Weighted Least Squares Approach To Assess Flight Test with Unbalanced Samples

• Activity Number: 495
• Type: Topic Contributed
• Date/Time: Thursday, August 10, 2006 : 8:30 AM to 10:20 AM
• Sponsor: Section on Statisticians in Defense and National Security
• Author(s): Winson Taam*+
• Companies: The Boeing Company
• Keywords: weighted least squares ; vibration data ; linear regression

Abstract

Flight test vibration data is used to assess structural stress of air vehicles. Prespecified maneuvers are designed to represent the flight envelop in which an air vehicle would experience during normal operation. Aeronautic and s vibration measurements are taken over time to characterize and compare improvement on vehicle design. However, certain segments of a maneuver could be more difficult to maintain in flight. Hence, the amount of data in these segments are under-sampled, while other segments are well-sampled. These under-sampled segments could be critical to a vehicle's structural integrity and should be weighted more importantly in any assessment of structural stress. Empirical models based on a weighted least squares method are used to assess design changes on a flight test program. This method is compared with traditional models based on ordinary least squares.