%% $Date: 2012-07-06 17:42:54#$
%% $Revision: 149 $
\index{velocity\_tas\_raf}
\algdesc{True air speed (RAF)}
{ %%%%%% Algorithm name %%%%%%
velocity\_tas\_raf
}
{ %%%%%% Algorithm summary %%%%%%
Calculates true air speed based on Mach number, measured temperature and thermometer recovery factor. 
Typical values of the themometer recovery factor range from 0.75-0.9 for platinum wire ratiometer (flush bulb type) thermometers,
and around 1.0 for TAT type thermometers.

}
{ %%%%%% Category %%%%%%
Thermodynamics
}
{ %%%%%% Inputs %%%%%%
$T_r$ & Vector & Measured temperature [K] \\
$M$ & Vector & Mach number \\
$e$ & Coeff. & thermometer recovery factor
}
{ %%%%%% Outputs %%%%%%
$V_t$ & Vector & True air speed [m/s]
}
{ %%%%%% Formula %%%%%%
\begin{displaymath}
V_t = \sqrt{\frac{R \gamma T_r M^2}{1 + 0.5(\gamma - 1) e M^2}}
\end{displaymath}
%
where the recovery factor $e$ can be determined for a thermometer by comparing its measured
temperature with the actual total and static temperature.
%
\begin{displaymath}
 e \equiv \frac{T_r - T_s}{T_t - T_s}
\end{displaymath}

}
{ %%%%%% Author %%%%%%
NCAR-EOL
}
{ %%%%%% References %%%%%% 
NCAR-RAF Bulletin \#23 \cite{NCAR23} 
}


