Date of Award


Document Type


Degree Name

Master of Science in Aeronautical Engineering


Department of Aeronautics and Astronautics

First Advisor

James K. Hodge, PhD


Optimal linear smoothing theory is applied to the data from the Speed of Sound record attempt of a three-wheeled rocket car on 17 December 1979. A forward-backward estimation method is used which employs a seven state forward-running extended Kalman filter and a Meditch-form backward recursive 'fixed-interval' smoothing algorithm. Data for this analysis is supplied by a longitudinal accelerometer mounted on the vehicle and tracking radar measurements of range, azimuth, and elevation. States of interest include two components of vehicle position and velocity, accelerometer time-correlated error, and radar range and azimuth bias errors. Two iterations of the forward-backward smoothing algorithm provide excellent covergence of state estimates and error variance. Based on this analysis a peak speed estimate of 1082.028 ft/sec or 1.008 Mach is obtained at 16.85 seconds from the start of the high speed run. After two iterations of the smoother the standard deviation of the peak speed estimate is reduced to 1.055 ft/sec. We conclude with a confidence level of nearly one, based on the assumptions and modeling techniques employed in this analysis, that the rocket car did, in fact, exceed the reference speed of sound on 17 December 1979.

AFIT Designator


DTIC Accession Number