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Latest YASim changes.

This commit is contained in:
david 2001-12-24 13:54:03 +00:00
parent 2b34388ea6
commit f0e6716953
20 changed files with 693 additions and 186 deletions

View file

@ -207,7 +207,8 @@ void Airplane::addVStab(Wing* vstab)
_vstabs.add(vstab); _vstabs.add(vstab);
} }
void Airplane::addFuselage(float* front, float* back, float width) void Airplane::addFuselage(float* front, float* back, float width,
float taper, float mid)
{ {
Fuselage* f = new Fuselage(); Fuselage* f = new Fuselage();
int i; int i;
@ -216,6 +217,8 @@ void Airplane::addFuselage(float* front, float* back, float width)
f->back[i] = back[i]; f->back[i] = back[i];
} }
f->width = width; f->width = width;
f->taper = taper;
f->mid = mid;
_fuselages.add(f); _fuselages.add(f);
} }
@ -358,12 +361,18 @@ float Airplane::compileWing(Wing* w)
int i; int i;
for(i=0; i<w->numSurfaces(); i++) { for(i=0; i<w->numSurfaces(); i++) {
Surface* s = (Surface*)w->getSurface(i); Surface* s = (Surface*)w->getSurface(i);
float td = s->getTotalDrag();
s->setTotalDrag(td);
_model.addSurface(s); _model.addSurface(s);
float mass = w->getSurfaceWeight(i);
mass = mass * Math::sqrt(mass);
float pos[3]; float pos[3];
s->getPosition(pos); s->getPosition(pos);
_model.getBody()->addMass(w->getSurfaceWeight(i), pos); _model.getBody()->addMass(mass, pos);
wgt += w->getSurfaceWeight(i); wgt += mass;
} }
return wgt; return wgt;
} }
@ -380,11 +389,22 @@ float Airplane::compileFuselage(Fuselage* f)
int j; int j;
for(j=0; j<segs; j++) { for(j=0; j<segs; j++) {
float frac = (j+0.5) / segs; float frac = (j+0.5) / segs;
float scale = 1;
if(frac < f->mid)
scale = f->taper+(1-f->taper) * (frac / f->mid);
else
scale = f->taper+(1-f->taper) * (frac - f->mid) / (1 - f->mid);
// Where are we?
float pos[3]; float pos[3];
Math::mul3(frac, fwd, pos); Math::mul3(frac, fwd, pos);
Math::add3(f->back, pos, pos); Math::add3(f->back, pos, pos);
_model.getBody()->addMass(segWgt, pos);
wgt += segWgt; // _Mass_ weighting goes as surface area^(3/2)
float mass = scale*segWgt * Math::sqrt(scale*segWgt);
_model.getBody()->addMass(mass, pos);
wgt += mass;
// Make a Surface too // Make a Surface too
Surface* s = new Surface(); Surface* s = new Surface();
@ -392,7 +412,7 @@ float Airplane::compileFuselage(Fuselage* f)
float sideDrag = len/wid; float sideDrag = len/wid;
s->setYDrag(sideDrag); s->setYDrag(sideDrag);
s->setZDrag(sideDrag); s->setZDrag(sideDrag);
s->setTotalDrag(segWgt); s->setTotalDrag(scale*segWgt);
// FIXME: fails for fuselages aligned along the Y axis // FIXME: fails for fuselages aligned along the Y axis
float o[9]; float o[9];

View file

@ -32,7 +32,8 @@ public:
void setTail(Wing* tail); void setTail(Wing* tail);
void addVStab(Wing* vstab); void addVStab(Wing* vstab);
void addFuselage(float* front, float* back, float width); void addFuselage(float* front, float* back, float width,
float taper=1, float mid=0.5);
int addTank(float* pos, float cap, float fuelDensity); int addTank(float* pos, float cap, float fuelDensity);
void addGear(Gear* g, float transitionTime); void addGear(Gear* g, float transitionTime);
void addThruster(Thruster* t, float mass, float* cg); void addThruster(Thruster* t, float mass, float* cg);
@ -58,6 +59,7 @@ public:
float getFuelDensity(int tank); // kg/m^3 float getFuelDensity(int tank); // kg/m^3
void compile(); // generate point masses & such, then solve void compile(); // generate point masses & such, then solve
void stabilizeThrust();
// Solution output values // Solution output values
int getSolutionIterations(); int getSolutionIterations();
@ -70,7 +72,7 @@ public:
private: private:
struct Tank { float pos[3]; float cap; float fill; struct Tank { float pos[3]; float cap; float fill;
float density; int handle; }; float density; int handle; };
struct Fuselage { float front[3], back[3], width; }; struct Fuselage { float front[3], back[3], width, taper, mid; };
struct GearRec { Gear* gear; Surface* surf; float wgt; float time; }; struct GearRec { Gear* gear; Surface* surf; float wgt; float time; };
struct ThrustRec { Thruster* thruster; struct ThrustRec { Thruster* thruster;
int handle; float cg[3]; float mass; }; int handle; float cg[3]; float mass; };
@ -85,7 +87,6 @@ private:
float compileWing(Wing* w); float compileWing(Wing* w);
float compileFuselage(Fuselage* f); float compileFuselage(Fuselage* f);
void compileGear(GearRec* gr); void compileGear(GearRec* gr);
void stabilizeThrust();
void applyDragFactor(float factor); void applyDragFactor(float factor);
void applyLiftRatio(float factor); void applyLiftRatio(float factor);
float clamp(float val, float min, float max); float clamp(float val, float min, float max);

View file

@ -35,6 +35,9 @@ float Atmosphere::data[][4] = {{ 0, 288.20, 101325, 1.22500 },
// P in pascals (N/m^2), rho is kg/m^3, T in kelvin. // P in pascals (N/m^2), rho is kg/m^3, T in kelvin.
const float R = 287.1; const float R = 287.1;
// Specific heat ratio for air, at "low" temperatures.
const float GAMMA = 1.4;
float Atmosphere::getStdTemperature(float alt) float Atmosphere::getStdTemperature(float alt)
{ {
return getRecord(alt, 1); return getRecord(alt, 1);
@ -95,7 +98,18 @@ float Atmosphere::calcDensity(float pressure, float temp)
float Atmosphere::calcMach(float spd, float temp) float Atmosphere::calcMach(float spd, float temp)
{ {
return spd / Math::sqrt(1.4 * R * temp); return spd / Math::sqrt(GAMMA * R * temp);
}
void Atmosphere::calcStaticAir(float p0, float t0, float d0, float v,
float* pOut, float* tOut, float* dOut)
{
const static float C0 = ((GAMMA-1)/(2*R*GAMMA));
const static float C1 = 1/(GAMMA-1);
*tOut = t0 + (v*v) * C0;
*dOut = d0 * Math::pow(*tOut / t0, C1);
*pOut = (*dOut) * R * (*tOut);
} }
float Atmosphere::getRecord(float alt, int recNum) float Atmosphere::getRecord(float alt, int recNum)

View file

@ -14,6 +14,13 @@ public:
static float calcMach(float spd, float temp); static float calcMach(float spd, float temp);
static float calcDensity(float pressure, float temp); static float calcDensity(float pressure, float temp);
// Given ambient ("0") pressure/density/temperature values,
// calculate the properties of static air (air accelerated to the
// aircraft's speed) at a given velocity. Includes
// compressibility, but not shock effects.
static void calcStaticAir(float p0, float t0, float d0, float v,
float* pOut, float* tOut, float* dOut);
private: private:
static float getRecord(float alt, int idx); static float getRecord(float alt, int idx);
static float data[][4]; static float data[][4];

