 investig systemat group naca 1 - seri cowl spinner investig systemat group naca 1 - seri cowl spinner investig conduct langlei propel-research tunnel studi cowl-spinner combin base naca 1-seri nose inlet systemat design data famili ellipsoid spinner main investig 11 spinner test combin 9 naca open-nose cowl test spinner effect locat shape spinner shape inner surfac cowl lip oper propel oval shank investig addit studi conduct determin correct procedur extrapol design condit determin low-speed test data design condit actual flight mach number design condit naca 1-seri cowl cowl-spinner combin present form chart wide rang spinner proport rate intern flow cowl near-maximum pressur recoveri select critic mach number rang spinner effect spinner propel cowl design condit present separ provid initi quantit data gener design procedur naca 1-seri cowl select spinner shape gener design procedur correl curv establish test data deriv compress-flow equat relat inlet-veloc ratio surfac pressur cowl spinner naca 1-seri cowl cowl-spinner combin design critic mach number high 0 90 