Hi Syd,I have added Wims information about blade geometry and rpm data to the xml file and changed some rotor parameters to meet the overall performance (I have no details about the airfoil sikorsky is using). Furthermore I have reduced the cyclic control. A problem is the cg. It is 50cm below the rotor disk, what is probably a much to small value. As a first small step I have placed the co-pilot below the rotor.
Best regards, Maik wim van hoydonck schrieb am 30.11.2006 10:32:
Hi, The following data is taken from Janes (S76c): Powerplant: 2 turbomeca Arriel 2S1 turboshafts with FADEC - each rated at 638 kW (856 shp) for take-off, - 731 kW (980 shp) OEI for 30 seconds, - 592 kW (794 shp) max continuous Standard fuel capacity: - 1083 litres of which 1064 litres are usable, - optional auxiliary tank capacity 405 litres Dimensions: - MR diameter: 13.41 m - MR blade chord: 0.39m - TR diameter: 2.44 m - TR blade chord: 0.16 m - MR tip speed (prouty) : 205.74 m/s -> rpm = 292.8 Performance: - Vnever exceed and max level speed: 155 kt (287 km/h) - Max range cruising speed: 140 kt (259 km/h) - rate of climb at S/L: 495 m (1625 ft)/ min - service ceiling: 3871 m - service ceiling, OEI: 975 m - hovering ceiling IGE: 1722 m - hovering ceiling OGE: 549 m - range at 140 kt at FL40, standard fuel: - no reserves: 439 n miles (813 km) I hope this is of any use. Greetings, Wim On 11/29/06, Maik Justus <[EMAIL PROTECTED]> wrote: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 2 Dec 2006 15:14:58 -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" + mincyclicele="-3" maxcyclicele="8" + mincyclicail="-3" maxcyclicail="4" + diameter="13.41" numblades="4" weightperblade="97" relbladecenter="0.5" + dynamic="1" rpm="293" 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="0.39" 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="1.1" > <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="0.16" number-of-segments="5" number-of-parts="4" rel-len-blade-start="0.33" @@ -166,7 +166,7 @@ Single Blade : 6.089 m <tank x="0" y="0" z="0" capacity="0"/> <weight x="2.2" y="0.0" z="-2" mass-prop="/sim/weight[0]/weight-lb"/> <!-- pilot --> -<weight x="-0.9" y="0.0" z="2" mass-prop="/sim/weight[1]/weight-lb"/> <!-- co-pilot --> +<weight x="-0.9" y="0.0" z="-2" mass-prop="/sim/weight[1]/weight-lb"/> <!-- co-pilot --> <ballast x="-0.05" y="0.0" z="-0.5" mass="1200"/> <ballast x="4.5" y="0.0" z="-1.9" mass="500"/>
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