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Updated to YASim-0.1.1

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curt 2001-12-06 18:13:24 +00:00
parent 6d077f4127
commit 4c422bbe6d
24 changed files with 348 additions and 149 deletions
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58
src/FDM/YASim/Airplane.cpp
View file

@ -10,8 +10,6 @@
#include "Airplane.hpp"
namespace yasim {
// FIXME: hook gear extension into the force calculation somehow...
Airplane::Airplane()
{
_emptyWeight = 0;
@ -19,10 +17,12 @@ Airplane::Airplane()
_wing = 0;
_tail = 0;
_ballast = 0;
_cruiseRho = 0;
_cruiseP = 0;
_cruiseT = 0;
_cruiseSpeed = 0;
_cruiseWeight = 0;
_approachRho = 0;
_approachP = 0;
_approachT = 0;
_approachSpeed = 0;
_approachAoA = 0;
_approachWeight = 0;
@ -51,8 +51,7 @@ void Airplane::iterate(float dt)
{
_model.iterate();
// Consume fuel
// FIXME
// FIXME: Consume fuel
}
ControlMap* Airplane::getControlMap()
@ -139,14 +138,16 @@ void Airplane::setApproach(float speed, float altitude)
void Airplane::setApproach(float speed, float altitude, float aoa)
{
_approachSpeed = speed;
_approachRho = Atmosphere::getStdDensity(altitude);
_approachP = Atmosphere::getStdPressure(altitude);
_approachT = Atmosphere::getStdTemperature(altitude);
_approachAoA = aoa;
}
void Airplane::setCruise(float speed, float altitude)
{
_cruiseSpeed = speed;
_cruiseRho = Atmosphere::getStdDensity(altitude);
_cruiseP = Atmosphere::getStdPressure(altitude);
_cruiseT = Atmosphere::getStdTemperature(altitude);
_cruiseAoA = 0;
_tailIncidence = 0;
}
@ -254,6 +255,7 @@ int Airplane::addWeight(float* pos, float size)
wr->handle = _model.getBody()->addMass(0, pos);
wr->surf = new Surface();
wr->surf->setPosition(pos);
wr->surf->setTotalDrag(size*size);
_model.addSurface(wr->surf);
_surfs.add(wr->surf);
@ -364,7 +366,7 @@ float Airplane::compileFuselage(Fuselage* f)
float len = Math::mag3(fwd);
float wid = f->width;
int segs = (int)Math::ceil(len/wid);
float segWgt = wid*wid/segs;
float segWgt = len*wid/segs;
for(int j=0; j<segs; j++) {
float frac = (j+0.5) / segs;
float pos[3];
@ -406,10 +408,11 @@ void Airplane::compileGear(GearRec* gr)
// Put the surface at the half-way point on the gear strut, give
// it a drag coefficient equal to a square of the same dimension
// (gear are really draggy) and make it symmetric.
// (gear are really draggy) and make it symmetric. Assume that
// the "length" of the gear is 3x the compression distance
float pos[3], cmp[3];
g->getCompression(cmp);
float length = Math::mag3(cmp);
float length = 3 * Math::mag3(cmp);
g->getPosition(pos);
Math::mul3(0.5, cmp, cmp);
Math::add3(pos, cmp, pos);
@ -486,6 +489,11 @@ void Airplane::compile()
tr->handle = _model.addThruster(tr->thruster);
}
// Ground effect
float gepos[3];
float gespan = _wing->getGroundEffect(gepos);
_model.setGroundEffect(gepos, gespan, .3);
solveGear();
solve();
@ -550,31 +558,15 @@ void Airplane::solveGear()
void Airplane::stabilizeThrust()
{
float thrust[3], tmp[3];
float last = 0;
while(1) {
thrust[0] = thrust[1] = thrust[2] = 0;
for(int i=0; i<_thrusters.size(); i++) {
Thruster* t = _model.getThruster(i);
t->integrate(0.033);
t->getThrust(tmp);
Math::add3(thrust, tmp, thrust);
}
float t = Math::mag3(thrust);
float ratio = (t+0.1)/(last+0.1);
if(ratio < 1.00001 && ratio > 0.99999)
break;
last = t;
}
for(int i=0; i<_thrusters.size(); i++)
_model.getThruster(i)->stabilize();
}
void Airplane::runCruise()
{
setupState(_cruiseAoA, _cruiseSpeed, &_cruiseState);
_model.setState(&_cruiseState);
_model.setAirDensity(_cruiseRho);
_model.setAir(_cruiseP, _cruiseT);
// The control configuration
_controls.reset();
@ -600,7 +592,7 @@ void Airplane::runCruise()
for(int i=0; i<_thrusters.size(); i++) {
Thruster* t = ((ThrustRec*)_thrusters.get(i))->thruster;
t->setWind(wind);
t->setDensity(_cruiseRho);
t->setAir(_cruiseP, _cruiseT);
}
stabilizeThrust();
@ -614,7 +606,7 @@ void Airplane::runApproach()
{
setupState(_approachAoA, _approachSpeed, &_approachState);
_model.setState(&_approachState);
_model.setAirDensity(_approachRho);
_model.setAir(_approachP, _approachT);
// The control configuration
_controls.reset();
@ -640,7 +632,7 @@ void Airplane::runApproach()
for(int i=0; i<_thrusters.size(); i++) {
Thruster* t = ((ThrustRec*)_thrusters.get(i))->thruster;
t->setWind(wind);
t->setDensity(_approachRho);
t->setAir(_approachP, _approachT);
}
stabilizeThrust();

