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src/FDM/YASim/yasim-test.cpp: added options to calculate settings at zero overall lift.

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-D shows speed and drag values at fixed altitude.

--aD shows best speed at different altitudes.

Example:
    yasim fgaddon-git/Harrier-GR3/Harrier-GR3.xml --aD
This commit is contained in:
Julian Smith 2019-12-16 09:55:10 +00:00
parent b85f2aba5c
commit 222a96503d
1 changed files with 85 additions and 3 deletions
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86
src/FDM/YASim/yasim-test.cpp
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@ -142,6 +142,73 @@ void yasim_drag(Airplane* a, const float aoa, const float alt, Airplane::Configu
printf("# cd_min %g at %d kts\n", cd_min, cd_min_kts);
}
/* Returns AoA for zero lift at specified altitude and speed. */
float yasim_find_zero_lift_aoa(Airplane* a, const float alt, float kts, Airplane::Configuration cfgID, float* acc)
{
_setup(a, cfgID, alt);
float aoa_deg = 0;
float aoa_deg_delta = 10;
while (1) {
float aoa = aoa_deg * DEG2RAD;
_calculateAcceleration(a, aoa, kts * KTS2MPS, acc);
float lift = acc[2];
if (lift > 0) aoa_deg -= aoa_deg_delta;
if (lift < 0) aoa_deg += aoa_deg_delta;
aoa_deg_delta /= 2;
if (aoa_deg_delta < 0.001) break;
//printf("aoa_deg=%g\n", aoa_deg);
}
//printf("alt=%g kts=%g: aoa_deg=%g\n", alt, kts, aoa_deg);
return aoa_deg;
}
/* Returns info about best speed at a particular height. */
void yasim_best_speed_at_height(Airplane* a, const float alt, Airplane::Configuration cfgID,
bool verbose, float& o_best_speed_kts, float& o_best_drag, float& o_best_aoa_deg)
{
o_best_speed_kts = 0;
o_best_drag = 1e9;
/* Could probably use a gradient-descent method, but for now we just use
linear list of speeds. */
for (float kts = 50; kts < 600; kts += 1) {
float acc[3];
float aoa_deg = yasim_find_zero_lift_aoa(a, alt, kts, cfgID, acc);
float aoa = aoa_deg * DEG2RAD;
float drag = acc[0] / -9.8;
float idrag = 9.8 * tan(aoa);
float drag_total = drag + idrag;
if (verbose) {
printf("acc=(% 10.4f % 10.2g % 10.4f)."
" alt=% 10.4f kts=% 10.4f: aoa_deg=% 10.4f drag=% 10.4f"
" idrag=% 10.4f drag_total=% 10.4f\n",
acc[0], acc[1], acc[2],
alt, kts, aoa_deg, drag,
idrag, drag_total);
}
if (drag_total < o_best_drag) {
o_best_speed_kts = kts;
o_best_drag = drag_total;
o_best_aoa_deg = aoa_deg;
}
}
}
/* Shows best speed at various heights. */
void yasim_show_best_speed_at_heights(Airplane* a, Airplane::Configuration cfgID)
{
for (int alt_ft=0; alt_ft < 50*1000; alt_ft += 1000) {
float alt_m = alt_ft * 12.0 * 2.54 / 100.0;
float best_speed_kts;
float best_drag;
float best_aoa_deg;
yasim_best_speed_at_height(a, alt_m, cfgID, false /*verbose*/,
best_speed_kts, best_drag, best_aoa_deg);
printf("altitude=% 6ift: best_speed=%gkts best_aoa=%.2fdeg drag=%g\n",
alt_ft, best_speed_kts, best_aoa_deg, best_drag);
}
}
void findMinSpeed(Airplane* a, float alt)
{
a->addControlSetting(Airplane::CRUISE, DEF_PROP_ELEVATOR_TRIM, 0.7f);
@ -238,6 +305,8 @@ int usage()
fprintf(stderr, " yasim <aircraft.xml> [-test] [-a meters] [-s kts] [-approach | -cruise] ]\n");
fprintf(stderr, " -g print lift/drag table: aoa, lift, drag, lift/drag \n");
fprintf(stderr, " -d print drag over TAS: kts, drag\n");
fprintf(stderr, " -D print kts at lowest drag at specified altitude\n");
fprintf(stderr, " --aD print kts at lowest drag at different altitudes\n");
fprintf(stderr, " -a set altitude in meters!\n");
fprintf(stderr, " -s set speed in knots\n");
fprintf(stderr, " -m print mass distribution table: id, x, y, z, mass \n");
@ -302,8 +371,8 @@ int main(int argc, char** argv)
yasim_masses(a);
}
}
else if(strcmp(argv[2], "-d") == 0) {
float alt = 2000, aoa = a->getCruiseAoA();
else if(!strcmp(argv[2], "-d") || !strcmp(argv[2], "-D") || !strcmp(argv[2], "--aD")) {
float alt = 2000;
for(int i=3; i<argc; i++) {
if (std::strcmp(argv[i], "-a") == 0) {
if (i+1 < argc) alt = std::atof(argv[++i]);
@ -312,8 +381,21 @@ int main(int argc, char** argv)
else if(std::strcmp(argv[i], "-cruise") == 0) cfg = Airplane::CRUISE;
else return usage();
}
if (strcmp(argv[2], "-d") == 0) {
float aoa = a->getCruiseAoA();
yasim_drag(a, aoa, alt, cfg);
}
else if (!strcmp(argv[2], "-D")) {
float best_speed_kts;
float best_drag;
float best_aoa_deg;
yasim_best_speed_at_height(a, alt, cfg, true /*verbose*/, best_speed_kts, best_drag, best_aoa_deg);
printf("altitude=%gm: best speed=%g best_aoa_deg=%g drag=%g\n", alt, best_speed_kts, best_aoa_deg, best_drag);
}
else if (!strcmp(argv[2], "--aD")) {
yasim_show_best_speed_at_heights(a, cfg);
}
}
else if(strcmp(argv[2], "-m") == 0) {
yasim_masses(a);
}