FGRotor Class Reference

Models a helicopter rotor. More...

#include <FGRotor.h>

Inheritance diagram for FGRotor:

Collaboration diagram for FGRotor:

Public Member Functions
	FGRotor (FGFDMExec *exec, Element *rotor_element, int num)
	Constructor for FGRotor. More...
	~FGRotor ()
	Destructor for FGRotor.
double	Calculate (double EnginePower)
	Returns the scalar thrust of the rotor, and adjusts the RPM value.
double	GetA0 (void) const
	Retrieves the rotor's coning angle.
double	GetA1 (void) const
	Retrieves the longitudinal flapping angle with respect to the rotor shaft.
double	GetB1 (void) const
	Retrieves the lateral flapping angle with respect to the rotor shaft.
double	GetCollectiveCtrl (void) const
	Retrieves the collective control input in radians.
double	GetCT (void) const
	Retrieves the thrust coefficient.
double	GetEngineRPM (void) const
	Retrieves the RPMs of the Engine, as seen from this rotor.
double	GetGearRatio (void)
	Tells the rotor's gear ratio, usually the engine asks for this.
double	GetGroundEffectScaleNorm (void) const
	Retrieves the ground effect scaling factor.
double	GetLambda (void) const
	Retrieves the inflow ratio.
double	GetLateralCtrl (void) const
	Retrieves the lateral control input in radians.
double	GetLongitudinalCtrl (void) const
	Retrieves the longitudinal control input in radians.
double	GetMu (void) const
	Retrieves the tip-speed (aka advance) ratio.
double	GetNu (void) const
	Retrieves the induced inflow ratio.
double	GetPhiDW (void) const
	Downwash angle - positive values point leftward (given a horizontal spinning rotor)
double	GetPowerRequired (void) const
	Returns the power required by the rotor.
double	GetRPM (void) const
	Retrieves the RPMs of the rotor.
double	GetThetaDW (void) const
	Downwash angle - positive values point forward (given a horizontal spinning rotor)
double	GetThrust (void) const
	Retrieves the thrust of the rotor.
std::string	GetThrusterLabels (int id, const std::string &delimeter)
std::string	GetThrusterValues (int id, const std::string &delimeter)
double	GetTorque (void) const
	Retrieves the torque.
double	GetVi (void) const
	Retrieves the induced velocity.
void	SetCollectiveCtrl (double c)
	Sets the collective control input in radians.
void	SetEngineRPM (double rpm)
void	SetGroundEffectScaleNorm (double g)
	Sets the ground effect scaling factor.
void	SetLateralCtrl (double c)
	Sets the lateral control input in radians.
void	SetLongitudinalCtrl (double c)
	Sets the longitudinal control input in radians.
void	SetRPM (double rpm)
Public Member Functions inherited from FGThruster
	FGThruster (FGFDMExec *FDMExec, Element *el, int num)
	Constructor.
virtual	~FGThruster ()
	Destructor.
double	GetGearRatio (void)
std::string	GetName (void)
virtual double	GetPowerRequired (void)
double	GetReverserAngle (void) const
double	GetThrust (void) const
eType	GetType (void)
virtual void	ResetToIC (void)
void	SetName (std::string name)
void	SetReverserAngle (double angle)
Public Member Functions inherited from FGForce
	FGForce (FGFDMExec *FDMExec)
	Constructor.
	FGForce (const FGForce &force)
	~FGForce ()
	Destructor.
const FGColumnVector3 &	GetActingLocation (void) const
double	GetActingLocationX (void) const
double	GetActingLocationY (void) const
double	GetActingLocationZ (void) const
const FGColumnVector3 &	GetAnglesToBody (void) const
double	GetAnglesToBody (int axis) const
virtual const FGColumnVector3 &	GetBodyForces (void)
double	GetBodyXForce (void) const
double	GetBodyYForce (void) const
double	GetBodyZForce (void) const
const FGColumnVector3 &	GetLocation (void) const
double	GetLocationX (void) const
double	GetLocationY (void) const
double	GetLocationZ (void) const
const FGColumnVector3 &	GetMoments (void) const
double	GetPitch (void) const
TransformType	GetTransformType (void) const
double	GetYaw (void) const
void	SetActingLocation (double x, double y, double z)
	Acting point of application. More...
void	SetActingLocation (const FGColumnVector3 &vv)
double	SetActingLocationX (double x)
double	SetActingLocationY (double y)
double	SetActingLocationZ (double z)
void	SetAnglesToBody (double broll, double bpitch, double byaw)
void	SetAnglesToBody (const FGColumnVector3 &vv)
void	SetLocation (double x, double y, double z)
void	SetLocation (const FGColumnVector3 &vv)
void	SetLocationX (double x)
void	SetLocationY (double y)
void	SetLocationZ (double z)
void	SetPitch (double pitch)
void	SetTransformType (TransformType ii)
void	SetYaw (double yaw)
const FGMatrix33 &	Transform (void) const
void	UpdateCustomTransformMatrix (void)
Public Member Functions inherited from FGJSBBase
	FGJSBBase ()
	Constructor for FGJSBBase.
virtual	~FGJSBBase ()
	Destructor for FGJSBBase.
void	disableHighLighting (void)
	Disables highlighting in the console output.
std::string	GetVersion (void)
	Returns the version number of JSBSim. More...
void	PutMessage (const Message &msg)
	Places a Message structure on the Message queue. More...
void	PutMessage (const std::string &text)
	Creates a message with the given text and places it on the queue. More...
void	PutMessage (const std::string &text, bool bVal)
	Creates a message with the given text and boolean value and places it on the queue. More...
void	PutMessage (const std::string &text, int iVal)
	Creates a message with the given text and integer value and places it on the queue. More...
void	PutMessage (const std::string &text, double dVal)
	Creates a message with the given text and double value and places it on the queue. More...
int	SomeMessages (void)
	Reads the message on the queue (but does not delete it). More...
void	ProcessMessage (void)
	Reads the message on the queue and removes it from the queue. More...
Message *	ProcessNextMessage (void)
	Reads the next message on the queue and removes it from the queue. More...

