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Support for a new "contra" attribute on propellers, which properly

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models them as contra-rotating pairs.
This commit is contained in:
andy 2004-12-13 23:48:43 +00:00
parent 8214364414
commit 28f50df1d5
3 changed files with 14 additions and 4 deletions
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3
src/FDM/YASim/FGFDM.cpp
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@ -717,6 +717,9 @@ void FGFDM::parsePropeller(XMLAttributes* a)
thruster->setVariableProp(min, max); thruster->setVariableProp(min, max);
} }
if(attrb(a, "contra"))
thruster->setContraPair(true);
if(a->hasAttribute("manual-pitch")) { if(a->hasAttribute("manual-pitch")) {
prop->setManualPitch(); prop->setManualPitch();
} }

13
src/FDM/YASim/PropEngine.cpp
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@ -17,6 +17,7 @@ PropEngine::PropEngine(Propeller* prop, Engine* eng, float moment)
_eng = eng; _eng = eng;
_moment = moment; _moment = moment;
_fuel = true; _fuel = true;
_contra = false;
} }
PropEngine::~PropEngine() PropEngine::~PropEngine()
@ -192,16 +193,20 @@ void PropEngine::integrate(float dt)
_omega = 0 - _omega; // don't allow negative RPM _omega = 0 - _omega; // don't allow negative RPM
// FIXME: introduce proper windmilling // FIXME: introduce proper windmilling
// Store the total angular momentum into _gyro // Store the total angular momentum into _gyro, unless the
Math::mul3(_omega*momt, _dir, _gyro); // propeller is a counter-rotating pair (which has zero net
// angular momentum, even though it *does* have an MoI for
// acceleration purposes).
Math::mul3(_contra ? 0 : _omega*momt, _dir, _gyro);
// Accumulate the engine torque, it acts 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 // (Note: engine torque, not propeller torque. They can be
// different, but the difference goes to accelerating the // different, but the difference goes to accelerating the
// rotation. It is the engine torque that is felt at the shaft // rotation. It is the engine torque that is felt at the shaft
// and works on the body.) // and works on the body.) (Note 2: contra-rotating propellers do
// not exert net torque on the aircraft).
float tau = _moment < 0 ? engTorque : -engTorque; float tau = _moment < 0 ? engTorque : -engTorque;
Math::mul3(tau, _dir, _torque); Math::mul3(_contra ? 0 : tau, _dir, _torque);
// Iterate the propeller governor, if we have one. Since engine // Iterate the propeller governor, if we have one. Since engine
// torque is basically constant with RPM, we want to make the // torque is basically constant with RPM, we want to make the

2
src/FDM/YASim/PropEngine.hpp
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@ -21,6 +21,7 @@ public:
void setVariableProp(float min, float max); void setVariableProp(float min, float max);
void setPropFeather(int state); void setPropFeather(int state);
void setGearRatio(float ratio) { _gearRatio = ratio; } void setGearRatio(float ratio) { _gearRatio = ratio; }
void setContraPair(bool contra) { _contra = contra; }
virtual PropEngine* getPropEngine() { return this; } virtual PropEngine* getPropEngine() { return this; }
virtual Engine* getEngine() { return _eng; } virtual Engine* getEngine() { return _eng; }
@ -48,6 +49,7 @@ private:
Engine* _eng; Engine* _eng;
bool _variable; bool _variable;
bool _contra; // contra-rotating propeller pair
int _magnetos; // 0=off, 1=right, 2=left, 3=both int _magnetos; // 0=off, 1=right, 2=left, 3=both
float _gearRatio; float _gearRatio;
float _advance; // control input, 0-1 float _advance; // control input, 0-1