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2003-05-07 01:52:04 +00:00
<?xml version="1.0"?>
<!--
************************************************************************
YASim aerodynamic model for a P-51D mustang
Started 2003-04-24 by Jim Wilson
This aerodynamic model is based on three-views, unauthoritative
performance data, and wild guesses. These sites provided particularly
useful information or were simply fun to visit:
Performance data:
http://www.hq.nasa.gov/office/pao/History/SP-468/app-a2.htm
http://www.olympicflightmuseum.com/aircraft_gallery/p51d_mustang.htm
http://www.btinternet.com/~lee_mail/P51.html
http://www.sprucegoose.org/pdfs/planes/P51Mustang.pdf
Weight and balance:
http://www.p51.wjackparker.com/P51_Additional_reference_material/x_maintenance.htm
http://www.nzfpm.co.nz/aircraft/p51d.htm
http://www.wpafb.af.mil/museum/engines/eng33.htm
Three-view:
http://members.optushome.com.au/gjmustang/docs/3-View.html
(Note: I have local copies if this url becomes un-available)
The reference datum for measurements is the nose.
************************************************************************
-->
<!-- Weight of everything but fuel (7010 empty) -->
<airplane mass="7390">
<!-- Approach configuration -->
Andy Ross's changes: Changes: Fit the solver to the known stall speed instead of an abstract approach configuration. That is, specify stall AoA and speed as "approach" values. At approach weight (20% fuel) I can now just barely hold the aircraft in the air without losing it at 87 kias. Note that the IAS guage seems to have a slight calibration error, it was reading something that looked more like 95 knots; I got the real value out of the property browser. Change the sign of the incidence value for the wing. It specifies a rotation about the axis pointing out the left wing, so positive values are "nose down". Increase the "effectiveness" of the tail surfaces quite a bit. Smaller surfaces do actually need higher values. YASim scales surface force coefficients with their areas, which is correct within a single wing. But between wing-like devides, generated forces kinda/sorta scale linearly with their spans. This is particularly important for tail draggers, since YASim's lack of prop wash modelling needs to be offset by extra elevator authority. Add a camber value to the wing. Most wing airfoils are asymmetric, and produce non-zero lift at zero AoA. I picked 0.1 (10% of stall lift at zero alpha) as a reasonable guess. If someone has airfoil data for the Mustang we could look this up exactly. This was the biggest change, which allows the cruise AoA to be much lower than approach or stall. Reduced the compression value for the tail wheel to 20cm. These things are very stiff; they "compress" only as much as the tires do. Even 0.2 is too much motion, but the numerics tend to go wacky when you give them very high spring coefficients. This helped the ground handling a little bit. Removed the extra damping from the main gear. My impression of tail draggers is that they tend to have "squishy" main gear. Again, this (subjectively) seemed to improve ground handling to me. I also tried reducing the spring constants to 0.5, but that ended up being too squishy -- you could see the ship (stopped on the ground) bank to the left by 2-3° when you pushed the throttle forward. Ground handling is still pretty difficult; I get the best results by holding the tail down until 90 knots or so and then very gently lowering the stick. The aircraft bobs once or twice and then lifts off. I don't think this is proper procedure, though. Andy
2003-05-07 01:53:39 +00:00
<approach speed="87" aoa="13">
<control-setting axis="/controls/engines/engine[0]/throttle" value="0.2"/>
2003-05-07 01:52:04 +00:00
<control-setting axis="/controls/engines/engine[0]/mixture" value="1.0"/>
<control-setting axis="/controls/engines/engine[0]/propeller-pitch" value="0.5"/>
<control-setting axis="/controls/flight/flaps" value="1.0"/>
<control-setting axis="/controls/gear/gear-down" value="1"/>
</approach>
<!-- Cruise configuration -->
<!-- 350 mph, 304 knots -->
<cruise speed="304" alt="25000">
<control-setting axis="/controls/engines/engine[0]/throttle" value="1.00"/>
