Airfoil file formats

LOAD recognizes four airfoil file formats: Plain, Labeled, ISES, MSES. All data lines are significant with the exception of lines beginning with “#”, which are ignored.

Table of contents

1. Plain coordinate file
2. Labeled coordinate file
3. ISES coordinate file
4. MSES coordinate file

Plain coordinate file

This contains only the X,Y coordinates, which run from the trailing edge, round the leading edge, back to the trailing edge in either direction:

X(1)  Y(1)
X(2)  Y(2)
 .     .
 .     .
X(N)  Y(N)

Labeled coordinate file

This is the same as the plain file, except that it also has an airfoil name string on the first line:

NACA 0012
X(1)  Y(1)
X(2)  Y(2)
 .     .

This is deemed the most convenient format to use. The presence of the name string is automatically recognized if it does not begin with a Fortran-readable pair of numbers. Hence, “00 12 NACA Airfoil” cannot be used as a name, since the “00 12” will be interpreted as the first pair of coordinates. “0012 NACA” is OK, however.

Some Fortran implementations will also choke on airfoil names that begin with T or F. These will be interpreted as logical variables, defeating the name-detection logic. Beginning the name with _T or _F is a workable solution to this “feature”.

ISES coordinate file

This has four or five ISES grid domain parameters in addition to the name:

NACA 0012
-2.0 3.0 -2.5 3.0
X(1)  Y(1)
X(2)  Y(2)
 .     .

If the second line has four or more numbers, then these are interpreted as the grid domain parameters.

MSES coordinate file

This is the same as the ISES coordinate file, except that it can contain multiple elements, each one separated by the line

999.0 999.0

The user is asked which of these elements is to be read in.