1 /*%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
7 ------------- Copyright (C) 2000 Jon S. Berndt (jsb@hal-pc.org) -------------
9 This program is free software; you can redistribute it and/or modify it under
10 the terms of the GNU 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 General Public License for more
19 You should have received a copy of the GNU 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 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"
44 /*%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
46 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%*/
48 #define ID_PROPELLER "$Id$"
50 /*%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
52 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%*/
56 /*%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
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60 /** Propeller modeling class.
61 FGPropeller models a propeller given the tabular data for Ct and Cp
62 indexed by advance ratio "J". The data for the propeller is
63 stored in a config file named "prop_name.xml". The propeller config file
64 is referenced from the main aircraft config file in the "Propulsion" section.
65 See the constructor for FGPropeller to see what is read in and what should
66 be stored in the config file.<br>
67 Several references were helpful, here:<ul>
68 <li>Barnes W. McCormick, "Aerodynamics, Aeronautics, and Flight Mechanics",
69 Wiley & Sons, 1979 ISBN 0-471-03032-5</li>
70 <li>Edwin Hartman, David Biermann, "The Aerodynamic Characteristics of
71 Full Scale Propellers Having 2, 3, and 4 Blades of Clark Y and R.A.F. 6
72 Airfoil Sections", NACA Report TN-640, 1938 (?)</li>
73 <li>Various NACA Technical Notes and Reports</li>
82 /*%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
84 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%*/
86 class FGPropeller : public FGThruster {
89 /** Constructor for FGPropeller.
90 @param exec a pointer to the main executive object
91 @param AC_cfg a pointer to the main aircraft config file object */
92 FGPropeller(FGFDMExec* exec, FGConfigFile* AC_cfg);
94 /// Destructor for FGPropeller - deletes the FGTable objects
97 /** Sets the Revolutions Per Minute for the propeller. Normally the propeller
98 instance will calculate its own rotational velocity, given the Torque
99 produced by the engine and integrating over time using the standard
100 equation for rotational acceleration "a": a = Q/I , where Q is Torque and
101 I is moment of inertia for the propeller.
102 @param rpm the rotational velocity of the propeller */
103 void SetRPM(double rpm) {RPM = rpm;}
105 /// Returns true of this propeller is variable pitch
106 bool IsVPitch(void) {return MaxPitch != MinPitch;}
108 /** This commands the pitch of the blade to change to the value supplied.
109 This call is meant to be issued either from the cockpit or by the flight
110 control system (perhaps to maintain constant RPM for a constant-speed
111 propeller). This value will be limited to be within whatever is specified
112 in the config file for Max and Min pitch. It is also one of the lookup
113 indices to the power and thrust tables for variable-pitch propellers.
114 @param pitch the pitch of the blade in degrees. */
115 void SetPitch(double pitch) {Pitch = pitch;}
117 /// Sets the P-Factor constant
118 void SetPFactor(double pf) {P_Factor = pf;}
120 /** Sets the rotation sense of the propeller.
121 @param s this value should be +/- 1 ONLY. +1 indicates clockwise rotation as
122 viewed by someone standing behind the engine looking forward into
123 the direction of flight. */
124 void SetSense(double s) { Sense = s;}
126 /// Retrieves the pitch of the propeller in degrees.
127 double GetPitch(void) { return Pitch; }
129 /// Retrieves the RPMs of the propeller
130 double GetRPM(void) { return RPM; }
132 /// Retrieves the propeller moment of inertia
133 double GetIxx(void) { return Ixx; }
135 /// Retrieves the Torque in foot-pounds (Don't you love the English system?)
136 double GetTorque(void) { return vTorque(eX); }
138 /** Retrieves the power required (or "absorbed") by the propeller -
139 i.e. the power required to keep spinning the propeller at the current
140 velocity, air density, and rotational rate. */
141 double GetPowerRequired(void);
143 /** Calculates and returns the thrust produced by this propeller.
144 Given the excess power available from the engine (in foot-pounds), the thrust is
145 calculated, as well as the current RPM. The RPM is calculated by integrating
146 the torque provided by the engine over what the propeller "absorbs"
147 (essentially the "drag" of the propeller).
148 @param PowerAvailable this is the excess power provided by the engine to
149 accelerate the prop. It could be negative, dictating that the propeller
151 @return the thrust in pounds */
152 double Calculate(double PowerAvailable);
153 FGColumnVector3 GetPFactor(void);
168 FGColumnVector3 vTorque;
171 void Debug(int from);
174 //%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%