flightgear/src/FDM/JSBSim/FGPropeller.h

/*%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

 Header:       FGPropeller.h
 Author:       Jon S. Berndt
 Date started: 08/24/00

 ------------- Copyright (C) 2000  Jon S. Berndt (jsb@hal-pc.org) -------------

 This program is free software; you can redistribute it and/or modify it under
 the terms of the GNU General Public License as published by the Free Software
 Foundation; either version 2 of the License, or (at your option) any later
 version.

 This program is distributed in the hope that it will be useful, but WITHOUT
 ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
 FOR A PARTICULAR PURPOSE.  See the GNU General Public License for more
 details.

 You should have received a copy of the GNU General Public License along with
 this program; if not, write to the Free Software Foundation, Inc., 59 Temple
 Place - Suite 330, Boston, MA  02111-1307, USA.

 Further information about the GNU General Public License can also be found on
 the world wide web at http://www.gnu.org.

HISTORY
--------------------------------------------------------------------------------
08/24/00  JSB  Created

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
SENTRY
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#ifndef FGPROPELLER_H
#define FGPROPELLER_H

/*%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
INCLUDES
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#include "FGThruster.h"
#include "FGTable.h"
#include "FGTranslation.h"

/*%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
DEFINITIONS
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#define ID_PROPELLER "$Id$"

/*%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
FORWARD DECLARATIONS
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/*%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
COMMENTS, REFERENCES, and NOTES [use "class documentation" below for API docs]
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/*%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
CLASS DOCUMENTATION
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/** Propeller modeling class.
    FGPropeller models a propeller given the tabular data for Ct, Cp, and
    efficiency indexed by advance ratio "J". The data for the propeller is
    stored in a config file named "prop_name.xml". The propeller config file
    is referenced from the main aircraft config file in the "Propulsion" section.
    See the constructor for FGPropeller to see what is read in and what should
    be stored in the config file.<br>
    Several references were helpful, here:<ul>
    <li>Barnes W. McCormick, "Aerodynamics, Aeronautics, and Flight Mechanics",
     Wiley & Sons, 1979 ISBN 0-471-03032-5</li>
    <li>Edwin Hartman, David Biermann, "The Aerodynamic Characteristics of
    Full Scale Propellers Having 2, 3, and 4 Blades of Clark Y and R.A.F. 6
    Airfoil Sections", NACA Report TN-640, 1938 (?)</li>
    <li>Various NACA Technical Notes and Reports</li>
    <ul>
    @author Jon S. Berndt
    @version $Id$
    @see FGEngine
    @see FGThruster
    @see FGTable
*/

/*%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
CLASS DECLARATION
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class FGPropeller : public FGThruster {

public:
  /** Constructor for FGPropeller.
      @param exec a pointer to the main executive object
      @param AC_cfg a pointer to the main aircraft config file object */
  FGPropeller(FGFDMExec* exec, FGConfigFile* AC_cfg);

  /// Destructor for FGPropeller - deletes the FGTable objects
  ~FGPropeller();

  /** Sets the Revolutions Per Minute for the propeller. Normally the propeller
      instance will calculate its own rotational velocity, given the Torque
      produced by the engine and integrating over time using the standard
      equation for rotational acceleration "a": a = Q/I , where Q is Torque and
      I is moment of inertia for the propeller.
      @param rpm the rotational velocity of the propeller */
  void SetRPM(float rpm) {RPM = rpm;}

  /** This commands the pitch of the blade to change to the value supplied.
      This call is meant to be issued either from the cockpit or by the flight
      control system (perhaps to maintain constant RPM for a constant-speed
      propeller). This value will be limited to be within whatever is specified
      in the config file for Max and Min pitch. It is also one of the lookup
      indices to the power, thrust, and efficiency tables for variable-pitch
      propellers.
      @param pitch the pitch of the blade in degrees. */
  void SetPitch(float pitch) {Pitch = pitch;}

  /// Retrieves the pitch of the propeller in degrees.
  float GetPitch(void)         { return Pitch;         }
  
  /// Retrieves the RPMs of the propeller
  float GetRPM(void)           { return RPM;           }
  
  /// Retrieves the propeller moment of inertia
  float GetIxx(void)           { return Ixx;           }
  
  /// Retrieves the Torque in foot-pounds (Don't you love the English system?)
  float GetTorque(void)        { return Torque;        }
  
  /** Retrieves the power required (or "absorbed") by the propeller -
      i.e. the power required to keep spinning the propeller at the current
      velocity, air density,  and rotational rate. */
  float GetPowerRequired(void);
  
  /** Calculates and returns the thrust produced by this propeller.
      Given the excess power available from the engine (in foot-pounds), the thrust is
      calculated, as well as the current RPM. The RPM is calculated by integrating
      the torque provided by the engine over what the propeller "absorbs"
      (essentially the "drag" of the propeller).
      @param PowerAvailable this is the excess power provided by the engine to
      accelerate the prop. It could be negative, dictating that the propeller
      would be slowed.
		  @return the thrust in pounds */
  float Calculate(float PowerAvailable);

private:
  int   numBlades;
  float RPM;
  float Ixx;
  float Diameter;
  float MaxPitch;
  float MinPitch;
  float Pitch;
  float Torque;
  FGTable *Efficiency;
  FGTable *cThrust;
  FGTable *cPower;
  void Debug(void);
};

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#endif