A continuing study of altitude determination deficiencies of the Service Aircraft Instrumentation Package (SAIP).
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Authors
Russell, Robert J.
Subjects
altitude determination errors
static pressure measurement
probe design
static pressure measurement
probe design
Advisors
Biblarz, Oscar
Date of Issue
1991-09
Date
Publisher
Monterey, California. Naval Postgraduate School
Language
en_US
Abstract
After correcting test equipment used in a previous study of the SAIP for an ambiguous grounding
requirement, research was continued on aerodynamic factors affecting SAIP altitude measurement. Existing equations
for incompressible flow over a cylinder and a sphere were used to model the static-pressure probe located on the front
of the SAIP pod and an algorithm was derived for the computation of the pressure coefficient, Cp
. Our low-speed wind
tunnel data show an overpressure at the static pressure ports when the angle of attack (({>) is less than 14°. The five-inch
diameter body of the SAIP, located aft of the static pressure probe, is responsible for creating a stagnation-like region
at the front of the SAIP probe which envelops the static-port location. Calculation of the altitude error (AZ) using the
model for Cp, corrected for compressibility, is within ± 15% of the error observed in flight at Mach 0.60.
Improvements in the compressibility correction as well as analyses using an aero-panel method are suggested before
sufficiently reliable fixes to the SAIP can be proposed.
Type
Thesis
Description
Series/Report No
Department
Aeronautical Engineering
Organization
Naval Postgraduate School
Identifiers
NPS Report Number
Sponsors
Funder
Format
69 p.;28 cm.
Citation
Distribution Statement
Approved for public release; distribution is unlimited.