Talking propellors

sanhozay
Posts: 167
Joined: Fri Sep 25, 2015 5:59 pm

Re: Talking propellors

Postby sanhozay » 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.

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.

bomber
Posts: 1379
Joined: Mon Nov 30, 2015 3:40 pm

Re: Talking propellors

Postby bomber » Thu Jul 02, 2020 2:20 pm

https://forum.flightgear.org/viewtopic. ... f9fbb674d1


Why is it so hard to put the man in touch with someone who might know the answer ?

This isn't the first time this sort of thing has happened over on this forum..... A split wing flight model, who does this I wonder ?
"If anyone ever tells you anything about an aeroplane which is so bloody complicated you can't understand it, take it from me - it's all balls" - R J Mitchell


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