6
src/FDM/YASim/Airplane.hpp
View file

@ -112,13 +112,15 @@ private:
Vector _cruiseControls;
State _cruiseState;
float _cruiseRho;
float _cruiseP;
float _cruiseT;
float _cruiseSpeed;
float _cruiseWeight;
Vector _approachControls;
State _approachState;
float _approachRho;
float _approachP;
float _approachT;
float _approachSpeed;
float _approachAoA;
float _approachWeight;

2
src/FDM/YASim/Atmosphere.cpp
View file

@ -7,7 +7,7 @@ namespace yasim {
// McCormick lists 299.16/101325/1.22500, but those don't agree with
// R=287. I chose to correct the temperature to 288.20, since 79F is
// pretty hot for a "standard" atmosphere.
// meters kelvin kPa kg/m^3
// meters kelvin Pa kg/m^3
float Atmosphere::data[][4] = {{ 0, 288.20, 101325, 1.22500 },
{ 900, 282.31, 90971, 1.12260 },
{ 1800, 276.46, 81494, 1.02690 },

3
src/FDM/YASim/ControlMap.cpp
View file

@ -1,5 +1,6 @@
#include "Jet.hpp"
#include "Thruster.hpp"
#include "PropEngine.hpp"
#include "Gear.hpp"
#include "Wing.hpp"
#include "Math.hpp"
@ -114,7 +115,7 @@ void ControlMap::applyControls()
switch(o->type) {
case THROTTLE: ((Thruster*)obj)->setThrottle(lval); break;
case MIXTURE: ((Thruster*)obj)->setMixture(lval); break;
case PROP: ((Thruster*)obj)->setPropAdvance(lval); break;
case ADVANCE: ((PropEngine*)obj)->setAdvance(lval); break;
case REHEAT: ((Jet*)obj)->setReheat(lval); break;
case BRAKE: ((Gear*)obj)->setBrake(lval); break;
case STEER: ((Gear*)obj)->setRotation(lval); break;

2
src/FDM/YASim/ControlMap.hpp
View file

@ -9,7 +9,7 @@ class ControlMap {
public:
~ControlMap();
enum OutputType { THROTTLE, MIXTURE, REHEAT, PROP,
enum OutputType { THROTTLE, MIXTURE, ADVANCE, REHEAT, PROP,
BRAKE, STEER, EXTEND,
INCIDENCE, FLAP0, FLAP1, SLAT, SPOILER };