Additional Inherited Members
Public Types inherited from FGThruster
enum	eType { ttNozzle, ttRotor, ttPropeller, ttDirect }
Public Types inherited from FGForce
enum	TransformType { tNone, tWindBody, tLocalBody, tCustom }
Public Types inherited from FGJSBBase
enum	{ eL = 1, eM, eN }
	Moments L, M, N.
enum	{ eP = 1, eQ, eR }
	Rates P, Q, R.
enum	{ eU = 1, eV, eW }
	Velocities U, V, W.
enum	{ eX = 1, eY, eZ }
	Positions X, Y, Z.
enum	{ ePhi = 1, eTht, ePsi }
	Euler angles Phi, Theta, Psi.
enum	{ eDrag = 1, eSide, eLift }
	Stability axis forces, Drag, Side force, Lift.
enum	{ eRoll = 1, ePitch, eYaw }
	Local frame orientation Roll, Pitch, Yaw.
enum	{ eNorth = 1, eEast, eDown }
	Local frame position North, East, Down.
enum	{ eLat = 1, eLong, eRad }
	Locations Radius, Latitude, Longitude.
enum	{   inNone = 0, inDegrees, inRadians, inMeters,   inFeet }
	Conversion specifiers.
Static Public Member Functions inherited from FGJSBBase
static double	CelsiusToFahrenheit (double celsius)
	Converts from degrees Celsius to degrees Fahrenheit. More...
static double	CelsiusToKelvin (double celsius)
	Converts from degrees Celsius to degrees Kelvin. More...
static double	CelsiusToRankine (double celsius)
	Converts from degrees Celsius to degrees Rankine. More...
static double	Constrain (double min, double value, double max)
	Constrain a value between a minimum and a maximum value.
static bool	EqualToRoundoff (double a, double b)
	Finite precision comparison. More...
static bool	EqualToRoundoff (float a, float b)
	Finite precision comparison. More...
static bool	EqualToRoundoff (float a, double b)
	Finite precision comparison. More...
static bool	EqualToRoundoff (double a, float b)
	Finite precision comparison. More...
static double	FahrenheitToCelsius (double fahrenheit)
	Converts from degrees Fahrenheit to degrees Celsius. More...
static double	FeetToMeters (double measure)
	Converts from feet to meters. More...
static double	GaussianRandomNumber (void)
static double	KelvinToCelsius (double kelvin)
	Converts from degrees Kelvin to degrees Celsius. More...
static double	KelvinToFahrenheit (double kelvin)
	Converts from degrees Kelvin to degrees Fahrenheit. More...
static double	KelvinToRankine (double kelvin)
	Converts from degrees Kelvin to degrees Rankine. More...
static double	MachFromVcalibrated (double vcas, double p, double psl, double rhosl)
	Calculate the Mach number from the calibrated airspeed. More...
static double	PitotTotalPressure (double mach, double p)
	Compute the total pressure in front of the Pitot tube. More...
static double	RankineToCelsius (double rankine)
	Converts from degrees Rankine to degrees Celsius. More...
static double	RankineToKelvin (double rankine)
	Converts from degrees Rankine to degrees Kelvin. More...
static double	sign (double num)
