DATCOM import not giving valid output for fields like dcdi_sym
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I was working on a project in MATLAB where I needed to import a DATCOM file but no matter what parameters I put, when I import it into MATLAB, the values stored for the control surface coefficients (like DCDI or clroll) are 99999 (NAN). Has anyone experienced anything similar/ has a solution to this?
The input code is as follows-
CASEID ----- MIKOYAN-GUREVICH MiG-17 -----
DIM FT
$FLTCON NMACH=5.0,MACH(1)=0.1,0.2,0.25,0.3,0.35$
$FLTCON
NALPHA=10.0,ALSCHD(1) =-4.0,-2.0,0.0,2.0, 4.0,6.0,8.0,10.0,12.0,14.0$
$FLTCON
NALT=5.0,
ALT(1)= 4500.0,4750.0,5000.0,5250.0,5500.0,
WT=13395.0,LOOP=1.0$
$SYNTHS XCG=11.17,ZCG=0.0,XW=3.63,ZW=0.42,ALIW=1.0,XH=28.73,
ZH=5.24,ALIH=0.0,XV=18.3,ZV=0.0,ZVF=1.0,VERTUP=.TRUE.$
$OPTINS SREF=243.0, CBARR=2.334, BLREF = 9.63$
$BODY NX=8.0,
X(1)=0.0,0.74,8.35,13.14,19.35,24.41,28.41,30.77,
S(1)=5.19,9.32,16.89,16.89,15.94,11.12,5.85,2.5$
NACA-W-6-66-012
$WGPLNF CHRDTP=7.02,SSPNOP=11.32,SSPNE=4.07,SSPN=15.71,
CHRDBP=8.4,CHRDR=14.0,SAVSI=45.0,SAVSO=45.0,CHSTAT=0.25,
TWISTA=0.0,DHDADI=-3.0,DHDADO=-3.0,TYPE=1.0$
NACA-H-6-66-009
$HTPLNF CHRDTP=1.86,SSPNE=5.42,SSPN=5.43,CHRDR=4.69,SAVSI=45.0,
CHSTAT=0.25,TYPE=1.0$
NACA-V-6-66-009
$VTPLNF CHRDTP=3.76,SSPNE=13.41,SSPN=8.18,CHRDR=12.47,SAVSI=55.0,
CHSTAT=0.25,TYPE=1.0$
$SYMFLP
FTYPE=1.0,
CHRDFI=1.407,
CHRDFO=1.407,
SPANFI=1.4,
SPANFO=5.1,
CB=0.12,
TC=0.14,
NTYPE=1.0,
PHETE = 3.03,
NDELTA=7.0,
DELTA(1)=-20.0,-10.0,-5.0,0.0,7.5,15.0,20.0
SCLD=-0.2,-0.1, -0.05,0.0, 0.06, 0.15,0.2
SCMD=-0.2,-0.1, -0.05,0.0, 0.06, 0.15,0.2$
$ASYFLP
STYPE = 4.0,
CHRDFI=2.23,
CHRDFO= 1.85,
SPANFI=9.42,
SPANFO=14.9,
NDELTA=9.0,
DELTAL=20.,15.,10.,5.,0.,-2.5,-5.,-10.,-15.,
DELTAR=20.,15.,10.,5.,0.,-2.5,-5.,-10.,-15.$
DAMP
BUILD
PLOT
NEXT CASE
11 Comments
Walter Roberson
on 8 Aug 2026 at 18:39
Those coefficients do not appear to be set by that file ??
How do you make MATLAB import this file ? As far as I see, it's an input file for Digital DATCOM (Data Compendium), an USAF aerodynamic calculation software.
Kian
on 8 Aug 2026 at 18:57
Walter Roberson
on 8 Aug 2026 at 21:16
Kian
27 minutes ago
Does the import work for the output file of the tutorial example from DATCOM
?
If not, you should contact support:
CASEID ----- MIKOYAN-GUREVICH MiG-17 -----
$FLTCON NMACH=1.0,MACH(1)=0.6,NALPHA=10.0,ALSCHD(1)=-4.0,-2.0,
0.0,2.0,4.0,6.0,8.0,10.0,12.0,14.0,NALT=1.0,ALT(1)=5000.0,
WT=13395.0,LOOP=1.$
$SYNTHS XCG=11.17,ZCG=0.0,XW=3.63,ZW=0.42,ALIW=1.0,XH=28.73,
ZH=5.24,ALIH=0.0,XV=18.3,ZV=0.0$
$OPTINS SREF=243.0$
$BODY NX=8.0,
X(1)=0.0,0.74,8.35,13.14,19.35,24.41,28.41,30.77,
S(1)=5.19,9.32,16.89,16.89,15.94,11.12,5.85,2.5$
NACA-W-6-66-012
$WGPLNF CHRDTP=7.02,SSPNOP=11.32,SSPNE=13.41,SSPN=15.71,
CHRDBP=8.4,CHRDR=14.0,SAVSI=45.0,SAVSO=45.0,CHSTAT=0.25,
TWISTA=0.0,DHDADI=-3.0,DHDADO=-3.0,TYPE=1.0$
NACA-H-6-66-009
$HTPLNF CHRDTP=1.86,SSPNE=5.42,SSPN=5.43,CHRDR=4.69,SAVSI=45.0,
CHSTAT=0.25,TYPE=1.0$
NACA-V-6-66-009
$VTPLNF CHRDTP=3.76,SSPNE=6.05,SSPN=8.18,CHRDR=12.47,SAVSI=55.0,
CHSTAT=0.25,TYPE=1.0$
DIM FT
BUILD
PLOT
NEXT CASE
Kian
21 minutes ago
I can reproduce your problem.
Here is a similar problem described:
https://uk.mathworks.com/matlabcentral/answers/734807-datcomimport-returns-all-coefficients-as-99999
I'm not sure if the problem arises because of your case formulation or because of the data import to MATLAB.
s = datcomimport('output.txt')
s{1}
s{1}.dcdi_sym
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