flaps and their effects
Posted: Mon Jul 13, 2020 7:16 pm
Here's the code for it..
On first inspection it doesn't look that bad... but look at this last line
1.5710 1.6 2.08 2.368 2.512
With a full flap defection at 90 degs AoA it's offering more drag than with no flaps deflected... that can't be as in that angle it's actually offering less surface area which mean that the coefficient should come down to reflect this.
But also consider this... if you're flying at zero AoA when applying flaps and the speed remains constant to get the same lift the AoA would have to reduce by 3 or so degrees to -3 degs.... Whereas the table is completely the other way around hardly any fidelity on the -ve angles of attack and all in the +ve...
This is wrong
Simon
Code: Select all
<function name="aero/coefficient/CDwbh">
<description>Drag_due_to_alpha</description>
<product>
<property>aero/qbar-psf</property>
<property>metrics/Sw-sqft</property>
<property>aero/function/kCDge</property>
<table>
<independentVar lookup="row">aero/alpha-rad</independentVar>
<independentVar lookup="column">fcs/flap-pos-deg</independentVar>
<tableData>
0 10 20 30
-0.0873 0.0041 0 0.0005 0.0014
-0.0698 0.0013 0.0004 0.0025 0.0041
-0.0524 0.0001 0.0023 0.0059 0.0084
-0.0349 0.0003 0.0057 0.0108 0.0141
-0.0175 0.002 0.0105 0.0172 0.0212
0.0000 0.0052 0.0168 0.0251 0.0299
0.0175 0.0099 0.0248 0.0346 0.0402
0.0349 0.0162 0.0342 0.0457 0.0521
0.0524 0.024 0.0452 0.0583 0.0655
0.0698 0.0334 0.0577 0.0724 0.0804
0.0873 0.0442 0.0718 0.0881 0.0968
0.1047 0.0566 0.0874 0.1053 0.1148
0.1222 0.0706 0.1045 0.124 0.1343
0.1396 0.086 0.1232 0.1442 0.1554
0.1571 0.0962 0.1353 0.1573 0.169
0.1745 0.1069 0.1479 0.1708 0.183
0.1920 0.118 0.161 0.1849 0.1975
0.2094 0.1298 0.1746 0.1995 0.2126
0.2269 0.1424 0.1892 0.2151 0.2286
0.2443 0.1565 0.2054 0.2323 0.2464
0.3491 0.2537 0.3298 0.3755 0.3983
0.5236 0.45 0.585 0.666 0.7065
0.6981 0.7 0.91 1.036 1.099
0.8727 1 1.3 1.48 1.57
1.0472 1.35 1.755 1.998 2.1195
1.2217 1.5 1.95 2.22 2.355
1.3963 1.57 2.041 2.3236 2.4649
1.5710 1.6 2.08 2.368 2.512
</tableData>
</table>
<property>gear/drag-coef[1]</property>
<property>gear/drag-coef[2]</property>
<property>gear/drag-coef[3]</property>
<property>gear/drag-coef[4]</property>
<property>gear/drag-coef[5]</property>
<property>gear/drag-coef[6]</property> <!-- Amphibious gear extended -->
</product>
</function>On first inspection it doesn't look that bad... but look at this last line
1.5710 1.6 2.08 2.368 2.512
With a full flap defection at 90 degs AoA it's offering more drag than with no flaps deflected... that can't be as in that angle it's actually offering less surface area which mean that the coefficient should come down to reflect this.
But also consider this... if you're flying at zero AoA when applying flaps and the speed remains constant to get the same lift the AoA would have to reduce by 3 or so degrees to -3 degs.... Whereas the table is completely the other way around hardly any fidelity on the -ve angles of attack and all in the +ve...
This is wrong
Simon