static double	VcalibratedFromMach (double mach, double p, double psl, double rhosl)
	Calculate the calibrated airspeed from the Mach number. More...
Public Attributes inherited from FGThruster
struct JSBSim::FGThruster::Inputs	in
Static Public Attributes inherited from FGJSBBase
static short	debug_lvl = 1
static char	highint [5] = {27, '[', '1', 'm', '\0' }
	highlights text
static char	halfint [5] = {27, '[', '2', 'm', '\0' }
	low intensity text
static char	normint [6] = {27, '[', '2', '2', 'm', '\0' }
	normal intensity text
static char	reset [5] = {27, '[', '0', 'm', '\0' }
	resets text properties
static char	underon [5] = {27, '[', '4', 'm', '\0' }
	underlines text
static char	underoff [6] = {27, '[', '2', '4', 'm', '\0' }
	underline off
static char	fgblue [6] = {27, '[', '3', '4', 'm', '\0' }
	blue text
static char	fgcyan [6] = {27, '[', '3', '6', 'm', '\0' }
	cyan text
static char	fgred [6] = {27, '[', '3', '1', 'm', '\0' }
	red text
static char	fggreen [6] = {27, '[', '3', '2', 'm', '\0' }
	green text
static char	fgdef [6] = {27, '[', '3', '9', 'm', '\0' }
	default text
Protected Member Functions inherited from FGJSBBase
void	Debug (int)
Static Protected Member Functions inherited from FGJSBBase
static std::string	CreateIndexedPropertyName (const std::string &Property, int index)
Protected Attributes inherited from FGThruster
int	EngineNum
double	GearRatio
std::string	Name
double	PowerRequired
double	ReverserAngle
double	Thrust
double	ThrustCoeff
eType	Type
Protected Attributes inherited from FGForce
FGFDMExec *	fdmex
FGMatrix33	mT
TransformType	ttype
FGColumnVector3	vActingXYZn
FGColumnVector3	vFn
FGColumnVector3	vH
FGColumnVector3	vMn
FGColumnVector3	vOrient
FGColumnVector3	vXYZn
Static Protected Attributes inherited from FGJSBBase
static const double	degtorad = 0.017453292519943295769236907684886
static const double	fpstokts = 1.0/ktstofps
static const double	fttom = 0.3048
static int	gaussian_random_number_phase = 0
static const double	hptoftlbssec = 550.0
static const double	in3tom3 = 1.638706E-5
static const double	inchtoft = 0.08333333
static const double	inhgtopa = 3386.38
static const std::string	JSBSim_version = "1.0 " __DATE__ " " __TIME__
static const double	kgtolb = 2.20462
static const double	kgtoslug = 0.06852168
static const double	ktstofps = 1.68781
static const double	lbtoslug = 1.0/slugtolb
static Message	localMsg
static const double	m3toft3 = 1.0/(fttom*fttom*fttom)
static double	Mair = 28.9645
static unsigned int	messageId = 0
static std::queue< Message >	Messages
static const std::string	needed_cfg_version = "2.0"
static const double	psftoinhg = 0.014138
static const double	psftopa = 47.88
static const double	radtodeg = 57.295779513082320876798154814105
static double	Reng = 1716.56
static double	Rstar = 1545.348
static const double	SHRatio = 1.40
static const double	slugtolb = 32.174049

