Output

All output goes directly to the terminal screen. H. Youngren’s plot package Xplot11 (libPlt.a) used by XFOIL drives monochrome and color X-Windows graphics, and generates B&W or color PostScript files for hardcopy. The default setup assumes color X-Windows graphics (if available), and B&W PostScript. These defaults are controlled by the IDEV and IDEVRP flags in SUBROUTINE INIT (in xfoil.f).

The Xplot11 library should work on all Unix systems. The Makefile in the ./plotlib/ directory requires some modifications for some machines.

The default X-graphics window is in Landscape mode, with a black (reverse-video) background. Normal-video can be selected by setting the Unix shell variable

 % setenv XPLOT11_BACKGROUND white

before Xfoil is started. The nicer reverse-video is restored with:

 % unsetenv XPLOT11_BACKGROUND

See the plotlib/Doc file for more info on the plot library.

Xplot11 provides a built-in Zoom/Unzoom capability which can be applied to whatever is on the screen. Zooming/Unzooming can be perfomed with the “Z” and “U” commands from nearly all the menus — these commands are not listed to reduce clutter.

Some of the menus also have their own Blowup/Reset commands.
The distinction is that XFOIL’s plots don’t try to adjust themselves to Zoom parameters, so a highly-“Zoomed” plot may show nothing at all. In contrast, Blowup/Reset instructs XFOIL to change its own plot scales, so a highly-“Blown-up” plot will at least show the axes.