              VORTEX LATTICE MINIMUM DRAG (VLMD)

The files for this program are in directory \vlmd on the CD-ROM:
  readme.txt      this file of general information
  vlmd.txt        instructions for use of VLMD
  geom.for        the source code for geometry in Fortran77
  geom.exe        the executable for MS-DOS (compiled with Lahey F77L)
  analysis.for    the source code for analysis in Fortran77             
  analysis.exe    the executable for MS-DOS (compiled with Lahey F77L)
  LAR15160.txt    the original COSMIC description of the program

Sample cases for this program are:
  case1.inp     input data for test case 1
  case1.out     combined output from geom and analysis for this test case.
  case2.inp     input data for test case 2
  case2.out     combined output from geom and analysis for this test case.
  case3.inp     input data for test case 3
  case1.out     combined output from geom and analysis for this test case.
  case4.inp     input data for test case 4
  case1.out     combined output from geom and analysis for this test case.

To use this program, create a directory on your hard disk and copy these 
files to that directory.

The Geom program asks for the name of the input file. This must be a file 
written to conform to the instructions in the NASA TN. Geom produces a file 
called geom.out and a specially formatted file called FORT25. This file is 
not designed to be read or printed; it is the input to Analysis. When 
Analysis is launched, it asks no questions, but takes the file called FORT25 
and completes the remainder of the calculations. This produces a file called
analysis.out that is designed to be printed. Unfortunately, the task of 
reformatting the output to fit on a screen with 80 columns did not get 
finished by the manufacturing deadline for the discs of version 5.0.
If you have a laser printer, you may be able to print in landscape mode with 
a smaller font and have it fit. I will make a revised version available when
time permits.



                      DESCRIPTION

A new subsonic method has been developed by which the mean camber surface
can be determined for trimmed noncoplanar planforms with minimum vortex
drag. The method uses a vortex lattice and overcomes previous difficulties
with chord loading specification. This method uses a Trefftz plane analysis
to determine the optimum span loading for minimum drag, then solves for the
mean camber surface of the wing, which will provide the required loading.
Pitching-moment or root-bending-moment constraints can be employed as well
at the design lift coefficient.

The above summary of the program is from NASA TN D-8090 by John Lamar of the
NASA Langley Research Center. If you are going to use this program, you
should obtain a copy of this Technical Note. This program was released
as COSMIC program L-15160. Only a few minor modifications were necessary
to make the programs function on a PC with Lahey Fortran F77L, version 5.01.
The program has also been checked with other Fortran compilers.