Detailed Description

Models a helicopter rotor.

Configuration File Format

<rotor name="{string}">
  <diameter unit="{LENGTH}"> {number} </diameter>
  <numblades> {number} </numblades>
  <gearratio> {number} </gearratio>
  <nominalrpm> {number} </nominalrpm>
  <minrpm> {number} </minrpm>
  <maxrpm> {number} </maxrpm>
  <chord unit="{LENGTH}"> {number} </chord>
  <liftcurveslope Xunit="1/RAD"> {number} </liftcurveslope>
  <twist unit="{ANGLE}"> {number} </twist>
  <hingeoffset unit="{LENGTH}"> {number} </hingeoffset>
  <flappingmoment unit="{MOMENT}"> {number} </flappingmoment>
  <massmoment Xunit="SLUG*FT"> {number} </massmoment>
  <polarmoment unit="{MOMENT}"> {number} </polarmoment>
  <inflowlag> {number} </inflowlag>
  <tiplossfactor> {number} </tiplossfactor>
  <maxbrakepower unit="{POWER}"> {number} </maxbrakepower>
  <gearloss unit="{POWER}"> {number} </gearloss>
  <gearmoment unit="{MOMENT}"> {number} </gearmoment>

  <controlmap> {MAIN|TAIL|TANDEM} </controlmap>
  <ExternalRPM> {number} </ExternalRPM>

  <groundeffectexp> {number} </groundeffectexp>
  <groundeffectshift unit="{LENGTH}"> {number} </groundeffectshift>

</rotor>

//  LENGTH means any of the supported units, same for ANGLE and MOMENT.
//  Xunit-attributes are a hint for currently unsupported units, so
//  values must be provided accordingly.

Configuration Parameters:

Brief description and the symbol frequently found in the literature.

    <diameter>           - Rotor disk diameter (2x R).
    <numblades>          - Number of blades (b).
    <gearratio>          - Ratio of (engine rpm) / (rotor rpm), usually > 1.
    <nominalrpm>         - RPM at which the rotor usally operates.
    <minrpm>             - Lowest RPM used in the model, optional and defaults to 1.
    <maxrpm>             - Largest RPM used in the model, optional and defaults to 2 x nominalrpm.
    <chord>              - Blade chord, (c).
    <liftcurveslope>     - Slope of curve of section lift against section angle of attack,
                             per rad (a).
    <twist>              - Blade twist from root to tip, (theta_1).
    <hingeoffset>        - Rotor flapping-hinge offset (e).
    <flappingmoment>     - Flapping moment of inertia (I_b).
    <massmoment>         - Blade mass moment. Mass of a single blade times the blade's
                             cg-distance from the hub, optional.
    <polarmoment>        - Moment of inertia for the whole rotor disk, optional.
    <inflowlag>          - Rotor inflow time constant, sec. Smaller values yield to quicker
                              responses (typical values for main rotor: 0.1 - 0.2 s).
    <tiplossfactor>      - Tip-loss factor. The Blade fraction that produces lift.
                              Value usually ranges between 0.95 - 1.0, optional (B).

