Re: Talking propellors
Posted: Wed Nov 23, 2016 9:06 am
2400 static RPM, thrust at 55 m/s = 1105N (248lb).
I'm using MH126/MH112/MH114/MH120 airfoils.
If I change nothing else and just scale the chord to get a static RPM of 2350, I get a thrust of 1121N (252lb) at 54m/s. So not a huge difference really. On reflection, I think I'll go back to the mid-range as I don't have a convincing argument to do otherwise.
I'm using MH126/MH112/MH114/MH120 airfoils.
Code: Select all
<propeller name="McCauley_1A105-SCM-7053">
<ixx unit="SLUG*FT2">1.716</ixx>
<constspeed>0</constspeed>
<diameter unit="IN">70.0</diameter>
<numblades>2</numblades>
<gearratio>1.0</gearratio>
<ct_factor>1.0</ct_factor>
<cp_factor>1.0</cp_factor>
<table name="C_THRUST" type="internal">
<tableData>
0.000 0.094056
0.050 0.093989
0.100 0.094660
0.150 0.093971
0.200 0.093125
0.250 0.092571
0.300 0.091176
0.350 0.088683
0.400 0.084732
0.450 0.079587
0.500 0.073712
0.550 0.067087
0.600 0.060346
0.650 0.053404
0.700 0.046278
0.750 0.038990
0.800 0.031548
0.850 0.023961
0.860 0.022425
0.870 0.020886
0.880 0.019340
0.890 0.017793
0.900 0.016234
0.910 0.014672
0.920 0.013107
0.930 0.011533
0.940 0.009962
0.950 0.008392
0.960 0.006823
0.970 0.005255
0.980 0.003687
0.990 0.002138
1.000 0.000580
1.010 -0.000955
1.020 -0.002477
</tableData>
</table>
<table name="C_POWER" type="internal">
<tableData>
0.000 0.054035
0.050 0.045168
0.100 0.053164
0.150 0.054307
0.200 0.055592
0.250 0.052712
0.300 0.053298
0.350 0.054014
0.400 0.053987
0.450 0.053186
0.500 0.051759
0.550 0.049558
0.600 0.046884
0.650 0.043679
0.700 0.039915
0.750 0.035575
0.800 0.030637
0.850 0.025083
0.860 0.023895
0.870 0.022683
0.880 0.021445
0.890 0.020183
0.900 0.018891
0.910 0.017575
0.920 0.016233
0.930 0.014862
0.940 0.013472
0.950 0.012062
0.960 0.010632
0.970 0.009181
0.980 0.007712
0.990 0.006240
1.000 0.004739
1.010 0.003244
1.020 0.001741
</tableData>
</table>
<!-- thrust effects of helical tip Mach -->
<table name="CT_MACH" type="internal">
<tableData>
0.85 1.0
1.05 0.8
</tableData>
</table>
<!-- power-required effects of helical tip Mach -->
<table name="CP_MACH" type="internal">
<tableData>
0.85 1.0
1.05 1.8
2.00 1.4
</tableData>
</table>
</propeller>If I change nothing else and just scale the chord to get a static RPM of 2350, I get a thrust of 1121N (252lb) at 54m/s. So not a huge difference really. On reflection, I think I'll go back to the mid-range as I don't have a convincing argument to do otherwise.