<function name="aero/function/CA-1">
<description>Quotient of inlet velocity and air velocity minus one</description>
<min>
<sum>
<quotient>
<product>
<property>propulsion/engine/n1</property>
<value>4</value> <!-- Approx 400 ft/s at max RPM -->
</product>
<property>velocities/u-aero-fps</property>
</quotient>
<value>-1.0</value>
</sum>
<value>9</value> <!-- Avoids unrealistic effects at very low speeds -->
</min>
</function>
<function name="aero/moment/Pitch_intake">
<description>Pitch moment due to airflow in intake</description>
<product>
<property>aero/qbarUW-psf</property>
<property>metrics/Sw-sqft</property>
<property>metrics/cbarw-ft</property>
<property>aero/alpha-rad</property>
<property>aero/function/CA-1</property>
<value>-0.05</value>
</product>
</function>
jam007 wrote in Sat Apr 15, 2017 3:55 pm:[...] I assume that airflow is non linear with thrust. Assuming that the engine is run close to optimum fuel/air ratio for different thrusts then makes the fuel flow a good start for calculating the intake flow of air.
Johan G wrote in Sun Apr 16, 2017 1:39 am:I would expect the mixture to be dependent on density altitude, or approximately on altitude.
Necolatis wrote in Sun Apr 16, 2017 10:53 pm:Must admit I think there is a good chance N1 does not scale with flow mass
Necolatis wrote in Sun Apr 16, 2017 10:53 pm:As for pitching I have decided to limit CA effect to 1-3 in the Viggen, there might be some reason, we don't know about, that is the reason they only talk about the effect within that limit. Just to be safe.
I think the reason high speeds is not mentioned is that the document only covers low speed.
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