38
src/FDM/YASim/FGFDM.cpp
View file

@ -22,6 +22,7 @@ static const float LBS2N = 4.44822;
static const float LBS2KG = 0.45359237;
static const float CM2GALS = 264.172037284;
static const float HP2W = 745.700;
static const float INHG2PA = 3386.389;
// Stubs, so that this can be compiled without the FlightGear
// binary. What's the best way to handle this?
@ -141,6 +142,7 @@ void FGFDM::startElement(const char* name, const XMLAttributes &atts)
v[2] = attrf(a, "z");
float mass = attrf(a, "mass") * LBS2KG;
j->setDryThrust(attrf(a, "thrust") * LBS2N);
j->setReheatThrust(attrf(a, "afterburner", 0) * LBS2N);
j->setPosition(v);
_airplane.addThruster(j, mass, v);
sprintf(buf, "/engines/engine[%d]", _nextEngine++);
@ -333,21 +335,36 @@ void FGFDM::parsePropeller(XMLAttributes* a)
float radius = attrf(a, "radius");
float speed = attrf(a, "cruise-speed") * KTS2MPS;
float omega = attrf(a, "cruise-rpm") * RPM2RAD;
float rho = Atmosphere::getStdDensity(attrf(a, "alt") * FT2M);
float power = attrf(a, "takeoff-power") * HP2W;
float omega0 = attrf(a, "takeoff-rpm") * RPM2RAD;
float power = attrf(a, "cruise-power") * HP2W;
float rho = Atmosphere::getStdDensity(attrf(a, "cruise-alt") * FT2M);
// FIXME: this is a hack. Find a better way to ask the engine how
// much power it can produce under cruise conditions.
float cruisePower = (power * (rho/Atmosphere::getStdDensity(0))
* (omega/omega0));
// Hack, fix this pronto:
float engP = attrf(a, "eng-power") * HP2W;
float engS = attrf(a, "eng-rpm") * RPM2RAD;
Propeller* prop = new Propeller(radius, speed, omega, rho, cruisePower,
omega0, power);
PistonEngine* eng = new PistonEngine(power, omega0);
Propeller* prop = new Propeller(radius, speed, omega, rho, power);
PistonEngine* eng = new PistonEngine(engP, engS);
PropEngine* thruster = new PropEngine(prop, eng, moment);
_airplane.addThruster(thruster, mass, cg);
if(a->hasAttribute("turbo-mul")) {
float mul = attrf(a, "turbo-mul");
float mp = attrf(a, "wastegate-mp", 1e6) * INHG2PA;
eng->setTurboParams(mul, mp);
}
if(a->hasAttribute("takeoff-power")) {
float power0 = attrf(a, "takeoff-power") * HP2W;
float omega0 = attrf(a, "takeoff-rpm") * RPM2RAD;
prop->setTakeoff(omega0, power0);
}
if(a->hasAttribute("max-rpm")) {
float max = attrf(a, "max-rpm") * RPM2RAD;
float min = attrf(a, "min-rpm") * RPM2RAD;
thruster->setVariableProp(min, max);
}
char buf[64];
sprintf(buf, "/engines/engine[%d]", _nextEngine++);
EngRec* er = new EngRec();
@ -381,6 +398,7 @@ int FGFDM::parseOutput(const char* name)
{
if(eq(name, "THROTTLE")) return ControlMap::THROTTLE;
if(eq(name, "MIXTURE")) return ControlMap::MIXTURE;
if(eq(name, "ADVANCE")) return ControlMap::ADVANCE;
if(eq(name, "REHEAT")) return ControlMap::REHEAT;
if(eq(name, "PROP")) return ControlMap::PROP;
if(eq(name, "BRAKE")) return ControlMap::BRAKE;

4
src/FDM/YASim/Gear.cpp
View file

@ -49,7 +49,7 @@ void Gear::setDynamicFriction(float dfric)
void Gear::setBrake(float brake)
{
_brake = brake;
_brake = Math::clamp(brake, 0, 1);
}
void Gear::setRotation(float rotation)
@ -59,7 +59,7 @@ void Gear::setRotation(float rotation)
void Gear::setExtension(float extension)
{
_extension = extension;
_extension = Math::clamp(extension, 0, 1);
}
void Gear::getPosition(float* out)

19
src/FDM/YASim/Jet.cpp
View file

@ -7,15 +7,13 @@ Jet::Jet()
{
_rho0 = Atmosphere::getStdDensity(0);
_thrust = 0;
_abThrust = 0;
_reheat = 0;
}
Thruster* Jet::clone()
void Jet::stabilize()
{
Jet* j = new Jet();
j->_thrust = _thrust;
j->_rho0 = _rho0;
return j;
return; // no-op for now
}
void Jet::setDryThrust(float thrust)
@ -23,14 +21,21 @@ void Jet::setDryThrust(float thrust)
_thrust = thrust;
}
void Jet::setReheatThrust(float thrust)
{
_abThrust = thrust;
}
void Jet::setReheat(float reheat)
{
_reheat = reheat;
_reheat = Math::clamp(reheat, 0, 1);
}
void Jet::getThrust(float* out)
{
float t = _thrust * _throttle * (_rho / _rho0);
float t = _thrust * _throttle;
t += (_abThrust - _thrust) * _reheat;
t *= _rho / _rho0;
Math::mul3(t, _dir, out);
}

5
src/FDM/YASim/Jet.hpp
View file

@ -11,9 +11,10 @@ class Jet : public Thruster {
public:
Jet();
virtual Thruster* clone();
virtual Jet* getJet() { return this; }
void setDryThrust(float thrust);
void setReheatThrust(float thrust);
void setReheat(float reheat);
virtual void getThrust(float* out);
@ -21,9 +22,11 @@ public:
virtual void getGyro(float* out);
virtual float getFuelFlow();
virtual void integrate(float dt);
virtual void stabilize();
private:
float _thrust;
float _abThrust;
float _rho0;
float _reheat;
};

7
src/FDM/YASim/Math.cpp
View file

@ -3,6 +3,13 @@
#include "Math.hpp"
namespace yasim {
float Math::clamp(float val, float min, float max)
{
if(val < min) return min;
if(val > max) return max;
return val;
}
float Math::abs(float f)
{
return ::fabs(f);