<control-setting axis="/controls/engines/engine[0]/mixture" value="1.00"/>
<control-setting axis="/controls/engines/engine[0]/propeller-pitch" value="1.0"/>
<control-setting axis="/controls/engines/engine[0]/boost" value="1.0"/>
<control-setting axis="/controls/flight/flaps" value="0.0"/>
<control-setting axis="/controls/gear/gear-down" value="0"/>
</cruise>
<!-- pilot's eyepoint -->
<cockpit x="-4.495" y="0" z="0.689"/>
<fuselage ax="0.0" ay="0.0" az="0.0" bx="-9.9" by="0.0" bz="0.0"
width="0.94" taper="0.14"/>
<!--
stall aoa not available
flap drag not available
-->
Andy Ross's changes: Changes: Fit the solver to the known stall speed instead of an abstract approach configuration. That is, specify stall AoA and speed as "approach" values. At approach weight (20% fuel) I can now just barely hold the aircraft in the air without losing it at 87 kias. Note that the IAS guage seems to have a slight calibration error, it was reading something that looked more like 95 knots; I got the real value out of the property browser. Change the sign of the incidence value for the wing. It specifies a rotation about the axis pointing out the left wing, so positive values are "nose down". Increase the "effectiveness" of the tail surfaces quite a bit. Smaller surfaces do actually need higher values. YASim scales surface force coefficients with their areas, which is correct within a single wing. But between wing-like devides, generated forces kinda/sorta scale linearly with their spans. This is particularly important for tail draggers, since YASim's lack of prop wash modelling needs to be offset by extra elevator authority. Add a camber value to the wing. Most wing airfoils are asymmetric, and produce non-zero lift at zero AoA. I picked 0.1 (10% of stall lift at zero alpha) as a reasonable guess. If someone has airfoil data for the Mustang we could look this up exactly. This was the biggest change, which allows the cruise AoA to be much lower than approach or stall. Reduced the compression value for the tail wheel to 20cm. These things are very stiff; they "compress" only as much as the tires do. Even 0.2 is too much motion, but the numerics tend to go wacky when you give them very high spring coefficients. This helped the ground handling a little bit. Removed the extra damping from the main gear. My impression of tail draggers is that they tend to have "squishy" main gear. Again, this (subjectively) seemed to improve ground handling to me. I also tried reducing the spring constants to 0.5, but that ended up being too squishy -- you could see the ship (stopped on the ground) bank to the left by 2-3° when you pushed the throttle forward. Ground handling is still pretty difficult; I get the best results by holding the tail down until 90 knots or so and then very gently lowering the stick. The aircraft bobs once or twice and then lifts off. I don't think this is proper procedure, though. Andy
2003-05-07 01:53:39 +00:00
<wing x="-3.96" y="0.49" z="-0.67" taper="0.466" incidence="-1"
length="5.16" chord="2.845" sweep="3.5" dihedral="5" camber=".1">
2003-05-07 01:52:04 +00:00
<stall aoa="14" width="4" peak="1.5"/>
<flap0 start="0.024" end="0.543" lift="1.2" drag="1.4"/>
<flap1 start="0.543" end="0.97" lift="1.2" drag="1.4"/>
<control-input axis="/controls/flight/flaps" control="FLAP0"/>
<control-output control="FLAP0" prop="/surface-positions/flap-pos-norm"/>
<control-speed control="FLAP0" transition-time="5"/>
<control-input axis="/controls/flight/aileron" control="FLAP1" split="true"/>
<control-input axis="/controls/flight/aileron-trim" control="FLAP1" split="true"/>
</wing>
