This technique did raise when I was faced with the challenge to model the wings' struts (vertical planes) in between the upper and lower wings of a biplane aircraft once I had no more airfoil surfaces available to use. The only way to go would be to shape the float/tank and the engine nacelle parts to conform the vertical planes I need. The following image shows those parts detached from one another so that you can understand how they were shaped.

For doing this way I had to overcome two major obstacles: first I need to shape those wings' struts as thin and "plane" as I could; second I need to hidden the polygons that connect each strut inside the wings' parts (that was difficult due the wings' thickness also). The only hope would be to get enough precision when placing the parts' nodes.

How-to steps:

1. Start modeling the parts using Plane-Maker in the traditional way, aiming to conform them the more precise in shape, size and positioning that you can do (as shown in the right image below);
   
   
2. Use the ACF2TXT utility to convert the plane ACF file to TXT format;
   
   

3. Search the TXT file for the set of arrays named "body_XYZ"*. These arrays are tridimensional where the first element relates to the plane's part, the second element relates to each part section and the third element relates to each section node. The values that go along with them are the respectively "X", "Y" and "Z" coordinates for that node;
   
   (*) For the tank/float pair, the target arrays would be the ones named "body_XYZ[23]" and "body_XYZ[24]";
   
   
4. For this plane part only the section elements from #0 to #6 are used by X-Plane render engine (they correspond to the seven section ribs of the part) and all node elements from #0 to #15, for each section;
   
   
5. Edit the nodes values manually with the precision you need. See the following txt code section to understand the idea;
   
   

   node	X	Y	Z
   body_XYZ[23][0][0]:	0	-0.72	0
   body_XYZ[23][0][1]:	0	-0.72	0
   body_XYZ[23][0][2]:	12.9	1.575	0
   body_XYZ[23][0][3]:	11.92	7	0
   body_XYZ[23][0][4]:	12.9	1.575	0
   body_XYZ[23][0][5]:	19.48	2.7	0
   ...

   
   
6. Finally convert the plane TXT file back to ACF format;
   

The "Edit-Convert-Check" cycle:

I developed a working cycle for edit the parts using the technique above that consists on:

1 - Edit the coordinate values of some nodes;
2 - Convert the TXT file to ACF format;
3 - Open the new converted ACF file in Plane-Maker to check the editing results;

I manage to do this by letting opened in the background of Windows OS, the Plane-Maker application, the TXT file editor and a shortcut configured to call ACF2TXT utility with the instructions to convert the editing file back to ACF format; for example:

acf2txt.exe -t 14bis.acf 14bis.txt

Then I do some coordinates values editing in the TXT editor, execute the converting shortcut, ALT-TAB to Plane-Maker and reopen the ACF file (that for a bless always open at the last shown position and zoom factor) checking the results of the editing, ALT-TAB again to TXT editor... again... again... until I reach the desired results.

Almost everything here done by me: Marcelo M. Marques - codename 31 M.M.M
mmarques@frontier.com.br