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Lee Elliot:

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I've added reheat to the engines to simulate water injection and then tweaked
it so that it's just about possible to take off with the full fuel load/ferry
configuration (a little under the mtow - 420,000lbs vs 450,000lbs).

It's interesting to note that the normal combat tow for the F model was
291,570lbs - equivilent to a fuel load of about 0.46 (this would actually
leave you with more fuel than in real life because some of that weight would
be the weapons load but here it's fuel)

Anyway, I've added all this info to the readme and explained some of the
reasoning behind the fdm there.

It still doesn't reach the correct altitudes, and certainly not with a full
fuel load, but it starts getting into the right ball park at combat tow.
This commit is contained in:
curt 2003-08-14 18:57:44 +00:00
parent d30cc31ceb
commit 9d5aa83f83
1 changed files with 91 additions and 89 deletions
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180
Aircraft-yasim/b52-yasim.xml
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@ -12,17 +12,6 @@ many of the numbers were obtained either by measuring a h/c
of the 3-view I used as a template for modelling or by reading
them out of my 3d modeller.
I found a reference to the wing incidence, sweep (see the wing
entry in the config) and the layout of the flaps and ailerons
(ailerons are positioned between the two sets of flaps on each
wing) but all the other numbers are guesswork. The X/YB52 had
only two positions for the flaps - up or down, with the down
position being at 35 deg. I found no references to this being
changed in later models. In view of that, although they're
pretty big, I've set the lift to only 1.3 and set extend time
to 35 seconds on the basis that the attitude change as a result
of going from full flaps to zero flaps shouldn't be too great.
The B52s had all moving tailplanes (9 deg up & 4 deg down) and
these cannot be represented correctly using yasim at the moment,
so in that respect this config is definitely a hack.
@ -33,9 +22,7 @@ Lee Elliott. leee-fgfs@spatial.freeserve.co.uk
<airplane mass="173599">
<!-- Approach configuration -->
<!-- Although the approach speed is set to 100 I reccommend that it is
kept above 120, especially if a lot of fuel remains -->
<approach speed="100" aoa="0.5">
<approach speed="100" aoa="1.0">
<control-setting axis="/controls/engines/engine[0]/throttle" value="0.4"/>
<control-setting axis="/controls/engines/engine[1]/throttle" value="0.4"/>
<control-setting axis="/controls/engines/engine[2]/throttle" value="0.4"/>
@ -44,35 +31,50 @@ Lee Elliott. leee-fgfs@spatial.freeserve.co.uk
<control-setting axis="/controls/engines/engine[5]/throttle" value="0.4"/>
<control-setting axis="/controls/engines/engine[6]/throttle" value="0.4"/>
<control-setting axis="/controls/engines/engine[7]/throttle" value="0.4"/>
<control-setting axis="/controls/engines/engine[0]/afterburner" value="0.0"/>
<control-setting axis="/controls/engines/engine[1]/afterburner" value="0.0"/>
<control-setting axis="/controls/engines/engine[2]/afterburner" value="0.0"/>
<control-setting axis="/controls/engines/engine[3]/afterburner" value="0.0"/>
<control-setting axis="/controls/engines/engine[4]/afterburner" value="0.0"/>
<control-setting axis="/controls/engines/engine[5]/afterburner" value="0.0"/>
<control-setting axis="/controls/engines/engine[6]/afterburner" value="0.0"/>
<control-setting axis="/controls/engines/engine[7]/afterburner" value="0.0"/>
<control-setting axis="/controls/flight/flaps" value="1.0"/>
<control-setting axis="/controls/flight/spoilers" value="0.0"/>
<control-setting axis="/controls/gear/gear-down" value="1"/>
</approach>
<!-- Cruise configuration -->
<!-- I found figures of 554 kt @ 21000 ft (max),
495 kt @ 46500 ft (max) and 454 kt cruise (no alt).