Andy Ross's changes: Changes: Fit the solver to the known stall speed instead of an abstract approach configuration. That is, specify stall AoA and speed as "approach" values. At approach weight (20% fuel) I can now just barely hold the aircraft in the air without losing it at 87 kias. Note that the IAS guage seems to have a slight calibration error, it was reading something that looked more like 95 knots; I got the real value out of the property browser. Change the sign of the incidence value for the wing. It specifies a rotation about the axis pointing out the left wing, so positive values are "nose down". Increase the "effectiveness" of the tail surfaces quite a bit. Smaller surfaces do actually need higher values. YASim scales surface force coefficients with their areas, which is correct within a single wing. But between wing-like devides, generated forces kinda/sorta scale linearly with their spans. This is particularly important for tail draggers, since YASim's lack of prop wash modelling needs to be offset by extra elevator authority. Add a camber value to the wing. Most wing airfoils are asymmetric, and produce non-zero lift at zero AoA. I picked 0.1 (10% of stall lift at zero alpha) as a reasonable guess. If someone has airfoil data for the Mustang we could look this up exactly. This was the biggest change, which allows the cruise AoA to be much lower than approach or stall. Reduced the compression value for the tail wheel to 20cm. These things are very stiff; they "compress" only as much as the tires do. Even 0.2 is too much motion, but the numerics tend to go wacky when you give them very high spring coefficients. This helped the ground handling a little bit. Removed the extra damping from the main gear. My impression of tail draggers is that they tend to have "squishy" main gear. Again, this (subjectively) seemed to improve ground handling to me. I also tried reducing the spring constants to 0.5, but that ended up being too squishy -- you could see the ship (stopped on the ground) bank to the left by 2-3° when you pushed the throttle forward. Ground handling is still pretty difficult; I get the best results by holding the tail down until 90 knots or so and then very gently lowering the stick. The aircraft bobs once or twice and then lifts off. I don't think this is proper procedure, though. Andy
2003-05-07 01:53:39 +00:00
<hstab x="-8.62" y="0.18" z="0.35" taper="0.639" effectiveness="4.0"
2003-05-07 01:52:04 +00:00
length="1.834" chord="1.256" sweep="0" incidence="2">
<stall aoa="15" width="4" peak="1.5"/>
Andy Ross's changes: Changes: Fit the solver to the known stall speed instead of an abstract approach configuration. That is, specify stall AoA and speed as "approach" values. At approach weight (20% fuel) I can now just barely hold the aircraft in the air without losing it at 87 kias. Note that the IAS guage seems to have a slight calibration error, it was reading something that looked more like 95 knots; I got the real value out of the property browser. Change the sign of the incidence value for the wing. It specifies a rotation about the axis pointing out the left wing, so positive values are "nose down". Increase the "effectiveness" of the tail surfaces quite a bit. Smaller surfaces do actually need higher values. YASim scales surface force coefficients with their areas, which is correct within a single wing. But between wing-like devides, generated forces kinda/sorta scale linearly with their spans. This is particularly important for tail draggers, since YASim's lack of prop wash modelling needs to be offset by extra elevator authority. Add a camber value to the wing. Most wing airfoils are asymmetric, and produce non-zero lift at zero AoA. I picked 0.1 (10% of stall lift at zero alpha) as a reasonable guess. If someone has airfoil data for the Mustang we could look this up exactly. This was the biggest change, which allows the cruise AoA to be much lower than approach or stall. Reduced the compression value for the tail wheel to 20cm. These things are very stiff; they "compress" only as much as the tires do. Even 0.2 is too much motion, but the numerics tend to go wacky when you give them very high spring coefficients. This helped the ground handling a little bit. Removed the extra damping from the main gear. My impression of tail draggers is that they tend to have "squishy" main gear. Again, this (subjectively) seemed to improve ground handling to me. I also tried reducing the spring constants to 0.5, but that ended up being too squishy -- you could see the ship (stopped on the ground) bank to the left by 2-3° when you pushed the throttle forward. Ground handling is still pretty difficult; I get the best results by holding the tail down until 90 knots or so and then very gently lowering the stick. The aircraft bobs once or twice and then lifts off. I don't think this is proper procedure, though. Andy
