----------------------------------------------------------------------
- REFERENCES: based on portions of c172_engine.c, called from ls_model
+ REFERENCES: simple and c172 models based on portions of
+ c172_engine.c, called from ls_model;
+ cherokee model based on cherokee_engine.c
----------------------------------------------------------------------
HISTORY: 01/30/2000 initial release
+ 06/18/2001 (RD) Added Throttle_pct_input.
----------------------------------------------------------------------
AUTHOR(S): Bipin Sehgal <bsehgal@uiuc.edu>
Jeff Scott <jscott@mail.com>
+ Robert Deters <rdeters@uiuc.edu>
Michael Selig <m-selig@uiuc.edu>
----------------------------------------------------------------------
USA or view http://www.gnu.org/copyleft/gpl.html.
**********************************************************************/
+#include <simgear/compiler.h>
#include "uiuc_engine.h"
+SG_USING_STD(cerr);
+
void uiuc_engine()
{
stack command_list;
string linetoken1;
string linetoken2;
+
+ if (outside_control == false)
+ pilot_throttle_no = false;
+ if (Throttle_pct_input)
+ {
+ double Throttle_pct_input_endTime = Throttle_pct_input_timeArray[Throttle_pct_input_ntime];
+ if (Simtime >= Throttle_pct_input_startTime &&
+ Simtime <= (Throttle_pct_input_startTime + Throttle_pct_input_endTime))
+ {
+ double time = Simtime - Throttle_pct_input_startTime;
+ Throttle_pct = uiuc_1Dinterpolation(Throttle_pct_input_timeArray,
+ Throttle_pct_input_dTArray,
+ Throttle_pct_input_ntime,
+ time);
+ pilot_throttle_no = true;
+ }
+ }
- /* [] mss questions: why do this here ... and then undo it later?
- ... does Throttle[3] get modified? */
Throttle[3] = Throttle_pct;
command_list = engineParts -> getCommands();
-
+
+ /*
if (command_list.begin() == command_list.end())
{
cerr << "ERROR: Engine not specified. Aircraft cannot fly without the engine" << endl;
exit(-1);
}
+ */
for (LIST command_line = command_list.begin(); command_line!=command_list.end(); ++command_line)
{
//cout << *command_line << endl;
- linetoken1 = engineParts -> getToken(*command_line, 1); // function parameters gettoken(string,tokenNo);
- linetoken2 = engineParts -> getToken(*command_line, 2); // 2 represents token No 2
+ linetoken1 = engineParts -> getToken(*command_line, 1);
+ linetoken2 = engineParts -> getToken(*command_line, 2);
switch(engine_map[linetoken2])
- {
- case simpleSingle_flag:
- {
- //c172 engine lines ... looks like 0.83 is just a thrust reduction
- /* F_X_engine = Throttle[3]*350/0.83; */
- /* F_Z_engine = Throttle[3]*4.9/0.83; */
- /* M_m_engine = F_X_engine*0.734*cbar; */
- F_X_engine = Throttle[3]*simpleSingleMaxThrust;
- break;
- }
- case c172_flag:
- {
- F_X_engine = Throttle[3]*350/0.83;
- F_Z_engine = Throttle[3]*4.9/0.83;
- M_m_engine = F_X_engine*0.734*cbar;
- break;
- }
- };
-
- Throttle_pct = Throttle[3];
- return;
+ {
+ case simpleSingle_flag:
+ {
+ F_X_engine = Throttle[3] * simpleSingleMaxThrust;
+ F_Y_engine = 0.0;
+ F_Z_engine = 0.0;
+ M_l_engine = 0.0;
+ M_m_engine = 0.0;
+ M_n_engine = 0.0;
+ break;
+ }
+ case simpleSingleModel_flag:
+ {
+ /* simple model based on Hepperle's equation
+ * exponent dtdvvt was computed in uiuc_menu.cpp */
+ F_X_engine = Throttle[3] * t_v0 * (1 - pow((V_rel_wind/v_t0),dtdvvt));
+ F_Y_engine = 0.0;
+ F_Z_engine = 0.0;
+ M_l_engine = 0.0;
+ M_m_engine = 0.0;
+ M_n_engine = 0.0;
+ if (b_slipstreamEffects) {
+ tc = F_X_engine/(Dynamic_pressure * LS_PI * propDia * propDia / 4);
+ w_induced = 0.5 * V_rel_wind * (-1 + pow((1+tc),.5));
+ eta_q = (2* w_induced + V_rel_wind)*(2* w_induced + V_rel_wind)/(V_rel_wind * V_rel_wind);
+ /* add in a die-off function so that eta falls off w/ alfa and beta */
+ eta_q = Cos_alpha * Cos_alpha * Cos_beta * Cos_beta * eta_q;
