1 /*%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
7 ------------- Copyright (C) 2000 Jon S. Berndt (jon@jsbsim.org) -------------
9 This program is free software; you can redistribute it and/or modify it under
10 the terms of the GNU Lesser General Public License as published by the Free Software
11 Foundation; either version 2 of the License, or (at your option) any later
14 This program is distributed in the hope that it will be useful, but WITHOUT
15 ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
16 FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public License for more
19 You should have received a copy of the GNU Lesser General Public License along with
20 this program; if not, write to the Free Software Foundation, Inc., 59 Temple
21 Place - Suite 330, Boston, MA 02111-1307, USA.
23 Further information about the GNU Lesser General Public License can also be found on
24 the world wide web at http://www.gnu.org.
27 --------------------------------------------------------------------------------
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32 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%*/
37 /*%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
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41 #include "FGThruster.h"
42 #include <math/FGTable.h>
44 /*%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
46 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%*/
48 #define ID_PROPELLER "$Id$"
50 /*%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
52 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%*/
56 /*%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
58 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%*/
60 /** FGPropeller models a propeller given the tabular data for Ct and Cp,
61 indexed by the advance ratio "J".
63 <h3>Configuration File Format:</h3>
65 <propeller name="{string}">
67 <diameter unit="IN"> {number} </diameter>
68 <numblades> {number} </numblades>
69 <gearratio> {number} </gearratio>
70 <minpitch> {number} </minpitch>
71 <maxpitch> {number} </maxpitch>
72 <minrpm> {number} </minrpm>
73 <maxrpm> {number} </maxrpm>
74 <reversepitch> {number} </reversepitch>
75 <sense> {1 | -1} </sense>
76 <p_factor> {number} </p_factor>
77 <ct_factor> {number} </ct_factor>
78 <cp_factor> {number} </cp_factor>
80 <table name="C_THRUST" type="internal">
86 <table name="C_POWER" type="internal">
95 <h3>Configuration Parameters:</h3>
97 \<ixx> - Propeller rotational inertia.
98 \<diameter> - Propeller disk diameter.
99 \<numblades> - Number of blades.
100 \<gearratio> - Ratio of (engine rpm) / (prop rpm).
101 \<minpitch> - Minimum blade pitch angle.
102 \<maxpitch> - Maximum blade pitch angle.
103 \<minrpm> - Minimum rpm target for constant speed propeller.
104 \<maxrpm> - Maximum rpm target for constant speed propeller.
105 \<reversepitch> - Blade pitch angle for reverse.
106 \<sense> - Direction of rotation (1=clockwise as viewed from cockpit,
107 -1=anti-clockwise as viewed from cockpit).
108 \<p_factor> - P factor.
109 \<ct_factor> - A multiplier for the coefficients of thrust.
110 \<cp_factor> - A multiplier for the coefficients of power.
113 Two tables are needed. One for coefficient of thrust (Ct) and one for
114 coefficient of power (Cp).
117 Several references were helpful, here:<ul>
118 <li>Barnes W. McCormick, "Aerodynamics, Aeronautics, and Flight Mechanics",
119 Wiley & Sons, 1979 ISBN 0-471-03032-5</li>
120 <li>Edwin Hartman, David Biermann, "The Aerodynamic Characteristics of
121 Full Scale Propellers Having 2, 3, and 4 Blades of Clark Y and R.A.F. 6
122 Airfoil Sections", NACA Report TN-640, 1938 (?)</li>
123 <li>Various NACA Technical Notes and Reports</li>
125 @author Jon S. Berndt
131 /*%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
133 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%*/
135 class FGPropeller : public FGThruster {
138 /** Constructor for FGPropeller.
139 @param exec a pointer to the main executive object
140 @param el a pointer to the thruster config file XML element
141 @param num the number of this propeller */
142 FGPropeller(FGFDMExec* exec, Element* el, int num = 0);
144 /// Destructor for FGPropeller - deletes the FGTable objects
147 /** Sets the Revolutions Per Minute for the propeller. Normally the propeller
148 instance will calculate its own rotational velocity, given the Torque
149 produced by the engine and integrating over time using the standard
150 equation for rotational acceleration "a": a = Q/I , where Q is Torque and
151 I is moment of inertia for the propeller.
152 @param rpm the rotational velocity of the propeller */
153 void SetRPM(double rpm) {RPM = rpm;}
155 /// Returns true of this propeller is variable pitch
156 bool IsVPitch(void) {return MaxPitch != MinPitch;}
158 /** This commands the pitch of the blade to change to the value supplied.
