site of this and another X-Plane projects of mine: http://xplane.sysd.org/

Allows you to:
 * export X-Plane (www.x-plane.com) aircraft data files to human-editable
   plaintext format and 3D mesh editable in AC3D modeler (www.ac3d.org).
 * import plaintext/3D mesh back to ACF file.
##############################################################################

Usage: acftools.exe  [parameters]
 o Commands:
	-extract [DEF]	: extract TXT from ACF (opt: using DEF definition)
        -generate       : generate ACF from TXT
        -merge          : merge body from AC3D file to TXT
 o Parameters:
        -acffile FILE   : name of ACF file to process
        -txtfile FILE   : name of TXT file to process
        -ac3dfile FILE  : name of AC3D file to process
        -noorder        : DO NOT sort vertices while merging bodies
        -noac3d         : DO NOT generate AC3D
        -(min|max)body N: write all bodies in specified range to AC3D
        -force LIST     : force extraction of bodies LIST (comma-separated N)
        -normalize N    : normalize wings to N vert/surface (N>=2 or no wings!)
 o Notes:
        * You can use abbreviations of commands/parameters (-gen or even -g
          instead of -generate).
        * The only required parameter for "extract" command is -acffile.
          Both -txtfile and -ac3dfile are derivated from it.
        * "generate" command and -txtfile has the same relation.
        * By default "extract" uses the latest DEF file.
        * "generate" doesn't need DEF at all (it is implicit in TXT)
        * If file to be created already exists backup is made automatically.
 o Examples:
        acftools.exe --extract=ACF700 --acffile="F-22 Raptor.acf"
        (extract 'F-22 Raptor.txt' from 'F-22 Raptor.acf')

        acftools.exe -e -acf "F-22 Raptor.acf"
        (same as above)

        acftools.exe -me -ac3d ladar.ac -txt "F-22 Raptor.txt"
        (merge *single* 3D body from 'ladar.ac' to 'F-22 Raptor.txt')

        acftools.exe -g -txt "F-22 Raptor.txt"
        (reverse operation; generate 'F-22 Raptor.acf' from 'F-22 Raptor.txt')