2003-05-07 01:53:39 +00:00
<flap0 start="0.0" end="1.8" lift="1.65" drag="1.2"/>
2003-05-07 01:52:04 +00:00
<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"/>
</hstab>
<!-- rudder has to be able to counteract aileron drag -->
Andy Ross's changes: Changes: Fit the solver to the known stall speed instead of an abstract approach configuration. That is, specify stall AoA and speed as "approach" values. At approach weight (20% fuel) I can now just barely hold the aircraft in the air without losing it at 87 kias. Note that the IAS guage seems to have a slight calibration error, it was reading something that looked more like 95 knots; I got the real value out of the property browser. Change the sign of the incidence value for the wing. It specifies a rotation about the axis pointing out the left wing, so positive values are "nose down". Increase the "effectiveness" of the tail surfaces quite a bit. Smaller surfaces do actually need higher values. YASim scales surface force coefficients with their areas, which is correct within a single wing. But between wing-like devides, generated forces kinda/sorta scale linearly with their spans. This is particularly important for tail draggers, since YASim's lack of prop wash modelling needs to be offset by extra elevator authority. Add a camber value to the wing. Most wing airfoils are asymmetric, and produce non-zero lift at zero AoA. I picked 0.1 (10% of stall lift at zero alpha) as a reasonable guess. If someone has airfoil data for the Mustang we could look this up exactly. This was the biggest change, which allows the cruise AoA to be much lower than approach or stall. Reduced the compression value for the tail wheel to 20cm. These things are very stiff; they "compress" only as much as the tires do. Even 0.2 is too much motion, but the numerics tend to go wacky when you give them very high spring coefficients. This helped the ground handling a little bit. Removed the extra damping from the main gear. My impression of tail draggers is that they tend to have "squishy" main gear. Again, this (subjectively) seemed to improve ground handling to me. I also tried reducing the spring constants to 0.5, but that ended up being too squishy -- you could see the ship (stopped on the ground) bank to the left by 2-3° when you pushed the throttle forward. Ground handling is still pretty difficult; I get the best results by holding the tail down until 90 knots or so and then very gently lowering the stick. The aircraft bobs once or twice and then lifts off. I don't think this is proper procedure, though. Andy
2003-05-07 01:53:39 +00:00
<vstab x="-9.30" y="0" z="-0.37" taper="0.432" effectiveness="4.0"
2003-05-07 01:52:04 +00:00
length="1.971" chord="2.65" sweep="25">
<stall aoa="15" width="4" peak="1.5"/>
<flap0 start="0" end="1" lift="1.3" drag="1.2"/>
<control-input axis="/controls/flight/rudder" control="FLAP0" invert="true"/>
<control-input axis="/controls/flight/rudder-trim" control="FLAP0" invert="true"/>
<control-output control="FLAP0" prop="/surface-positions/rudder-pos-norm"
min="1" max="-1"/>
</vstab>
<propeller x="-0.75" y="0" z="0"
radius="1.75"
mass="1690" moment="110"
eng-power="1490" eng-rpm="2300"
turbo-mul="2.0" wastegate-mp="47"
cruise-alt="25000" cruise-power="1350"
cruise-speed="304" cruise-rpm="2700"
min-rpm="800" max-rpm="3000" >
<actionpt x="-1.25" y="0" z="0"/>
<control-input axis="/controls/engines/engine[0]/throttle" control="THROTTLE"/>
<control-input axis="/controls/engines/engine[0]/starter" control="STARTER"/>
<control-input axis="/controls/engines/engine[0]/magnetos" control="MAGNETOS"/>
<control-input axis="/controls/engines/engine[0]/mixture" control="MIXTURE"/>
<control-input axis="/controls/engines/engine[0]/propeller-pitch" control="ADVANCE"/>
<control-input axis="/controls/engines/engine[0]/boost" control="BOOST"/>
</propeller>