View file

@ -1,6 +1,7 @@
#include "Jet.hpp" #include "Jet.hpp"
#include "Thruster.hpp" #include "Thruster.hpp"
#include "PropEngine.hpp" #include "PropEngine.hpp"
#include "PistonEngine.hpp"
#include "Gear.hpp" #include "Gear.hpp"
#include "Wing.hpp" #include "Wing.hpp"
#include "Math.hpp" #include "Math.hpp"
@ -19,11 +20,8 @@ ControlMap::~ControlMap()
delete v; delete v;
} }
for(i=0; i<_outputs.size(); i++) { for(i=0; i<_outputs.size(); i++)
OutRec* o = (OutRec*)_outputs.get(i); delete (OutRec*)_outputs.get(i);
delete[] o->values;
delete o;
}
} }
int ControlMap::newInput() int ControlMap::newInput()
@ -32,6 +30,21 @@ int ControlMap::newInput()
return _inputs.add(v); return _inputs.add(v);
} }
void ControlMap::addMapping(int input, int type, void* object, int options,
float src0, float src1, float dst0, float dst1)
{
addMapping(input, type, object, options);
// The one we just added is last in the list (ugly, awful hack!)
Vector* maps = (Vector*)_inputs.get(input);
MapRec* m = (MapRec*)maps->get(maps->size() - 1);
m->src0 = src0;
m->src1 = src1;
m->dst0 = dst0;
m->dst1 = dst1;
}
void ControlMap::addMapping(int input, int type, void* object, int options) void ControlMap::addMapping(int input, int type, void* object, int options)
{ {
// See if the output object already exists // See if the output object already exists
@ -50,25 +63,22 @@ void ControlMap::addMapping(int input, int type, void* object, int options)
out = new OutRec(); out = new OutRec();
out->type = type; out->type = type;
out->object = object; out->object = object;
out->n = 0;
out->values = 0;
_outputs.add(out); _outputs.add(out);
} }
// Make space for the new input value
int idx = out->n++;
delete[] out->values;
out->values = new float[out->n];
// Add the new option tag
out->options.add((void*)options);
// Make a new input record // Make a new input record
MapRec* map = new MapRec(); MapRec* map = new MapRec();
map->out = out; map->out = out;
map->idx = idx; map->opt = options;
map->idx = out->maps.add(map);
// And add it to the approproate vector. // The default ranges differ depending on type!
map->src1 = map->dst1 = 1;
map->src0 = map->dst0 = 0;
if(type==FLAP0 || type==FLAP1 || type==STEER)
map->src0 = map->dst0 = -1;
// And add it to the approproate vectors.
Vector* maps = (Vector*)_inputs.get(input); Vector* maps = (Vector*)_inputs.get(input);
maps->add(map); maps->add(map);
} }
@ -76,22 +86,29 @@ void ControlMap::addMapping(int input, int type, void* object, int options)
void ControlMap::reset() void ControlMap::reset()
{ {
// Set all the values to zero // Set all the values to zero
int i; for(int i=0; i<_outputs.size(); i++) {
for(i=0; i<_outputs.size(); i++) {
OutRec* o = (OutRec*)_outputs.get(i); OutRec* o = (OutRec*)_outputs.get(i);
int j; for(int j=0; j<o->maps.size(); j++)
for(j=0; j<o->n; j++) ((MapRec*)o->maps.get(j))->val = 0;
o->values[j] = 0;
} }
} }
void ControlMap::setInput(int input, float value) void ControlMap::setInput(int input, float val)
{ {
Vector* maps = (Vector*)_inputs.get(input); Vector* maps = (Vector*)_inputs.get(input);
int i; for(int i=0; i<maps->size(); i++) {
for(i=0; i<maps->size(); i++) { MapRec* m = (MapRec*)maps->get(i);
MapRec* map = (MapRec*)maps->get(i);
map->out->values[map->idx] = value; float val2 = val;
// Do the scaling operation. Clamp to [src0:src1], rescale to
// [0:1] within that range, then map to [dst0:dst1].
if(val2 < m->src0) val2 = m->src0;
if(val2 > m->src1) val2 = m->src1;
val2 = (val2 - m->src0) / (m->src1 - m->src0);
val2 = m->dst0 + val2 * (m->dst1 - m->dst0);
m->val = val2;
} }
} }
@ -105,15 +122,16 @@ void ControlMap::applyControls()
// control axes like ailerons. // control axes like ailerons.
float lval = 0, rval = 0; float lval = 0, rval = 0;
int i; int i;
for(i=0; i<o->n; i++) { for(i=0; i<o->maps.size(); i++) {
float val = o->values[i]; MapRec* m = (MapRec*)o->maps.get(i);
int opt = (int)o->options.get(i); float val = m->val;
if(opt & OPT_SQUARE)
if(m->opt & OPT_SQUARE)
val = val * Math::abs(val); val = val * Math::abs(val);
if(opt & OPT_INVERT) if(m->opt & OPT_INVERT)
val = -val; val = -val;
lval += val; lval += val;
if(opt & OPT_SPLIT) if(m->opt & OPT_SPLIT)
rval -= val; rval -= val;
else else
rval += val; rval += val;
@ -125,6 +143,7 @@ void ControlMap::applyControls()
case MIXTURE: ((Thruster*)obj)->setMixture(lval); break; case MIXTURE: ((Thruster*)obj)->setMixture(lval); break;
case ADVANCE: ((PropEngine*)obj)->setAdvance(lval); break; case ADVANCE: ((PropEngine*)obj)->setAdvance(lval); break;
case REHEAT: ((Jet*)obj)->setReheat(lval); break; case REHEAT: ((Jet*)obj)->setReheat(lval); break;
case VECTOR: ((Jet*)obj)->setRotation(lval); break;
case BRAKE: ((Gear*)obj)->setBrake(lval); break; case BRAKE: ((Gear*)obj)->setBrake(lval); break;
case STEER: ((Gear*)obj)->setRotation(lval); break; case STEER: ((Gear*)obj)->setRotation(lval); break;
case EXTEND: ((Gear*)obj)->setExtension(lval); break; case EXTEND: ((Gear*)obj)->setExtension(lval); break;
@ -132,6 +151,9 @@ void ControlMap::applyControls()
case FLAP0: ((Wing*)obj)->setFlap0(lval, rval); break; case FLAP0: ((Wing*)obj)->setFlap0(lval, rval); break;
case FLAP1: ((Wing*)obj)->setFlap1(lval, rval); break; case FLAP1: ((Wing*)obj)->setFlap1(lval, rval); break;
case SPOILER: ((Wing*)obj)->setSpoiler(lval, rval); break; case SPOILER: ((Wing*)obj)->setSpoiler(lval, rval); break;
case BOOST:
((Thruster*)obj)->getPistonEngine()->setBoost(lval);
break;
} }
} }
} }

View file

@ -11,7 +11,8 @@ public:
enum OutputType { THROTTLE, MIXTURE, ADVANCE, REHEAT, PROP, enum OutputType { THROTTLE, MIXTURE, ADVANCE, REHEAT, PROP,
BRAKE, STEER, EXTEND, BRAKE, STEER, EXTEND,
INCIDENCE, FLAP0, FLAP1, SLAT, SPOILER }; INCIDENCE, FLAP0, FLAP1, SLAT, SPOILER, VECTOR,
BOOST };
enum { OPT_SPLIT = 0x01, enum { OPT_SPLIT = 0x01,
OPT_INVERT = 0x02, OPT_INVERT = 0x02,
@ -26,6 +27,12 @@ public:
// of object! // of object!
void addMapping(int input, int output, void* object, int options=0); void addMapping(int input, int output, void* object, int options=0);
// An additional form to specify a mapping range. Input values
// outside of [src0:src1] are clamped, and are then mapped to
// [dst0:dst1] before being set on the object.
void addMapping(int input, int output, void* object, int options,
float src0, float src1, float dst0, float dst1);
// Resets our accumulated input values. Call before any // Resets our accumulated input values. Call before any
// setInput() invokations. // setInput() invokations.
void reset(); void reset();
@ -38,9 +45,9 @@ public:
void applyControls(); void applyControls();
private: private:
struct OutRec { int type; void* object; int n; struct OutRec { int type; void* object; Vector maps; };
float* values; Vector options; }; struct MapRec { OutRec* out; int idx; int opt; float val;
struct MapRec { OutRec* out; int idx; }; float src0; float src1; float dst0; float dst1; };
// A list of (sub)Vectors containing a bunch of MapRec objects for // A list of (sub)Vectors containing a bunch of MapRec objects for
// each input handle. // each input handle.

