90e7c4ec43
generates a data file of aerodynamic lift and drag (and L/D) against AoA at a specified speed and altitude through a full circle. Wrote it to track down the YF-23 superthrust issue, but it wasn't any help. All the forces look fine.
118 lines
3.8 KiB
C++
118 lines
3.8 KiB
C++
#include <stdio.h>
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#include <simgear/props/props.hxx>
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#include <simgear/xml/easyxml.hxx>
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#include "FGFDM.hpp"
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#include "Atmosphere.hpp"
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#include "Airplane.hpp"
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using namespace yasim;
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// Stubs. Not needed by a batch program, but required to link.
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bool fgSetFloat (const char * name, float val) { return false; }
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bool fgSetBool(char const * name, bool val) { return false; }
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bool fgGetBool(char const * name, bool def) { return false; }
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SGPropertyNode* fgGetNode (const char * path, bool create) { return 0; }
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SGPropertyNode* fgGetNode (const char * path, int i, bool create) { return 0; }
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float fgGetFloat (const char * name, float defaultValue) { return 0; }
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float fgGetDouble (const char * name, double defaultValue) { return 0; }
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float fgSetDouble (const char * name, double defaultValue) { return 0; }
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static const float RAD2DEG = 57.2957795131;
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static const float DEG2RAD = 0.0174532925199;
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static const float KTS2MPS = 0.514444444444;
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// Generate a graph of lift, drag and L/D against AoA at the specified
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// speed and altitude. The result is a space-separated file of
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// numbers: "aoa lift drag LD" (aoa in degrees, lift and drag in
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// G's). You can use this in gnuplot like so (assuming the output is
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// in a file named "dat":
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//
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// plot "dat" using 1:2 with lines title 'lift', \
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// "dat" using 1:3 with lines title 'drag', \
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// "dat" using 1:4 with lines title 'LD'
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//
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void yasim_graph(Airplane* a, float alt, float kts)
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{
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Model* m = a->getModel();
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State s;
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m->setAir(Atmosphere::getStdPressure(alt),
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Atmosphere::getStdTemperature(alt),
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Atmosphere::getStdDensity(alt));
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m->getBody()->recalc();
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for(int deg=-179; deg<=179; deg++) {
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float aoa = deg * DEG2RAD;
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Airplane::setupState(aoa, kts * KTS2MPS, &s);
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m->getBody()->reset();
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m->initIteration();
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m->calcForces(&s);
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float acc[3];
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m->getBody()->getAccel(acc);
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Math::tmul33(s.orient, acc, acc);
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float drag = acc[0] * (-1/9.8);
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float lift = 1 + acc[2] * (1/9.8);
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printf("%d %g %g %g\n", deg, lift, drag, lift/drag);
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}
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}
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int usage()
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{
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fprintf(stderr, "Usage: yasim <ac.xml> [-g [-a alt] [-s kts]]\n");
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return 1;
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}
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int main(int argc, char** argv)
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{
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FGFDM* fdm = new FGFDM();
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Airplane* a = fdm->getAirplane();
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if(argc < 2) return usage();
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// Read
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try {
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string file = argv[1];
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readXML(file, *fdm);
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} catch (const sg_exception &e) {
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printf("XML parse error: %s (%s)\n",
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e.getFormattedMessage().c_str(), e.getOrigin().c_str());
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}
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// ... and run
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a->compile();
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if(a->getFailureMsg())
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printf("SOLUTION FAILURE: %s\n", a->getFailureMsg());
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if(!a->getFailureMsg() && argc > 2 && strcmp(argv[2], "-g") == 0) {
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float alt = 5000, kts = 100;
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for(int i=3; i<argc; i++) {
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if (strcmp(argv[i], "-a") == 0) alt = atof(argv[++i]);
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else if(strcmp(argv[i], "-s") == 0) kts = atof(argv[++i]);
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else return usage();
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}
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yasim_graph(a, alt, kts);
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} else {
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float aoa = a->getCruiseAoA() * RAD2DEG;
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float tail = -1 * a->getTailIncidence() * RAD2DEG;
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float drag = 1000 * a->getDragCoefficient();
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float cg[3];
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a->getModel()->getBody()->getCG(cg);
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printf("Solution results:");
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printf(" Iterations: %d\n", a->getSolutionIterations());
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printf(" Drag Coefficient: %f\n", drag);
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printf(" Lift Ratio: %f\n", a->getLiftRatio());
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printf(" Cruise AoA: %f\n", aoa);
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printf(" Tail Incidence: %f\n", tail);
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printf("Approach Elevator: %f\n", a->getApproachElevator());
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printf(" CG: %.3f, %.3f, %.3f\n", cg[0], cg[1], cg[2]);
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}
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delete fdm;
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return 0;
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}
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