Ordvac.com

Extensive research and computation by John M. Leonard of the Rolls-Royce Heritage Trust (Rolls Aerospace currently owns Allison) indicate that an engine turning at 14,300 rpm driving a 6.8:1 gearbox, as the T40 did, would push the tips of a 12-foot-diameter propeller to a far more logical Mach 1.18. The propeller hub frequency would have thus been 2100 rpm, or 35 Hz. The blade passing ... ................
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