    <maxbrakepower>      - Rotor brake, 20-30 hp should work for a mid size helicopter.
    <gearloss>           - Friction in gear, 0.2% to 3% of the engine power, optional (see notes).
    <gearmoment>         - Approximation for the moment of inertia of the gear (and engine),
                              defaults to 0.1 * polarmoment, optional.

    <controlmap>         - Defines the control inputs used (see notes).

    <ExternalRPM>        - Links the rotor to another rotor, or an user controllable property.

    Experimental properties

    <groundeffectexp>    - Exponent for ground effect approximation. Values usually range from 0.04
                            for large rotors to 0.1 for smaller ones. As a rule of thumb the effect
                            vanishes at a height 2-3 times the rotor diameter.
                              formula used: exp ( - groundeffectexp * (height+groundeffectshift) )
                            Omitting or setting to 0.0 disables the effect calculation.
    <groundeffectshift>  - Further adjustment of ground effect, approx. hub height or slightly above
                            (This lessens the influence of the ground effect).

Notes:

- Controls -

The behavior of the rotor is controlled/influenced by following inputs.

• The power provided by the engine. This is handled by the regular engine controls.
• The collective control input. This is read from the fdm property propulsion/engine[x]/collective-ctrl-rad. See below for tail rotor
• The lateral cyclic input. Read from propulsion/engine[x]/lateral-ctrl-rad.
• The longitudinal cyclic input. Read from propulsion/engine[x]/longitudinal-ctrl-rad.

• The tail rotor collective (aka antitorque, aka pedal) control input. Read from propulsion/engine[x]/antitorque-ctrl-rad or propulsion/engine[x]/tail-collective-ctrl-rad.

- Tail/tandem rotor -

Providing <ExternalRPM> 0 </ExternalRPM> the tail rotor's RPM is linked to to the main (=first, =0) rotor, and specifing <controlmap> TAIL </controlmap> tells this rotor to read the collective input from propulsion/engine[1]/antitorque-ctrl-rad (The TAIL-map ignores lateral and longitudinal input). The rotor needs to be attached to a dummy engine, e.g. an 1HP electrical engine. A tandem rotor is setup analogous.

- Sense -

The 'sense' parameter from the thruster is interpreted as follows, sense=1 means counter clockwise rotation of the main rotor, as viewed from above. This is as a far as I know more popular than clockwise rotation, which is defined by setting sense to -1. Concerning coaxial designs - by setting 'sense' to zero, a Kamov-style rotor is modeled (i.e. the rotor produces no torque).

- Engine issues -

In order to keep the rotor/engine speed constant, use of a RPM-Governor system is encouraged (see examples).

In case the model requires the manual use of a clutch the <gearloss> property might need attention.

• Electrical: here the gear-loss should be rather large to keep the engine controllable when the clutch is open (although full throttle might still make it spin away).
• Piston: this engine model already has some internal friction loss and also looses power if it spins too high. Here the gear-loss could be set to 0.25% of the engine power (which is also the approximated default).

• Turboprop: Here the default value might be a bit too small. Also it's advisable to adjust the power table for rpm values that are far beyond the nominal value.

- Scaling the ground effect -

The property propulsion/engine[x]/groundeffect-scale-norm allows fdm based scaling of the ground effect influence. For instance the effect vanishes at speeds above approx. 50kts, or one likes to land on a 'perforated' helipad.

- Development hints -

Setting <ExternalRPM> -1 </ExternalRPM> the rotor's RPM is controlled by the propulsion/engine[x]/x-rpm-dict property. This feature can be useful when developing a FDM.