159 This call is meant to be issued either from the cockpit or by the flight
160 control system (perhaps to maintain constant RPM for a constant-speed
161 propeller). This value will be limited to be within whatever is specified
162 in the config file for Max and Min pitch. It is also one of the lookup
163 indices to the power and thrust tables for variable-pitch propellers.
164 @param pitch the pitch of the blade in degrees. */
165 void SetPitch(double pitch) {Pitch = pitch;}
167 void SetAdvance(double advance) {Advance = advance;}
169 /// Sets the P-Factor constant
170 void SetPFactor(double pf) {P_Factor = pf;}
172 /// Sets coefficient of thrust multiplier
173 void SetCtFactor(double ctf) {CtFactor = ctf;}
175 /// Sets coefficient of power multiplier
176 void SetCpFactor(double cpf) {CpFactor = cpf;}
178 /** Sets the rotation sense of the propeller.
179 @param s this value should be +/- 1 ONLY. +1 indicates clockwise rotation as
180 viewed by someone standing behind the engine looking forward into
181 the direction of flight. */
182 void SetSense(double s) { Sense = s;}
184 /// Retrieves the pitch of the propeller in degrees.
185 double GetPitch(void) { return Pitch; }
187 /// Retrieves the RPMs of the propeller
188 double GetRPM(void) const { return RPM; }
190 /// Retrieves the propeller moment of inertia
191 double GetIxx(void) { return Ixx; }
193 /// Retrieves the coefficient of thrust multiplier
194 double GetCtFactor(void) { return CtFactor; }
196 /// Retrieves the coefficient of power multiplier
197 double GetCpFactor(void) { return CpFactor; }
199 /// Retrieves the propeller diameter
200 double GetDiameter(void) { return Diameter; }
202 /// Retrieves propeller thrust table
203 FGTable* GetCThrustTable(void) const { return cThrust;}
204 /// Retrieves propeller power table
205 FGTable* GetCPowerTable(void) const { return cPower; }
207 /// Retrieves the Torque in foot-pounds (Don't you love the English system?)
208 double GetTorque(void) { return vTorque(eX); }
210 /** Retrieves the power required (or "absorbed") by the propeller -
211 i.e. the power required to keep spinning the propeller at the current
212 velocity, air density, and rotational rate. */
213 double GetPowerRequired(void);
215 /** Calculates and returns the thrust produced by this propeller.
216 Given the excess power available from the engine (in foot-pounds), the thrust is
217 calculated, as well as the current RPM. The RPM is calculated by integrating
218 the torque provided by the engine over what the propeller "absorbs"
219 (essentially the "drag" of the propeller).
220 @param PowerAvailable this is the excess power provided by the engine to
221 accelerate the prop. It could be negative, dictating that the propeller
223 @return the thrust in pounds */
224 double Calculate(double PowerAvailable);
225 FGColumnVector3 GetPFactor(void);
226 string GetThrusterLabels(int id, string delimeter);
227 string GetThrusterValues(int id, string delimeter);
229 void SetReverseCoef (double c) { Reverse_coef = c; }
230 double GetReverseCoef (void) { return Reverse_coef; }
231 void SetReverse (bool r) { Reversed = r; }
232 bool GetReverse (void) { return Reversed; }
233 void SetFeather (bool f) { Feathered = f; }
234 bool GetFeather (void) { return Feathered; }
235 double GetThrustCoefficient(void) const {return ThrustCoeff;}
254 FGColumnVector3 vTorque;
259 void Debug(int from);
260 double ReversePitch; // Pitch, when fully reversed
261 bool Reversed; // true, when propeller is reversed
262 double Reverse_coef; // 0 - 1 defines AdvancePitch (0=MIN_PITCH 1=REVERSE_PITCH)
263 bool Feathered; // true, if feather command
266 //%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%