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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41 #include "FGThruster.h"
43 #include "FGTranslation.h"
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47 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%*/
49 #define ID_PROPELLER "$Id$"
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55 /*%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
56 COMMENTS, REFERENCES, and NOTES [use "class documentation" below for API docs]
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63 /** Propeller modeling class.
64 FGPropeller models a propeller given the tabular data for Ct, Cp, and
65 efficiency indexed by advance ratio "J". The data for the propeller is
66 stored in a config file named "prop_name.xml". The propeller config file
67 is referenced from the main aircraft config file in the "Propulsion" section.
68 See the constructor for FGPropeller to see what is read in and what should
69 be stored in the config file.<br>
70 Several references were helpful, here:<ul>
71 <li>Barnes W. McCormick, "Aerodynamics, Aeronautics, and Flight Mechanics",
72 Wiley & Sons, 1979 ISBN 0-471-03032-5</li>
73 <li>Edwin Hartman, David Biermann, "The Aerodynamic Characteristics of
74 Full Scale Propellers Having 2, 3, and 4 Blades of Clark Y and R.A.F. 6
75 Airfoil Sections", NACA Report TN-640, 1938 (?)</li>
76 <li>Various NACA Technical Notes and Reports</li>
85 /*%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
87 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%*/
89 class FGPropeller : public FGThruster {
92 /** Constructor for FGPropeller.
93 @param exec a pointer to the main executive object
94 @param AC_cfg a pointer to the main aircraft config file object */
95 FGPropeller(FGFDMExec* exec, FGConfigFile* AC_cfg);
97 /// Destructor for FGPropeller - deletes the FGTable objects
100 /** Sets the Revolutions Per Minute for the propeller. Normally the propeller
101 instance will calculate its own rotational velocity, given the Torque
102 produced by the engine and integrating over time using the standard
103 equation for rotational acceleration "a": a = Q/I , where Q is Torque and
104 I is moment of inertia for the propeller.
105 @param rpm the rotational velocity of the propeller */
106 void SetRPM(float rpm) {RPM = rpm;}
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, thrust, and efficiency tables for variable-pitch
115 @param pitch the pitch of the blade in degrees. */
116 void SetPitch(float pitch) {Pitch = pitch;}
118 /// Retrieves the pitch of the propeller in degrees.
119 float GetPitch(void) { return Pitch; }
121 /// Retrieves the RPMs of the propeller
122 float GetRPM(void) { return RPM; }
124 /// Retrieves the propeller moment of inertia
125 float GetIxx(void) { return Ixx; }
127 /// Retrieves the Torque in foot-pounds (Don't you love the English system?)
128 float GetTorque(void) { return Torque; }
130 /** Retrieves the power required (or "absorbed") by the propeller -
131 i.e. the power required to keep spinning the propeller at the current
132 velocity, air density, and rotational rate. */
133 float GetPowerRequired(void);
135 /** Calculates and returns the thrust produced by this propeller.
136 Given the excess power available from the engine (in foot-pounds), the thrust is
137 calculated, as well as the current RPM. The RPM is calculated by integrating
138 the torque provided by the engine over what the propeller "absorbs"
139 (essentially the "drag" of the propeller).
140 @param PowerAvailable this is the excess power provided by the engine to
141 accelerate the prop. It could be negative, dictating that the propeller
143 @return the thrust in pounds */
144 float Calculate(float PowerAvailable);
161 //%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%