References:

<dl>    
<dt>/SH79/</dt><dd>Shaugnessy, J. D., Deaux, Thomas N., and Yenni, Kenneth R.,
          "Development and Validation of a Piloted Simulation of a
          Helicopter and External Sling Load",  NASA TP-1285, 1979.</dd>
<dt>/BA41/</dt><dd>Bailey,F.J.,Jr., "A Simplified Theoretical Method of Determining
          the Characteristics of a Lifting Rotor in Forward Flight", NACA Rep.716, 1941.</dd>
<dt>/AM50/</dt><dd>Amer, Kenneth B.,"Theory of Helicopter Damping in Pitch or Roll and a
          Comparison With Flight Measurements", NACA TN-2136, 1950.</dd>
<dt>/TA77/</dt><dd>Talbot, Peter D., Corliss, Lloyd D., "A Mathematical Force and Moment
          Model of a UH-1H Helicopter for Flight Dynamics Simulations", NASA TM-73,254, 1977.</dd>
<dt>/GE49/</dt><dd>Gessow, Alfred, Amer, Kenneth B. "An Introduction to the Physical 
          Aspects of Helicopter Stability", NACA TN-1982, 1949.</dd>
</dl>

@author Thomas Kreitler
@version $Id: FGRotor.h,v 1.17 2015/09/27 10:03:53 bcoconni Exp $

Definition at line 242 of file FGRotor.h.

Constructor & Destructor Documentation

FGRotor()

FGRotor	(	FGFDMExec *	exec,
		Element *	rotor_element,
		int	num
	)

Constructor for FGRotor.

Parameters

exec	a pointer to the main executive object
rotor_element	a pointer to the thruster config file XML element
num	the number of this rotor

Definition at line 77 of file FGRotor.cpp.

  : FGThruster(exec, rotor_element, num),
    rho(0.002356),                                  // environment
    Radius(0.0), BladeNum(0),                       // configuration parameters
    Sense(1.0), NominalRPM(0.0), MinimalRPM(0.0), MaximalRPM(0.0), 
    ExternalRPM(0), RPMdefinition(0), ExtRPMsource(NULL), SourceGearRatio(1.0),
    BladeChord(0.0), LiftCurveSlope(0.0), BladeTwist(0.0), HingeOffset(0.0),
    BladeFlappingMoment(0.0), BladeMassMoment(0.0), PolarMoment(0.0),
    InflowLag(0.0), TipLossB(0.0),
    GroundEffectExp(0.0), GroundEffectShift(0.0), GroundEffectScaleNorm(1.0),
    LockNumberByRho(0.0), Solidity(0.0),            // derived parameters
    RPM(0.0), Omega(0.0),                           // dynamic values
    beta_orient(0.0),
    a0(0.0), a_1(0.0), b_1(0.0), a_dw(0.0),
    a1s(0.0), b1s(0.0),
    H_drag(0.0), J_side(0.0), Torque(0.0), C_T(0.0),
    lambda(-0.001), mu(0.0), nu(0.001), v_induced(0.0),
    theta_downwash(0.0), phi_downwash(0.0),
    ControlMap(eMainCtrl),                          // control
    CollectiveCtrl(0.0), LateralCtrl(0.0), LongitudinalCtrl(0.0),
    Transmission(NULL),                             // interaction with engine
    EngineRPM(0.0), MaxBrakePower(0.0), GearLoss(0.0), GearMoment(0.0)
{
  FGColumnVector3 location(0.0, 0.0, 0.0), orientation(0.0, 0.0, 0.0);
  Element *thruster_element;
  double engine_power_est = 0.0;

  // initialise/set remaining variables
  SetTransformType(FGForce::tCustom);
  Type = ttRotor;
  GearRatio = 1.0;

  dt = exec->GetDeltaT();
  for (int i=0; i<5; i++) R[i] = 0.0;
  for (int i=0; i<5; i++) B[i] = 0.0;

