Hello to all
I'm developing with a friend the PZL M18B "Dromader" in JSBSim, doing this
first with aeromatic generated data; and now, we are mixing them with real
aircraft data from very reliable sources. However, the engine behavior seems
very different in numbers compared with what we expect from it:
Engine: ASz-62IRM18
Max.RPM: 2200 / Min.RPM: 550
Constant speed propeller
- The reduction gear ratio of the real engine is 0.687, but writting that
value the engine has too low RPM, that it even can't start. Trying to
"invent" a calculation for the ratio, i got a new 1.45 gear reduction ratio,
but that number still being unaccurate. In example, according to engine
manual, if RPM are 1900 with a fine propeller pitch, changing the prop pitch
to coarse will reduce the RPM to 1500; but in the model RPMs are reduced
even to 1000 RPM. I guess that FDM needs a ratio number wich are different
to originals, true?
- The max.RPM of the engine are 2200 RPM. But the model just reach circa
1600 RPM with full throttle and fine propeller.
- The min.RPM of the engine are 550 RPM. But with min.throttle and coarse
propeller it reach 790 RPM.
- These values of RPM change and increase when the model starts to move (!).
It's possible to get RPM over 2000 only when flying, but the min.RPM turns
then too much strong to try sucessfull landings.
How can i fix each point?
For better understanding, i'll add the values of my xml files:
ENGINE
------
<piston_engine name="ASz-62IRM18">
<minmp unit="INHG"> 24.21 </minmp>
<maxmp unit="INHG"> 41.34 </maxmp>
<displacement unit="IN3"> 1823 </displacement>
<bore unit="IN"> 6.10 </bore>
<stroke unit="IN"> 6.87 </stroke>
<cylinders> 9 </cylinders>
<compression-ratio> 6.4 </compression-ratio>
<maxhp unit="HP"> 980 </maxhp>
<cycles> 4 </cycles>
<idlerpm> 550 </idlerpm>
<maxrpm> 2200 </maxrpm>
<maxthrottle> 1 </maxthrottle>
<minthrottle> 0 </minthrottle>
<bsfc unit="LBS/HP*HR"> 0.671 </bsfc>
</piston_engine>
PROPELLER
---------
<propeller name="AW-2-30">
<ixx> 14.7823 </ixx>
<diameter unit="IN">129.92 </diameter>
<numblades> 4 </numblades>
<gearratio> 1.45 </gearratio>
<minpitch> 17 </minpitch>
<maxpitch> 32 </maxpitch>
<minrpm> 380 </minrpm>
<maxrpm> 1510 </maxrpm>
<constspeed> 1 </constspeed>
<sense> 1 </sense>
<table name="C_THRUST" type="internal">
(Here is the table in the XMLs)
</table>
<table name="C_POWER" type="internal">
(Here is the table in the XMLs)
</table>
</propeller>
Well, I was needed to ask here, because the documentation available in
JSBSim manual and/or wiki was insufficient to do it for myself. I'll be very
glad to get any info to work.
Thanks
---
PD: What is "ixx", "Spark fail drop", "Volumetric efficiency" and "Dynamic
(and static) fmep"? How can i to adjust the cooling factor to aivoid engine
overheating?
--
Pavel Cueto
音響技師の学生
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