Andy Ross's changes: Changes: Fit the solver to the known stall speed instead of an abstract approach configuration. That is, specify stall AoA and speed as "approach" values. At approach weight (20% fuel) I can now just barely hold the aircraft in the air without losing it at 87 kias. Note that the IAS guage seems to have a slight calibration error, it was reading something that looked more like 95 knots; I got the real value out of the property browser. Change the sign of the incidence value for the wing. It specifies a rotation about the axis pointing out the left wing, so positive values are "nose down". Increase the "effectiveness" of the tail surfaces quite a bit. Smaller surfaces do actually need higher values. YASim scales surface force coefficients with their areas, which is correct within a single wing. But between wing-like devides, generated forces kinda/sorta scale linearly with their spans. This is particularly important for tail draggers, since YASim's lack of prop wash modelling needs to be offset by extra elevator authority. Add a camber value to the wing. Most wing airfoils are asymmetric, and produce non-zero lift at zero AoA. I picked 0.1 (10% of stall lift at zero alpha) as a reasonable guess. If someone has airfoil data for the Mustang we could look this up exactly. This was the biggest change, which allows the cruise AoA to be much lower than approach or stall. Reduced the compression value for the tail wheel to 20cm. These things are very stiff; they "compress" only as much as the tires do. Even 0.2 is too much motion, but the numerics tend to go wacky when you give them very high spring coefficients. This helped the ground handling a little bit. Removed the extra damping from the main gear. My impression of tail draggers is that they tend to have "squishy" main gear. Again, this (subjectively) seemed to improve ground handling to me. I also tried reducing the spring constants to 0.5, but that ended up being too squishy -- you could see the ship (stopped on the ground) bank to the left by 2-3° when you pushed the throttle forward. Ground handling is still pretty difficult; I get the best results by holding the tail down until 90 knots or so and then very gently lowering the stick. The aircraft bobs once or twice and then lifts off. I don't think this is proper procedure, though. Andy
2003-05-07 01:53:39 +00:00
<!-- Tail wheel -->
<gear x="-7.90" y="0" z="-1.03" compression="0.2">
2003-05-07 01:52:04 +00:00
</gear>
<!-- left main -->
Andy Ross's changes: Changes: Fit the solver to the known stall speed instead of an abstract approach configuration. That is, specify stall AoA and speed as "approach" values. At approach weight (20% fuel) I can now just barely hold the aircraft in the air without losing it at 87 kias. Note that the IAS guage seems to have a slight calibration error, it was reading something that looked more like 95 knots; I got the real value out of the property browser. Change the sign of the incidence value for the wing. It specifies a rotation about the axis pointing out the left wing, so positive values are "nose down". Increase the "effectiveness" of the tail surfaces quite a bit. Smaller surfaces do actually need higher values. YASim scales surface force coefficients with their areas, which is correct within a single wing. But between wing-like devides, generated forces kinda/sorta scale linearly with their spans. This is particularly important for tail draggers, since YASim's lack of prop wash modelling needs to be offset by extra elevator authority. Add a camber value to the wing. Most wing airfoils are asymmetric, and produce non-zero lift at zero AoA. I picked 0.1 (10% of stall lift at zero alpha) as a reasonable guess. If someone has airfoil data for the Mustang we could look this up exactly. This was the biggest change, which allows the cruise AoA to be much lower than approach or stall. Reduced the compression value for the tail wheel to 20cm. These things are very stiff; they "compress" only as much as the tires do. Even 0.2 is too much motion, but the numerics tend to go wacky when you give them very high spring coefficients. This helped the ground handling a little bit. Removed the extra damping from the main gear. My impression of tail draggers is that they tend to have "squishy" main gear. Again, this (subjectively) seemed to improve ground handling to me. I also tried reducing the spring constants to 0.5, but that ended up being too squishy -- you could see the ship (stopped on the ground) bank to the left by 2-3° when you pushed the throttle forward. Ground handling is still pretty difficult; I get the best results by holding the tail down until 90 knots or so and then very gently lowering the stick. The aircraft bobs once or twice and then lifts off. I don't think this is proper procedure, though. Andy