<!-- I found the following performance figures
638 mph (554 kt) @ 21000 ft
570 mph (495 kt) @ 46500 ft
523 mph (454 kt) cruising speed (no alt specified)
I found some references that implied that the max speeds were
limited by buffet and flutter and not by engine power i.e. an
E model was fitted with an electronically controlled system
designed to reduce stress on the airframe during low-level
operations and was able to fly 10 knots faster than the speed
at which a normal b52 would have disintegrated due to flutter.
The service ceiling at combat weight (291570 lbs) is 46700 ft and I
assume that's at the cruise speed (454 kt)
With these settings I was able sustain flight at 37,000 ft @ about
520 KTAS. I've been able to achieve greater altitudes but the
speed gradually bleeds off.
I've not been able to get a solution that solves using 495 kt @ 46500 ft
and using the figure of 554 kt @ 21000 ft results in the a/c not being
able to climb nearly high enough so the numbers specified are currently
the best compromise I've found so far.
-->
<cruise speed="554" alt="21000">
<control-setting axis="/controls/engines/engine[0]/throttle" value="0.5"/>
<control-setting axis="/controls/engines/engine[1]/throttle" value="0.5"/>
<control-setting axis="/controls/engines/engine[2]/throttle" value="0.5"/>
<control-setting axis="/controls/engines/engine[3]/throttle" value="0.5"/>
<control-setting axis="/controls/engines/engine[4]/throttle" value="0.5"/>
<control-setting axis="/controls/engines/engine[5]/throttle" value="0.5"/>
<control-setting axis="/controls/engines/engine[6]/throttle" value="0.5"/>
<control-setting axis="/controls/engines/engine[7]/throttle" value="0.5"/>
<control-setting axis="/controls/engines/engine[0]/throttle" value="0.6"/>
<control-setting axis="/controls/engines/engine[1]/throttle" value="0.6"/>
<control-setting axis="/controls/engines/engine[2]/throttle" value="0.6"/>
<control-setting axis="/controls/engines/engine[3]/throttle" value="0.6"/>
<control-setting axis="/controls/engines/engine[4]/throttle" value="0.6"/>
<control-setting axis="/controls/engines/engine[5]/throttle" value="0.6"/>
<control-setting axis="/controls/engines/engine[6]/throttle" value="0.6"/>
<control-setting axis="/controls/engines/engine[7]/throttle" value="0.6"/>
<control-setting axis="/controls/engines/engine[0]/afterburner" value="0.0"/>
<control-setting axis="/controls/engines/engine[1]/afterburner" value="0.0"/>
<control-setting axis="/controls/engines/engine[2]/afterburner" value="0.0"/>
<control-setting axis="/controls/engines/engine[3]/afterburner" value="0.0"/>
<control-setting axis="/controls/engines/engine[4]/afterburner" value="0.0"/>
<control-setting axis="/controls/engines/engine[5]/afterburner" value="0.0"/>
<control-setting axis="/controls/engines/engine[6]/afterburner" value="0.0"/>
<control-setting axis="/controls/engines/engine[7]/afterburner" value="0.0"/>
<control-setting axis="/controls/flight/flaps" value="0.0"/>
<control-setting axis="/controls/flight/spoilers" value="0.0"/>
<control-setting axis="/controls/gear/gear-down" value="0"/>
@ -95,24 +97,25 @@ Lee Elliott. leee-fgfs@spatial.freeserve.co.uk
aileron, which I've located outboard of the flaps.
