Andy Ross wrote
> Vivian Meazza wrote:
> > How do we set the reduction gearing ratio?
>
> Set the "gear-ratio" attribute of the propeller tag. This is the
> reduction ratio, so typical values will be less than 1.0.
>
> > Can we do a constant speed propeller?
>
> The min-rpm and max-rpm attributes define the range of the blue lever.
> These are the speeds to which the propeller will seek; it may not be
> able to achieve them in practice. The documentation for these was,
> er, wrong. I'll fix that.
>
> > And can we set the handedness of the propeller to RH?
>
> Sure thing. Use a negative moment value. :) No joke: that will have
> exactly the effect of a counter-rotating engine. The DC-3 uses this
> trick for the starboard engine, for example. I'll add some
> documentation for that as well.
>
> Andy
>
I have almost finished the Spitfire model. Texturing, animation and a 3d
cockpit remain to do. However, I am having some difficulty with the engine
reduction gear ratio. I've used using the following numbers which give a
reasonable solution in YASim.
<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="18.32"
cruise-alt="17500" cruise-power="1100"
cruise-speed="308" cruise-rpm="2850"
takeoff-power="1100" takeoff-rpm="2850"
manual-pitch="true">
<actionpt x="-0.75" y="0" z="0"/>
<control-input axis="/controls/engines/engine[0]/propeller-pitch"
control="PROPPITCH" src0="0" src1="1" dst0="0.1" dst1="0.6"/>
</propeller>
The model flies reasonably well, with the following output data when
throttle = 1:
max-hp = 1140.491452
mp-osi = 26.050 - does the "wastegate" work? - is this psi?
power-pct = 105.863353
prop-thrust = 1314.603118
rpm = 3014.603118
I've kept to manual pitch control for now.
I've tried this, although I would think, incorrectly:
<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="18.32"
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]/propeller-pitch"
control="PROPPITCH"
src0="0" src1="1" dst0="0.1" dst1="0.6"/>
</propeller>
The model still flies reasonably well, with the following output data when
throttle = 1:
max-hp = 1140.491452
mp-osi = 29.729 - does the "wastegate" work? - is this psi?
power-pct = 222.856
prop-thrust = 1375.645173
rpm = 6176.318088 - this is wrong
Finally, I tried this:
<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="18.32"
cruise-alt="17500" cruise-power="1100"
cruise-speed="308" cruise-rpm="1360"
takeoff-power="1100" takeoff-rpm="2850"
manual-pitch="true"
gear-ratio = "0.477">
<control-input axis="/controls/engines/engine[0]/propeller-pitch"
control="PROPPITCH"
src0="0" src1="1" dst0="0.1" dst1="0.6"/>
</propeller>
The model does not fly, failing to accelerate (insufficient prop thrust),
with the following output data when throttle = 1:
max-hp = 1140.491452
mp-osi = 29.729
power-pct = 225.856 - wrong
prop-thrust = 659.082929 - wrong
rpm = 6232.318088 - even more wrong
I've tried increasing pitch, to no avail. I've tried <takeoff-power="1100"
takeoff-rpm="1360" - then YASim crashes
What is the obvious mistake that I am making?
Regards
Vivian Meazza
_______________________________________________
Flightgear-devel mailing list
[EMAIL PROTECTED]
http://mail.flightgear.org/mailman/listinfo/flightgear-devel
