JSBSim Flight Dynamics Model  1.0 (02 March 2017)
An Open Source Flight Dynamics and Control Software Library in C++
FGPropeller.cpp
1 /*%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
2 
3  Module: FGPropeller.cpp
4  Author: Jon S. Berndt
5  Date started: 08/24/00
6  Purpose: Encapsulates the propeller object
7 
8  ------------- Copyright (C) 2000 Jon S. Berndt (jon@jsbsim.org) -------------
9 
10  This program is free software; you can redistribute it and/or modify it under
11  the terms of the GNU Lesser General Public License as published by the Free Software
12  Foundation; either version 2 of the License, or (at your option) any later
13  version.
14 
15  This program is distributed in the hope that it will be useful, but WITHOUT
16  ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
17  FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public License for more
18  details.
19 
20  You should have received a copy of the GNU Lesser General Public License along with
21  this program; if not, write to the Free Software Foundation, Inc., 59 Temple
22  Place - Suite 330, Boston, MA 02111-1307, USA.
23 
24  Further information about the GNU Lesser General Public License can also be found on
25  the world wide web at http://www.gnu.org.
26 
27 FUNCTIONAL DESCRIPTION
28 --------------------------------------------------------------------------------
29 
30 HISTORY
31 --------------------------------------------------------------------------------
32 08/24/00 JSB Created
33 
34 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
35 INCLUDES
36 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%*/
37 
38 #include <iostream>
39 #include <sstream>
40 
41 #include "FGPropeller.h"
42 #include "input_output/FGXMLElement.h"
43 
44 using namespace std;
45 
46 namespace JSBSim {
47 
48 IDENT(IdSrc,"$Id: FGPropeller.cpp,v 1.59 2017/02/26 12:09:46 bcoconni Exp $");
49 IDENT(IdHdr,ID_PROPELLER);
50 
51 /*%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
52 CLASS IMPLEMENTATION
53 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%*/
54 
55 // This class currently makes certain assumptions when calculating torque and
56 // p-factor. That is, that the axis of rotation is the X axis of the aircraft -
57 // not just the X-axis of the engine/propeller. This may or may not work for a
58 // helicopter.
59 
60 FGPropeller::FGPropeller(FGFDMExec* exec, Element* prop_element, int num)
61  : FGThruster(exec, prop_element, num)
62 {
63  Element *table_element, *local_element;
64  string name="";
65  FGPropertyManager* PropertyManager = exec->GetPropertyManager();
66 
67  MaxPitch = MinPitch = P_Factor = Pitch = Advance = MinRPM = MaxRPM = 0.0;
68  Sense = 1; // default clockwise rotation
69  ReversePitch = 0.0;
70  Reversed = false;
71  Feathered = false;
72  Reverse_coef = 0.0;
73  GearRatio = 1.0;
74  CtFactor = CpFactor = 1.0;
75  ConstantSpeed = 0;
76  cThrust = cPower = CtMach = CpMach = 0;
77  Vinduced = 0.0;
78 
79  if (prop_element->FindElement("ixx"))
80  Ixx = max(prop_element->FindElementValueAsNumberConvertTo("ixx", "SLUG*FT2"), 0.001);
81 
82  Sense_multiplier = 1.0;
83  if (prop_element->HasAttribute("version")
84  && prop_element->GetAttributeValueAsNumber("version") > 1.0)
85  Sense_multiplier = -1.0;
86 
87  if (prop_element->FindElement("diameter"))
88  Diameter = max(prop_element->FindElementValueAsNumberConvertTo("diameter", "FT"), 0.001);
89  if (prop_element->FindElement("numblades"))
90  numBlades = (int)prop_element->FindElementValueAsNumber("numblades");
91  if (prop_element->FindElement("gearratio"))
92  GearRatio = max(prop_element->FindElementValueAsNumber("gearratio"), 0.001);
93  if (prop_element->FindElement("minpitch"))
94  MinPitch = prop_element->FindElementValueAsNumber("minpitch");
95  if (prop_element->FindElement("maxpitch"))
96  MaxPitch = prop_element->FindElementValueAsNumber("maxpitch");
97  if (prop_element->FindElement("minrpm"))
98  MinRPM = prop_element->FindElementValueAsNumber("minrpm");