+ /* determine the eta_q values for the respective coefficients */
+ if (eta_q_Cm_q_fac) {eta_q_Cm_q *= eta_q * eta_q_Cm_q_fac;}
+ if (eta_q_Cm_adot_fac) {eta_q_Cm_adot *= eta_q * eta_q_Cm_adot_fac;}
+ if (eta_q_Cmfade_fac) {eta_q_Cmfade *= eta_q * eta_q_Cmfade_fac;}
+ if (eta_q_Cm_de_fac) {eta_q_Cm_de *= eta_q * eta_q_Cm_de_fac;}
+ if (eta_q_Cl_beta_fac) {eta_q_Cl_beta *= eta_q * eta_q_Cl_beta_fac;}
+ if (eta_q_Cl_p_fac) {eta_q_Cl_p *= eta_q * eta_q_Cl_p_fac;}
+ if (eta_q_Cl_r_fac) {eta_q_Cl_r *= eta_q * eta_q_Cl_r_fac;}
+ if (eta_q_Cl_dr_fac) {eta_q_Cl_dr *= eta_q * eta_q_Cl_dr_fac;}
+ if (eta_q_CY_beta_fac) {eta_q_CY_beta *= eta_q * eta_q_CY_beta_fac;}
+ if (eta_q_CY_p_fac) {eta_q_CY_p *= eta_q * eta_q_CY_p_fac;}
+ if (eta_q_CY_r_fac) {eta_q_CY_r *= eta_q * eta_q_CY_r_fac;}
+ if (eta_q_CY_dr_fac) {eta_q_CY_dr *= eta_q * eta_q_CY_dr_fac;}
+ if (eta_q_Cn_beta_fac) {eta_q_Cn_beta *= eta_q * eta_q_Cn_beta_fac;}
+ if (eta_q_Cn_p_fac) {eta_q_Cn_p *= eta_q * eta_q_Cn_p_fac;}
+ if (eta_q_Cn_r_fac) {eta_q_Cn_r *= eta_q * eta_q_Cn_r_fac;}
+ if (eta_q_Cn_dr_fac) {eta_q_Cn_dr *= eta_q * eta_q_Cn_dr_fac;}
+ }
+ /* Need engineOmega for gyroscopic moments */
+ engineOmega = minOmega + Throttle[3] * (maxOmega - minOmega);
+ break;
+ }
+ case c172_flag:
+ {
+ //c172 engine lines ... looks like 0.83 is just a thrust increase
+ F_X_engine = Throttle[3] * 350 / 0.83;
+ F_Z_engine = Throttle[3] * 4.9 / 0.83;
+ M_m_engine = F_X_engine * 0.734 * cbar;
+ break;
+ }
+ case cherokee_flag:
+ {
+ static float
+ dP = (180.0-117.0)*745.7, // Watts
+ dn = (2700.0-2350.0)/60.0, // d_rpm (I mean d_rps, in seconds)
+ D = 6.17*0.3048, // prop diameter
+ dPh = (58.0-180.0)*745.7, // change of power as function of height
+ dH = 25000.0*0.3048;
+
+ float
+ n, // [rps]
+ H, // altitude [m]
+ J, // advance ratio (ratio of horizontal speed to prop tip speed)
+ T, // thrust [N]
+ V, // velocity [m/s]
+ P, // power [W]
+ eta_engine; // engine efficiency
+
+ /* assumption -> 0.0 <= Throttle[3] <=1.0 */
+ P = fabs(Throttle[3]) * 180.0 * 745.7; /*180.0*745.7 ->max avail power [W]*/
+ n = dn/dP * (P-117.0*745.7) + 2350.0/60.0;
+
+ /* V [m/s] */
+ V = (V_rel_wind < 10.0 ? 10.0 : V_rel_wind*0.3048);
+ J = V / n / D;
+
+ /* Propeller efficiency */
+ eta_engine = (J < 0.7 ? ((0.8-0.55)/(.7-.3)*(J-0.3) + 0.55) :
+ (J > 0.85 ? ((0.6-0.8)/(1.0-0.85)*(J-0.85) + 0.8) : 0.8));
+
+ /* power on Altitude */
+ H = Altitude * 0.3048; /* H == Altitude [m] */
+ P *= (dPh/dH * H + 180.0*745.7) / (180.0*745.7);
+ T = eta_engine * P/V; /* Thrust [N] */
+
+ /*assumption: Engine's line of thrust passes through cg */
+ F_X_engine = T * 0.2248; /* F_X_engine in lb */
+ F_Y_engine = 0.0;
+ F_Z_engine = 0.0;
+ break;
+ }
+ case forcemom_flag:
+ {
+ double Xp_input_endTime = Xp_input_timeArray[Xp_input_ntime];
+ if (Simtime >= Xp_input_startTime &&
+ Simtime <= (Xp_input_startTime + Xp_input_endTime))
+ {
+ double time = Simtime - Xp_input_startTime;
+ F_X_engine = uiuc_1Dinterpolation(Xp_input_timeArray,
+ Xp_input_XpArray,
+ Xp_input_ntime,
+ time);
+ }
+ double Zp_input_endTime = Zp_input_timeArray[Zp_input_ntime];
+ if (Simtime >= Zp_input_startTime &&
+ Simtime <= (Zp_input_startTime + Zp_input_endTime))
+ {
+ double time = Simtime - Zp_input_startTime;
+ F_Z_engine = uiuc_1Dinterpolation(Zp_input_timeArray,
+ Zp_input_ZpArray,
+ Zp_input_ntime,
+ time);
+ }
+ double Mp_input_endTime = Mp_input_timeArray[Mp_input_ntime];
+ if (Simtime >= Mp_input_startTime &&
+ Simtime <= (Mp_input_startTime + Mp_input_endTime))
+ {
+ double time = Simtime - Mp_input_startTime;
+ M_m_engine = uiuc_1Dinterpolation(Mp_input_timeArray,
+ Mp_input_MpArray,
+ Mp_input_ntime,
+ time);
+ }
+ }
+ };
}
+ return;
}
// end uiuc_engine.cpp
projects / flightgear.git / blobdiff