View file

@ -4,6 +4,7 @@
#include <Main/fg_props.hxx> #include <Main/fg_props.hxx>
#include "Jet.hpp" #include "Jet.hpp"
#include "SimpleJet.hpp"
#include "Gear.hpp" #include "Gear.hpp"
#include "Atmosphere.hpp" #include "Atmosphere.hpp"
#include "PropEngine.hpp" #include "PropEngine.hpp"
@ -23,6 +24,8 @@ static const float LBS2KG = 0.45359237;
static const float CM2GALS = 264.172037284; static const float CM2GALS = 264.172037284;
static const float HP2W = 745.700; static const float HP2W = 745.700;
static const float INHG2PA = 3386.389; static const float INHG2PA = 3386.389;
static const float K2DEGF = 1.8;
static const float CIN2CM = 1.6387064e-5;
// Stubs, so that this can be compiled without the FlightGear // Stubs, so that this can be compiled without the FlightGear
// binary. What's the best way to handle this? // binary. What's the best way to handle this?
@ -43,16 +46,10 @@ FGFDM::~FGFDM()
delete[] a->name; delete[] a->name;
delete a; delete a;
} }
for(i=0; i<_pistons.size(); i++) { for(i=0; i<_thrusters.size(); i++) {
EngRec* er = (EngRec*)_pistons.get(i); EngRec* er = (EngRec*)_thrusters.get(i);
delete[] er->prefix; delete[] er->prefix;
delete (PropEngine*)er->eng; delete er->eng;
delete er;
}
for(i=0; i<_jets.size(); i++) {
EngRec* er = (EngRec*)_pistons.get(i);
delete[] er->prefix;
delete (Jet*)er->eng;
delete er; delete er;
} }
for(i=0; i<_weights.size(); i++) { for(i=0; i<_weights.size(); i++) {
@ -77,12 +74,8 @@ Airplane* FGFDM::getAirplane()
void FGFDM::init() void FGFDM::init()
{ {
// We don't want to use these ties (we set the values ourselves)
fgUntie("/consumables/fuel/tank[0]/level-gal_us");
fgUntie("/consumables/fuel/tank[1]/level-gal_us");
// Allows the user to start with something other than full fuel // Allows the user to start with something other than full fuel
_airplane.setFuelFraction(fgGetFloat("/yasim/fuel-fraction", 1)); _airplane.setFuelFraction(fgGetFloat("/sim/fuel-fraction", 1));
// This has a nasty habit of being false at startup. That's not // This has a nasty habit of being false at startup. That's not
// good. // good.
@ -122,6 +115,15 @@ void FGFDM::startElement(const char* name, const XMLAttributes &atts)
_airplane.addVStab(parseWing(a, name)); _airplane.addVStab(parseWing(a, name));
} else if(eq(name, "propeller")) { } else if(eq(name, "propeller")) {
parsePropeller(a); parsePropeller(a);
} else if(eq(name, "thruster")) {
SimpleJet* j = new SimpleJet();
_currObj = j;
v[0] = attrf(a, "x"); v[1] = attrf(a, "y"); v[2] = attrf(a, "z");
j->setPosition(v);
_airplane.addThruster(j, 0, v);
v[0] = attrf(a, "vx"); v[1] = attrf(a, "vy"); v[2] = attrf(a, "vz");
j->setDirection(v);
j->setThrust(attrf(a, "thrust") * LBS2N);
} else if(eq(name, "jet")) { } else if(eq(name, "jet")) {
Jet* j = new Jet(); Jet* j = new Jet();
_currObj = j; _currObj = j;
@ -129,15 +131,29 @@ void FGFDM::startElement(const char* name, const XMLAttributes &atts)
v[1] = attrf(a, "y"); v[1] = attrf(a, "y");
v[2] = attrf(a, "z"); v[2] = attrf(a, "z");
float mass = attrf(a, "mass") * LBS2KG; float mass = attrf(a, "mass") * LBS2KG;
j->setDryThrust(attrf(a, "thrust") * LBS2N); j->setMaxThrust(attrf(a, "thrust") * LBS2N,
j->setReheatThrust(attrf(a, "afterburner", 0) * LBS2N); attrf(a, "afterburner", 0) * LBS2N);
j->setVectorAngle(attrf(a, "rotate", 0) * DEG2RAD);
float n1min = attrf(a, "n1-idle", 55);
float n1max = attrf(a, "n1-max", 102);
float n2min = attrf(a, "n2-idle", 73);
float n2max = attrf(a, "n2-max", 103);
j->setRPMs(n1min, n1max, n2min, n2max);
if(a->hasAttribute("tsfc")) j->setTSFC(attrf(a, "tsfc"));
if(a->hasAttribute("egt")) j->setEGT(attrf(a, "egt"));
if(a->hasAttribute("epr")) j->setEPR(attrf(a, "epr"));
if(a->hasAttribute("exhaust-speed"))
j->setVMax(attrf(a, "exhaust-speed") * KTS2MPS);
j->setPosition(v); j->setPosition(v);
_airplane.addThruster(j, mass, v); _airplane.addThruster(j, mass, v);
sprintf(buf, "/engines/engine[%d]", _nextEngine++); sprintf(buf, "/engines/engine[%d]", _nextEngine++);
EngRec* er = new EngRec(); EngRec* er = new EngRec();
er->eng = j; er->eng = j;
er->prefix = dup(buf); er->prefix = dup(buf);
_jets.add(er); _thrusters.add(er);
} else if(eq(name, "gear")) { } else if(eq(name, "gear")) {
Gear* g = new Gear(); Gear* g = new Gear();
_currObj = g; _currObj = g;
@ -151,6 +167,8 @@ void FGFDM::startElement(const char* name, const XMLAttributes &atts)
g->setCompression(v); g->setCompression(v);
g->setStaticFriction(attrf(a, "sfric", 0.8)); g->setStaticFriction(attrf(a, "sfric", 0.8));
g->setDynamicFriction(attrf(a, "dfric", 0.7)); g->setDynamicFriction(attrf(a, "dfric", 0.7));
if(a->hasAttribute("castering"))
g->setCastering(true);
float transitionTime = attrf(a, "retract-time", 0); float transitionTime = attrf(a, "retract-time", 0);
_airplane.addGear(g, transitionTime); _airplane.addGear(g, transitionTime);
} else if(eq(name, "fuselage")) { } else if(eq(name, "fuselage")) {
@ -161,14 +179,16 @@ void FGFDM::startElement(const char* name, const XMLAttributes &atts)
b[0] = attrf(a, "bx"); b[0] = attrf(a, "bx");
b[1] = attrf(a, "by"); b[1] = attrf(a, "by");
b[2] = attrf(a, "bz"); b[2] = attrf(a, "bz");
_airplane.addFuselage(v, b, attrf(a, "width")); float taper = attrf(a, "taper", 1);
float mid = attrf(a, "midpoint", 0.5);
_airplane.addFuselage(v, b, attrf(a, "width"), taper, mid);
} else if(eq(name, "tank")) { } else if(eq(name, "tank")) {
v[0] = attrf(a, "x"); v[0] = attrf(a, "x");
v[1] = attrf(a, "y"); v[1] = attrf(a, "y");
v[2] = attrf(a, "z"); v[2] = attrf(a, "z");
float density = 6.0; // gasoline, in lbs/gal float density = 6.0; // gasoline, in lbs/gal
