Hi Syd,I have tried to adjust the rotor parameters to fit the real heli. Unfortunately I have only very few data for the s76c, therefore I have changed only some geometric data an changed the rpm to get the same tip-speed as the bo. The geometric data is from a poor scaled drawing of the s76c, maybe you have a better drawing and could correct the values for the width of the blade ("chord") and the position of the flapping hinge (rellenflaphinge). I found the airfoil sikorsky is using for the s76, but I did not found drag/lift curves for this airfoil. But I think, that the flight behavior with this parameter set is more realistic than with the parameters in cvs (not as easy to fly as the bo). The sound configuration need some adjustment to the changed rpm (I think, we need other samples).
Maik
Index: S76c.xml =================================================================== RCS file: /var/cvs/FlightGear-0.9/data/Aircraft/Sikorsky-76C/S76c.xml,v retrieving revision 1.2 diff -u -p -r1.2 S76c.xml --- S76c.xml 28 Nov 2006 08:20:26 -0000 1.2 +++ S76c.xml 29 Nov 2006 19:47:48 -0000 @@ -22,12 +22,12 @@ Single Blade : 6.089 m </cruise> -<rotor name="main" x="0.0" y="0.0" z="0" nx="0.05" ny="0" nz="1." fx="1" fy="0" fz="0" ccw="0" +<rotor name="main" x="0.0" y="0.0" z="0" nx="0.10" ny="0" nz="1." fx="1" fy="0" fz="0" ccw="0" maxcollective="15.8" mincollective="0.2" mincyclicele="-4.7" maxcyclicele="10.5" mincyclicail="-4.23" maxcyclicail="5.65" - diameter="13.41" numblades="4" weightperblade="95" relbladecenter="0.5" - dynamic="1" rpm="442" rellenflaphinge="0.18" delta3="0" + diameter="13.41" numblades="4" weightperblade="97" relbladecenter="0.5" + dynamic="1" rpm="330" rellenflaphinge="0.07" delta3="1" delta=".25" pitch-a="10" pitch-b="15" @@ -42,7 +42,7 @@ Single Blade : 6.089 m ground-effect-constant="0.1" twist="-8.5" taper="1" - chord="0.27" + chord="0.32" number-of-segments="8" number-of-parts="8" rel-len-where-incidence-is-measured="0.7" @@ -57,7 +57,7 @@ Single Blade : 6.089 m stall-change-over="5.5" drag-factor-stall="2.0" cyclic-factor="0.8" - rotor-correction-factor="0.7" + rotor-correction-factor="0.85" > <control-input axis="/controls/flight/aileron-trim" control="CYCLICAIL" split="true"/> <control-input axis="/controls/flight/aileron" control="CYCLICAIL" @@ -76,7 +76,7 @@ Single Blade : 6.089 m <rotor name="tail" x="-8.12" y="0.4" z="0.424" nx="0.0" ny="1" nz="0.0" fx="1" fy="0" fz="0" ccw="0" maxcollective="20" mincollective="-10" diameter="2.44" numblades="4" weightperblade="2" relbladecenter="0.7" - dynamic="1" rpm="2219" rellenflaphinge="0.0" delta3="1" translift="0" delta="0.5" + dynamic="1" rpm="1750" rellenflaphinge="0.07" delta3="1" translift="0" delta="0.5" pitch-a="10" pitch-b="15" airfoil-lift-coefficient="6.4" @@ -84,7 +84,7 @@ Single Blade : 6.089 m airfoil-drag-coefficient1="0.10" notorque="0" taper="1" - chord="0.205" + chord="0.23" number-of-segments="5" number-of-parts="4" rel-len-blade-start="0.33"
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