2003-05-07 01:53:39 +00:00
<gear x="-2.79" y="1.81" z="-2.20" compression="0.8" spring="1.0">
2003-05-07 01:52:04 +00:00
<control-input axis="/controls/gear/wheel[0]/brake" control="BRAKE"/>
<control-input axis="/controls/gear/parking-brake" control="BRAKE" split="true"/>
<control-input axis="/controls/gear/gear-down" control="EXTEND"/>
<control-speed control="EXTEND" transition-time="6"/>
<control-output control="EXTEND" prop="/gear/gear[0]/position-norm"/>
</gear>
<!-- right main -->
Andy Ross's changes: Changes: Fit the solver to the known stall speed instead of an abstract approach configuration. That is, specify stall AoA and speed as "approach" values. At approach weight (20% fuel) I can now just barely hold the aircraft in the air without losing it at 87 kias. Note that the IAS guage seems to have a slight calibration error, it was reading something that looked more like 95 knots; I got the real value out of the property browser. Change the sign of the incidence value for the wing. It specifies a rotation about the axis pointing out the left wing, so positive values are "nose down". Increase the "effectiveness" of the tail surfaces quite a bit. Smaller surfaces do actually need higher values. YASim scales surface force coefficients with their areas, which is correct within a single wing. But between wing-like devides, generated forces kinda/sorta scale linearly with their spans. This is particularly important for tail draggers, since YASim's lack of prop wash modelling needs to be offset by extra elevator authority. Add a camber value to the wing. Most wing airfoils are asymmetric, and produce non-zero lift at zero AoA. I picked 0.1 (10% of stall lift at zero alpha) as a reasonable guess. If someone has airfoil data for the Mustang we could look this up exactly. This was the biggest change, which allows the cruise AoA to be much lower than approach or stall. Reduced the compression value for the tail wheel to 20cm. These things are very stiff; they "compress" only as much as the tires do. Even 0.2 is too much motion, but the numerics tend to go wacky when you give them very high spring coefficients. This helped the ground handling a little bit. Removed the extra damping from the main gear. My impression of tail draggers is that they tend to have "squishy" main gear. Again, this (subjectively) seemed to improve ground handling to me. I also tried reducing the spring constants to 0.5, but that ended up being too squishy -- you could see the ship (stopped on the ground) bank to the left by 2-3° when you pushed the throttle forward. Ground handling is still pretty difficult; I get the best results by holding the tail down until 90 knots or so and then very gently lowering the stick. The aircraft bobs once or twice and then lifts off. I don't think this is proper procedure, though. Andy
2003-05-07 01:53:39 +00:00
<gear x="-2.79" y="-1.81" z="-2.20" compression="0.8" spring="1.0">
2003-05-07 01:52:04 +00:00
<control-input axis="/controls/gear/wheel[1]/brake" control="BRAKE"/>
<control-input axis="/controls/gear/parking-brake" control="BRAKE" split="true"/>
<control-input axis="/controls/gear/gear-down" control="EXTEND"/>
<control-speed control="EXTEND" transition-time="6"/>
<control-output control="EXTEND" prop="/gear/gear[1]/position-norm"/>
</gear>
<!-- Guess on wing tank positions -->
<tank x="-3.20" y="1.0" z="-0.61" capacity="726"/>
<tank x="-3.20" y="-1.0" z="-0.61" capacity="726"/>
<tank x="-5.00" y="0" z="0" capacity="671"/>
<!-- pilot -->
<ballast x="-4.495" y="0" z="0.689" mass="180"/>
<!-- armament -->
<!-- Had too much weight I think...disable until stall speed fixed
<ballast x="-3.20" y="0.7" z="-0.60" mass="800"/>
<ballast x="-3.20" y="-0.7" z="-0.60" mass="800"/>
-->
<!-- prop -->
<!--
<ballast x="0.1" y="0" z="0.0" mass="200"/>
-->
</airplane>