3
src/FDM/YASim/Math.hpp
View file

@ -6,6 +6,9 @@ namespace yasim {
class Math
{
public:
// Dumb utilities
static float clamp(float val, float min, float max);
// Simple wrappers around library routines
static float abs(float f);
static float sqrt(float f);

35
src/FDM/YASim/Model.cpp
View file

@ -77,7 +77,7 @@ void Model::initIteration()
localWind(pos, _s, v);
t->setWind(v);
t->setDensity(_rho);
t->setAir(_P, _T);
t->integrate(_integrator.getInterval());
t->getTorque(v);
@ -126,6 +126,11 @@ int Model::addThruster(Thruster* t)
return _thrusters.add(t);
}
int Model::numThrusters()
{
return _thrusters.size();
}
Thruster* Model::getThruster(int handle)
{
return (Thruster*)_thrusters.get(handle);
@ -146,6 +151,13 @@ int Model::addGear(Gear* gear)
return _gears.add(gear);
}
void Model::setGroundEffect(float* pos, float span, float mul)
{
Math::set3(pos, _wingCenter);
_groundEffectSpan = span;
_groundEffect = mul;
}
// The first three elements are a unit vector pointing from the global
// origin to the plane, the final element is the distance from the
// origin (the radius of the earth, in most implementations). So
@ -156,13 +168,10 @@ void Model::setGroundPlane(double* planeNormal, double fromOrigin)
_ground[3] = fromOrigin;
}
void Model::setAirDensity(float rho)
{
_rho = rho;
}
void Model::setAir(float pressure, float temp)
{
_P = pressure;
_T = temp;
_rho = Atmosphere::calcDensity(pressure, temp);
}
@ -197,6 +206,8 @@ void Model::calcForces(State* s)
// Do each surface, remembering that the local velocity at each
// point is different due to rotation.
float faero[3];
faero[0] = faero[1] = faero[2] = 0;
for(int i=0; i<_surfaces.size(); i++) {
Surface* sf = (Surface*)_surfaces.get(i);
@ -207,6 +218,7 @@ void Model::calcForces(State* s)
float force[3], torque[3];
sf->calcForce(vs, _rho, force, torque);
Math::add3(faero, force, faero);
_body.addForce(pos, force);
_body.addTorque(torque);
}
@ -218,6 +230,17 @@ void Model::calcForces(State* s)
float ground[4];
ground[3] = localGround(s, ground);
// Account for ground effect by multiplying the vertical force
// component by an amount linear with the fraction of the wingspan
// above the ground.
float dist = ground[4] - Math::dot3(ground, _wingCenter);
if(dist > 0 && dist < _groundEffectSpan) {
float fz = Math::dot3(faero, ground);
Math::mul3(fz * _groundEffect * dist/_groundEffectSpan,
ground, faero);
_body.addForce(faero);
}
// Convert the velocity and rotation vectors to local coordinates
float lrot[3], lv[3];
Math::vmul33(s->orient, s->rot, lrot);

9
src/FDM/YASim/Model.hpp
View file

@ -35,6 +35,7 @@ public:
Gear* getGear(int handle);
// Semi-private methods for use by the Airplane solver.
int numThrusters();
Thruster* getThruster(int handle);
void setThruster(int handle, Thruster* t);
void initIteration();
@ -44,8 +45,8 @@ public:
// Per-iteration settables
//
void setGroundPlane(double* planeNormal, double fromOrigin);
void setGroundEffect(float* pos, float span, float mul);
void setWind(float* wind);
void setAirDensity(float rho);
void setAir(float pressure, float temp);
// BodyEnvironment callbacks
@ -65,7 +66,13 @@ private:
Vector _surfaces;
Vector _gears;
float _groundEffectSpan;
float _groundEffect;
float _wingCenter[3];
double _ground[4];
float _P;
float _T;
float _rho;
float _wind[3];

