Path: utzoo!attcan!utgpu!jarvis.csri.toronto.edu!rutgers!ucsd!ames!skipper!shafer From: shafer@drynix.dfrf.nasa.gov Newsgroups: sci.space.shuttle Subject: Re: Atlantis is home! Message-ID: Date: 23 May 89 15:31:19 GMT References: <272@skipper.dfrf.nasa.gov> <9090001@hp-lsd.HP.COM> <4453@ttidca.TTI.COM> <862@m3.mfci.UUCP> <3305@kalliope.rice.edu> <871@m3.mfci.UUCP> Sender: news@skipper.dfrf.nasa.gov Organization: NASA Dryden, Edwards, Cal. Lines: 29 In-reply-to: colwell@mfci.UUCP's message of 23 May 89 13:04:44 GMT About sonic booms--you guys must live in the wrong neighborhood :-) Sonic booms are quite common here at Dryden, since we're right under the medium- altitude supersonic corridor. Come visit us, for the public tour, and you'll probably hear several. The overpressure and other characteristics of the shock are functions of the aircraft altitude, Mach, size, and weight. If the aircraft is very high, for example, the shock will have dissipated somewhat before it reaches the ground and the boom will be more like a rumble. The best booms are very sharp and distinct, with quite a bit of high-frequency content. These come from relatively low, fast, close aircraft. Double booms, like the Shuttle produces, aren't that uncommon. An F-4 can produce a very nice double boom--I've heard & seen them do it. There's a clue in that statement, that they were low enough and close enough that I could see them doing it. Any aerodynamics text will show you the shock waves coming off an aircraft. If you want to see pictures, look in Van Dyke's book, "An Album of Fluid Motion." He has a chapter of shock wave pictures and another of supersonic flow. This is an outstanding book, which everyone interested in aerodynamics should have. -- M F Shafer NASA Ames-Dryden Flight Research Facility shafer@elxsi.dfrf.nasa.gov or shafer@drynix.dfrf.nasa.gov NASA management doesn't know what I'm doing and I don't know what they're doing, and everybody's happy this way.