-->
<wing x="-16.0" y="1.6" z="1.2" taper="0.4" incidence="6"
length="31.1" chord="10.0" sweep="34.5" dihedral="-3.0" camber="0.16">
<stall aoa="18.0" width="2" peak="1.3"/>
<flap0 start="0.0" end="0.62" lift="1.45" drag="1.8"/>
<flap1 start="0.62" end="0.7" lift="1.3" drag="1.2"/>
<spoiler start="0.5" end="0.75" lift="0.0" drag="8.0"/>
length="31.1" chord="10.0" sweep="34.5" dihedral="-1.0" camber="0.16">
<stall aoa="18.0" width="3" peak="1.3"/>
<flap0 start="0.0" end="0.62" lift="1.45" drag="2.2"/>
<flap1 start="0.62" end="0.7" lift="1.3" drag="1.3"/>
<spoiler start="0.5" end="0.75" lift="0.0" drag="1.8"/>
<control-input axis="/controls/flight/flaps" control="FLAP0"/>
<control-input axis="/controls/flight/aileron" control="FLAP1" split="true"/>
<control-input axis="/controls/flight/spoilers" control="SPOILER" split="false"/>
<control-input axis="/controls/flight/spoilers" control="SPOILER"/>
<control-output control="FLAP0" prop="/surface-positions/flap-pos-norm"/>
<control-output control="FLAP0" side="left" prop="/surface-positions/left-flap-pos-norm"/>
<control-output control="FLAP0" side="right" prop="/surface-positions/right-flap-pos-norm"/>
<control-output control="FLAP1" side="left" prop="/surface-positions/left-aileron-pos-norm"/>
<control-output control="FLAP1" side="right" prop="/surface-positions/right-aileron-pos-norm"/>
<control-output control="SPOILER" side="left" prop="/surface-positions/left-spoiler-pos-norm"/>
<control-output control="SPOILER" side="right" prop="/surface-positions/right-spoiler-pos-norm"/>
<control-speed control="FLAP0" transition-time="35"/>
<control-speed control="FLAP1" transition-time="0.3"/>
<control-speed control="FLAP0" transition-time="45"/>
<control-speed control="FLAP1" transition-time="0.5"/>
<control-speed control="SPOILER" transition-time="0.5"/>
</wing>
@ -120,9 +123,9 @@ Lee Elliott. leee-fgfs@spatial.freeserve.co.uk
stall AoA figure.
-->
<hstab x="-41.5" y="1.0" z="0.8" taper="0.25" effectiveness="1.0"
length="7.5" chord="7.5" sweep="40.0" dihedral="0.0">
length="7.5" chord="7.5" sweep="40.0" dihedral="0.0" camber="0.01">
<stall aoa="25.0" width="3" peak="1.5"/>
<flap0 start="0" end="1" lift="1.5" drag="1.2"/>
<flap0 start="0" end="1" lift="1.3" drag="1.4"/>
<control-input axis="/controls/flight/elevator" control="FLAP0"/>
<control-input axis="/controls/flight/elevator-trim" control="FLAP0"/>
<control-output control="FLAP0" prop="/surface-positions/elevator-pos-norm"/>
@ -146,115 +149,114 @@ Lee Elliott. leee-fgfs@spatial.freeserve.co.uk
I couldn't find a weight for the engines and have guessed at 4000lb
-->
<!-- Left wing engines -->
<!-- Left Outer Left -->
<jet x="-23.0" y="20.0" z="-1.0"
mass="4000"
thrust="11200">
<jet x="-23.0" y="20.0" z="-1.0" mass="4000" tsfc="0.7" thrust="11200" afterburner="13500">
<control-input axis="/controls/engines/engine[0]/throttle" control="THROTTLE"/>
<control-input axis="/controls/engines/engine[0]/afterburner" control="REHEAT"/>
</jet>
<!-- Left Outer Right -->
<jet x="-23.0" y="18.0" z="-1.0"
mass="4000"
thrust="11200">
<jet x="-23.0" y="18.0" z="-1.0" mass="4000" tsfc="0.7" thrust="11200" afterburner="13500">
<control-input axis="/controls/engines/engine[1]/throttle" control="THROTTLE"/>
<control-input axis="/controls/engines/engine[0]/afterburner" control="REHEAT"/>
