I know that's not exactly proper grammar - what I mean to ask, of course, is whether the long-duct nacelles on the series -62/-63 Eight provided better noise insulation than those of the non-hushkitted 707 and 720. Here is a takeoff clip filmed by videographer Henry Tenby last year aboard the Honeywell engine testbed aircraft, a 720. I assume these are JT3D1 engines. Immediately what you can hear is the full spectrum of high-pitched compressor scream and whistle; these classic nacelles sure don't seem to offer much in the way of sound insulation, as the core of the fan engine is fully exposed. As we know, the long-duct nacelle on the DC-8 at least directed the bypass around the core to the end of the engine. Did those long nacelles significantly cut noise before any huskitting was applied? Can anyone here who flew on those jets remember a difference in sound quality for passengers sitting in front of the wing?
720 takeoff video
(I put in an embedded player version, but didn't know how to alter the script to turn off autoplay.)
[Edited 2008-03-09 08:59:17]