From: skunk-works-digest-owner@harbor.ecn.purdue.edu To: skunk-works-digest@harbor.ecn.purdue.edu Subject: Skunk Works Digest V4 #115 Reply-To: skunk-works-digest@harbor.ecn.purdue.edu Errors-To: skunk-works-digest-owner@harbor.ecn.purdue.edu Precedence: bulk Skunk Works Digest Wednesday, 12 January 1994 Volume 04 : Number 115 In this issue: Re: booms Re: booms Sonic Studies in Rachel Re: booms re: sending cryptographicly tagged e-mail. Re: booms Re: Sonic Studies in Rachel Da Booms... See the end of the digest for information on subscribing to the skunk-works or skunk-works-digest mailing lists and on how to retrieve back issues. ---------------------------------------------------------------------- From: mangan@Kodak.COM (Paul Mangan) Date: Tue, 11 Jan 94 07:45:09 EST Subject: Re: booms Thanks, this is an outstanding answer that gets right to the heart of my question. Mary, I really am only curious and do appreciate your answer, too. My curiousity goes back to the time when my dad worked with the Skunk Works. I got to go on a few trips with him and got to see a few things a 14 year old shouldn't have. But, the secretaries were nice to me and would take me on tours while my dad conducted business. Since then I try to follow what different agencies are doing because eventually we see the research used in advanced aircraft. > From skunk-works-owner@ecn.purdue.edu Mon Jan 10 22:32:33 1994 > To: skunk-works@orchestra.ecn.purdue.edu > Subject: Re: booms > Sender: skunk-works-owner@ecn.purdue.edu > Content-Length: 2658 > X-Lines: 67 > > > > Paul Mangan writes: > >This ALMOST leads me to wonder if there is such a thing as a noisless > >or low noise sonic boom. In other words can the shape of a sonic > >boom's cone be made to change to reduce the noise signature > >and imitate an earthquake. > > > >What does a sonic boom register on the open ended scale that measures > >earthquakes? For example, does anyone know what the seismologists > >pick up when the Space Shuttle returns from orbit. > > > >I hope I don't sound too suspicious, I really am just curious. > > As the altitude of the aircraft that produces the shock system increases, > the delta-P of the boom caused by that shock system decays, and the > duration of the boom wave increases. > > I call your attention to the following sources: > > 1. OXCART History lpn 18 > "Neither on this nor on other flights was there much trouble from sonic > boom. To be sure, the inhabitants of a small village some 30 miles from > the site were troubled as the aircraft broke through the sound barrier > while gaining altitude. A change of course remedied this. At altitude > OXCART produced no more than an ominous rumble on the ground and since > the plane was invisible to the naked eye no one associated this sound > with its actual source." > > 2. NASP Sonic Boom presentation foil: > > Human response to boom overpressures: > .7 lb/ft**2 - None annoyed > 1.0 lb/ft**2 - 10% annoyed > 3.0 lb/ft**2 - All annoyed > > The typical ascent profile of NASP portrayed on this chart shows the > following (numbers are approximate from reading them off the curve): > > Mach Alt Boom Overpressure > -------------------------------- > 1.3 30K 5.0 lb/ft**2 > 2.0 50K 3.0 lb/ft**2 > 3.0 68K 2.0 lb/ft**2 > 6.0 95K 1.0 lb/ft**2 > 9.0 118K 0.7 lb/ft**2 > > Since part of the reason that Mary ran the periscope tests on the F-104 > was for NASP, I assumed (was hoping) that the usage of the USGS sensors > might also be to do some confirmation testing of NASP boom issues using > NASA's SR-71. One can see the legitimacy of perhaps doing that in the > above chart. > > Yes, airplane designs can be optimized to reduce sonic boom effects. Far-field > N-wave theory seems to be quite good in certain cases. I've seen theoretical > vs. actual N-waves for a whole host of different size aircraft that match quite > well, including the XB-70 and the B-58. > > As far as the USGS sensors are concerned, you'll have to ask. I don't think > they get an N-wave directly however. > > This sonic boom stuff is all part of the science of aeroacoustics. There are > many references available on this in technical college libraries. > > Larry > > > ------------------------------ From: PHARABOD@frcpn11.in2p3.fr Date: Tue, 11 Jan 94 15:32:39 MET Subject: Re: booms >This ALMOST leads me to wonder if there is such a thing as a noisless >or low noise sonic boom. In other words can the shape of a sonic >boom's cone be made to change to reduce the noise signature >and imitate an earthquake. >Paul Mangan (Mon, 10 Jan 94 07:54:12 EST) There are other means. Here is an interesting excerpt from AW&ST: - ------------------------------------------------------------------ AVIATION WEEK & SPACE TECHNOLOGY, March 9, 1992 - "Black World" Engineers, Scientists Encourage Using Highly Classified Technology for Civil Applications - William B. Scott/Los Angeles: " [stuff deleted] In 1968, Aviation Week reported that Northrop was evaluating "electrical forces to condition the air flowing around an aircraft at supersonic speeds" to reduce drag, heating and sonic boom effects. The findings were promising enough to