jjb@sequent.UUCP (Jeff Berkowitz) (05/24/89)
In article <SHAFER.89May23083119@drynix.dfrf.nasa.gov> shafer@drynix.dfrf.nasa.gov writes: >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. When I lived in Santa Barbara, shuttle landings were announced by a window- rattling THUM-BUM (or was it "BA-BOOM"? :-). Santa Barbara is about 100 miles north of LA on the coast. We learned that we had a few (six or seven?) minutes after from the boom to get the TV and catch the touchdown at Edwards. Point is that the shuttle must have been quite high when we heard it (can anyone answer to the shuttle's altitude seven minutes before touchdown?) The double boom was distinct. I suspect that the shuttle manifests the double boom at relatively long distances/high altitudes because it's travelling a WHOLE lot faster than F-4's (or anything else). -- Jeff Berkowitz N6QOM uunet!sequent!jjb Sequent Computer Systems Custom Systems Group
sef@druco.ATT.COM (Scott E. Farleigh) (05/26/89)
In article <16466@sequent.UUCP>, jjb@sequent.UUCP (Jeff Berkowitz) writes: > The double boom was distinct. I suspect that the shuttle manifests the > double boom at relatively long distances/high altitudes because it's > travelling a WHOLE lot faster than F-4's (or anything else). > -- > Jeff Berkowitz N6QOM uunet!sequent!jjb > Sequent Computer Systems Custom Systems Group It is "anything else", the double boom comes from the leading AND trailing edges of the wing. A wave is built up on both edges, therefore the Ba-Boom (or if you're from Nebraska Ka-Boom). As the aircraft flies higher the pronounced double boom disappears into one boom. Scott E. Farleigh