35
src/FDM/YASim/PistonEngine.cpp
View file

@ -1,3 +1,5 @@
#include "Atmosphere.hpp"
#include "Math.hpp"
#include "PistonEngine.hpp"
namespace yasim {
@ -11,13 +13,34 @@ PistonEngine::PistonEngine(float power, float speed)
_omega0 = speed;
// We must be at sea level under standard conditions
_rho0 = 1.225; // kg/m^3
_rho0 = Atmosphere::getStdDensity(0);
// Further presume that takeoff is (duh) full throttle and
// peak-power, that means that by our efficiency function, we are
// at 11/8 of "ideal" fuel flow.
float realFlow = _f0 * (11.0/8.0);
_mixCoeff = realFlow * 1.1 / _omega0;
_turbo = 1;
_maxMP = 1e6; // No waste gate on non-turbo engines.
}
void PistonEngine::setTurboParams(float turbo, float maxMP)
{
_turbo = turbo;
_maxMP = maxMP;
// This changes the "sea level" manifold air density
float P0 = Atmosphere::getStdPressure(0);
float P = P0 * _turbo;
if(P > _maxMP) P = _maxMP;
float T = Atmosphere::getStdTemperature(0) * Math::pow(P/P0, 2./7.);
_rho0 = P / (287.1 * T);
}
float PistonEngine::getPower()
{
return _P0;
}
void PistonEngine::setThrottle(float t)
@ -30,13 +53,21 @@ void PistonEngine::setMixture(float m)
_mixture = m;
}
void PistonEngine::calc(float density, float speed,
void PistonEngine::calc(float P, float T, float speed,
float* torqueOut, float* fuelFlowOut)
{
// The actual fuel flow
float fuel = _mixture * _mixCoeff * speed;
// manifold air density
if(_turbo != 1) {
float P1 = P * _turbo;
if(P1 > _maxMP) P1 = _maxMP;
T *= Math::pow(P1/P, 2./7.);
P = P1;
}
float density = P / (287.1 * T);
float rho = density * _throttle;
// How much fuel could be burned with ideal (i.e. uncorrected!)

8
src/FDM/YASim/PistonEngine.hpp
View file

@ -7,16 +7,19 @@ class PistonEngine {
public:
// Initializes an engine from known "takeoff" parameters.
PistonEngine(float power, float spd);
void setTurboParams(float mul, float maxMP);
void setThrottle(float throttle);
void setMixture(float mixture);
float getPower();
// Calculates power output and fuel flow, based on a given
// throttle setting (0-1 corresponding to the fraction of
// "available" manifold pressure), mixture (fuel flux per rpm,
// 0-1, where 1 is "max rich", or a little bit more than needed
// for rated power at sea level)
void calc(float density, float speed,
void calc(float pressure, float temp, float speed,
float* powerOut, float* fuelFlowOut);
private:
@ -29,6 +32,9 @@ private:
// Runtime settables:
float _throttle;
float _mixture;
float _turbo;
float _maxMP;
};
}; // namespace yasim

85
src/FDM/YASim/PropEngine.cpp
View file

@ -10,6 +10,8 @@ PropEngine::PropEngine(Propeller* prop, PistonEngine* eng, float moment)
_omega = 52.3;
_dir[0] = 1; _dir[1] = 0; _dir[2] = 0;
_variable = false;
_prop = prop;
_eng = eng;
_moment = moment;
@ -21,21 +23,23 @@ PropEngine::~PropEngine()
delete _eng;
}
void PropEngine::setAdvance(float advance)
{
_advance = Math::clamp(advance, 0, 1);
}
void PropEngine::setVariableProp(float min, float max)
{
_variable = true;
_minOmega = min;
_maxOmega = max;
}
