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fgdata/Aircraft-yasim/seahawk-WV908-yasim.xml
curt 22b63476ff Lee Elliott: 
I've done a new Sea Hawk.  Well, the model and the fdm aren't new, just
slightly modified, but I've incorporated some more animation stuff and tried
a different way of texturing it.

The animation additions are things I worked out for the YF23 (still can't get
it to fly again) - mostly u/c related stuff.

This actual aircraft (WV908) is in the Royal Navy Historical Flight and so is
kept unusally clean;)  In the photographs I looked at, hardly any fuseage
panel lines were visible so I've not tried to include any.  Instead of the
normal fuselage side views and wing plan textures I've just used fairly
high-res detail 'patches' for the markings, applied to 'carrier' objects.

This is much more like the way I'd do things if I was working on a picture in
my 3d software - there I'd apply multiple textures to an object, as required,
using scope and priority settings to get what I want.  With .ac format models
you can only apply a single texture to an object - hence the need for the
carrier objects.  These are sections of the underlying 'real' object that
have been moved out/away from from the original object surface so that they
cover them.

The pros are 1) the resolution of the details is much higher - have a close
look at the Ace of Diamonds art on the nose and on the bit that sticks out of
the front of the tail-fin (I don't know the proper name for this), and 2)
less texture space is needed.

The most obvious con is that there's more potential for z-buffer problems.  I
notice that whilst on the ground (in chase view), there appears to be
z-buffer fighting for the texture patches but once the a/c has taken off and
has got to about 200ft or so, it clears up.  I've no idea why this should
happen as I'm not changing any of the view settings.

There are a few things I still need to figure out in this respect - I think
there's an issue with graduated textures - they seem to get reduced to 16bpp
and show a lot of banding that's absent on the texture and the model appears
inverted from tower views, at least in 16bpp, but ok from the chase view, and
stuff like that.

I said that the model and fdm aren't new but they have been modified a bit.
I've only reduced the approach aoa in the fdm but the model, whilst basically
the same, has had quite a few changes to accomodate the new u/c and texture
patches.  It also got into FG by a slightly different route - I found that
AC3D would support polys with > 3 sides and after looking at and comparing
.ac and .obj file formats (I can export from RS3D in .obj format) I wrote a C
prog to convert .obj format files into .ac format files.  It's a nasty bit of
hackery that even uses a temporary workfile (LOL), and it will only work with
the simplest of .obj files (e.g. no vertice normal or texture info) but it
allows me to export the model geometry in .obj format, convert it, and load
it straight into AC3D without turning everything into triangles or flipping
face normals.

The funny thing is that objects that consist of just a single rectangle (e.g.
an aileron or flap surface) are not recognised by FG and they have to be
split into two triangles, and once the model's loaded up into FG I can see
from some of the rendering artifacts that it's all still reduced to triangles
prior to display anyway. Still, it saves me from having to do a lot of face
flipping.

Really, the texturing method is experimental and I hope I get some feed-back
on it regarding display and performance issues.  Ultimately, I'd like to try
to reduce the texture size down from 512x512 to 256x256 - nearly half of the
current texture 'space' is unused.
2003-04-21 20:28:24 +00:00

