JSBSim Thrusters: Difference between revisions

JSBSim Thrusters (view source)

212 bytes removed , 3 November 2011

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 * 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). Typically Ct is slightly greater than than Cp for small J, crosses (is equal to) Cp at some point (typically, 60-80% of the way from J=0 to the point where Ct=0)), and then remains smaller than Cp for larger J.  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.
 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.