Analysis of Wind Tunnel Polar Replicates Using the Modern Design of Experiments (Invited)

Comparison of Resource Requirements for a Wind Tunnel Test Designed with Conventional vs. Modern Design of Experiments Methods

“…We then have: 21 y y y  (10) Since the square of the derivative of y with respect to either y 1 or y 2 is 1, and since the standard deviation in both y 1 and y 2 is , Eq. (9) for this case reduces to:…”

“…The systematic component of the unexplained variance often dominates the random component, and is caused by persisting and slowly varying covariate effects such as temperature, flow angularity changes, instrument drift, and the like. The paper reporting the initial phase of this investigation focused on quality issues, 10 and contains more detail about the unexplained variance in the missile test that serves as an illustration of scaling principles in this paper. As will be shown below, an adequate response model requires that we augment the minimum p points by a factor that is directly proportional to the unexplained variance of the data (square of the standard deviation).…”

“…Differences between OFAT and MDOE approaches to assuring and assessing quality have been reported in a separate paper. 10 This paper focuses on differences in the test matrices, highlighting the resource savings (assumed to be a function of data volume requirements) that can be achieved with a formal experiment design.…”

“…This information is useful in the planning stage of any MDOE experiment design, as MDOE data volume requirements depend on the magnitude and nature of the unexplained variance that can be anticipated in a worst-case scenario, and minimizing the volume of data required for a test is a key cost control tactic. These unexplained variance estimates were reported 10 at the 27th AIAA Aerodynamic Measurement Technology and Ground Testing Conference in Chicago.…”

A Practical Methodology for Quantifying the Random and Systematic Components of Unexplained Variance in a Wind Tunnel

“…A tunnel with such behavior would be said to be in a state of "statistical control." Unfortunately, statistical control is elusive in the real world; random fluctuations in wind tunnel response measurements are often found to occur about mean values that change systematically (not randomly) with time [10][11][12][13] . Box, Hunter, and Hunter address this in the second edition of their seminal text on experiment design 3 where they say, "The idea of a process in a perfect state of control contravenes the Second Law of Thermodynamics: Thus an exact state of control is unrealizable, and must be regarded as a purely theoretical concept."…”