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flightgear/src/FDM/UIUCModel/uiuc_engine.cpp
curt 9a5ec79e11 Updates to the UIUCModel code. This includes some big compile time 
speedups to uiuc_menu.cpp.

(Note these were originally submitted before the cutoff date for new
features, but something was corrupted in the transfer so I granted a bit
of leeway in the schedule.)
2002-09-02 23:26:28 +00:00

213 lines
6.9 KiB
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/**********************************************************************
FILENAME: uiuc_engine.cpp
----------------------------------------------------------------------
DESCRIPTION: determine the engine forces and moments
----------------------------------------------------------------------
STATUS: alpha version
----------------------------------------------------------------------
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>
----------------------------------------------------------------------
VARIABLES:
----------------------------------------------------------------------
INPUTS: -engine model
----------------------------------------------------------------------
OUTPUTS: -F_X_engine
-F_Z_engine
-M_m_engine
----------------------------------------------------------------------
CALLED BY: uiuc_wrapper.cpp
----------------------------------------------------------------------
CALLS TO: none
----------------------------------------------------------------------
COPYRIGHT: (C) 2000 by Michael Selig
This program is free software; you can redistribute it and/or
modify it under the terms of the GNU General Public License
as published by the Free Software Foundation.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program; if not, write to the Free Software
Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307,
USA or view http://www.gnu.org/copyleft/gpl.html.
**********************************************************************/
#include <simgear/compiler.h>
#include "uiuc_engine.h"
#if !defined (SG_HAVE_NATIVE_SGI_COMPILERS)
SG_USING_STD(cerr);
#endif
void uiuc_engine()
{
stack command_list;
string linetoken1;
string linetoken2;
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);
}
}
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);
linetoken2 = engineParts -> getToken(*command_line, 2);
switch(engine_map[linetoken2])
{
case simpleSingle_flag:
{
F_X_engine = Throttle[3] * simpleSingleMaxThrust;
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
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