  // get positions 
  thruster_element = rotor_element->GetParent()->FindElement("sense");
  if (thruster_element) {
    double s = thruster_element->GetDataAsNumber();
    if (s < -0.1) {
      Sense = -1.0; // 'CW' as seen from above
    } else if (s < 0.1) {
      Sense = 0.0;  // 'coaxial'
    } else {
      Sense = 1.0; // 'CCW' as seen from above
    }
  }

  thruster_element = rotor_element->GetParent()->FindElement("location");
  if (thruster_element) {
    location = thruster_element->FindElementTripletConvertTo("IN");
  } else {
    cerr << "No thruster location found." << endl;
  }

  thruster_element = rotor_element->GetParent()->FindElement("orient");
  if (thruster_element) {
    orientation = thruster_element->FindElementTripletConvertTo("RAD");
  } else {
    cerr << "No thruster orientation found." << endl;
  }

  SetLocation(location);
  SetAnglesToBody(orientation);
  InvTransform = Transform().Transposed(); // body to custom/native

  // wire controls
  ControlMap = eMainCtrl;
  if (rotor_element->FindElement("controlmap")) {
    string cm = rotor_element->FindElementValue("controlmap");
    cm = to_upper(cm);
    if (cm == "TAIL") {
      ControlMap = eTailCtrl;
    } else if (cm == "TANDEM") {
      ControlMap = eTandemCtrl;
    } else {
      cerr << "# found unknown controlmap: '" << cm << "' using main rotor config."  << endl;
    }
  }

  // ExternalRPM -- is the RPM dictated ?
  if (rotor_element->FindElement("ExternalRPM")) {
    ExternalRPM = 1;
    SourceGearRatio = 1.0;
    RPMdefinition = (int) rotor_element->FindElementValueAsNumber("ExternalRPM");
    int rdef = RPMdefinition;
    if (RPMdefinition>=0) {
      // avoid ourself and (still) unknown engines.
      if (!exec->GetPropulsion()->GetEngine(RPMdefinition) || RPMdefinition==num) {
        RPMdefinition = -1;
      } else {
        FGThruster *tr = exec->GetPropulsion()->GetEngine(RPMdefinition)->GetThruster();
        SourceGearRatio = tr->GetGearRatio();
        // cout << "# got sources' GearRatio: " << SourceGearRatio << endl;
      }
    }
    if (RPMdefinition != rdef) {
      cerr << "# discarded given RPM source (" << rdef << ") and switched to external control (-1)." << endl;
    }
  }

  // process rotor parameters
  engine_power_est = Configure(rotor_element);

  // setup transmission if needed
  if (!ExternalRPM) {

    Transmission = new FGTransmission(exec, num, dt);

    Transmission->SetThrusterMoment(PolarMoment);

    // The MOI sensed behind the gear ( MOI_engine*sqr(GearRatio) ).
    GearMoment = ConfigValueConv(rotor_element, "gearmoment", 0.1*PolarMoment, "SLUG*FT2");
    GearMoment = Constrain(1e-6, GearMoment, 1e9);
    Transmission->SetEngineMoment(GearMoment);

    Transmission->SetMaxBrakePower(MaxBrakePower);

    GearLoss = ConfigValueConv(rotor_element, "gearloss", 0.0025 * engine_power_est, "HP");
    GearLoss = Constrain(0.0, GearLoss, 1e9);
    GearLoss *= hptoftlbssec;
    Transmission->SetEngineFriction(GearLoss);

  }

  // shaft representation - a rather simple transform,
  // but using a matrix is safer.
  TboToHsr.InitMatrix(   0.0, 0.0, 1.0,
                         0.0, 1.0, 0.0,
                        -1.0, 0.0, 0.0  );
  HsrToTbo  =  TboToHsr.Transposed();

  // smooth out jumps in hagl reported, otherwise the ground effect
  // calculation would cause jumps too. 1Hz seems sufficient.
  damp_hagl = Filter(1.0, dt);

  // enable import-export
  bindmodel(exec->GetPropertyManager());

  Debug(0);

}  // Constructor

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The documentation for this class was generated from the following files:

• FGRotor.h
• FGRotor.cpp