if(a->hasAttribute("jet")) density = 6.72; if(a->hasAttribute("jet")) density = 6.72;
density *= LBS2KG/CM2GALS; density *= LBS2KG*CM2GALS;
_airplane.addTank(v, attrf(a, "capacity") * LBS2KG, density); _airplane.addTank(v, attrf(a, "capacity") * LBS2KG, density);
} else if(eq(name, "ballast")) { } else if(eq(name, "ballast")) {
v[0] = attrf(a, "x"); v[0] = attrf(a, "x");
@ -213,10 +233,17 @@ void FGFDM::startElement(const char* name, const XMLAttributes &atts)
opt |= a->hasAttribute("split") ? ControlMap::OPT_SPLIT : 0; opt |= a->hasAttribute("split") ? ControlMap::OPT_SPLIT : 0;
opt |= a->hasAttribute("invert") ? ControlMap::OPT_INVERT : 0; opt |= a->hasAttribute("invert") ? ControlMap::OPT_INVERT : 0;
opt |= a->hasAttribute("square") ? ControlMap::OPT_SQUARE : 0; opt |= a->hasAttribute("square") ? ControlMap::OPT_SQUARE : 0;
_airplane.getControlMap()->addMapping(parseAxis(axis),
parseOutput(output), ControlMap* cm = _airplane.getControlMap();
_currObj, if(a->hasAttribute("src0")) {
opt); cm->addMapping(parseAxis(axis), parseOutput(output),
_currObj, opt,
attrf(a, "src0"), attrf(a, "src1"),
attrf(a, "dst0"), attrf(a, "dst1"));
} else {
cm->addMapping(parseAxis(axis), parseOutput(output),
_currObj, opt);
}
} else { } else {
// assert: must be under a "cruise" or "approach" tag // assert: must be under a "cruise" or "approach" tag
float value = attrf(a, "value", 0); float value = attrf(a, "value", 0);
@ -257,29 +284,52 @@ void FGFDM::setOutputProperties()
{ {
char buf[256]; char buf[256];
int i; int i;
float fuelDensity = 718.95; // default to gasoline: ~6 lb/gal
for(i=0; i<_airplane.numTanks(); i++) { for(i=0; i<_airplane.numTanks(); i++) {
fuelDensity = _airplane.getFuelDensity(i);
sprintf(buf, "/consumables/fuel/tank[%d]/level-gal_us", i); sprintf(buf, "/consumables/fuel/tank[%d]/level-gal_us", i);
fgSetFloat(buf, fgSetFloat(buf, CM2GALS*_airplane.getFuel(i)/fuelDensity);
CM2GALS*_airplane.getFuel(i)/_airplane.getFuelDensity(i));
} }
for(i=0; i<_pistons.size(); i++) { for(i=0; i<_thrusters.size(); i++) {
EngRec* er = (EngRec*)_pistons.get(i); EngRec* er = (EngRec*)_thrusters.get(i);
PropEngine* p = (PropEngine*)er->eng; Thruster* t = er->eng;
sprintf(buf, "%s/rpm", er->prefix);
fgSetFloat(buf, p->getOmega() / RPM2RAD);
sprintf(buf, "%s/fuel-flow-gph", er->prefix); sprintf(buf, "%s/fuel-flow-gph", er->prefix);
fgSetFloat(buf, p->getFuelFlow() * (3600*2.2/5)); // FIXME, wrong fgSetFloat(buf, (t->getFuelFlow()/fuelDensity) * 3600 * CM2GALS);
}
for(i=0; i<_jets.size(); i++) { if(t->getPropEngine()) {
EngRec* er = (EngRec*)_jets.get(i); PropEngine* p = t->getPropEngine();
Jet* j = (Jet*)er->eng;
sprintf(buf, "%s/fuel-flow-gph", er->prefix); sprintf(buf, "%s/rpm", er->prefix);
fgSetFloat(buf, j->getFuelFlow() * (3600*2.2/6)); // FIXME, wrong fgSetFloat(buf, p->getOmega() / RPM2RAD);
}
if(t->getPistonEngine()) {
PistonEngine* p = t->getPistonEngine();
sprintf(buf, "%s/mp-osi", er->prefix);
fgSetFloat(buf, p->getMP() * (1/INHG2PA));
sprintf(buf, "%s/egt-degf", er->prefix);
fgSetFloat(buf, p->getEGT() * K2DEGF + 459.4);
}
if(t->getJet()) {
Jet* j = t->getJet();
sprintf(buf, "%s/n1", er->prefix);
fgSetFloat(buf, j->getN1());
sprintf(buf, "%s/n2", er->prefix);
fgSetFloat(buf, j->getN2());
sprintf(buf, "%s/epr", er->prefix);
fgSetFloat(buf, j->getEPR());
sprintf(buf, "%s/egt-degf", er->prefix);
fgSetFloat(buf, j->getEGT() * K2DEGF + 459.4);
}
} }
} }
@ -337,6 +387,12 @@ void FGFDM::parsePropeller(XMLAttributes* a)
PropEngine* thruster = new PropEngine(prop, eng, moment); PropEngine* thruster = new PropEngine(prop, eng, moment);
_airplane.addThruster(thruster, mass, cg); _airplane.addThruster(thruster, mass, cg);
if(a->hasAttribute("displacement"))
eng->setDisplacement(attrf(a, "displacement") * CIN2CM);
if(a->hasAttribute("compression"))
eng->setCompression(attrf(a, "compression"));
if(a->hasAttribute("turbo-mul")) { if(a->hasAttribute("turbo-mul")) {
float mul = attrf(a, "turbo-mul"); float mul = attrf(a, "turbo-mul");
float mp = attrf(a, "wastegate-mp", 1e6) * INHG2PA; float mp = attrf(a, "wastegate-mp", 1e6) * INHG2PA;
@ -360,7 +416,7 @@ void FGFDM::parsePropeller(XMLAttributes* a)
EngRec* er = new EngRec(); EngRec* er = new EngRec();
er->eng = thruster; er->eng = thruster;
er->prefix = dup(buf); er->prefix = dup(buf);
_pistons.add(er); _thrusters.add(er);
_currObj = thruster; _currObj = thruster;
} }
@ -391,6 +447,8 @@ int FGFDM::parseOutput(const char* name)
if(eq(name, "MIXTURE")) return ControlMap::MIXTURE; if(eq(name, "MIXTURE")) return ControlMap::MIXTURE;
if(eq(name, "ADVANCE")) return ControlMap::ADVANCE; if(eq(name, "ADVANCE")) return ControlMap::ADVANCE;
if(eq(name, "REHEAT")) return ControlMap::REHEAT; if(eq(name, "REHEAT")) return ControlMap::REHEAT;
if(eq(name, "BOOST")) return ControlMap::BOOST;
if(eq(name, "VECTOR")) return ControlMap::VECTOR;
if(eq(name, "PROP")) return ControlMap::PROP; if(eq(name, "PROP")) return ControlMap::PROP;
if(eq(name, "BRAKE")) return ControlMap::BRAKE; if(eq(name, "BRAKE")) return ControlMap::BRAKE;
if(eq(name, "STEER")) return ControlMap::STEER; if(eq(name, "STEER")) return ControlMap::STEER;
@ -401,7 +459,7 @@ int FGFDM::parseOutput(const char* name)
if(eq(name, "SLAT")) return ControlMap::SLAT; if(eq(name, "SLAT")) return ControlMap::SLAT;
if(eq(name, "SPOILER")) return ControlMap::SPOILER; if(eq(name, "SPOILER")) return ControlMap::SPOILER;
// error here... // error here...
return -1; return *(int*)0;
} }
void FGFDM::parseWeight(XMLAttributes* a) void FGFDM::parseWeight(XMLAttributes* a)

