Door drag

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

Door drag

Postby bomber » Mon Jul 13, 2020 6:24 pm

Here's the code

Code: Select all

            <function name="aero/coefficient/CDdoorL">
                <description>Drag_due_to_door_left</description>
                <product>
                    <property>aero/qbar-psf</property>
                    <property>metrics/Sw-sqft</property>
                    <property>/sim/model/door-positions/leftDoor/position-norm-effective</property>
                    <value>0.0300</value>
                </product>
            </function>


SO yet again we're using the wing area as a reference area.... looking at images I'd say the door opens to about 70degs which would be 0.94 of it's flat plate 90 degs area.

The difference in area of the door and wing is a ratio of 15.39....

So what we know is that the door at 90degs would offer a flat plate Cd of 1.28... at 70degs this would be 1.2.

So if we were to use the door area as the reference the above value of 0.03 would need to be 1.2/15.39 = 0.078 to give the equivalent drag

basically out by factor of 2.6

Simon
"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

Richard
Posts: 114
Joined: Sun Sep 11, 2016 5:57 pm

Re: Door drag

Postby Richard » Mon Jul 13, 2020 8:24 pm

bomber wrote:So if we were to use the door area as the reference the above value of 0.03 would need to be 1.2/15.39 = 0.078 to give the equivalent drag basically out by factor of 2.6


Raise an issue on their github.


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