</jet>
<!-- Left Inner Left -->
<jet x="-15.0" y="12.0" z="-1.0"
mass="4000"
thrust="11200">
<jet x="-15.0" y="12.0" z="-1.0" mass="4000" tsfc="0.7" thrust="11200" afterburner="13500">
<control-input axis="/controls/engines/engine[2]/throttle" control="THROTTLE"/>
<control-input axis="/controls/engines/engine[0]/afterburner" control="REHEAT"/>
</jet>
<!-- Left Inner Right -->
<jet x="-15.0" y="10.0" z="-1.0"
mass="4000"
thrust="11200">
<jet x="-15.0" y="10.0" z="-1.0" mass="4000" tsfc="0.7" thrust="11200" afterburner="13500">
<control-input axis="/controls/engines/engine[3]/throttle" control="THROTTLE"/>
<control-input axis="/controls/engines/engine[0]/afterburner" control="REHEAT"/>
</jet>
<!-- Right wing engines -->
<!-- Right Inner Left -->
<jet x="-15.0" y="-10.0" z="-1.0"
mass="4000"
thrust="11200">
<jet x="-15.0" y="-10.0" z="-1.0" mass="4000" tsfc="0.7" thrust="11200" afterburner="13500">
<control-input axis="/controls/engines/engine[4]/throttle" control="THROTTLE"/>
<control-input axis="/controls/engines/engine[0]/afterburner" control="REHEAT"/>
</jet>
<!-- Right Inner Right -->
<jet x="-15.0" y="-12.0" z="-1.0"
mass="4000"
thrust="11200">
<jet x="-15.0" y="-12.0" z="-1.0" mass="4000" tsfc="0.7" thrust="11200" afterburner="13500">
<control-input axis="/controls/engines/engine[5]/throttle" control="THROTTLE"/>
<control-input axis="/controls/engines/engine[0]/afterburner" control="REHEAT"/>
</jet>
<!-- Right Outer Left -->
<jet x="-23.0" y="-18.0" z="-1.0"
mass="4000"
thrust="11200">
<jet x="-23.0" y="-18.0" z="-1.0" mass="4000" tsfc="0.7" thrust="11200" afterburner="13500">
<control-input axis="/controls/engines/engine[6]/throttle" control="THROTTLE"/>
<control-input axis="/controls/engines/engine[0]/afterburner" control="REHEAT"/>
</jet>
<!-- Right Outer Right -->
<jet x="-23.0" y="-20.0" z="-1.0"
mass="4000"
thrust="11200">
<jet x="-23.0" y="-20.0" z="-1.0" mass="4000" tsfc="0.7" thrust="11200" afterburner="13500">
<control-input axis="/controls/engines/engine[7]/throttle" control="THROTTLE"/>
<control-input axis="/controls/engines/engine[0]/afterburner" control="REHEAT"/>
</jet>
<!-- Landing Gear -->
<!-- Front Left -->
<gear x="-13.2" y="2.0" z="-2.9" retract-time="7" compression="1.0">
<control-input axis="/controls/flight/rudder" control="STEER" square="true"/>
<control-input axis="/controls/gear/gear-down" control="EXTEND"/>
<control-input axis="/controls/gear/gear[0]/wheel[0]/brake" control="BRAKE"/>
<control-input axis="/controls/gear/gear[0]/wheel[1]/brake" control="BRAKE"/>
<control-input axis="/controls/gear/parking-brake" control="BRAKE"/>
<control-speed control="EXTEND" transition-time="7"/>
<control-output control="EXTEND" prop="/gear/gear/position-norm"/>
<control-speed control="BRAKE" transition-time="0.7"/>
<control-output control="EXTEND" prop="/gear/gear[0]/position-norm"/>
</gear>
<!-- Front Right -->
<gear x="-13.2" y="-2.0" z="-2.9" retract-time="7" compression="1.0">
<control-input axis="/controls/flight/rudder" control="STEER" square="true"/>
<control-input axis="/controls/gear/gear-down" control="EXTEND"/>
<control-input axis="/controls/gear/gear[1]/wheel[0]/brake" control="BRAKE"/>
<control-input axis="/controls/gear/gear[1]/wheel[1]/brake" control="BRAKE"/>
<control-input axis="/controls/gear/parking-brake" control="BRAKE"/>
