2 #include "Propeller.hpp"
4 #include "PropEngine.hpp"
7 PropEngine::PropEngine(Propeller* prop, Engine* eng, float moment)
9 // Start off at 500rpm, because the start code doesn't exist yet
11 _dir[0] = 1; _dir[1] = 0; _dir[2] = 0;
22 PropEngine::~PropEngine()
28 void PropEngine::setMagnetos(int pos)
33 void PropEngine::setAdvance(float advance)
35 _advance = Math::clamp(advance, 0, 1);
38 void PropEngine::setPropPitch(float proppitch)
40 // update Propeller property
41 _prop->setPropPitch(proppitch);
44 void PropEngine::setVariableProp(float min, float max)
51 bool PropEngine::isRunning()
53 return _eng->isRunning();
56 bool PropEngine::isCranking()
58 return _eng->isCranking();
61 float PropEngine::getOmega()
66 void PropEngine::setOmega (float omega)
71 void PropEngine::getThrust(float* out)
74 for(i=0; i<3; i++) out[i] = _thrust[i];
77 void PropEngine::getTorque(float* out)
80 for(i=0; i<3; i++) out[i] = _torque[i];
83 void PropEngine::getGyro(float* out)
86 for(i=0; i<3; i++) out[i] = _gyro[i];
89 float PropEngine::getFuelFlow()
94 void PropEngine::stabilize()
96 float speed = -Math::dot3(_wind, _dir);
97 _eng->setThrottle(_throttle);
98 _eng->setMixture(_mixture);
100 _eng->setMagnetos(3);
101 _eng->setRunning(true);
104 _omega = _minOmega + _advance * (_maxOmega - _minOmega);
105 _prop->modPitch(1e6); // Start at maximum pitch and move down
110 bool goingUp = false;
114 _prop->calc(_rho, speed, _omega * _gearRatio, &dummy, &ptau);
115 _eng->calc(_pressure, _temp, _omega);
117 float etau = _eng->getTorque();
118 float tdiff = etau - ptau;
120 if(Math::abs(tdiff/_moment) < 0.1)
124 if(!goingUp) step *= 0.5f;
126 if(!_variable) _omega += step;
127 else _prop->modPitch(1+(step*0.005f));
129 if(goingUp) step *= 0.5f;
131 if(!_variable) _omega -= step;
132 else _prop->modPitch(1-(step*0.005f));
137 _eng->setRunning(false);
140 void PropEngine::init()
143 _eng->setStarter(false);
144 _eng->setMagnetos(0);
147 void PropEngine::integrate(float dt)
149 float speed = -Math::dot3(_wind, _dir);
151 float propTorque, engTorque, thrust;
153 _eng->setThrottle(_throttle);
154 _eng->setStarter(_starter);
155 _eng->setMagnetos(_magnetos);
156 _eng->setMixture(_mixture);
157 _eng->setFuelState(_fuel);
159 _prop->calc(_rho, speed, _omega * _gearRatio, &thrust, &propTorque);
160 _eng->calc(_pressure, _temp, _omega);
162 engTorque = _eng->getTorque();
163 _fuelFlow = _eng->getFuelFlow();
165 // Turn the thrust into a vector and save it
166 Math::mul3(thrust, _dir, _thrust);
168 // Euler-integrate the RPM. This doesn't need the full-on
169 // Runge-Kutta stuff.
170 float rotacc = (engTorque-propTorque)/Math::abs(_moment);
171 _omega += dt * rotacc;
173 _omega = 0 - _omega; // don't allow negative RPM
174 // FIXME: introduce proper windmilling
176 // Store the total angular momentum into _gyro
177 Math::mul3(_omega*_moment, _dir, _gyro);
179 // Accumulate the engine torque, it acts on the body as a whole.
180 // (Note: engine torque, not propeller torque. They can be
181 // different, but the difference goes to accelerating the
182 // rotation. It is the engine torque that is felt at the shaft
183 // and works on the body.)
184 float tau = _moment < 0 ? engTorque : -engTorque;
185 Math::mul3(tau, _dir, _torque);
187 // Iterate the propeller governor, if we have one. Since engine
188 // torque is basically constant with RPM, we want to make the
189 // propeller torque at the target RPM equal to the engine by
190 // varying the pitch. Assume the the torque goes as the square of
191 // the RPM (roughly correct) and compute a "target" torque for the
192 // _current_ RPM. Seek to that. This is sort of a continuous
193 // Newton-Raphson, basically.
195 float targetOmega = _minOmega + _advance*(_maxOmega-_minOmega);
196 float ratio2 = (_omega*_omega)/(targetOmega*targetOmega);
197 float targetTorque = engTorque * ratio2;
199 float mod = propTorque < targetTorque ? 1.04f : (1.0f/1.04f);
201 // Convert to an acceleration here, so that big propellers
202 // don't seek faster than small ones.
203 float diff = Math::abs((propTorque - targetTorque) / _moment);
204 if(diff < 10) mod = 1 + (mod-1)*(0.1f*diff);
206 _prop->modPitch(mod);
210 }; // namespace yasim