View file

@ -19,6 +19,7 @@ public:
~FGFDM(); ~FGFDM();
void init(); void init();
void iterate(float dt); void iterate(float dt);
void getExternalInput(float dt=1e6);
Airplane* getAirplane(); Airplane* getAirplane();
@ -27,10 +28,9 @@ public:
private: private:
struct AxisRec { char* name; int handle; }; struct AxisRec { char* name; int handle; };
struct EngRec { char* prefix; void* eng; }; struct EngRec { char* prefix; Thruster* eng; };
struct WeightRec { char* prop; float size; int handle; }; struct WeightRec { char* prop; float size; int handle; };
void getExternalInput(float dt);
void setOutputProperties(); void setOutputProperties();
Wing* parseWing(XMLAttributes* a, const char* name); Wing* parseWing(XMLAttributes* a, const char* name);
@ -56,8 +56,7 @@ private:
Vector _weights; Vector _weights;
// Engine types. Contains an EngRec structure. // Engine types. Contains an EngRec structure.
Vector _jets; Vector _thrusters;
Vector _pistons;
// Parsing temporaries // Parsing temporaries
void* _currObj; void* _currObj;

View file

@ -16,6 +16,7 @@ Gear::Gear()
_brake = 0; _brake = 0;
_rot = 0; _rot = 0;
_extension = 1; _extension = 1;
_castering = false;
} }
void Gear::setPosition(float* position) void Gear::setPosition(float* position)
@ -65,6 +66,11 @@ void Gear::setExtension(float extension)
_extension = Math::clamp(extension, 0, 1); _extension = Math::clamp(extension, 0, 1);
} }
void Gear::setCastering(bool c)
{
_castering = c;
}
void Gear::getPosition(float* out) void Gear::getPosition(float* out)
{ {
int i; int i;
@ -128,6 +134,11 @@ float Gear::getCompressFraction()
return _frac; return _frac;
} }
bool Gear::getCastering()
{
return _castering;
}
void Gear::calcForce(RigidBody* body, float* v, float* rot, float* ground) void Gear::calcForce(RigidBody* body, float* v, float* rot, float* ground)
{ {
// Init the return values // Init the return values
@ -191,6 +202,10 @@ void Gear::calcForce(RigidBody* body, float* v, float* rot, float* ground)
_wow = (fmag - damp) * -Math::dot3(cmpr, ground); _wow = (fmag - damp) * -Math::dot3(cmpr, ground);
Math::mul3(-_wow, ground, _force); Math::mul3(-_wow, ground, _force);
// Castering gear feel no force in the ground plane
if(_castering)
return;
// Wheels are funky. Split the velocity along the ground plane // Wheels are funky. Split the velocity along the ground plane
// into rolling and skidding components. Assuming small angles, // into rolling and skidding components. Assuming small angles,
// we generate "forward" and "left" unit vectors (the compression // we generate "forward" and "left" unit vectors (the compression
@ -237,8 +252,8 @@ void Gear::calcForce(RigidBody* body, float* v, float* rot, float* ground)
float Gear::calcFriction(float wgt, float v) float Gear::calcFriction(float wgt, float v)
{ {
// How slow is stopped? 50 cm/second? // How slow is stopped? 10 cm/second?
const float STOP = 0.5; const float STOP = 0.1;
const float iSTOP = 1/STOP; const float iSTOP = 1/STOP;
v = Math::abs(v); v = Math::abs(v);
if(v < STOP) return v*iSTOP * wgt * _sfric; if(v < STOP) return v*iSTOP * wgt * _sfric;

View file

@ -37,6 +37,7 @@ public:
void setBrake(float brake); void setBrake(float brake);
void setRotation(float rotation); void setRotation(float rotation);
void setExtension(float extension); void setExtension(float extension);
void setCastering(bool castering);
void getPosition(float* out); void getPosition(float* out);
void getCompression(float* out); void getCompression(float* out);
@ -47,6 +48,7 @@ public:
float getBrake(); float getBrake();
float getRotation(); float getRotation();
float getExtension(); float getExtension();
bool getCastering();
// Takes a velocity of the aircraft relative to ground, a rotation // Takes a velocity of the aircraft relative to ground, a rotation
// vector, and a ground plane (all specified in local coordinates) // vector, and a ground plane (all specified in local coordinates)
@ -63,6 +65,7 @@ public:
private: private:
float calcFriction(float wgt, float v); float calcFriction(float wgt, float v);
bool _castering;
float _pos[3]; float _pos[3];
float _cmpr[3]; float _cmpr[3];
float _spring; float _spring;

View file

@ -5,25 +5,90 @@ namespace yasim {
Jet::Jet() Jet::Jet()
{ {
_rho0 = Atmosphere::getStdDensity(0); _maxThrust = 0;
_thrust = 0; _abFactor = 1;
_abThrust = 0;
_reheat = 0; _reheat = 0;
_rotControl = 0;
_maxRot = 0;
// Initialize parameters for an early-ish subsonic turbojet. More
// recent turbofans will typically have a lower vMax, epr0, and
// tsfc.
_vMax = 800;
_epr0 = 3.0;
_tsfc = 0.8;
_egt0 = 1050;
_n1Min = 55;
_n1Max = 102;
_n2Min = 73;
_n2Max = 103;
setSpooling(4); // 4 second spool time? s'bout right.
// And initialize to an engine that is idling
_n1 = _n1Min;
_n2 = _n2Min;
// And sanify the remaining junk, just in case.
_epr = 1;
_fuelFlow = 0;
_egt = 273;
_tempCorrect = 1;
_pressureCorrect = 1;
} }
void Jet::stabilize() void Jet::stabilize()
{ {
return; // no-op for now // Just run it for an hour, there's no need to iterate given the
// algorithms used.
integrate(3600);
} }
void Jet::setDryThrust(float thrust) void Jet::setMaxThrust(float thrust, float afterburner)
{ {
_thrust = thrust; _maxThrust = thrust;
if(afterburner == 0) _abFactor = 1;
else _abFactor = afterburner/thrust;
} }
void Jet::setReheatThrust(float thrust) void Jet::setVMax(float spd)
{ {
_abThrust = thrust; _vMax = spd;
}
void Jet::setTSFC(float tsfc)
{
_tsfc = tsfc;
}
void Jet::setRPMs(float idleN1, float maxN1, float idleN2, float maxN2)
{
_n1Min = idleN1;
_n1Max = maxN1;
_n2Min = idleN2;
_n2Max = maxN2;
}
void Jet::setEGT(float takeoffEGT)
{
_egt0 = takeoffEGT;
}
void Jet::setEPR(float takeoffEPR)
{
_epr0 = takeoffEPR;
}
void Jet::setSpooling(float time)
{
// 2.3 = -ln(0.1), i.e. x=2.3 is the 90% point we're defining
// The extra fudge factor is there because the N1 speed (which
// determines thrust) lags the N2 speed.
_decay = 1.5 * 2.3 / time;
}
void Jet::setVectorAngle(float angle)
{
_maxRot = angle;
} }
void Jet::setReheat(float reheat) void Jet::setReheat(float reheat)
@ -31,12 +96,108 @@ void Jet::setReheat(float reheat)
_reheat = Math::clamp(reheat, 0, 1); _reheat = Math::clamp(reheat, 0, 1);
} }
void Jet::setRotation(float rot)
{
if(rot < 0) rot = 0;
if(rot > 1) rot = 1;
_rotControl = rot;
}
float Jet::getN1()
{
return _n1 * _tempCorrect;
}
float Jet::getN2()
{
return _n2 * _tempCorrect;
}
float Jet::getEPR()
{
return _epr;
}
float Jet::getEGT()
{
// Exactly zero means "off" -- return the ambient temperature
if(_egt == 0) return _temp;
return _egt * _tempCorrect * _tempCorrect;
}
float Jet::getFuelFlow()
{
return _fuelFlow * _pressureCorrect;
}
void Jet::integrate(float dt)
{
// Sea-level values
const static float P0 = Atmosphere::getStdPressure(0);
const static float T0 = Atmosphere::getStdTemperature(0);
const static float D0 = Atmosphere::getStdDensity(0);
float speed = -Math::dot3(_wind, _dir);
float statT, statP, statD;
Atmosphere::calcStaticAir(_pressure, _temp, _rho, speed,
&statP, &statT, &statD);
_pressureCorrect = statP/P0;
_tempCorrect = Math::sqrt(statT/T0);
// Linearly taper maxThrust to zero at vMax
float vCorr = 1 - (speed/_vMax);
float maxThrust = _maxThrust * vCorr * (statD/D0);
_thrust = maxThrust * _throttle;
// Now get a "beta" (i.e. EPR - 1) value. The output values are
// expressed as functions of beta.
float ibeta0 = 1/(_epr0 - 1);
float betaTarget = (_epr0 - 1) * (_thrust/_maxThrust) * (P0/_pressure)
* (_temp/statT);
float n2Target = _n2Min + (betaTarget*ibeta0) * (_n2Max - _n2Min);
// Note that this "first" beta value is used to compute a target
// for N2 only Integrate the N2 speed and back-calculate a beta1
// target. The N1 speed will seek to this.
_n2 = (_n2 + dt*_decay * n2Target) / (1 + dt*_decay);
float betaN2 = (_epr0-1) * (_n2 - _n2Min) / (_n2Max - _n2Min);
float n1Target = _n1Min + betaN2*ibeta0 * (_n1Max - _n1Min);
_n1 = (_n1 + dt*_decay * n1Target) / (1 + dt*_decay);
// The actual thrust produced is keyed to the N1 speed. Add the
// afterburners in at the end.
float betaN1 = (_epr0-1) * (_n1 - _n1Min) / (_n1Max - _n1Min);
_thrust *= betaN1/(betaTarget+.00001); // blowup protection
_thrust *= 1 + _reheat*(_abFactor-1);
// Finally, calculate the output variables. Use a 80/20 mix of
// the N2/N1 speeds as the key.
float beta = 0.8*betaN2 + 0.2*betaN1;
_epr = beta + 1;
float ff0 = _maxThrust*_tsfc*(1/(3600*9.8)); // takeoff fuel flow, kg/s
_fuelFlow = ff0 * beta*ibeta0;
_fuelFlow *= 1 + (3.5 * _reheat * _abFactor); // Afterburners take
// 3.5 times as much
// fuel per thrust unit
_egt = T0 + beta*ibeta0 * (_egt0 - T0);
}
void Jet::getThrust(float* out) void Jet::getThrust(float* out)
{ {
float t = _thrust * _throttle; Math::mul3(_thrust, _dir, out);
t += (_abThrust - _thrust) * _reheat;
t *= _rho / _rho0; // Rotate about the Y axis for thrust vectoring
Math::mul3(t, _dir, out); float angle = _rotControl * _maxRot;
float s = Math::sin(angle);
float c = Math::cos(angle);
float o0 = out[0];
out[0] = c * o0 + s * out[2];
out[2] = -s * o0 + c * out[2];
} }
void Jet::getTorque(float* out) void Jet::getTorque(float* out)
@ -51,14 +212,4 @@ void Jet::getGyro(float* out)
return; return;
} }
float Jet::getFuelFlow()
{
return 0;
}
void Jet::integrate(float dt)
{
return;
}
}; // namespace yasim }; // namespace yasim

