JSBSim Thrusters

FGPropeller

FGPropeller models a propeller given the tabular data for Ct and Cp, indexed by the advance ratio "J".

Configuration File Format

<sense> {1 | -1} </sense> 
<propeller name="{string}">
  <ixx> {number} </ixx>
  <diameter unit="IN"> {number} </diameter>
  <numblades> {number} </numblades>
  <gearratio> {number} </gearratio>
  <minpitch> {number} </minpitch>
  <maxpitch> {number} </maxpitch>
  <minrpm> {number} </minrpm>
  <maxrpm> {number} </maxrpm>
  <constspeed> {number} </constspeed>
  <reversepitch> {number} </reversepitch>
  <p_factor> {number} </p_factor>
  <ct_factor> {number} </ct_factor>
  <cp_factor> {number} </cp_factor>

  <table name="C_THRUST" type="internal">
    <tableData>
      {numbers}
    </tableData>
  </table>

  <table name="C_POWER" type="internal">
    <tableData>
      {numbers}
    </tableData>
  </table>

  <table name="CT_MACH" type="internal">
    <tableData>
      {numbers}
    </tableData>
  </table>

  <table name="CP_MACH" type="internal">
    <tableData>
      {numbers}
    </tableData>
  </table>


</propeller>

Parameter definitions

ixx	Propeller rotational inertia.
diameter	Propeller disk diameter.
numblades	Number of blades.
gearratio	Ratio of (engine rpm) / (prop rpm).
minpitch	Minimum blade pitch angle.
maxpitch	Maximum blade pitch angle.
minrpm	Minimum rpm target for constant speed propeller.
maxrpm	Maximum rpm target for constant speed propeller.
constspeed	1 = constant speed mode, 0 = manual pitch mode.
reversepitch	Blade pitch angle for reverse.
sense	Direction of rotation (1=clockwise as viewed from cockpit, -1=anti-clockwise as viewed from cockpit). Sense is specified in the parent tag of the propeller.
p_factor	P factor.
ct_factor	A multiplier for the coefficients of thrust.
cp_factor	A multiplier for the coefficients of power.

Notes

• Two tables are needed. One for coefficient of thrust (Ct) and one for coefficient of power (Cp).
• Two tables are optional. They apply a factor to Ct and Cp based on the helical tip Mach.
• Several references were helpful, here:
  • Barnes W. McCormick, "Aerodynamics, Aeronautics, and Flight Mechanics", Wiley & Sons, 1979 ISBN 0-471-03032-5
  • 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 (?)
  • Various NACA Technical Notes and Reports