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<!-- Hawker Sea Hawk yasim config. This is a hack and not an
authentic representation of the aircraft. Having said
that, the numbers, where I could find them, roughly match
those of the original aircraft.
Lee Elliott. leee-fgfs@spatial.freeserve.co.uk
-->
<airplane mass="9720">
<!-- Approach configuration.
I couldn't find any approach data but I think that the way
the aircraft sits tail down on it's u/c indicates that it
must land at a fairly shallow AoA to avoid hitting tail
first. The speed is a guess.
I could see no sign or mention of spoilers or airbrakes in any
of the docs or pictures I found.
-->
<approach speed="110" aoa="4">
<control-setting axis="/controls/engines/engine[0]/throttle" value="0.5"/>
<control-setting axis="/controls/flight/flaps" value="1.0"/>
<control-setting axis="/controls/gear/gear-down" value="1"/>
</approach>
<!-- Cruise configuration.
Max speed at sea level is 599 mph = 521 knots. The same source
also quoted 587 mph at 'altitude'.
-->
<cruise speed="521" alt="0">
<control-setting axis="/controls/engines/engine[0]/throttle" value="1.0"/>
<control-setting axis="/controls/flight/flaps" value="0.0"/>
<control-setting axis="/controls/gear/gear-down" value="0"/>
</cruise>
<cockpit x="3.0" y="0.0" z="0.7"/>
<fuselage ax="5.10" ay="0" az="0" bx="5.88" by="0" bz="0"
width="1.3"/>
<!-- The wing length is from tips to fuselage, including intakes.
The aileron figures are probably too low but the roll rate seemed
too high otherwise.
-->
<wing x="0.1" y="0.65" z="0.0" taper="0.5" incidence="0.0"
length="5.3" chord="3.0" sweep="-3.0" dihedral="3.0" camber="0.006">
<stall aoa="17" width="3" peak="1.3"/>
<flap0 start="0.1" end="0.4" lift="1.4" drag="1.6"/>
<flap1 start="0.4" end="0.95" lift="1.05" drag="1.2"/>
<control-input axis="/controls/flight/flaps" control="FLAP0"/>
<control-input axis="/controls/flight/aileron" control="FLAP1" split="true"/>
<control-input axis="/controls/flight/aileron-trim" control="FLAP1" split="true"/>
<control-output control="FLAP0" prop="/surface-positions/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="right" prop="/surface-positions/right-spoiler-pos-norm"/> -->
<control-speed control="FLAP0" transition-time="5"/>
<control-speed control="FLAP1" transition-time="0.5"/>
</wing>
<hstab x="-5.2" y="0.10" z="0.76" taper="0.3" effectiveness="1.6"
length="1.7" chord="1.2" sweep="0.0" dihedral="0.0" camber="0.0">
<stall aoa="17" width="5" peak="1.5"/>
<flap0 start="0" end="1" lift="1.5" drag="1.2"/>
<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"/>
<control-speed control="FLAP0" transition-time="0.5"/>
</hstab>
<vstab x="-5.2" y="0.0" z="0.2" taper="0.8"
length="1.4" chord="1.8" sweep="10.0">
<stall aoa="16" width="5" peak="1.5"/>
<flap0 start="0" end="1" lift="1.15" drag="1.3"/>
<control-input axis="/controls/flight/rudder" control="FLAP0" invert="true"/>
<control-output control="FLAP0" prop="/surface-positions/rudder-pos-norm"/>
<control-speed control="FLAP0" transition-time="0.5"/>
</vstab>
<!-- Engines and tanks.
1 x Roll-Royce Nene 103. I've no idea how much it actually
weighs.
-->
<jet x="0.3" y="0.0" z="0.0" mass="1000" thrust="5200">
<control-input axis="/controls/engines/engine[0]/throttle" control="THROTTLE"/>
</jet>
<!-- Fuel tanks in front, behind and above (saddle tank - actually feeds into
tank two in real life) the engine. -->
<tank x="1.4" y="0.0" z="0.0" jet="true" capacity="2000"/>
<tank x="-1.3" y="0.0" z="0.0" jet="true" capacity="2000"/>
<tank x="0.5" y="0.0" z="0.5" jet="true" capacity="1200"/>
<!-- Undercarriage -->
<!-- Front -->
<gear x="4.0" y="0.0" z="-1.53" compression="0.7" spring="1.0">
<control-input axis="/controls/flight/rudder" control="STEER" square="true"/>
<control-input axis="/controls/gear/gear-down" control="EXTEND"/>
<control-speed control="EXTEND" transition-time="7"/>
<control-output control="EXTEND" prop="/gear/gear[0]/position-norm"/>
<control-output control="STEER" prop="/gear/gear[0]/steering-norm"/>
</gear>
<!-- Left Main -->
<gear x="-0.09" y="1.4" z="-1.34" compression="0.7" spring="1.8">
<control-input axis="/controls/gear/wheel[1]/brake" control="BRAKE"/>
<control-input axis="/controls/gear/gear-down" control="EXTEND"/>
<control-speed control="EXTEND" transition-time="7"/>
<control-output control="EXTEND" prop="/gear/gear[1]/position-norm"/>
</gear>
<!-- Right Main -->
<gear x="-0.09" y="-1.4" z="-1.34" compression="0.7" spring="1.8">
<control-input axis="/controls/gear/wheel[2]/brake" control="BRAKE"/>
<control-input axis="/controls/gear/gear-down" control="EXTEND"/>
<control-speed control="EXTEND" transition-time="7"/>
<control-output control="EXTEND" prop="/gear/gear[2]/position-norm"/>
</gear>
<!-- Canopy -->
<gear x="3.0" y="0.0" z="0.6" compression="0.6">
<control-input axis="/controls/gear/parking-brake" control="EXTEND"/>
<control-speed control="EXTEND" transition-time="10"/>
<control-output control="EXTEND" prop="/gear/canopy/position-norm"/>
</gear>
<!-- Ballast -->
<ballast x="3.0" y="0" z="1.0" mass="1200"/> <!-- C/pit + Pilot -->
<ballast x="3.5" y="0" z="-0.5" mass="1000"/> <!-- Gun -->
<ballast x="2.0" y="0" z="0.0" mass="1000"/> <!-- trim ballast -->
</airplane>
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