justify funding of additional research (AW&ST Jan. 22, p. 21). By negatively ionizing air molecules ahead of an aircraft, then charging the nose to the same polarity, an electrostatic field was formed. The field tended to repel or alter the molecules' path as the aircraft approached, according to the article. " [end of quotation] - ----------------------------------------------------------------- Other ways, more exotic, have been suggested. J. Pharabod ------------------------------ From: psychospy@aol.com Date: Tue, 11 Jan 94 11:18:53 EST Subject: Sonic Studies in Rachel larry quotes from the OXCART story: > "To be sure, the inhabitants of a small village some 30 miles from > the site were troubled as the aircraft broke through the sound barrier > while gaining altitude. A change of course remedied this." That small village must be Rachel. By the way, 1993 was a big year for acoustic studies in Rachel. In the early part of the year (probably Feb.) some nice men with BIG microphones stayed at the Little A-Le-Inn for a few weeks. They spent all hours of the day and night out in the ranges north and west of Groom Lake recording who-know-what noises (bird calls, probably). They were contractors for an engineering company presumably working for the AF. Shortly thereafter, a crew of about eight very nice people (students and grandmothers) from Minnesota spent about a week interviewing everybody in Rachel about their "feelings." They worked for a polling firm hired by NASA to find out "the problems and benefits of living in a rural community." I think it touching that NASA is concerned about the quality of our lives here, but it turns out that nearly all of the questions in the poll concerned residents reactions to the sonic booms. The same crew returned about six months later (in Oct. I think) to conduct the same poll again, presumably to see if our feelings had changed. There is nothing mysterious about the sonic booms here. Rachel is underneath a major corridor and exercise area for Red Flag, so we get window-cracking booms all the time. (So often, in fact, that if a really interesting boom or rumble did happen, we probably wouldn't notice.) It is understandably that the AF might be concerned about our feelings here, but why would NASA be involved? Another tidbit: The Nellis Range Complex is surrounded by a network of USGS seismic monitors, most of them solar powered and broadcasting their data by radio. Each apparatus is very simple, broadcasting a steady tone that fluctuates with ground vibrations. Anyone with a scanner and some basic recording equipment can pick up the broadcast and monitor for sonic booms, e.g. for nonexistent aircraft in and out of Groom. The Civilian Oversight Network is hard at work on this one. Anyone with ideas should get in touch with me. ------------------------------ From: PHARABOD@frcpn11.in2p3.fr Date: Tue, 11 Jan 94 17:35:29 MET Subject: Re: booms Now that the USGS sensors have been tested with the sonic booms generated by the SR-71, is it possible to know more about the origin of the booms generally attributed to Aurora ? If these booms have been registered, which is probable, a re-analysis of the records, using the information coming from the SR-71 experiment, would be very interesting. J. Pharabod ------------------------------ From: Corey Lawson Date: Tue, 11 Jan 1994 09:46:18 -0800 (PST) Subject: re: sending cryptographicly tagged e-mail. To beat a dead horses... You don't have to clog the list with this stuff. You CAN send it amongst yourselves, those that are interested in spoofing the NSA. That way, you do not put those who really are at risk for job loss for having received information tagged classified. Although I am not in Mary's position, I have been. The Govt's view on this kind of "prank" is about as keen as the Customs agents are when you joke thhat you are carrying two kilos of Coke (a Cola) in your luggage, and then wonder why it's been torn open, for you to repack while everyone watches you? Like it or not, there are consequences for every action. Whether they are intended or not, the initiator does bear some responsibility for those consequences. Asking...no, in this case, it's FORCING, others to accept the outcome for you is...lame. I was going to say unmanly, but I won't. - -Corey Lawson csl@stein.u.washington.edu or alfalfa@booster.u.washington.edu ------------------------------ From: larry@ichips.intel.com Date: Tue, 11 Jan 1994 12:13:34 -0800 Subject: Re: booms J. Pharabod writes: >There are other means. Here is an interesting excerpt from AW&ST: >------------------------------------------------------------------ >AVIATION WEEK & SPACE TECHNOLOGY, March 9, 1992 - "Black World" >Engineers, Scientists Encourage Using Highly Classified Technology >for Civil Applications - William B. Scott/Los Angeles: > >" [stuff deleted] > > In 1968, Aviation Week reported that Northrop was evaluating > "electrical forces to condition the air flowing around an aircraft at > supersonic speeds" to reduce drag, heating and sonic boom effects. > The findings were promising enough to justify funding of additional > research (AW&ST Jan. 