3ca5b27927
here's an update to the b52 - it's just some relatively minor changes to the fdm and panels. I've been trying to improve the take-off and landing characteristics, or at least get them to fit the pictures and film I've seen. The best way to take off is by using the autopilot - at sea level just extend the flaps, punch in the altitude hold on the autopilot (and heading if you're lazy), and apply full power. It'll also take of with the default the default elevator trim of -0.07 but it 'staircases' a little bit - the auto pilot smooths that out. I've included some notes and observations about taking-off and landing in the readme. While I wouldn't claim any sort of accuracy for it, I hope it manages to get some of the characteristics right.
283 lines
12 KiB
XML
Executable file
283 lines
12 KiB
XML
Executable file
<!-- B52-F yasim config.
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Notes.
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B-52F with full fuel load, no weapon load.
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This config cannot be regarded as an accurate representation
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of a B-52F. I've used the real numbers, where I've been able
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to find them, but a lot of this config is semi-educated
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guesswork. I think all the bits are in the right places but
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many of the numbers were obtained either by measuring a h/c
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of the 3-view I used as a template for modelling or by reading
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them out of my 3d modeller.
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I found a reference to the wing incidence, sweep (see the wing
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entry in the config) and the layout of the flaps and ailerons
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(ailerons are positioned between the two sets of flaps on each
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wing) but all the other numbers are guesswork. The X/YB52 had
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only two positions for the flaps - up or down, with the down
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position being at 35 deg. I found no references to this being
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changed in later models. In view of that, although they're
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pretty big, I've set the lift to only 1.3 and set extend time
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to 35 seconds on the basis that the attitude change as a result
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of going from full flaps to zero flaps shouldn't be too great.
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The B52s had all moving tailplanes (9 deg up & 4 deg down) and
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these cannot be represented correctly using yasim at the moment,
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so in that respect this config is definitely a hack.
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Lee Elliott. leee-fgfs@spatial.freeserve.co.uk
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-->
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<airplane mass="173599">
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<!-- Approach configuration -->
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<!-- Although the approach speed is set to 100 I reccommend that it is
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kept above 120, especially if a lot of fuel remains -->
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<approach speed="100" aoa="0.5">
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<control-setting axis="/controls/engines/engine[0]/throttle" value="0.4"/>
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<control-setting axis="/controls/engines/engine[1]/throttle" value="0.4"/>
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<control-setting axis="/controls/engines/engine[2]/throttle" value="0.4"/>
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<control-setting axis="/controls/engines/engine[3]/throttle" value="0.4"/>
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<control-setting axis="/controls/engines/engine[4]/throttle" value="0.4"/>
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<control-setting axis="/controls/engines/engine[5]/throttle" value="0.4"/>
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<control-setting axis="/controls/engines/engine[6]/throttle" value="0.4"/>
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<control-setting axis="/controls/engines/engine[7]/throttle" value="0.4"/>
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<control-setting axis="/controls/flight/flaps" value="1.0"/>
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<control-setting axis="/controls/flight/spoilers" value="0.0"/>
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<control-setting axis="/controls/gear/gear-down" value="1"/>
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</approach>
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<!-- Cruise configuration -->
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<!-- I found figures of 554 kt @ 21000 ft (max),
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495 kt @ 46500 ft (max) and 454 kt cruise (no alt).
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I found some references that implied that the max speeds were
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limited by buffet and flutter and not by engine power i.e. an
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E model was fitted with an electronically controlled system
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designed to reduce stress on the airframe during low-level
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operations and was able to fly 10 knots faster than the speed
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at which a normal b52 would have disintegrated due to flutter.
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With these settings I was able sustain flight at 37,000 ft @ about
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520 KTAS. I've been able to achieve greater altitudes but the
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speed gradually bleeds off.
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-->
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<cruise speed="554" alt="21000">
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<control-setting axis="/controls/engines/engine[0]/throttle" value="0.5"/>
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<control-setting axis="/controls/engines/engine[1]/throttle" value="0.5"/>
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<control-setting axis="/controls/engines/engine[2]/throttle" value="0.5"/>
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<control-setting axis="/controls/engines/engine[3]/throttle" value="0.5"/>
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<control-setting axis="/controls/engines/engine[4]/throttle" value="0.5"/>
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<control-setting axis="/controls/engines/engine[5]/throttle" value="0.5"/>
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<control-setting axis="/controls/engines/engine[6]/throttle" value="0.5"/>
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<control-setting axis="/controls/engines/engine[7]/throttle" value="0.5"/>
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<control-setting axis="/controls/flight/flaps" value="0.0"/>
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<control-setting axis="/controls/flight/spoilers" value="0.0"/>
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<control-setting axis="/controls/gear/gear-down" value="0"/>
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</cruise>
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<cockpit x="-2.2" y="0.0" z="2.0"/>
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<fuselage ax="0" ay="0" az="0" bx="-49.05" by="0" bz=".64"
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width="3.2" taper="0.5" midpoint="0.3"/>
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<!-- Wing incidence was set at 6 degrees because the tandem u/c meant
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that the aircraft couldn't rotate in the conventional fashion. I
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found lots of references to the sweep angle of 35 degrees but
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none of them stated the chord point for it i.e. leading edge or
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quarter-chord. As yasim uses mid-chord I've subtracted 0.5 degree
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as a fudge factor.
