[Jsbsim-cvslogs] CVS: JSBSim/utils/aeromatic++/Systems Controls.cpp, 1.46, 1.47

[Erik H. <eh...@us...>]

Update of /cvsroot/jsbsim/JSBSim/utils/aeromatic++/Systems
In directory sfp-cvs-1.v30.ch3.sourceforge.com:/tmp/cvs-serv8714/Systems

Modified Files:
	Controls.cpp 
Log Message:
Calculate CD0 based on the build-up method

Index: Controls.cpp
===================================================================
RCS file: /cvsroot/jsbsim/JSBSim/utils/aeromatic++/Systems/Controls.cpp,v
retrieving revision 1.46
retrieving revision 1.47
diff -C2 -r1.46 -r1.47
*** Controls.cpp	18 Aug 2016 13:19:52 -0000	1.46
--- Controls.cpp	19 Aug 2016 10:20:42 -0000	1.47
***************
*** 154,171 ****
  
      // drag
      float Sv = _aircraft->_vtail.area;
  
      // Sfus: Fuselage wetted area
!     float TC = _aircraft->_wing.thickness/cbarw;
!     float k0 = 0.075f;
!     float k1 = 0.2f*TC; // 1.256f; // correction factor for wing thickness
! //  float k2 = 1.12f;           // fuselage fineness ratio correction factor
!     float Cf = 0.006f;          // skin Friction Coefficient
!     float fwings = Cf*(Sw+Sh+Sv)*2.04f*k1;
!     float CD0w = fwings/Sw;
! //  float ffus   = Cf*Sfus*k2;
! //  float CD0f = ffus/Sw;
! //  _aircraft->_CD0 = CD0f + CD0w;
!     _aircraft->_CD0 *= (1.0f - sinf(sweep));
  
      // lift
--- 154,227 ----
  
      // drag
+ // http://faculty.dwc.edu/sadraey/Chapter%203.%20Drag%20Force%20and%20its%20Coefficient.pdf
      float Sv = _aircraft->_vtail.area;
+     float TC = _aircraft->_wing.thickness/cbarw;
+ 
+     float Re = 150000;
+     float Cf = 1.328f/sqrtf(Re);
+ 
+     float M2, M = 0.01f;
+     float fM = 1.0f - 0.08f*powf(M, 1.45f);
  
      // Sfus: Fuselage wetted area
!     float D = _aircraft->get_fuselage_diameter();
!     float L = _aircraft->_length;
!     float fLD = 1.0f + 60.0f/powf(L/D, 3.0f) + 0.0025f*(L/D);
!     float Sfus = 0.75f*PI*D*L;
!     float CD0f = Cf*fLD*fM*(Sfus/Sw);
! 
!     // Main Wing
!     Cf = 0.2f*Cf + 0.8f*0.455f/powf(logf(Re),2.58f);
!     float CDminw = 0.004f;
!     float fD = powf(CDminw/0.004f, 0.4f);
!     float fTC = 1.0f + 2.7f*TC + 100.0f*powf(TC, 4.0f);
!     float Swing = 2.0f*(1.0f + 0.5f*TC)*bw*cbarw;
!     float CD0w = Cf*fM*fTC*fD*(Swing/Sw);
!     CD0w *= (1.0f - sinf(sweep));
! 
!     // Horizontal tail
!     float cbarh = _aircraft->_htail.chord_mean;
!     float TCh = _aircraft->_htail.thickness/cbarh;
!     float CDminh = 0.002f;
!     float fDh = powf(CDminh/0.004f, 0.4f);
!     float fTCh = 1.0f + 2.7f*TCh + 100.0f*powf(TCh, 4.0f);
!     float CD0h = Cf*fM*fTCh*fDh*(Swing/Sw);
!     CD0h *= (1.0f - sinf(_aircraft->_htail.sweep));
! 
!     // Vertical tail
!     float bv = _aircraft->_vtail.span;
!     float cbarv = _aircraft->_vtail.chord_mean;
!     float TCv = _aircraft->_vtail.thickness/cbarv;
!     float CDminv = 0.002f;
!     float fDv = powf(CDminv/0.004f, 0.4f);
!     float fTCv = 1.0f + 2.7f*TCv + 100.0f*powf(TCv, 4.0f);
!     float Svtail = 2.0f*(1.0f + 0.5f*TCv)*bv*cbarv;
!     float CD0v = Cf*fM*fTCv*fDv*(Svtail/Sv);
!     CD0v *= (1.0f - sinf(_aircraft->_vtail.sweep));
! 
!     float Kc = 1.05f;
!     switch(_aircraft->_atype)
!     {
!     case LIGHT:
!         if (_aircraft->_no_engines > 0) Kc = 1.3f;
!         break;
!     case PERFORMANCE:
!     case PROP_TRANSPORT:
!         Kc = 1.2f;
!         break;
!     case FIGHTER:
!     case JET_TRANSPORT:
!         Kc = 1.1f;
!         break;
! //  case BIPLANE:
!     default:
!         Kc = 1.5f;
!         break;
!     }
! #if 0
!  printf("CD0: %f (%f), Kc: %f, CD0f: %f, CD0w: %f, CD0h: %f, CD0v: %f\n", _aircraft->_CD0, Kc*(CD0f + CD0w + CD0h + CD0v), Kc, CD0f, CD0w, CD0h, CD0v);
! #endif
!     _aircraft->_CD0 = Kc*(CD0f + CD0w + CD0h + CD0v);
! 
  
      // lift
***************
*** 185,190 ****
      float Er = _aircraft->_vtail.flap_ratio;    // rudder
  
!     float M = 0.0f;
!     float M2 = M*M;
  
      float dsdB = 0.0f;          // ds/dB
--- 241,246 ----
      float Er = _aircraft->_vtail.flap_ratio;    // rudder
  
!     M = 0.0f;
!     M2 = M*M;
  
      float dsdB = 0.0f;          // ds/dB
***************
*** 197,202 ****
      float zw = -0.0f; // z-pos. wing: positive down
      float zv = -1.0f; // z-pos. vertical tail:  positive down
!     float fus_diameter = _aircraft->get_fuselage_diameter();
!     float Clbwf = 1.2f*sqrt(AR)*((zw+2.0f*fus_diameter)/(bw*bw));
      float Clbvt = -(zv/bw)*CLah[0];
  
--- 253,257 ----
      float zw = -0.0f; // z-pos. wing: positive down
      float zv = -1.0f; // z-pos. vertical tail:  positive down
!     float Clbwf = 1.2f*sqrt(AR)*((zw+2.0f*D)/(bw*bw));
      float Clbvt = -(zv/bw)*CLah[0];
  
***************
*** 287,290 ****
--- 342,347 ----
  
      // yaw
+     float k0 = 0.075f;
+     float k1 = 1.0f+TC; // 1.256f; // correction factor for wing thickness
      _aircraft->_Cnbeta = nv*Vv*CLav[0]*(1.0-dsdB);
      _aircraft->_Cnr = -(k0*CL*CL + k1*CD0w) - 2.0f*nv*Vv*CLav[0]*(lv/bw);
***************
*** 419,422 ****
--- 476,481 ----
  
      file << std::setprecision(4) << std::fixed << std::showpoint;
+     file << "    <!-- CD0 is based on fuselage, wing, horizontal- en vertical tail -->" << std::endl;
+     file << "    <!-- Antennas, struts and wires are not taken into account        -->" << std::endl;
      file << "    <function name=\"aero/force/Drag_zero_lift\">" << std::endl;
      file << "       <description>Drag at zero lift</description>" << std::endl;