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+
+ Typical XFOIL session keyboard inputs.
+ All commands can be in lowercase.
+ Blank lines below are only for easier reading -- they are not Return's!
+ A command with its argument(s) ommitted will result in an input prompt.
+ Some files in ./runs are used here.
+
+ Note: The Eppler 387 coordinates are not smooth, so the Cp plots will
+ appear "noisy". Xfoil's results will not be affected noticably
+ by such cosmetic defects, unless they are very severe.
+
+
+LOAD e387.dat ( or: NACA 4410
+
+GDES (enter GDES menu) |
+CADD (add points at corners) | These commands are optional,
+<return> (accept default input) | and are recommended only for
+<return> (accept default input) | Eppler and Selig airfoils
+<return> (accept default input) | to give smoother LE shapes
+<return> (return to Top Level) |
+
+PANEL (regenerate paneling since better panel node spacing is needed)
+
+OPER (enter OPER menu)
+ALFA 5.0
+ASEQ 0.0 6.0 2.0
+
+VISC 1.0e5 (set viscous mode, with argument anticipating Re prompt)
+CL 0.78
+CREF
+CPX
+BL (plot boundary layer profiles)
+cp_100_040.387
+CREF
+
+INIT (force initialization of viscous solution for big alpha change)
+ALFA -2.5
+! (keep iterating on this difficult case)
+
+PACC (set up for new polar 1)
+<return> (decline writing to polar save file)
+<return> (decline writing to polar dump file)
+ASEQ -2.5 -2.0 0.05 (small steps when bottom transition is moving fast)
+ASEQ -1.5 8.0 0.5 (bigger steps OK over most of polar)
+ASEQ 8.2 9.0 0.2 (small steps when close to stall is more reliable)
+PPLOT
+PACC (turn off polar 1 accumulation)
+
+PPAX
+<return> (default alpha axis OK)
+<return> (default CL axis OK)
+0.0 0.04 0.02 (better CD axis)
+<return> (default CM axis OK)
+PPLOT
+
+RGET polref_100.387 (read in experimental polar data)
+PPLOT
+
+VPAR (enter viscous parameter menu)
+N 11.0 (set new lower turbulence level)
+<return> (back to OPER)
+
+INIT
+ALFA -2.5
+PACC (set up for new polar 2)
+<return> (decline writing to polar save file)
+<return> (decline writing to polar dump file)
+ASEQ -2.5 -2.0 0.05 (small steps when bottom transition is moving fast)
+ASEQ -1.5 8.0 0.5 (bigger steps OK over most of polar)
+ASEQ 8.2 9.0 0.2 (small steps when close to stall is more reliable)
+PPLOT (both polars compared to experimental polar)
+PACC
+VISC
+
+PWRT 1 (write polar 1 to save file)
+e387_09.100 (filename indicates Eppler 387, Ncrit=9, Re=100K)
+
+ALFA 4.0 (set inviscid solution for MDES design operations)
+<return> (exit OPER)
+
+MDES
+AQ 0.0 4.0 8.0
+RESE
+BLOW (zoom in on region of interest, undo with RESE)
+MODI (modify some segment of one of the q(s) curves with cursor)
+MODI (repeat if necessary to modify further...)
+MODI
+.
+.
+EXEC
+<return>
+PANEL
+OPER
+CL 0.5
+ etc....
+<return>
+GDES
+GSET
+CAMB
+INPC
+0.0 0.0
+0.5 0.03
+1.0 0.0
+ADD
+<return>
+PLOT
+TCPL (turn off camber/thickness plotting activated in CAMB)
+FLAP 0.70 0.04 -5.0
+PLOT
+EXEC
+<return>
+OPER
+ALFA 5.0
+ etc....
+
+
+
+=========================================================================
+
+ Typical XFOIL session to generate and plot two polars.
+ All commands can be in lowercase.
+ Blank lines below are only for easier reading -- they are not Return's!
+ A command with its argument(s) ommitted will result in an input prompt.
+
+
+LOAD airfoil_file.dat
+
+GDES (enter GDES menu) |
+CADD (add points at corners) | These commands are optional,
+<return> (accept default input) | and are recommended only for
+<return> (accept default input) | Eppler and Selig airfoils
+<return> (accept default input) | to give smoother LE shapes
+<return> (return to Top Level) |
+
+PANE (optional: use if input airfoil_file.dat has inadequate points)
+
+OPER (enter OPER menu)
+VISC 2e5 (toggle viscous mode, with Re = 200000)
+TYPE 2 (optional: use if constant-lift polars are to be used)
+
+ALFA -2 (specify minimum alpha (must give CL>0 for Type 2 polar))
+PACC (toggle auto accumulation on for new polar 1)
+polar1_file (choose polar save filename, or <return> for no file writing)
+<return> (decline dump file writing)
+ASEQ -2 8 0.2 (compute alpha sequence to generate polar)
+PPLO (optional: plot the polar we have so far)
+ASEQ 8.2 9 0.2 (compute additional points if needed)
+PPLO
+PACC (toggle auto accumulation off)
+
+RE 1.5e5 (set new Re = 150k, still using Type 2 CL dependence)
+INIT (current alpha=9, so re-initialize for very different alpha)
+
+ALFA -2
+PACC (toggle auto accumulation on for new polar 2)
+polar2_file (choose polar save filename, or <return> for no file writing)
+<return> (decline dump file writing)
+ASEQ -2 9 0.2 (compute alpha sequence to generate polar)
+PACC (toggle auto accumulation off)
+
+PPLO (plot all two polars currently stored)
+PGET polar3_file (optional: read previously-generated polar save file)
+PPLO (plot all three polars currently stored)
+HARD (make Postscript file of current polar plot)
+
+<return>
+QUIT
+
+
+
+Notes:
+
+1) Sometimes you may not want to automatically write the polar to a file.
+In this case the PACC command is followed by a <return> rather than a filename:
+
+PACC
+<return>
+
+You can later use PWRT if you decide to write out the polar after all:
+
+PWRT (will display all stored polars available for writing)
+2 (choose polar 2 for writing)
+polar2_file (specify output filename)
+
+This approach is "dangerous" in that if XFOIL crashes, the stored polars
+are lost. This may or may not be a big deal, depending on how many polar
+points you have. XFOIL doesn't crash very easily, but it can happen.
+A common cause is accidental specification of a silly flow condition, e.g.
+
+ALFA 90
+
+In viscous mode this will produce all sorts of numerical fireworks,
+and possibly an arithmetic fault.
+
+
+2) Saved polar files can be plotted with the separate PPLOT program.
+Or you can use XFOIL itself, by reading in each polar file via PGET,
+and then plotting them via PPLO. PDEL, PSUM, etc. can also be used
+to set up a list of polars that you want to plot. PPAX can be used
+to change the polar plot axis limits.
+
+
+3) It is sometimes necessary to change the airfoil name in the polar save file.
+This can be easily done with a text editor. But do not change the other
+information headers, since this might confuse the polar file read routine.
+