22, p. 21). > > By negatively ionizing air molecules ahead of an aircraft, then > charging the nose to the same polarity, an electrostatic field was > formed. The field tended to repel or alter the molecules' path as the > aircraft approached, according to the article. " Ah yes, Electroaerodynamics! That research was quite interesting! There is a nice picture of what the electric field does to the shock, from one of their fluid tunnel tests, in the 3/11/68 issue of Product Engineering, on pg 35-36. Their fluid tunnel work with fluids of different dielectric strengths was quite promising! When they went to a supersonic wind tunnel, they found that arcing occurred between the model and the walls of the tunnel, due to the high voltages they were applying to the model. So they had to electrically isolate the walls of the tunnel from the model. Once that was done they ran many experiments, varying many different parameters, since they were doing ground-breaking research. In one test at Mach 1.4, the shock off the model COMPLETELY DISAPPEARED!! However, one of the things that makes me skeptical about this actually being developed further is that these sources are completely declassified. I agree however that it is quite fascinating! My opinion on this is that if you were going to be at a high enough altitude, that the distance attenuation effects on the boom would be adequate. There would be no need to go to exotic technologies like Electroaerodynamics. I feel that something like electroaerodynamics would be useful at lower than sonic boom optimized altitudes. Also, the glow from such a thing would make the vehicle quite noticeable. Coupling the lower altitude, and the glow, ... it would look like a, .... UFO! Larry ------------------------------ From: larry@ichips.intel.com Date: Tue, 11 Jan 1994 15:12:37 -0800 Subject: Re: Sonic Studies in Rachel larry quotes from the OXCART story: >> "To be sure, the inhabitants of a small village some 30 miles from >> the site were troubled as the aircraft broke through the sound barrier >> while gaining altitude. A change of course remedied this." psychospy (Glenn?) writes: >There is nothing mysterious about the sonic booms here. Rachel is underneath >a major corridor and exercise area for Red Flag, so we get window-cracking >booms all the time. (So often, in fact, that if a really interesting boom or >rumble did happen, we probably wouldn't notice.) ... Well this is the first I've heard of this, about booms all the time! I wish I had known this before I put my foot in my mouth about nothing going on in the Groom area. This is significant actually. So it would be difficult to hear a loud rumbly aircraft coming and going, and once the public land lookouts are gone, a loud airplane could actually come and go at the Groom facility at will. Actually, would this be all bad? What if the government acknowledged the Groom Lake test facility exists in public, and the kinds of things they do there. That way the facility would be more open to congressional oversight, and the government could test their 'whatevers' there in secret. You may even be able to perceive more (legally) after the facility is more 'secure'. Although that may be why the studies you mentioned (and thanks for the information), are being done. These days, I would assume that any attempt to place a city, no matter how small, in the environment of a loud, rumbly (beautiful noise to me) airplane has to have studies that assess the impact to the public welfare. They also have to cover themselves and understand just how good public available technology can hear what is going on, and process the sound waves to discriminate information. Or perhaps they need to understand the scope of what they have subjected people up to now is. In any event, it's quite interesting! The above of course is pure speculation on my part. Are there other cities that are viewed as cities that are boomed a lot by Red Flag or whatever? Do these cities also get visiting therapists? What do others think? Larry ------------------------------ From: Rick Pavek Date: Tue, 11 Jan 1994 20:09:10 -0800 Subject: Da Booms... Do you think, perhaps, that they may be doing an environmental impact study? Before they go to the public with information about the site? Rick "Inquiring Minds Want to Know" Pavek SR-75/XR-7 _|_*O*_|_ | Rick Pavek \ __|__ / | HA!! kuryakin@halcyon.com \_______/_(O)_\_______/ | Ruby - \___/---\___/ | Galactic Gumshoe ------------------------------ End of Skunk Works Digest V4 #115 ********************************* To subscribe to skunk-works-digest, send the command: subscribe skunk-works-digest in the body of a message to "listserv@harbor.ecn.purdue.edu". If you want to subscribe something other than the account the mail is coming from, such as a local redistribution list, then append that address to the "subscribe" command; for example, to subscribe "local-skunk-works": subscribe skunk-works-digest local-skunk-works@your.domain.net To unsubscribe, send mail to the same address, with the command: unsubscribe skunk-works-digest in the body. 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