99  if (prop_element->FindElement("maxrpm")) {
100  MaxRPM = prop_element->FindElementValueAsNumber("maxrpm");
101  ConstantSpeed = 1;
102  }
103  if (prop_element->FindElement("constspeed"))
104  ConstantSpeed = (int)prop_element->FindElementValueAsNumber("constspeed");
105  if (prop_element->FindElement("reversepitch"))
106  ReversePitch = prop_element->FindElementValueAsNumber("reversepitch");
107  while((table_element = prop_element->FindNextElement("table")) != 0) {
108  name = table_element->GetAttributeValue("name");
109  try {
110  if (name == "C_THRUST") {
111  cThrust = new FGTable(PropertyManager, table_element);
112  } else if (name == "C_POWER") {
113  cPower = new FGTable(PropertyManager, table_element);
114  } else if (name == "CT_MACH") {
115  CtMach = new FGTable(PropertyManager, table_element);
116  } else if (name == "CP_MACH") {
117  CpMach = new FGTable(PropertyManager, table_element);
118  } else {
119  cerr << "Unknown table type: " << name << " in propeller definition." << endl;
120  }
121  } catch (std::string& str) {
122  throw("Error loading propeller table:" + name + ". " + str);
123  }
124  }
125  if( (cPower == 0) || (cThrust == 0)){
126  cerr << "Propeller configuration must contain C_THRUST and C_POWER tables!" << endl;
127  }
128 
129  local_element = prop_element->GetParent()->FindElement("sense");
130  if (local_element) {
131  double Sense = local_element->GetDataAsNumber();
132  SetSense(Sense >= 0.0 ? 1.0 : -1.0);
133  }
134  local_element = prop_element->GetParent()->FindElement("p_factor");
135  if (local_element) {
136  P_Factor = local_element->GetDataAsNumber();
137  }
138  if (P_Factor < 0) {
139  cerr << "P-Factor value in propeller configuration file must be greater than zero" << endl;
140  }
141  if (prop_element->FindElement("ct_factor"))
142  SetCtFactor( prop_element->FindElementValueAsNumber("ct_factor") );
143  if (prop_element->FindElement("cp_factor"))
144  SetCpFactor( prop_element->FindElementValueAsNumber("cp_factor") );
145 
146  Type = ttPropeller;
147  RPM = 0;
148  vTorque.InitMatrix();
149  vH.InitMatrix();
150  D4 = Diameter*Diameter*Diameter*Diameter;
151  D5 = D4*Diameter;
152  Pitch = MinPitch;
153 
154  string property_name, base_property_name;
155  base_property_name = CreateIndexedPropertyName("propulsion/engine", EngineNum);
156  property_name = base_property_name + "/engine-rpm";
157  PropertyManager->Tie( property_name.c_str(), this, &FGPropeller::GetEngineRPM );
158  property_name = base_property_name + "/advance-ratio";
159  PropertyManager->Tie( property_name.c_str(), &J );
160  property_name = base_property_name + "/blade-angle";
161  PropertyManager->Tie( property_name.c_str(), &Pitch );
162  property_name = base_property_name + "/thrust-coefficient";
163  PropertyManager->Tie( property_name.c_str(), this, &FGPropeller::GetThrustCoefficient );
164  property_name = base_property_name + "/propeller-rpm";
165  PropertyManager->Tie( property_name.c_str(), this, &FGPropeller::GetRPM );
166  property_name = base_property_name + "/helical-tip-Mach";
167  PropertyManager->Tie( property_name.c_str(), this, &FGPropeller::GetHelicalTipMach );
168  property_name = base_property_name + "/constant-speed-mode";
169  PropertyManager->Tie( property_name.c_str(), this, &FGPropeller::GetConstantSpeed,
171  property_name = base_property_name + "/prop-induced-velocity_fps";
172  PropertyManager->Tie( property_name.c_str(), this, &FGPropeller::GetInducedVelocity,
174 
175  Debug(0);
176 }
177 
178 //%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
179 
181 {
182  delete cThrust;
183  delete cPower;
184  delete CtMach;
185  delete CpMach;
186 
187  Debug(1);
188 }
189 
190 //%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
191 
193 {
194  FGThruster::ResetToIC();
195  Vinduced = 0.0;
196 }
197 
198 //%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
199 //
200 // We must be getting the aerodynamic velocity here, NOT the inertial velocity.