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Yasim also only allows for one [real] flap entry per wing so I've
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used a single spane but reduced it's length by the width of the
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aileron, which I've located outboard of the flaps.
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-->
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<wing x="-16.0" y="1.6" z="1.2" taper="0.4" incidence="6"
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length="31.1" chord="10.0" sweep="34.5" dihedral="-3.0" camber="0.16">
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<stall aoa="18.0" width="2" peak="1.3"/>
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<flap0 start="0.0" end="0.62" lift="1.45" drag="1.8"/>
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<flap1 start="0.62" end="0.7" lift="1.3" drag="1.2"/>
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<spoiler start="0.5" end="0.75" lift="0.0" drag="8.0"/>
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<control-input axis="/controls/flight/flaps" control="FLAP0"/>
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<control-input axis="/controls/flight/aileron" control="FLAP1" split="true"/>
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<control-input axis="/controls/flight/spoilers" control="SPOILER" split="false"/>
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<control-output control="FLAP0" prop="/surface-positions/flap-pos-norm"/>
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<control-output control="FLAP1" side="left" prop="/surface-positions/left-aileron-pos-norm"/>
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<control-output control="FLAP1" side="right" prop="/surface-positions/right-aileron-pos-norm"/>
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<control-output control="SPOILER" side="left" prop="/surface-positions/left-spoiler-pos-norm"/>
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<control-output control="SPOILER" side="right" prop="/surface-positions/right-spoiler-pos-norm"/>
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<control-speed control="FLAP0" transition-time="35"/>
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<control-speed control="FLAP1" transition-time="0.3"/>
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<control-speed control="SPOILER" transition-time="0.5"/>
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</wing>
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<!-- The hstab/elevators are nearly deltas ao I've given them a high
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stall AoA figure.
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-->
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<hstab x="-41.5" y="1.0" z="0.8" taper="0.25" effectiveness="1.0"
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length="7.5" chord="7.5" sweep="40.0" dihedral="0.0">
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<stall aoa="25.0" width="3" 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/flight/elevator" control="FLAP0"/>
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<control-input axis="/controls/flight/elevator-trim" control="FLAP0"/>
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<control-output control="FLAP0" prop="/surface-positions/elevator-pos-norm"/>
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<control-speed control="FLAP0" transition-time="0.5"/>
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</hstab>
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<vstab x="-41.5" y="0" z="2.0" taper="0.4"
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length="8.5" chord="7.5" sweep="35.0">
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<stall aoa="20.0" width="3" peak="1.5"/>
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<flap0 start="0" end="1" lift="1.15" drag="1.3"/>
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<control-input axis="/controls/flight/rudder" control="FLAP0" invert="true"/>
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<control-output control="FLAP0" prop="/surface-positions/rudder-pos-norm"/>
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</vstab>
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<!-- Engine entries -->
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<!-- I've used the dry thrust rating of the J57-P-43WA turbojet (11200 lb)
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here instead of the wet-thrust (13500 lb). This will make take offs a
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little more sluggish but is about equivilent of a B-52B with wet-thrust.
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This model is a little heavier though.