float PropEngine::getOmega()
{
return _omega;
}
Thruster* PropEngine::clone()
{
// FIXME: bloody mess
PropEngine* p = new PropEngine(_prop, _eng, _moment);
cloneInto(p);
p->_prop = new Propeller(*_prop);
p->_eng = new PistonEngine(*_eng);
return p;
}
void PropEngine::getThrust(float* out)
{
for(int i=0; i<3; i++) out[i] = _thrust[i];
@ -56,6 +60,44 @@ float PropEngine::getFuelFlow()
return _fuelFlow;
}
void PropEngine::stabilize()
{
float speed = -Math::dot3(_wind, _dir);
_eng->setThrottle(_throttle);
_eng->setMixture(_mixture);
if(_variable) {
_omega = _minOmega + _advance * (_maxOmega - _minOmega);
_prop->modPitch(1e6); // Start at maximum pitch and move down
} else {
_omega = 52;
}
bool goingUp = false;
float step = 10;
while(true) {
float etau, ptau, dummy;
_prop->calc(_rho, speed, _omega, &dummy, &ptau);
_eng->calc(_P, _T, _omega, &etau, &dummy);
float tdiff = etau - ptau;
if(Math::abs(tdiff/_moment) < 0.1)
break;
if(tdiff > 0) {
if(!goingUp) step *= 0.5;
goingUp = true;
if(!_variable) _omega += step;
else _prop->modPitch(1+(step*0.005));
} else {
if(goingUp) step *= 0.5;
goingUp = false;
if(!_variable) _omega -= step;
else _prop->modPitch(1-(step*0.005));
}
}
}
void PropEngine::integrate(float dt)
{
float speed = -Math::dot3(_wind, _dir);
@ -67,14 +109,19 @@ void PropEngine::integrate(float dt)
_prop->calc(_rho, speed, _omega,
&thrust, &propTorque);
_eng->calc(_rho, _omega, &engTorque, &_fuelFlow);
_eng->calc(_P, _T, _omega, &engTorque, &_fuelFlow);
// Turn the thrust into a vector and save it
Math::mul3(thrust, _dir, _thrust);
// Euler-integrate the RPM. This doesn't need the full-on
// Runge-Kutta stuff.
_omega += dt*(engTorque-propTorque)/Math::abs(_moment);
float rotacc = (engTorque-propTorque)/Math::abs(_moment);
_omega += dt * rotacc;
// Clamp to a 500 rpm idle. This should probably be settable, and
// needs to go away when the startup code gets written.
if(_omega < 52.3) _omega = 52.3;
// FIXME: Integrate the propeller governor here, when that gets
// implemented...
@ -82,13 +129,25 @@ void PropEngine::integrate(float dt)
// Store the total angular momentum into _gyro
Math::mul3(_omega*_moment, _dir, _gyro);
// Accumulate the engine torque, it acta on the body as a whole.
// Accumulate the engine torque, it acts on the body as a whole.
// (Note: engine torque, not propeller torque. They can be
// different, but the difference goes to accelerating the
// rotation. It is the engine torque that is felt at the shaft
// and works on the body.)
float tau = _moment < 0 ? engTorque : -engTorque;
Math::mul3(tau, _dir, _torque);
// Play with the variable propeller, but only if the propeller is
// vaguely stable alread (accelerating less than 100 rpm/s)
if(_variable && Math::abs(rotacc) < 20) {
float target = _minOmega + _advance*(_maxOmega-_minOmega);
float mod = 1.04;
if(target > _omega) mod = 1/mod;
float diff = Math::abs(target - _omega);
if(diff < 1) mod = 1 + (mod-1)*diff;
if(thrust < 0) mod = 1;
_prop->modPitch(mod);
}
}
}; // namespace yasim