201 // We need the velocity with respect to the wind.
202 //
203 // Remembering that Torque * omega = Power, we can derive the torque on the
204 // propeller and its acceleration to give a new RPM. The current RPM will be
205 // used to calculate thrust.
206 //
207 // Because RPM could be zero, we need to be creative about what RPM is stated as.
208 
209 double FGPropeller::Calculate(double EnginePower)
210 {
211  FGColumnVector3 localAeroVel = Transform().Transposed() * in.AeroUVW;
212  double omega, PowerAvailable;
213 
214  double Vel = localAeroVel(eU) + Vinduced;
215  double rho = in.Density;
216  double RPS = RPM/60.0;
217 
218  // Calculate helical tip Mach
219  double Area = 0.25*Diameter*Diameter*M_PI;
220  double Vtip = RPS * Diameter * M_PI;
221  HelicalTipMach = sqrt(Vtip*Vtip + Vel*Vel) / in.Soundspeed;
222 
223  if (RPS > 0.0) J = Vel / (Diameter * RPS); // Calculate J normally
224  else J = Vel / Diameter;
225 
226  PowerAvailable = EnginePower - GetPowerRequired();
227 
228  if (MaxPitch == MinPitch) { // Fixed pitch prop
229  ThrustCoeff = cThrust->GetValue(J);
230  } else { // Variable pitch prop
231  ThrustCoeff = cThrust->GetValue(J, Pitch);
232  }
233 
234  // Apply optional scaling factor to Ct (default value = 1)
235  ThrustCoeff *= CtFactor;
236 
237  // Apply optional Mach effects from CT_MACH table
238  if (CtMach) ThrustCoeff *= CtMach->GetValue(HelicalTipMach);
239 
240  Thrust = ThrustCoeff*RPS*RPS*D4*rho;
241 
242  // Induced velocity in the propeller disk area. This formula is obtained
243  // from momentum theory - see B. W. McCormick, "Aerodynamics, Aeronautics,
244  // and Flight Mechanics" 1st edition, eqn. 6.15 (propeller analysis chapter).
245  // Since Thrust and Vel can both be negative we need to adjust this formula
246  // To handle sign (direction) separately from magnitude.
247  double Vel2sum = Vel*abs(Vel) + 2.0*Thrust/(rho*Area);
248 
249  if( Vel2sum > 0.0)
250  Vinduced = 0.5 * (-Vel + sqrt(Vel2sum));
251  else
252  Vinduced = 0.5 * (-Vel - sqrt(-Vel2sum));
253 
254  // P-factor is simulated by a shift of the acting location of the thrust.
255  // The shift is a multiple of the angle between the propeller shaft axis
256  // and the relative wind that goes through the propeller disk.
257  if (P_Factor > 0.0001) {
258  double tangentialVel = localAeroVel.Magnitude(eV, eW);
259 
260  if (tangentialVel > 0.0001) {
261  double angle = atan2(tangentialVel, localAeroVel(eU));
262  double factor = Sense * P_Factor * angle / tangentialVel;
263  SetActingLocationY( GetLocationY() + factor * localAeroVel(eW));
264  SetActingLocationZ( GetLocationZ() + factor * localAeroVel(eV));
265  }
266  }
267 
268  omega = RPS*2.0*M_PI;
269 
270  vFn(eX) = Thrust;
271 
272  // The Ixx value and rotation speed given below are for rotation about the
273  // natural axis of the engine. The transform takes place in the base class
274  // FGForce::GetBodyForces() function.