View file

@ -5,18 +5,35 @@
namespace yasim { namespace yasim {
// Incredibly dumb placeholder for a Jet implementation. But it does
// what's important, which is provide thrust.
class Jet : public Thruster { class Jet : public Thruster {
public: public:
Jet(); Jet();
virtual Jet* getJet() { return this; } virtual Jet* getJet() { return this; }
void setDryThrust(float thrust); void setMaxThrust(float thrust, float afterburner=0);
void setReheatThrust(float thrust); void setVMax(float spd);
void setTSFC(float tsfc);
void setRPMs(float idleN1, float maxN1, float idleN2, float maxN2);
void setEGT(float takeoffEGT);
void setEPR(float takeoffEPR);
void setVectorAngle(float angle);
// The time it takes the engine to reach 90% thrust from idle
void setSpooling(float time);
// Sets the reheat control
void setReheat(float reheat); void setReheat(float reheat);
// Sets the thrust vector control (0-1)
void setRotation(float rot);
float getN1();
float getN2();
float getEPR();
float getEGT();
// From Thruster:
virtual void getThrust(float* out); virtual void getThrust(float* out);
virtual void getTorque(float* out); virtual void getTorque(float* out);
virtual void getGyro(float* out); virtual void getGyro(float* out);
@ -25,10 +42,33 @@ public:
virtual void stabilize(); virtual void stabilize();
private: private:
float _thrust;
float _abThrust;
float _rho0;
float _reheat; float _reheat;
float _maxThrust; // Max dry thrust at sea level
float _abFactor; // Afterburner thrust multiplier
float _maxRot;
float _rotControl;
float _decay; // time constant for the exponential integration
float _vMax; // speed at which thrust is zero
float _epr0; // EPR at takeoff thrust
float _tsfc; // TSFC ((lb/hr)/lb) at takeoff thrust and zero airspeed
float _egt0; // EGT at takeoff thrust
float _n1Min; // N1 at ground idle
float _n1Max; // N1 at takeoff thrust
float _n2Min; // N2 at ground idle
float _n2Max; // N2 at takeoff thrust
float _thrust; // Current thrust
float _epr; // Current EPR
float _n1; // Current UNCORRECTED N1 (percent)
float _n2; // Current UNCORRECTED N2 (percent)
float _fuelFlow; // Current UNCORRECTED fuel flow (kg/s)
float _egt; // Current UNCORRECTED EGT (kelvin)
float _tempCorrect; // Intake temp / std temp (273 K)
float _pressureCorrect; // Intake pressure / std pressure
}; };
}; // namespace yasim }; // namespace yasim

View file

@ -4,6 +4,6 @@ libYASim_a_SOURCES = YASim.cxx Airplane.cpp Atmosphere.cpp ControlMap.cpp \
FGFDM.cpp Gear.cpp Glue.cpp Integrator.cpp Jet.cpp \ FGFDM.cpp Gear.cpp Glue.cpp Integrator.cpp Jet.cpp \
Math.cpp Model.cpp PistonEngine.cpp Propeller.cpp \ Math.cpp Model.cpp PistonEngine.cpp Propeller.cpp \
PropEngine.cpp RigidBody.cpp Surface.cpp \ PropEngine.cpp RigidBody.cpp Surface.cpp \
Thruster.cpp Wing.cpp Thruster.cpp Wing.cpp SimpleJet.cpp
INCLUDES += -I$(top_srcdir) -I$(top_srcdir)/src INCLUDES += -I$(top_srcdir) -I$(top_srcdir)/src