13
src/FDM/YASim/PropEngine.hpp
View file

@ -13,7 +13,12 @@ public:
PropEngine(Propeller* prop, PistonEngine* eng, float moment);
virtual ~PropEngine();
virtual Thruster* clone();
void setAdvance(float advance);
void setVariableProp(float min, float max);
virtual PropEngine* getPropEngine() { return this; }
virtual PistonEngine* getPistonEngine() { return _eng; }
virtual Propeller* getPropeller() { return _prop; }
// Dynamic output
virtual void getThrust(float* out);
@ -23,6 +28,7 @@ public:
// Runtime instructions
virtual void integrate(float dt);
virtual void stabilize();
float getOmega();
@ -31,6 +37,11 @@ private:
Propeller* _prop;
PistonEngine* _eng;
bool _variable;
float _advance; // control input, 0-1
float _maxOmega;
float _minOmega;
float _omega; // RPM, in radians/sec
float _thrust[3];
float _torque[3];

66
src/FDM/YASim/Propeller.cpp
View file

@ -1,36 +1,48 @@
#include <stdio.h>
#include "Atmosphere.hpp"
#include "Math.hpp"
#include "Propeller.hpp"
namespace yasim {
Propeller::Propeller(float radius, float v, float omega,
float rho, float power, float omega0,
float power0)
float rho, float power)
{
// Initialize numeric constants:
_lambdaPeak = Math::pow(9.0, -1.0/8.0);
_beta = 1.0/(Math::pow(9.0, -1.0/8.0) - Math::pow(9.0, -9.0/8.0));
_lambdaPeak = Math::pow(5.0, -1.0/4.0);
_beta = 1.0/(Math::pow(5.0, -1.0/4.0) - Math::pow(5.0, -5.0/4.0));
_r = radius;
_etaC = 0.85; // make this settable?
_J0 = v/(omega*_lambdaPeak);
_baseJ0 = _J0;
float V2 = v*v + (_r*omega)*(_r*omega);
_F0 = 2*_etaC*power/(rho*v*V2);
float stallAngle = 0.25;
_lambdaS = _r*(_J0/_r - stallAngle) / _J0;
// Now compute a correction for zero forward speed to make the
// takeoff performance correct.
float torque0 = power0/omega0;
float thrust, torque;
_takeoffCoef = 1;
calc(Atmosphere::getStdDensity(0), 0, omega0, &thrust, &torque);
_takeoffCoef = torque/torque0;
_matchTakeoff = false;
}
void Propeller::setTakeoff(float omega0, float power0)
{
// Takeoff thrust coefficient at lambda==0
_matchTakeoff = true;
float V2 = _r*omega0 * _r*omega0;
float gamma = _etaC * _beta / _J0;
float torque = power0 / omega0;
float density = Atmosphere::getStdDensity(0);
_tc0 = (torque * gamma) / (0.5 * density * V2 * _F0);
}
void Propeller::modPitch(float mod)
{
_J0 *= mod;
if(_J0 < 0.25*_baseJ0) _J0 = 0.25*_baseJ0;
if(_J0 > 4*_baseJ0) _J0 = 4*_baseJ0;
}
void Propeller::calc(float density, float v, float omega,
float* thrustOut, float* torqueOut)
{
@ -47,7 +59,7 @@ void Propeller::calc(float density, float v, float omega,
float torque = 0;
if(lambda > 1) {
lambda = 1.0/lambda;
torque = (density*V2*_F0*_J0)/(8*_etaC*_beta*(1-_lambdaPeak));
torque = (density*V2*_F0*_J0)/(4*_etaC*_beta*(1-_lambdaPeak));
}
// There's an undefined point at 1. Just offset by a tiny bit to
@ -56,24 +68,18 @@ void Propeller::calc(float density, float v, float omega,
// point number!)
if(lambda == 1) lambda = 0.9999;
// Compute thrust, remembering to clamp lambda to the stall point
float lambda2 = lambda < _lambdaS ? _lambdaS : lambda;
float thrust = (0.5*density*V2*_F0/(1-_lambdaPeak))*(1-lambda2);
// Calculate lambda^8
float l8 = lambda*lambda; l8 = l8*l8; l8 = l8*l8;
// Calculate lambda^4
float l4 = lambda*lambda; l4 = l4*l4;
// thrust/torque ratio
float gamma = (_etaC*_beta/_J0)*(1-l8);
float gamma = (_etaC*_beta/_J0)*(1-l4);
// Correct slow speeds to get the takeoff parameters correct
if(lambda < _lambdaPeak) {
// This will interpolate takeoffCoef along a descending from 1
// at lambda==0 to 0 at the peak, fairing smoothly into the
// flat peak.
float frac = (lambda - _lambdaPeak)/_lambdaPeak;
gamma *= 1 + (_takeoffCoef - 1)*frac*frac;
}
// Compute a thrust, clamp to takeoff thrust to prevend huge
// numbers at slow speeds.
float tc = (1 - lambda) / (1 - _lambdaPeak);
if(_matchTakeoff && tc > _tc0) tc = _tc0;
float thrust = 0.5 * density * V2 * _F0 * tc;
if(torque > 0) {
torque -= thrust/gamma;

12
src/FDM/YASim/Propeller.hpp
View file

@ -14,8 +14,11 @@ public:
// numbers for RPM and power (with air speed and density being
// zero and sea level). RPM values are in radians per second, of
// course.
Propeller(float radius, float v, float omega, float rho, float power,
float omega0, float power0);
Propeller(float radius, float v, float omega, float rho, float power);
void setTakeoff(float omega0, float power0);
void modPitch(float mod);
void calc(float density, float v, float omega,
float* thrustOut, float* torqueOut);
@ -23,12 +26,13 @@ public:
private:
float _r; // characteristic radius
float _J0; // zero-thrust advance ratio
float _lambdaS; // "propeller stall" normalized advance ratio
float _baseJ0; // ... uncorrected for prop advance
float _F0; // thrust coefficient
float _etaC; // Peak efficiency
float _lambdaPeak; // constant, ~0.759835;
float _beta; // constant, ~1.48058;
float _takeoffCoef; // correction to get the zero-speed torque right
float _tc0; // thrust "coefficient" at takeoff
bool _matchTakeoff; // Does _tc0 mean anything?
};
}; // namespace yasim

12
src/FDM/YASim/Surface.cpp
View file

@ -236,8 +236,16 @@ float Surface::controlDrag()
d *= 1 + _spoilerPos * (_spoilerDrag - 1);
d *= 1 + _slatPos * (_slatDrag - 1);
// FIXME: flaps should REDUCE drag when the reduce lift!
d *= 1 + Math::abs(_flapPos) * (_flapDrag - 1);
// Negative flap deflections don't affect drag until their lift
// multiplier exceeds the "camber" (cz0) of the surface.
float fp = _flapPos;
if(fp < 0) {
fp = -fp;
fp -= _cz0/(_flapLift-1);
if(fp < 0) fp = 0;
}
d *= 1 + fp * (_flapDrag - 1);
return d;
}

