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JSBSim Thrusters: Difference between revisions
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=== | ===C_THRUST and C_POWER tables=== | ||
The C_THRUST and C_POWER tables are required. | |||
The independent variable for both tables is Advance Ratio (J). The dependent variable is the coefficient of thrust (Ct) for the C_THRUST and the coefficient of power (Cp) for C_POWER. | |||
[http://www.mh-aerotools.de/airfoils/pylonprops_1.htm Propellors for F3D Models explains the theory] and has [http://www.mh-aerotools.de/airfoils/pylonprops_2.htm formulas] and [http://www.mh-aerotools.de/airfoils/pylonprops_3.htm many graphs] showing the relationship between J, Ct, and Cp. | |||
Relevant formulas: | Relevant formulas relating the variables in the tables: | ||
* Thrust: T = Ct/(rho * n^2 * D^4) | * Thrust: T = Ct/(rho * n^2 * D^4) | ||
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Ct/Cp gives the efficiency (eta), and propeller shape and general design give each propeller a distinctive [http://www.mh-aerotools.de/airfoils/pylonprops_3.htm efficiency curve]. For fixed-pitch propellers, the propeller is generally designed to reach peak efficiency either at climb velocity & RPM, cruise velocity and RPM, or some compromise between the two. [http://en.wikipedia.org/wiki/Controllable_pitch_propeller Variable pitch propellers] and [http://en.wikipedia.org/wiki/Constant_speed_propeller constant speed propellers] bring different factors into play. | Ct/Cp gives the efficiency (eta), and propeller shape and general design give each propeller a distinctive [http://www.mh-aerotools.de/airfoils/pylonprops_3.htm efficiency curve]. For fixed-pitch propellers, the propeller is generally designed to reach peak efficiency either at climb velocity & RPM, cruise velocity and RPM, or some compromise between the two. [http://en.wikipedia.org/wiki/Controllable_pitch_propeller Variable pitch propellers] and [http://en.wikipedia.org/wiki/Constant_speed_propeller constant speed propellers] bring different factors into play. | ||
=== Optional Tables === | |||
Two tables are optional. They apply a factor to Ct and Cp based on the helical tip Mach. | |||
=== Notes === | |||
* Several references were helpful, here: | * Several references were helpful, here: | ||
**Barnes W. McCormick, "Aerodynamics, Aeronautics, and Flight Mechanics", Wiley & Sons, 1979 ISBN 0-471-03032-5 | **Barnes W. McCormick, "Aerodynamics, Aeronautics, and Flight Mechanics", Wiley & Sons, 1979 ISBN 0-471-03032-5 | ||