View file

@ -3,11 +3,16 @@
#include "PistonEngine.hpp" #include "PistonEngine.hpp"
namespace yasim { namespace yasim {
const static float HP2W = 745.7;
const static float CIN2CM = 1.6387064e-5;
PistonEngine::PistonEngine(float power, float speed) PistonEngine::PistonEngine(float power, float speed)
{ {
_boost = 1;
// Presume a BSFC (in lb/hour per HP) of 0.45. In SI that becomes // Presume a BSFC (in lb/hour per HP) of 0.45. In SI that becomes
// (2.2 lb/kg, 745.7 W/hp, 3600 sec/hour) 3.69e-07 kg/Ws. // (2.2 lb/kg, 745.7 W/hp, 3600 sec/hour) 7.62e-08 kg/Ws.
_f0 = power * 3.69e-07; _f0 = power * 7.62e-08;
_power0 = power; _power0 = power;
_omega0 = speed; _omega0 = speed;
@ -23,6 +28,12 @@ PistonEngine::PistonEngine(float power, float speed)
_turbo = 1; _turbo = 1;
_maxMP = 1e6; // No waste gate on non-turbo engines. _maxMP = 1e6; // No waste gate on non-turbo engines.
// Guess at reasonable values for these guys. Displacements run
// at about 2 cubic inches per horsepower or so, at least for
// non-turbocharged engines.
_compression = 8;
_displacement = power * (2*CIN2CM/HP2W);
} }
void PistonEngine::setTurboParams(float turbo, float maxMP) void PistonEngine::setTurboParams(float turbo, float maxMP)
@ -32,13 +43,23 @@ void PistonEngine::setTurboParams(float turbo, float maxMP)
// This changes the "sea level" manifold air density // This changes the "sea level" manifold air density
float P0 = Atmosphere::getStdPressure(0); float P0 = Atmosphere::getStdPressure(0);
float P = P0 * _turbo; float P = P0 * (1 + _boost * (_turbo - 1));
if(P > _maxMP) P = _maxMP; if(P > _maxMP) P = _maxMP;
float T = Atmosphere::getStdTemperature(0) * Math::pow(P/P0, 2./7.); float T = Atmosphere::getStdTemperature(0) * Math::pow(P/P0, 2./7.);
_rho0 = P / (287.1 * T); _rho0 = P / (287.1 * T);
} }
float PistonEngine::getPower() void PistonEngine::setDisplacement(float d)
{
_displacement = d;
}
void PistonEngine::setCompression(float c)
{
_compression = c;
}
float PistonEngine::getMaxPower()
{ {
return _power0; return _power0;
} }
@ -53,22 +74,52 @@ void PistonEngine::setMixture(float m)
_mixture = m; _mixture = m;
} }
void PistonEngine::calc(float P, float T, float speed, void PistonEngine::setBoost(float boost)
float* torqueOut, float* fuelFlowOut)
{ {
// The actual fuel flow _boost = boost;
float fuel = _mixture * _mixCoeff * speed; }
// manifold air density float PistonEngine::getTorque()
if(_turbo != 1) { {
float P1 = P * _turbo; return _torque;
if(P1 > _maxMP) P1 = _maxMP; }
T *= Math::pow(P1/P, 2./7.);
P = P1;
}
float density = P / (287.1 * T);
float rho = density * _throttle; float PistonEngine::getFuelFlow()
{
return _fuelFlow;
}
float PistonEngine::getMP()
{
return _mp;
}
float PistonEngine::getEGT()
{
return _egt;
}
void PistonEngine::calc(float pressure, float temp, float speed)
{
// Calculate manifold pressure as ambient pressure modified for
// turbocharging and reduced by the throttle setting. According
// to Dave Luff, minimum throttle at sea level corresponds to 6"
// manifold pressure. Assume that this means that minimum MP is
// always 20% of ambient pressure.
_mp = pressure * (1 + _boost*(_turbo-1)); // turbocharger
_mp *= (0.2 + 0.8 * _throttle); // throttle
if(_mp > _maxMP) _mp = _maxMP; // wastegate
// Air entering the manifold does so rapidly, and thus the
// pressure change can be assumed to be adiabatic. Calculate a
// temperature change, and use that to get the density.
float T = temp * Math::pow(_mp/pressure, 2.0/7.0);
float rho = _mp / (287.1 * T);
// The actual fuel flow is determined only by engine RPM and the
// mixture setting. Not all of this will burn with the same
// efficiency.
_fuelFlow = _mixture * speed * _mixCoeff;
// How much fuel could be burned with ideal (i.e. uncorrected!) // How much fuel could be burned with ideal (i.e. uncorrected!)
// combustion. // combustion.
@ -81,18 +132,39 @@ void PistonEngine::calc(float P, float T, float speed,
// interpolate. This vaguely matches a curve I copied out of a // interpolate. This vaguely matches a curve I copied out of a
// book for a single engine. Shrug. // book for a single engine. Shrug.
float burned; float burned;
float r = fuel/burnable; float r = _fuelFlow/burnable;
if (burnable == 0) burned = 0; if (burnable == 0) burned = 0;
else if(r < .625) burned = fuel; else if(r < .625) burned = _fuelFlow;
else if(r > 1.375) burned = burnable; else if(r > 1.375) burned = burnable;
else burned = fuel + (burnable-fuel)*(r-.625)*(4.0/3.0); else
burned = _fuelFlow + (burnable-_fuelFlow)*(r-.625)*(4.0/3.0);
// And finally the power is just the reference power scaled by the // And finally the power is just the reference power scaled by the
// amount of fuel burned. // amount of fuel burned, and torque is that divided by RPM.
float power = _power0 * burned/_f0; float power = _power0 * burned/_f0;
_torque = power/speed;
*torqueOut = power/speed; // Now EGT. This one gets a little goofy. We can calculate the
*fuelFlowOut = fuel; // work done by an isentropically expanding exhaust gas as the
// mass of the gas times the specific heat times the change in
// temperature. The mass is just the engine displacement times
// the manifold density, plus the mass of the fuel, which we know.
// The change in temperature can be calculated adiabatically as a
// function of the exhaust gas temperature and the compression
// ratio (which we know). So just rearrange the equation to get
// EGT as a function of engine power. Cool. I'm using a value of
// 1300 J/(kg*K) for the exhaust gas specific heat. I found this
// on a web page somewhere; no idea if it's accurate. Also,
// remember that four stroke engines do one combustion cycle every
// TWO revolutions, so the displacement per revolution is half of
// what we'd expect. And diddle the work done by the gas a bit to
// account for non-thermodynamic losses like internal friction;
// 10% should do it.
float massFlow = _fuelFlow + (rho * 0.5 * _displacement * speed);
float specHeat = 1300;
float corr = 1.0/(Math::pow(_compression, 0.4) - 1);
_egt = corr * (power * 1.1) / (massFlow * specHeat);
} }
}; // namespace yasim }; // namespace yasim

View file

@ -8,33 +8,43 @@ public:
// Initializes an engine from known "takeoff" parameters. // Initializes an engine from known "takeoff" parameters.
PistonEngine(float power, float spd); PistonEngine(float power, float spd);
void setTurboParams(float mul, float maxMP); void setTurboParams(float mul, float maxMP);
void setDisplacement(float d);
void setCompression(float c);
void setThrottle(float throttle); void setThrottle(float throttle);
void setMixture(float mixture); void setMixture(float mixture);
void setBoost(float boost); // fraction of turbo-mul used
float getPower(); float getMaxPower(); // max sea-level power
// Calculates power output and fuel flow, based on a given void calc(float pressure, float temp, float speed);
// throttle setting (0-1 corresponding to the fraction of float getTorque();
// "available" manifold pressure), mixture (fuel flux per rpm, float getFuelFlow();
// 0-1, where 1 is "max rich", or a little bit more than needed float getMP();
// for rated power at sea level) float getEGT();
void calc(float pressure, float temp, float speed,
float* powerOut, float* fuelFlowOut);
private: private:
// Static configuration:
float _power0; // reference power setting float _power0; // reference power setting
float _omega0; // " engine speed float _omega0; // " engine speed
float _rho0; // " manifold air density float _rho0; // " manifold air density
float _f0; // "ideal" fuel flow at P0/omega0 float _f0; // "ideal" fuel flow at P0/omega0
float _mixCoeff; // fuel flow per omega at full mixture float _mixCoeff; // fuel flow per omega at full mixture
float _turbo; // (or super-)charger pressure multiplier
float _maxMP; // wastegate setting
float _displacement; // piston stroke volume
float _compression; // compression ratio (>1)
// Runtime settables: // Runtime settables:
float _throttle; float _throttle;
float _mixture; float _mixture;
float _boost;
float _turbo; // Runtime state/output:
float _maxMP; float _mp;
float _torque;
float _fuelFlow;
float _egt;
}; };
}; // namespace yasim }; // namespace yasim

