Andy Ross wrote
> Vivian Meazza wrote:
> > wastegate-mp="18.32"
> > [...]
> > mp-osi = 26.050 - does the "wastegate" work? - is this psi?
>
> The units are absolute pressure in inches of mercury (I
> honestly don't know what the "-osi" suffix means). The
> wastegate should indeed work. However, it is an overpressure
> release valve. It cannot suck a vacuum in the manifold if
> ambient pressure is already higher than its setting. :)
>
> Typical values for the wastegate are going to be
> significantly higher than one atmosphere (== ~28" Hg), but
> I'm sure that varies with supercharger design. Probably some
> aircraft don't have them at all.
>
> > The model does not fly, failing to accelerate (insufficient prop
> > thrust), with the following output data when throttle = 1:
>
> Outside the wastegate setting (which is a noop in this case)
> nothing looks clearly incorrect. Can you post the whole file
> so I can try it?
>
Here's the whole file as requested:
<?xml version="1.0"?>
<!--
************************************************************************
YASim aerodynamic model for a Spitfire IIa
The reference datum for measurements is the nose.
************************************************************************
-->
<!-- Weight of everything but fuel (4873 empty) -->
<airplane mass="5200">
<!-- Approach configuration -->
<approach speed="75" aoa="13">
<control-setting axis="/controls/engines/engine[0]/throttle" value="0.2"/>
<control-setting axis="/controls/engines/engine[0]/mixture" value="1.0"/>
<control-setting axis="/controls/engines/engine[0]/propeller-pitch"
value="0.2"/>
<control-setting axis="/controls/engines/engine[0]/boost"
value="0.25"/>
<control-setting axis="/controls/flight/flaps" value="1.0"/>
<control-setting axis="/controls/gear/gear-down" value="1"/>
</approach>
<!-- Cruise configuration -->
<cruise speed="308" alt="17500">
<control-setting axis="/controls/engines/engine[0]/throttle"
value="0.90"/>
<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"/>
<control-setting axis="/controls/flight/flaps" value="0.0"/>
<control-setting axis="/controls/gear/gear-down" value="0"/>
</cruise>
<!-- pilot's eye point -->
<cockpit x="-3.86" y="0" z="0.55"/>
<fuselage
ax="0.0" ay="0.0" az="0.0"
bx="-9.13" by="0.0" bz="0.0"
width="0.94" taper="0.38" midpoint="0.4"
/>
<!--
stall aoa not available
flap drag not available
-->
<wing x="-2.99" y="0.77" z="-0.81" taper="0.3" incidence="2" twist="-2.0"
length="4.576" chord="2.845" sweep="-3.5" dihedral="6" >
<stall aoa="20" width="4" peak="1.5"/>
<flap0 start="0.00" end="0.437" lift="1.3" drag="1.8"/>
<flap1 start="0.437" end="0.90" lift="1.2" drag="1.2"/>
<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>
<!-- tailplanee -->
<hstab x="-8.22" y="0.25" z="0.0" taper="0.639" effectiveness="2"
length="1.215" chord="1.246" sweep="5" >
<stall aoa="24" width="4" peak="1.5"/>
<flap0 start="0.0" end="1" lift="1.65" drag="1.5"/>
<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>
<!-- tail -->
<vstab x="-8.52" y="0" z="-0.29" taper="0.386" effectiveness="2"
length="1.598" chord="0.994" sweep="5" >
<stall aoa="15" width="4" peak="1.5"/>
<flap0 start="0" end="1" lift="1.65" drag="1.5"/>
<control-input axis="/controls/flight/rudder" square="true"
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>
<!-- wastegate setting should not apply. set here so that calculations
would approximate.
YASim doesn't model gear supercharger. Have read various figures
(turbo-mul) 4.0 to 5.8 for
running the second stage blower. Fixing this would probably give more
reasonable
performance at lower altitude -->
<!-- moment = radius(m)* propeller mass(kg)/2 - equation provided by Andy
Ross -->
<!-- cruise-rpm documented gear ratio of 0.479 min-rpm="600"
max-rpm="3000"-->
<propeller x="-1.10" y="0" z="0"
radius="1.638" moment="37.15"
mass="2000"
eng-power="1140" eng-rpm="2850"
turbo-mul="4.0" wastegate-mp="48.2454"
cruise-alt="17500" cruise-power="1100"
cruise-speed="308" cruise-rpm="2850"
takeoff-power="1100"
takeoff-rpm="2850"
manual-pitch="true"
gear-ratio = "0.477">
<actionpt x="-0.75" 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="PROPPITCH"
src0="0" src1="1" dst0="0.1" dst1="0.8"/>
<control-input axis="/controls/engines/engine[0]/boost" control="BOOST"/>
</propeller>
<!-- Tail wheel -->
<!-- tail wheel castering(locked to make the aircraft controllable) -->
<gear x="-7.90" y="0" z="-0.96" compression="0.2">
<control-input axis="/controls/gear/tailwheel-lock" control="CASTERING"/>
</gear>
<!-- left main -->
<gear x="-2.10" y="0.86" z="-2.10" compression="0.4" spring="0.7"
damp="3.0">
<control-input axis="/controls/gear/brake-left" control="BRAKE"/>
<control-input axis="/controls/gear/brake-parking" 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 -->
<gear x="-2.10" y="-0.86" z="-2.10" compression="0.4" spring="0.7"
damp="3.0">
<control-input axis="/controls/gear/brake-right" control="BRAKE"/>
<control-input axis="/controls/gear/brake-parking" 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>
<!-- Fuselage tanks.
Weight of contents calculated using 100 octane AVGAS density of 695 kg/m3 @
15degC
-->
<tank x="-2.80" y="0" z="0.17" capacity="335"/> <!-- upper 48 imp gals -->
<tank x="-2.56" y="0" z="-0.45" capacity="258"/> <!-- lower 37 imp gals -->
<!-- ballast and weights -->
<ballast x="-3.95" y="0" z="-0.1" mass="335"/> <!-- Cockpit, sundries-->
<!-- 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"/>
-->
<!-- pilot -->
<weight x="-3.805" y="0" z="-0.20" mass-prop="/yasim/spitfire/pilot-lb"/>
</airplane>
With these settings the aircraft does not fly, and the rpm value is
ridiculous - 6828. mp-osi = 30.012
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