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I couldn't find a weight for the engines and have guessed at 4000lb
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-->
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<!-- Left wing engines -->
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<!-- Left Outer Left -->
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<jet x="-23.0" y="20.0" z="-1.0"
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mass="4000"
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thrust="11200">
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<control-input axis="/controls/engines/engine[0]/throttle" control="THROTTLE"/>
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</jet>
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<!-- Left Outer Right -->
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<jet x="-23.0" y="18.0" z="-1.0"
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mass="4000"
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thrust="11200">
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<control-input axis="/controls/engines/engine[1]/throttle" control="THROTTLE"/>
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</jet>
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<!-- Left Inner Left -->
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<jet x="-15.0" y="12.0" z="-1.0"
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mass="4000"
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thrust="11200">
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<control-input axis="/controls/engines/engine[2]/throttle" control="THROTTLE"/>
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</jet>
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<!-- Left Inner Right -->
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<jet x="-15.0" y="10.0" z="-1.0"
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mass="4000"
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thrust="11200">
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<control-input axis="/controls/engines/engine[3]/throttle" control="THROTTLE"/>
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</jet>
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<!-- Right wing engines -->
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<!-- Right Inner Left -->
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<jet x="-15.0" y="-10.0" z="-1.0"
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mass="4000"
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thrust="11200">
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<control-input axis="/controls/engines/engine[4]/throttle" control="THROTTLE"/>
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</jet>
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<!-- Right Inner Right -->
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<jet x="-15.0" y="-12.0" z="-1.0"
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mass="4000"
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thrust="11200">
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<control-input axis="/controls/engines/engine[5]/throttle" control="THROTTLE"/>
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</jet>
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<!-- Right Outer Left -->
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<jet x="-23.0" y="-18.0" z="-1.0"
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mass="4000"
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thrust="11200">
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<control-input axis="/controls/engines/engine[6]/throttle" control="THROTTLE"/>
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</jet>
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<!-- Right Outer Right -->
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<jet x="-23.0" y="-20.0" z="-1.0"
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mass="4000"
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thrust="11200">
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<control-input axis="/controls/engines/engine[7]/throttle" control="THROTTLE"/>
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</jet>
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<!-- Front Left -->
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<gear x="-13.2" y="2.0" z="-2.9" retract-time="7" compression="1.0">
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<control-input axis="/controls/flight/rudder" control="STEER" square="true"/>
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<control-input axis="/controls/gear/gear-down" control="EXTEND"/>
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<control-speed control="EXTEND" transition-time="7"/>
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<control-output control="EXTEND" prop="/gear/gear/position-norm"/>
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</gear>
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<!-- Front Right -->
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<gear x="-13.2" y="-2.0" z="-2.9" retract-time="7" compression="1.0">
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<control-input axis="/controls/flight/rudder" control="STEER" square="true"/>
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<control-input axis="/controls/gear/gear-down" control="EXTEND"/>
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<control-speed control="EXTEND" transition-time="7"/>
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<control-output control="EXTEND" prop="/gear/gear/position-norm"/>
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</gear>
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<!-- Rear Left -->
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<gear x="-28.0" y="2.0" z="-2.9" retract-time="7" compression="1.0">
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<control-input axis="/controls/gear/wheel[0]/brake" control="BRAKE"/>
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<control-input axis="/controls/gear/gear-down" control="EXTEND"/>
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<control-speed control="EXTEND" transition-time="7"/>
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<control-output control="EXTEND" prop="/gear/gear/position-norm"/>
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</gear>
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<!-- Rear Right -->
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<gear x="-28.0" y="-2.0" z="-2.9" retract-time="7" compression="1.0">
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<control-input axis="/controls/gears/wheel[0]/brake" control="BRAKE"/>
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<control-input axis="/controls/gear/gear-down" control="EXTEND"/>
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<control-speed control="EXTEND" transition-time="7"/>
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<control-output control="EXTEND" prop="/gear/gear/position-norm"/>
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</gear>
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<!-- Left Wing -->
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<gear x="-31.0" y="23.0" z="-2.0" retract-time="7" compression="2.5">
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<control-input axis="/controls/gear/wheel[0]/brake" control="BRAKE"/>
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<control-input axis="/controls/gear/gear-down" control="EXTEND"/>
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<control-speed control="EXTEND" transition-time="7"/>
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<control-output control="EXTEND" prop="/gear/gear/position-norm"/>
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</gear>
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<!-- Right Wing -->
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<gear x="-31.0" y="-23.0" z="-2.0" retract-time="7" compression="2.5">
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<control-input axis="/controls/gear/wheel[1]/brake" control="BRAKE"/>
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<control-input axis="/controls/gear/gear-down" control="EXTEND"/>
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<control-speed control="EXTEND" transition-time="7"/>
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<control-output control="EXTEND" prop="/gear/gear/position-norm"/>
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</gear>
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<!-- Fuel tanks -->
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<!-- Total fuel for the F model was 41553 gal incl the external tanks
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There are a total of ten internal tanks, three located in the wings
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and four along the top of the fuselage above the bomb bay. I don't
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know what percentage was held in the wings vs. the fuselage but I'm
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guessing that more was held in the fuselage tank than half of the
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wing tank total.
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There are also two external wing tanks holding 3000 gal each.
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fgfs seems to convert gal to lbs using a ratio of 1:6 giving a total
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of 249318 lb of fuel, of which 18000 lb are in each external tank.
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That leaves 213318 of fuel to be distributed in the wings and
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fuselage.
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-->
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<tank x="-20.0" y="10.0" z="2.0" capacity="70000"/>
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<tank x="-20.0" y="-10.0" z="2.0" capacity="70000"/>
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<tank x="-20.0" y="0.0" z="2.3" capacity="73318"/>
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<tank x="-30.0" y="28.0" z="1.5" capacity="18000"/>
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<tank x="-30.0" y="-28.0" z="1.5" capacity="18000"/>
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<!-- This is to level the aircraft on the ground
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-->
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<ballast x="-12.0" y="0" z="0" mass="40000"/>
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</airplane>
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