View file

@ -79,9 +79,10 @@ void PropEngine::stabilize()
bool goingUp = false; bool goingUp = false;
float step = 10; float step = 10;
while(true) { while(true) {
float etau, ptau, dummy; float ptau, dummy;
_prop->calc(_rho, speed, _omega, &dummy, &ptau); _prop->calc(_rho, speed, _omega, &dummy, &ptau);
_eng->calc(_pressure, _temp, _omega, &etau, &dummy); _eng->calc(_pressure, _temp, _omega);
float etau = _eng->getTorque();
float tdiff = etau - ptau; float tdiff = etau - ptau;
if(Math::abs(tdiff/_moment) < 0.1) if(Math::abs(tdiff/_moment) < 0.1)
@ -110,9 +111,10 @@ void PropEngine::integrate(float dt)
_eng->setThrottle(_throttle); _eng->setThrottle(_throttle);
_eng->setMixture(_mixture); _eng->setMixture(_mixture);
_prop->calc(_rho, speed, _omega, _prop->calc(_rho, speed, _omega, &thrust, &propTorque);
&thrust, &propTorque); _eng->calc(_pressure, _temp, _omega);
_eng->calc(_pressure, _temp, _omega, &engTorque, &_fuelFlow); engTorque = _eng->getTorque();
_fuelFlow = _eng->getFuelFlow();
// Turn the thrust into a vector and save it // Turn the thrust into a vector and save it
Math::mul3(thrust, _dir, _thrust); Math::mul3(thrust, _dir, _thrust);

View file

@ -0,0 +1,46 @@
#include "Math.hpp"
#include "SimpleJet.hpp"
namespace yasim {
SimpleJet::SimpleJet()
{
_thrust = 0;
}
void SimpleJet::setThrust(float thrust)
{
_thrust = thrust;
}
void SimpleJet::getThrust(float* out)
{
Math::mul3(_thrust * _throttle, _dir, out);
}
void SimpleJet::getTorque(float* out)
{
out[0] = out[1] = out[2] = 0;
}
void SimpleJet::getGyro(float* out)
{
out[0] = out[1] = out[2] = 0;
}
float SimpleJet::getFuelFlow()
{
return 0;
}
void SimpleJet::integrate(float dt)
{
return;
}
void SimpleJet::stabilize()
{
return;
}
}; // namespace yasim

View file

@ -0,0 +1,25 @@
#ifndef _SIMPLEJET_HPP
#define _SIMPLEJET_HPP
#include "Thruster.hpp"
namespace yasim {
// As simple a Thruster subclass as you can find. It makes thrust. Period.
class SimpleJet : public Thruster
{
public:
SimpleJet();
void setThrust(float thrust);
virtual void getThrust(float* out);
virtual void getTorque(float* out);
virtual void getGyro(float* out);
virtual float getFuelFlow();
virtual void integrate(float dt);
virtual void stabilize();
private:
float _thrust;
};
}; // namespace yasim
#endif // _SIMPLEJET_HPP

View file

@ -39,9 +39,12 @@ void YASim::printDEBUG()
if(debugCount >= 3) { if(debugCount >= 3) {
debugCount = 0; debugCount = 0;
// printf("RPM %.1f FF %.1f\n", // printf("N1 %5.1f N2 %5.1f FF %7.1f EPR %4.2f EGT %6.1f\n",
// fgGetFloat("/engines/engine[0]/rpm"), // fgGetFloat("/engines/engine[0]/n1"),
// fgGetFloat("/engines/engine[0]/fuel-flow-gph")); // fgGetFloat("/engines/engine[0]/n2"),
// fgGetFloat("/engines/engine[0]/fuel-flow-gph"),
// fgGetFloat("/engines/engine[0]/epr"),
// fgGetFloat("/engines/engine[0]/egt"));
// printf("gear: %f\n", fgGetFloat("/controls/gear-down")); // printf("gear: %f\n", fgGetFloat("/controls/gear-down"));
@ -59,14 +62,9 @@ YASim::YASim(double dt)
set_delta_t(dt); set_delta_t(dt);
_fdm = new FGFDM(); _fdm = new FGFDM();
// Because the integration method is via fourth-order Runge-Kutta, _dt = dt;
// we only get an "output" state for every 4 times the internal
// forces are calculated. So divide dt by four to account for
// this, and only run an iteration every fourth time through
// update.
_dt = dt * 4;
_fdm->getAirplane()->getModel()->getIntegrator()->setInterval(_dt); _fdm->getAirplane()->getModel()->getIntegrator()->setInterval(_dt);
_updateCount = 0;
} }
void YASim::report() void YASim::report()
@ -97,6 +95,25 @@ void YASim::report()
} }
} }
void YASim::bind()
{
// Run the superclass bind to set up a bunch of property ties
FGInterface::bind();
// Now UNtie the ones that we are going to set ourselves.
fgUntie("/consumables/fuel/tank[0]/level-gal_us");
fgUntie("/consumables/fuel/tank[1]/level-gal_us");
char buf[256];
for(int i=0; i<_fdm->getAirplane()->getModel()->numThrusters(); i++) {
sprintf(buf, "/engines/engine[%d]/fuel-flow-gph", i); fgUntie(buf);
sprintf(buf, "/engines/engine[%d]/rpm", i); fgUntie(buf);
sprintf(buf, "/engines/engine[%d]/mp-osi", i); fgUntie(buf);
sprintf(buf, "/engines/engine[%d]/egt-degf", i); fgUntie(buf);
}
}
void YASim::init() void YASim::init()
{ {
Airplane* a = _fdm->getAirplane(); Airplane* a = _fdm->getAirplane();
@ -142,6 +159,8 @@ void YASim::init()
sprintf(buf, "/controls/afterburner[%d]", i); fgSetFloat(buf, 0); sprintf(buf, "/controls/afterburner[%d]", i); fgSetFloat(buf, 0);
} }
fgSetFloat("/controls/slats", 0);
fgSetFloat("/controls/spoilers", 0);
// Are we at ground level? If so, lift the plane up so the gear // Are we at ground level? If so, lift the plane up so the gear
// clear the ground // clear the ground
@ -167,8 +186,11 @@ void YASim::init()
// Blank the state, and copy in ours // Blank the state, and copy in ours
State s; State s;
m->setState(&s); m->setState(&s);
copyToYASim(true); copyToYASim(true);
_fdm->getExternalInput();
_fdm->getAirplane()->stabilizeThrust();
set_inited(true); set_inited(true);
} }
@ -180,18 +202,11 @@ void YASim::update(int iterations)
int i; int i;
for(i=0; i<iterations; i++) { for(i=0; i<iterations; i++) {
// Remember, update only every 4th call
_updateCount++;
if(_updateCount >= 4) {
copyToYASim(false); copyToYASim(false);
_fdm->iterate(_dt); _fdm->iterate(_dt);
copyFromYASim(); copyFromYASim();
printDEBUG(); printDEBUG();
_updateCount = 0;
}
} }
} }
@ -420,7 +435,7 @@ void YASim::copyFromYASim()
pe->getTorque(tmp); pe->getTorque(tmp);
float power = Math::mag3(tmp) * pe->getOmega(); float power = Math::mag3(tmp) * pe->getOmega();
float maxPower = pe->getPistonEngine()->getPower(); float maxPower = pe->getPistonEngine()->getMaxPower();
fge->set_MaxHP(maxPower * W2HP); fge->set_MaxHP(maxPower * W2HP);
fge->set_Percentage_Power(100 * power/maxPower); fge->set_Percentage_Power(100 * power/maxPower);

View file

@ -11,6 +11,7 @@ public:
// Load externally set stuff into the FDM // Load externally set stuff into the FDM
virtual void init(); virtual void init();
virtual void bind();
// Run an iteration // Run an iteration
virtual void update(int iterations); virtual void update(int iterations);
@ -23,7 +24,6 @@ public:
void printDEBUG(); void printDEBUG();
yasim::FGFDM* _fdm; yasim::FGFDM* _fdm;
int _updateCount;
float _dt; float _dt;
}; };