275 
276  vH(eX) = Ixx*omega*Sense*Sense_multiplier;
277 
278  if (omega > 0.0) ExcessTorque = PowerAvailable / omega;
279  else ExcessTorque = PowerAvailable / 1.0;
280 
281  RPM = (RPS + ((ExcessTorque / Ixx) / (2.0 * M_PI)) * in.TotalDeltaT) * 60.0;
282 
283  if (RPM < 0.0) RPM = 0.0; // Engine won't turn backwards
284 
285  // Transform Torque and momentum first, as PQR is used in this
286  // equation and cannot be transformed itself.
287  vMn = in.PQRi*(Transform()*vH) + Transform()*vTorque;
288 
289  return Thrust; // return thrust in pounds
290 }
291 
292 //%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
293 
295 {
296  double cPReq;
297 
298  if (MaxPitch == MinPitch) { // Fixed pitch prop
299  cPReq = cPower->GetValue(J);
300 
301  } else { // Variable pitch prop
302 
303  if (ConstantSpeed != 0) { // Constant Speed Mode
304 
305  // do normal calculation when propeller is neither feathered nor reversed
306  // Note: This method of feathering and reversing was added to support the
307  // turboprop model. It's left here for backward compatiblity, but
308  // now feathering and reversing should be done in Manual Pitch Mode.
309  if (!Feathered) {
310  if (!Reversed) {
311 
312  double rpmReq = MinRPM + (MaxRPM - MinRPM) * Advance;
313  double dRPM = rpmReq - RPM;
314  // The pitch of a variable propeller cannot be changed when the RPMs are
315  // too low - the oil pump does not work.
316  if (RPM > 200) Pitch -= dRPM * in.TotalDeltaT;
317  if (Pitch < MinPitch) Pitch = MinPitch;
318  else if (Pitch > MaxPitch) Pitch = MaxPitch;
319 
320  } else { // Reversed propeller
321 
322  // when reversed calculate propeller pitch depending on throttle lever position
323  // (beta range for taxing full reverse for braking)
324  double PitchReq = MinPitch - ( MinPitch - ReversePitch ) * Reverse_coef;
325  // The pitch of a variable propeller cannot be changed when the RPMs are
326  // too low - the oil pump does not work.
327  if (RPM > 200) Pitch += (PitchReq - Pitch) / 200;
328  if (RPM > MaxRPM) {
329  Pitch += (MaxRPM - RPM) / 50;
330  if (Pitch < ReversePitch) Pitch = ReversePitch;
331  else if (Pitch > MaxPitch) Pitch = MaxPitch;
332  }
333  }
334 
335  } else { // Feathered propeller
336  // ToDo: Make feathered and reverse settings done via FGKinemat
337  Pitch += (MaxPitch - Pitch) / 300; // just a guess (about 5 sec to fully feathered)
338  }
339 
340  } else { // Manual Pitch Mode, pitch is controlled externally
341 
342  }
343 
344  cPReq = cPower->GetValue(J, Pitch);
345  }
346 
347  // Apply optional scaling factor to Cp (default value = 1)
348  cPReq *= CpFactor;
349 
350  // Apply optional Mach effects from CP_MACH table
351  if (CpMach) cPReq *= CpMach->GetValue(HelicalTipMach);
352 
353  double RPS = RPM / 60.0;
354  double local_RPS = RPS < 0.01 ? 0.01 : RPS;
355 
356  PowerRequired = cPReq*local_RPS*local_RPS*local_RPS*D5*in.Density;
357  vTorque(eX) = -Sense*PowerRequired / (local_RPS*2.0*M_PI);
358 
359  return PowerRequired;
360 }
361 
362 //%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
363 
365 {
366  double px=0.0, py, pz;
367 
368  py = Thrust * Sense * (GetActingLocationY() - GetLocationY()) / 12.0;
369  pz = Thrust * Sense * (GetActingLocationZ() - GetLocationZ()) / 12.0;
370 
371  return FGColumnVector3(px, py, pz);
372 }
373 
374 //%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
375 
376 string FGPropeller::GetThrusterLabels(int id, const string& delimeter)
377 {
378  std::ostringstream buf;
379 
380  buf << Name << " Torque (engine " << id << ")" << delimeter
