a2711ac610
elevator and trim give ridiculously high airspeeds. Increase the elevator effectiveness slightly. Increase the vertical stabilizer effectiveness, and give it a 1.5 degree incidence angle, to compensate for asymmetric propeller effects. Increase the rudder effectiveness to help with cross-wind takeoffs and landings.
139 lines
5.4 KiB
XML
139 lines
5.4 KiB
XML
<?xml version="1.0"?>
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<!--
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************************************************************************
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YASim aerodynamic model for a Piper J3 Cub.
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Started 2002-08-15 by David Megginson.
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This aerodynamic model is based on three-views, unauthoritative
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performance data, and wild guesses. These sites provided particularly
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useful information or were simply fun to visit:
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Performance data:
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http://www.marss.com/cub.htm
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Weight and balance:
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http://www.danford.net/balance.htm
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Three-view:
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http://www.fiddlersgreen.net/aircraft/private/j3cub/j3cub_info/j3_info.htm
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Useless but fun free paper model:
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http://www.fiddlersgreen.net/aircraft/private/j3cub/j3cub.htm
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Useless but fun 1945 Piper Cub ad from FLYING:
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http://www.fiddlersgreen.net/aircraft/private/j3cub/j3cub_info/piperad.jpg
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The reference datum for measurements is the leading edge of the wing,
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since it is what the weight-and-balance site above uses.
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************************************************************************
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-->
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<!--
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680lb empty weight.
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-->
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<!-- FIXME: this includes the engine; is that correct? -->
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<airplane mass="680">
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<!-- Approach configuration -->
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<approach speed="20" aoa="15">
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<control-setting axis="/controls/throttle[0]" value="0.5"/>
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<control-setting axis="/controls/mixture[0]" value="1.0"/>
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</approach>
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<!-- Cruise configuration -->
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<cruise speed="64" alt="0">
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<control-setting axis="/controls/throttle[0]" value="0.75"/>
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<control-setting axis="/controls/mixture[0]" value="0.75"/>
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<control-setting axis="/controls/elevator" value="0.1"/>
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</cruise>
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<!-- pilot's eyepoint -->
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<cockpit x="-0.23" y="0" z="-0.30"/>
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<fuselage ax="1.37" ay="0" az="-0.71" bx="-4.81" by="0" bz="-0.65"
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width="0.71" taper="0.16" midpoint="0.17"/>
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<!--
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I treat it as a perfectly rectangular wing for now. Note that
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the dihedral is exaggerated to simulate hull-interference effects
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on a high-wing aircraft; once YASim models that properly, the
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angle should be reduced to something like 2 degrees.
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Note that the J3 Cub has no flaps. With a stall speed of 25kt, who
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needs them? From what I've read, the ailerons add lots of drag.
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-->
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<wing x="-0.80" y="0.42" z="0.0" taper="1.0" incidence="2" twist="-2"
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length="4.87" chord="1.60" sweep="0" dihedral="5" camber="0.1">
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<stall aoa="17" width="2" peak="1.5"/>
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<flap0 start=".31" end="0.85" lift="1.5" drag="1.4"/>
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<control-input axis="/controls/aileron" control="FLAP0" split="true"/>
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<control-input axis="/controls/aileron-trim" control="FLAP0" split="true"/>
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<control-output control="FLAP0" side="left"
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prop="/surface-positions/left-aileron-pos-norm"/>
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<control-output control="FLAP0" side="right"
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prop="/surface-positions/right-aileron-pos-norm"/>
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</wing>
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<hstab x="-4.87" y="0.05" z="-0.42" taper="0.8" effectiveness="1.24"
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length="1.49" chord="1.13" sweep="0">
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<stall aoa="16" width="4" peak="1.5"/>
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<flap0 start="0" end="1" lift="1.5" drag="1.2"/>
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<control-input axis="/controls/elevator" control="FLAP0"/>
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<control-input axis="/controls/elevator-trim" control="FLAP0"/>
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<control-output control="FLAP0" prop="/surface-positions/elevator-pos-norm"/>
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</hstab>
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<!-- rudder has to be able to counteract aileron drag -->
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<vstab x="-4.87" y="0" z="-0.65" taper="0.38" effectiveness="2.0"
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length="1.31" chord="1.37" sweep="0" incidence="1.5">
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<stall aoa="16" width="4" peak="1.5"/>
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<flap0 start="0" end="1" lift="2.0" drag="1.2"/>
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<control-input axis="/controls/rudder" control="FLAP0" invert="true"/>
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<control-input axis="/controls/rudder-trim" control="FLAP0" invert="true"/>
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<control-output control="FLAP0" prop="/surface-positions/rudder-pos-norm"
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min="1" max="-1"/>
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</vstab>
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<!-- FIXME: engine mass (just a guess; it's a small engine) -->
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<!-- Assume 75% power at 8000ft -->
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<propeller radius="0.90"
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cruise-speed="70" cruise-rpm="2150"
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cruise-alt="8000" cruise-power="49"
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takeoff-power="55" takeoff-rpm="2300"
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eng-power="65" eng-rpm="2500"
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x="0.71" y="0" z="-0.65" mass="150" moment="4">
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<actionpt x="1.31" y="0" z="-0.65"/>
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<control-input axis="/controls/throttle[0]" control="THROTTLE"/>
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<control-input axis="/controls/starter[0]" control="STARTER"/>
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<control-input axis="/controls/magnetos[0]" control="MAGNETOS"/>
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<control-input axis="/controls/mixture[0]" control="MIXTURE"/>
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</propeller>
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<gear x="-5.17" y="0" z="-0.71" compression="0.1">
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<control-input axis="/controls/rudder" control="STEER"
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src0="-1.0" src1="1.0"
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dst0="0.5" dst1="-0.5"/>
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</gear>
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<gear x="0" y="0.95" z="-1.96" compression="0.01"> <!-- left main -->
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<control-input axis="/controls/brakes[0]" control="BRAKE" split="true"/>
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<control-input axis="/controls/parking-brake" control="BRAKE" split="true"/>
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</gear>
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<gear x="0" y="-0.95" z="-1.96" compression="0.01"> <!-- right main -->
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<control-input axis="/controls/brakes[1]" control="BRAKE" split="true"/>
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<control-input axis="/controls/parking-brake" control="BRAKE" split="true"/>
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</gear>
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<!-- There's just one 12-gallon tank, right behind the engine (!!!) -->
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<tank x="-0.45" y="0" z="-0.89" capacity="72"/>
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<!--
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Note the tandem seating; the x values (arms) come from the
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weight-and-balance page cited at the start.
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-->
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<!-- pilot -->
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<weight x="-0.91" y="0" z="-0.70" mass-prop="/yasim/j3cub/pilot-lb"/>
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<!-- passenger -->
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<weight x="-0.23" y="0" z="-0.70" mass-prop="/yasim/j3cub/passenger-lb"/>
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</airplane>
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