SAE AIR5866

“An Assessment of Planar Waves” provides background on some of the history of planar waves, which are time-dependent variations of inlet recovery, as well as establishing a hierarchy for categorizing various types of planar waves. It further identifies approaches for establishing compression-component and engine sensitivities to planar waves, and methods for accounting for the destabilizing effects of planar waves. This document contains an extensive list and categorization (see Appendix A) of references to aid both the newcomer and the practitioner on this subject. The committee acknowledges that this document addresses only the impact of planar waves on compression-component stability and does not address the impact of planar waves on augmenter rumble, engine structural issues, and/or pilot discomfort. Due to the needs of the industry, this document has been upgraded to an AIR (Aerospace Information Report) from an ARD (Aerospace Research Document) status and was formerly catalogued as ARD500026. Most of the report is unchanged since the material is as useful now as it was when first published in 1995. A few paragraphs have been updated to reflect knowledge gained on recent aircraft programs. Other changes reflect consistency with more recently adopted definitions, and minor editorial and typographical corrections. However in the course of this upgrade, it became apparent that the original figures were no longer available nor were the means to recreate them. In some cases, figures have been redrawn. For the remaining figures (and tables), the best available copy was scanned. The committee apologizes for any lack of clarity produced by this procedure.