381  << Name << " PFactor Pitch (engine " << id << ")" << delimeter
382  << Name << " PFactor Yaw (engine " << id << ")" << delimeter
383  << Name << " Thrust (engine " << id << " in lbs)" << delimeter;
384  if (IsVPitch())
385  buf << Name << " Pitch (engine " << id << ")" << delimeter;
386  buf << Name << " RPM (engine " << id << ")";
387 
388  return buf.str();
389 }
390 
391 //%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
392 
393 string FGPropeller::GetThrusterValues(int id, const string& delimeter)
394 {
395  std::ostringstream buf;
396 
397  FGColumnVector3 vPFactor = GetPFactor();
398  buf << vTorque(eX) << delimeter
399  << vPFactor(ePitch) << delimeter
400  << vPFactor(eYaw) << delimeter
401  << Thrust << delimeter;
402  if (IsVPitch())
403  buf << Pitch << delimeter;
404  buf << RPM;
405 
406  return buf.str();
407 }
408 
409 //%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
410 // The bitmasked value choices are as follows:
411 // unset: In this case (the default) JSBSim would only print
412 // out the normally expected messages, essentially echoing
413 // the config files as they are read. If the environment
414 // variable is not set, debug_lvl is set to 1 internally
415 // 0: This requests JSBSim not to output any messages
416 // whatsoever.
417 // 1: This value explicity requests the normal JSBSim
418 // startup messages
419 // 2: This value asks for a message to be printed out when
420 // a class is instantiated
421 // 4: When this value is set, a message is displayed when a
422 // FGModel object executes its Run() method
423 // 8: When this value is set, various runtime state variables
424 // are printed out periodically
425 // 16: When set various parameters are sanity checked and
426 // a message is printed out when they go out of bounds
427 
428 void FGPropeller::Debug(int from)
429 {
430  if (debug_lvl <= 0) return;
431 
432  if (debug_lvl & 1) { // Standard console startup message output
433  if (from == 0) { // Constructor
434  cout << "\n Propeller Name: " << Name << endl;
435  cout << " IXX = " << Ixx << endl;
436  cout << " Diameter = " << Diameter << " ft." << endl;
437  cout << " Number of Blades = " << numBlades << endl;
438  cout << " Gear Ratio = " << GearRatio << endl;
439  cout << " Minimum Pitch = " << MinPitch << endl;
440  cout << " Maximum Pitch = " << MaxPitch << endl;
441  cout << " Minimum RPM = " << MinRPM << endl;
442  cout << " Maximum RPM = " << MaxRPM << endl;
443 // Tables are being printed elsewhere...
444 // cout << " Thrust Coefficient: " << endl;
445 // cThrust->Print();
446 // cout << " Power Coefficient: " << endl;
447 // cPower->Print();
448 // cout << " Mach Thrust Coefficient: " << endl;
449 // if(CtMach)
450 // {
451 // CtMach->Print();
452 // } else {
453 // cout << " NONE" << endl;
454 // }
455 // cout << " Mach Power Coefficient: " << endl;
456 // if(CpMach)
457 // {
458 // CpMach->Print();
459 // } else {
460 // cout << " NONE" << endl;
461 // }
462  }
463  }
464  if (debug_lvl & 2 ) { // Instantiation/Destruction notification
465  if (from == 0) cout << "Instantiated: FGPropeller" << endl;
466  if (from == 1) cout << "Destroyed: FGPropeller" << endl;
467  }
468  if (debug_lvl & 4 ) { // Run() method entry print for FGModel-derived objects
469  }
470  if (debug_lvl & 8 ) { // Runtime state variables
471  }
472  if (debug_lvl & 16) { // Sanity checking
473  }
474  if (debug_lvl & 64) {
475  if (from == 0) { // Constructor
476  cout << IdSrc << endl;
477  cout << IdHdr << endl;
478  }
479  }
480 }
481 }
~FGPropeller()
Destructor for FGPropeller - deletes the FGTable objects.
