Title: An engineering study of altitude determination deficiencies of the Service Aircraft Instrumentation Package (SAIP)
Description: Altitude determination errors of the U. S. Navy's Service Aircraft Instrumentation  Package (SAIl'), an airborne positioning pod, were examined in a multifaceted study  involving in-flight evaluations, wind tunnel testing and pressure sensitivity  experiments. The original objectives of the research' related to identifying  aerodynamic sources of pod static pressure inaccuracies and recommending specific  remedies to alleviate these errors. After an extensive evaluation, results revealed  that.the problem exists not in the aerodynamic measurement performance of the probe,  but in the electronic circuitry residing within the Air Data Unit (ADU). The ADU  houses mUltiple pressure transducers, each associated with different static and dynamic  pressure ports, in a single module. This circuit configuration leads to electrical  interference and an attendant degradation of the static pressure output voltage.  Accurate static pressure voltages, which can be subsequently converted into appropriate  SAIl' barometric altitudes, are obtained by electrically isolating the three ADU dynamic  pressure transducers from the single operative static pressure transducer and remaining  ADU circuitry.
Subjects: Aeronautical instruments, Aeronautics