29
src/FDM/YASim/Thruster.cpp
View file

@ -8,8 +8,7 @@ Thruster::Thruster()
for(int i=0; i<3; i++) _pos[i] = _wind[i] = 0;
_throttle = 0;
_mixture = 0;
_propAdvance = 0;
_rho = 0;
_P = _T = _rho = 0;
}
Thruster::~Thruster()
@ -38,17 +37,12 @@ void Thruster::setDirection(float* dir)
void Thruster::setThrottle(float throttle)
{
_throttle = throttle;
_throttle = Math::clamp(throttle, 0, 1);
}
void Thruster::setMixture(float mixture)
{
_mixture = mixture;
}
void Thruster::setPropAdvance(float propAdvance)
{
_propAdvance = propAdvance;
_mixture = Math::clamp(mixture, 0, 1);
}
void Thruster::setWind(float* wind)
@ -56,20 +50,11 @@ void Thruster::setWind(float* wind)
for(int i=0; i<3; i++) _wind[i] = wind[i];
}
void Thruster::setDensity(float rho)
void Thruster::setAir(float pressure, float temp)
{
_rho = rho;
}
void Thruster::cloneInto(Thruster* out)
{
for(int i=0; i<3; i++) {
out->_pos[i] = _pos[i];
out->_dir[i] = _dir[i];
}
out->_throttle = _throttle;
out->_mixture = _mixture;
out->_propAdvance = _propAdvance;
_P = pressure;
_T = temp;
_rho = _P / (287.1 * _T);
}
}; // namespace yasim

24
src/FDM/YASim/Thruster.hpp
View file

@ -3,23 +3,33 @@
namespace yasim {
class Jet;
class PropEngine;
class Propeller;
class PistonEngine;
class Thruster {
public:
Thruster();
virtual ~Thruster();
// Typing info, these are the possible sub-type (or sub-parts)
// that a thruster might have. Any might return null. A little
// clumsy, but much simpler than an RTTI-based implementation.
virtual Jet* getJet() { return 0; }
virtual PropEngine* getPropEngine() { return 0; }
virtual Propeller* getPropeller() { return 0; }
virtual PistonEngine* getPistonEngine() { return 0; }
// Static data
void getPosition(float* out);
void setPosition(float* pos);
void getDirection(float* out);
void setDirection(float* dir);
virtual Thruster* clone()=0;
// Controls
void setThrottle(float throttle);
void setMixture(float mixture);
void setPropAdvance(float advance);
// Dynamic output
virtual void getThrust(float* out)=0;
@ -29,19 +39,19 @@ public:
// Runtime instructions
void setWind(float* wind);
void setDensity(float rho);
void setAir(float pressure, float temp);
virtual void integrate(float dt)=0;
virtual void stabilize()=0;
protected:
void cloneInto(Thruster* out);
float _pos[3];
float _dir[3];
float _throttle;
float _mixture;
float _propAdvance;
float _wind[3];
float _P;
float _T;
float _rho;
};

15
src/FDM/YASim/Wing.cpp
View file

@ -157,6 +157,8 @@ void Wing::setSpoiler(float start, float end, float lift, float drag)
void Wing::setFlap0(float lval, float rval)
{
lval = Math::clamp(lval, -1, 1);
rval = Math::clamp(rval, -1, 1);
for(int i=0; i<_flap0Surfs.size(); i++) {
((Surface*)_flap0Surfs.get(i))->setFlap(lval);
if(_mirror) ((Surface*)_flap0Surfs.get(++i))->setFlap(rval);
@ -165,6 +167,8 @@ void Wing::setFlap0(float lval, float rval)
void Wing::setFlap1(float lval, float rval)
{
lval = Math::clamp(lval, -1, 1);
rval = Math::clamp(rval, -1, 1);
for(int i=0; i<_flap1Surfs.size(); i++) {
((Surface*)_flap1Surfs.get(i))->setFlap(lval);
if(_mirror) ((Surface*)_flap1Surfs.get(++i))->setFlap(rval);
@ -173,6 +177,8 @@ void Wing::setFlap1(float lval, float rval)
void Wing::setSpoiler(float lval, float rval)
{
lval = Math::clamp(lval, 0, 1);
rval = Math::clamp(rval, 0, 1);
for(int i=0; i<_spoilerSurfs.size(); i++) {
((Surface*)_spoilerSurfs.get(i))->setSpoiler(lval);
if(_mirror) ((Surface*)_spoilerSurfs.get(++i))->setSpoiler(rval);
@ -181,10 +187,19 @@ void Wing::setSpoiler(float lval, float rval)
void Wing::setSlat(float val)
{
val = Math::clamp(val, 0, 1);
for(int i=0; i<_slatSurfs.size(); i++)
((Surface*)_slatSurfs.get(i))->setSlat(val);
}
float Wing::getGroundEffect(float* posOut)
{
for(int i=0; i<3; i++) posOut[i] = _base[i];
float span = _length * Math::cos(_sweep) * Math::cos(_dihedral);
span = 2*(span + Math::abs(_base[2]));
return span;
}
void Wing::compile()
{
// Have we already been compiled?

3
src/FDM/YASim/Wing.hpp
View file

@ -44,6 +44,9 @@ public:
// Compile the thing into a bunch of Surface objects
void compile();
// Ground effect information
float getGroundEffect(float* posOut);
// Query the list of Surface objects
int numSurfaces();
Surface* getSurface(int n);