Element * GetParent(void)
Returns a pointer to the parent of an element.
Definition: FGXMLElement.h:231
double GetEngineRPM(void) const
Calculates the RPMs of the engine based on gear ratio.
Definition: FGPropeller.h:239
double GetRPM(void) const
Retrieves the RPMs of the propeller.
Definition: FGPropeller.h:236
std::string GetAttributeValue(const std::string &key)
Retrieves an attribute.
double GetPowerRequired(void)
Retrieves the power required (or "absorbed") by the propeller - i.e.
void SetConstantSpeed(int mode)
Sets propeller into constant speed mode, or manual pitch mode.
Definition: FGPropeller.h:218
bool HasAttribute(const std::string &key)
Determines if an element has the supplied attribute.
Definition: FGXMLElement.h:162
double FindElementValueAsNumberConvertTo(const std::string &el, const std::string &target_units)
Searches for the named element and converts and returns the data belonging to it. ...
STL namespace.
void SetCpFactor(double cpf)
Sets coefficient of power multiplier.
Definition: FGPropeller.h:224
Element * FindElement(const std::string &el="")
Searches for a specified element.
double FindElementValueAsNumber(const std::string &el="")
Searches for the named element and returns the data belonging to it as a number.
bool IsVPitch(void) const
Returns true of this propeller is variable pitch.
Definition: FGPropeller.h:198
Base class for specific thrusting devices such as propellers, nozzles, etc.
Definition: FGThruster.h:84
double Calculate(double EnginePower)
Calculates and returns the thrust produced by this propeller.
double GetThrustCoefficient(void) const
Retrieves the thrust coefficient.
Definition: FGPropeller.h:302
FGPropertyManager * GetPropertyManager(void)
Returns a pointer to the property manager object.
Definition: FGFDMExec.cpp:1099
double GetInducedVelocity(void) const
Get the propeller induced velocity.
Definition: FGPropeller.h:310
std::string GetThrusterLabels(int id, const std::string &delimeter)
Generate the labels for the thruster standard CSV output.
void Tie(const std::string &name, bool *pointer, bool useDefault=true)
Tie a property to an external bool variable.
double GetDataAsNumber(void)
Converts the element data to a number.
void SetSense(double s)
Sets the rotation sense of the propeller.
Definition: FGPropeller.h:230
double GetAttributeValueAsNumber(const std::string &key)
Retrieves an attribute value as a double precision real number.
std::string GetThrusterValues(int id, const std::string &delimeter)
Generate the values for the thruster standard CSV output.
void SetInducedVelocity(double Vi)
Set the propeller induced velocity.
Definition: FGPropeller.h:308
This class implements a 3 element column vector.
double GetHelicalTipMach(void) const
Retrieves the Mach number at the propeller tips.
Definition: FGPropeller.h:304
int GetConstantSpeed(void) const
Returns a non-zero value if the propeller is constant speed.
Definition: FGPropeller.h:306
Element * FindNextElement(const std::string &el="")
Searches for the next element as specified.
FGMatrix33 Transposed(void) const
Transposed matrix.
Definition: FGMatrix33.h:243
double Magnitude(void) const
Length of the vector.
void SetCtFactor(double ctf)
Sets coefficient of thrust multiplier.
Definition: FGPropeller.h:221
FGColumnVector3 GetPFactor(void) const
Retrieves the P-Factor constant.
void ResetToIC(void)
Reset the initial conditions.
Encapsulates the JSBSim simulation executive.
Definition: FGFDMExec.h:189
Lookup table class.
Definition: FGTable.h:243