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JSBSim Thrusters: Difference between revisions
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→C_THRUST and C_POWER tables
m (It is possible to use FGElectric with a direct thruster.) |
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* Ct = coefficient of thrust | * Ct = coefficient of thrust | ||
* Cp = coefficient of power | * Cp = coefficient of power | ||
* v = velocity of aircraft (m/s) | * v = true velocity of aircraft (m/s) | ||
* D = diameter of propeller disk (m) | * D = diameter of propeller disk (m) | ||
* n = rotations per second (1/s) (note RPS, not RPM) | * n = rotations per second (1/s) (note RPS, not RPM) | ||
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* T = thrust (N) | * T = thrust (N) | ||
For a typical propeller, both Cp and Ct are downward sloping curves that reach 0 when J is somewhere in the range 0-4 (depending on blade angle and other factors). Cp and Ct can be negative; this indicates the drag induced by the prop when the airspeed is relatively fast compared with prop RPM. | For a typical propeller, both Cp and Ct are downward sloping curves that reach 0 when J is somewhere in the range 0-4 (depending on blade angle and other factors). Cp and Ct can be negative; this indicates the drag induced by the prop when the airspeed is relatively fast compared with prop RPM. At higher pitch angles Ct may have a positive slope or be flat in the lower J range. | ||
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. | ||
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</tableData> | </tableData> | ||
</table> | </table> | ||
<!-- power-required effects of helical tip Mach --> | |||
<table name="CP_MACH" type="internal"> | |||
<tableData> | |||
0.85 1.0 | |||
1.05 1.8 | |||
2.00 1.4 | |||
</tableData> | |||
</table> | |||
</nowiki> | </nowiki> | ||