<control-speed control="EXTEND" transition-time="7"/>
<control-output control="EXTEND" prop="/gear/gear/position-norm"/>
<control-speed control="BRAKE" transition-time="0.7"/>
<control-output control="EXTEND" prop="/gear/gear[1]/position-norm"/>
</gear>
<!-- Rear Left -->
<gear x="-28.0" y="2.0" z="-2.9" retract-time="7" compression="1.0">
<control-input axis="/controls/gear/wheel[0]/brake" control="BRAKE"/>
<control-input axis="/controls/gear/parking-brake" control="BRAKE"/>
<control-input axis="/controls/gear/gear-down" control="EXTEND"/>
<control-input axis="/controls/gear/gear[2]/wheel[0]/brake" control="BRAKE"/>
<control-input axis="/controls/gear/gear[2]/wheel[1]/brake" control="BRAKE"/>
<control-input axis="/controls/gear/parking-brake" control="BRAKE"/>
<control-speed control="EXTEND" transition-time="7"/>
<control-output control="EXTEND" prop="/gear/gear/position-norm"/>
<control-speed control="BRAKE" transition-time="0.7"/>
<control-output control="EXTEND" prop="/gear/gear[2]/position-norm"/>
</gear>
<!-- Rear Right -->
<gear x="-28.0" y="-2.0" z="-2.9" retract-time="7" compression="1.0">
<control-input axis="/controls/gears/wheel[0]/brake" control="BRAKE"/>
<control-input axis="/controls/gear/parking-brake" control="BRAKE"/>
<control-input axis="/controls/gear/gear-down" control="EXTEND"/>
<control-input axis="/controls/gear/gear[3]/wheel[0]/brake" control="BRAKE"/>
<control-input axis="/controls/gear/gear[3]/wheel[1]/brake" control="BRAKE"/>
<control-input axis="/controls/gear/parking-brake" control="BRAKE"/>
<control-speed control="EXTEND" transition-time="7"/>
<control-output control="EXTEND" prop="/gear/gear/position-norm"/>
<control-speed control="BRAKE" transition-time="0.7"/>
<control-output control="EXTEND" prop="/gear/gear[3]/position-norm"/>
</gear>
<!-- Left Wing -->
<gear x="-31.0" y="23.0" z="-2.0" retract-time="7" compression="2.5">
<control-input axis="/controls/gear/wheel[0]/brake" control="BRAKE"/>
<control-input axis="/controls/gear/parking-brake" control="BRAKE"/>
<gear x="-31.0" y="23.0" z="-2.0" retract-time="5" compression="2.5">
<control-input axis="/controls/gear/gear-down" control="EXTEND"/>
<control-speed control="EXTEND" transition-time="7"/>
<control-output control="EXTEND" prop="/gear/gear/position-norm"/>
<control-speed control="EXTEND" transition-time="5"/>
<control-output control="EXTEND" prop="/gear/gear[4]/position-norm"/>
</gear>
<!-- Right Wing -->
<gear x="-31.0" y="-23.0" z="-2.0" retract-time="7" compression="2.5">
<control-input axis="/controls/gear/wheel[1]/brake" control="BRAKE"/>
<control-input axis="/controls/gear/parking-brake" control="BRAKE"/>
<gear x="-31.0" y="-23.0" z="-2.0" retract-time="5" compression="2.5">
<control-input axis="/controls/gear/gear-down" control="EXTEND"/>
<control-speed control="EXTEND" transition-time="7"/>
<control-output control="EXTEND" prop="/gear/gear/position-norm"/>
<control-speed control="EXTEND" transition-time="5"/>
<control-output control="EXTEND" prop="/gear/gear[5]/position-norm"/>
</gear>
<!-- Fuel tanks -->
@ -282,6 +284,6 @@ Lee Elliott. leee-fgfs@spatial.freeserve.co.uk
<!-- This is to level the aircraft on the ground
-->
<ballast x="-12.0" y="0" z="0" mass="40000"/>
<ballast x="-4.0" y="0" z="0" mass="20000"/>
</airplane>