rafwinds -- recompute winds on NCAR/RAF aircraft
rafwinds [-g] [-t] at0 fat si0 fsi ftas fwp lag
Rafwinds expects a Candis file on the standard input containing NCAR/RAF aircraft data concatenated into a single variable slice. A similar file is produced on the standard output with the derived winds recomputed from aircraft velocity, true airspeed, and slip and attack angles. If the optional -g flag is present, the aircraft motion is a combination of the low frequency part of the GPS velocity and the high frequency part of the INS velocity. This removes the 84 min oscillation from the aircraft velocity, and hence the winds. When the -g flag is invoked, the INS lon/lat and horizontal aircraft velocity fields are overwritten by the combined fields. If the optional -t flag is present, the true airspeed is corrected for humidity effects by the formula V = V_dry*(1 + 0.299*r) where r is the mixing ratio in g/g. This formula is derived from the DLR calculation for humidity effects.
The purpose of this program is to allow offset and gain errors in the attack and slip angles and gain errors in the true airspeed and aircraft vertical velocity to be corrected. In addition, a constant lag factor may be inserted between INS-derived variables and other variables. The attack angle is multiplied by fat and added to at0. The slip angle is multiplied by fsi and added to si0. The true airspeed and aircraft vertical speed are respectively multiplied by ftas and fwp. Finally, a lag correction in the amount of lag seconds is made. The x, y, and z components of the wind are then computed. They are given the field names "unew", "vnew", and "wnew".
Standard RAF variable names are assumed. Deviations (and time evolution of names) will cause confusion.
Rafread, rafdap.