C***********************************************************************
C Module: cdfun.f
C
C Copyright (C) 2005 Mark Drela
C
C This program is free software; you can redistribute it and/or modify
C it under the terms of the GNU General Public License as published by
C the Free Software Foundation; either version 2 of the License, or
C (at your option) any later version.
C
C This program is distributed in the hope that it will be useful,
C but WITHOUT ANY WARRANTY; without even the implied warranty of
C MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
C GNU General Public License for more details.
C
C You should have received a copy of the GNU General Public License
C along with this program; if not, write to the Free Software
C Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
C***********************************************************************
SUBROUTINE CDFUN(CL, RE, MA, CLCD0,CD0,CD2,REREF,REEXP, MCRIT,
& CD,CD_CL,CD_RE,CD_MA )
REAL MA, MCRIT
C
DATA CDMF / 10.0 /
DATA IEXP / 3 /
C
C---- CD-scaling factor
FAC = (RE/REREF)**REEXP
FAC_RE = REEXP*FAC/RE
C
C---- CD(CL;Re) function
CLB = CL - CLCD0
CD = (CD0 + CD2*CLB**2 )*FAC
CD_CL = ( CD2*CLB*2.0)*FAC
CD_RE = (CD0 + CD2*CLB**2 )*FAC_RE
CD_MA = 0.
C
IF(MA .GT. MCRIT) THEN
CD = CD + CDMF*(MA-MCRIT)** IEXP
CD_MA = CD_MA + CDMF*(MA-MCRIT)**(IEXP-1) * FLOAT(IEXP)
ENDIF
C
RETURN
END ! CDFUN
SUBROUTINE DCDFUN( BE, WA, WT, CLCD0,CL0,DCLDA,
& DCD,DCD_BE,DCD_WA,DCD_WT )
C
A = BE - ATAN2(WA,WT)
A_BE = 1.0
A_WA = -WT/(WA**2 + WT**2)
A_WT = WA/(WA**2 + WT**2)
C
ACD0 = (CLCD0-CL0)/DCLDA
DCD = 2.0*SIN(A-ACD0)**2
DCD_A = 4.0*SIN(A-ACD0)*COS(A-ACD0)
C
DCD_BE = DCD_A*A_BE
DCD_WA = DCD_A*A_WA
DCD_WT = DCD_A*A_WT
C
RETURN
END ! DCDFUN
