From: skunk-works-digest-owner@mail.orst.edu To: skunk-works-digest@mail.orst.edu Subject: Skunk Works Digest V5 #275 Reply-To: skunk-works-digest@mail.orst.edu Errors-To: skunk-works-digest-owner@mail.orst.edu Precedence: bulk Skunk Works Digest Saturday, 20 May 1995 Volume 05 : Number 275 In this issue: Air spike and linear aerospike engine Re: AW&ST May, 15, 1995 -- F-117 to Aurora Silent Helos discussion Re: Air spike and linear aerospike engine Hollywood -- and Skunk Works planes Re: Air spike and linear aerospike engine Silence -Roar- Silence 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: BROWN A <92913938@mmu.ac.uk> Date: Fri, 19 May 1995 13:17:31 GMT Subject: Air spike and linear aerospike engine Just recently, there's been lots of talk about both the Linear Aerospike engine in the X-33, and the "Air spike" concept. As a poor ,impoverished student, I can't afford to buy "Aviation Leak". As a result, I don't get much information about the really new concepts. From the discussions here, they both sound very interesting, and I'd really like to find out more about them. If anyone can help with information, especially about the "Air spike" idea, please let me know. I've been asked to give some talks over the summer, to my old Air Training Corps squadron, about various advanced concepts such as hypersonic flight. It would be really great if I could tell them about both of these fascinating concepts. BTW I've never come across any helio called the Sea Bat either. The closest I can think of is the Sting Bat, which I think was the losing competitor for the LHX contract ( No corrections please, I'm away from my main library at the moment, so I'm going by memory.) "Quiet helios?" It is possible that the "quiet" H-60's mentioned recently could have been due to atmospheric effects. Under certain conditions, it is possible for sound to be refracted away from an observer, creating a "zone of silence". I know this to be true as I live under the flight- path of a nightly mail flight made by a DC-3. It always follows the same basic track, as I'm close enough to the take-off point for wind effects to be insignificant. As it always goes over at the same time, just after midnight, you can normally hear it very clearly. Sometimes, though, you don't hear it, even though you can clearly see its navigation lights and the wind is blowing towards you. This initially puzzled me, until I realised that what was happening was the same refraction effect which Sonar operators (such as a good friend of mine who has just left the Royal Navy) are used to. A change in density in the air (or water) causes the sound to be refracted from its straight path. Under certain circumstances, such as a strong temperature gradient, this deflection can be very pronounced and can even create sound "channels" which funnel sound in distinct directions. It is possible that such a temperature gradient existed when the H-60's were flying (very likely at dusk), and that sounds produced even just a few feet off the ground were being refracted away from the observers. As the helios landed, they passed below this gradient into the "ground channel", where the propagation time for the sound would explain them not being heard until after landing. (Just my theory. It could be that "they" really have cracked the noise problem!) BTW, (staying with sound) anyone know if any illustrations exist of the "Stealth Sub" the Skunk Works designed, and that the USN hated? Adrian Brown (92913938@mmu.ac.uk) Dept of Maths & Physics. Manchester Metropolitan University. Manchester. England. "No scientist is ever right, they just can't be proved wrong at the time!" - R.P. Feynman. ------------------------------ From: "J. Pharabod" Date: Fri, 19 May 95 18:06:09 SET Subject: Re: AW&ST May, 15, 1995 -- F-117 to Aurora Regarding: 'AIR SPIKE' COULD EASE HYPERSONIC FLIGHT PROBLEMS, page 66-67, a SKEPTIC correspondent found info in "The Review" (an Rensselaer Polytechnic Institute faculty/staff newsletter). This article can be found at: http://www.rpi.edu/dept/NewsComm/Review/may/may05/space.html They do describe a possible design of a "lens shaped" craft. J. Pharabod ------------------------------ From: MiGEater1@aol.com Date: Fri, 19 May 1995 12:58:28 -0400 Subject: Silent Helos discussion Regarding Black Helos at Roswell Atmospheric effects may certainly refracted the sound away from us. And with the temperature changes at dusk, it seems very likely. I thought about the possibility of a temperature inversion at the time. They didn't return until 10 p.m. local. But, the two helicopters set down (6000 feet away in still air) and under a minute later, the navigation lights and sound all came on at the same time. It was very odd and we honestly didn't know they were helicopters until that time. There were just these two floating lights, instrument panels perhaps, (through the night vision scopes) moving between us and the horizon that made their way to the ramp at the airport. Cheers to all, John ------------------------------ From: kuryakin@arn.net (Illya Kuryakin) Date: Fri, 19 May 1995 12:49:15 -0500 Subject: Re: Air spike and linear aerospike engine +"Quiet helios?" + It is possible that the "quiet" H-60's mentioned recently could +have been due to atmospheric effects. Under certain conditions, it is +possible for sound to be refracted away from an observer, creating a +"zone of silence". I know this to be true as I live under the flight- +path of a nightly mail flight made by a DC-3. It always follows the +same basic track, as I'm close enough to the take-off point for wind I've heard the story from another source... and I'll endeavor to comment on it. The helos were witnessed at relatively short range... less than a half mile. They circled the observers. There were other aircraft (F-18's and F-14's, etc) idling on the ground at least one mile away that could be heard. These helos were silenced. The units involved, also from what I understand, did not show up on the 'unclassified' list... Illya Illya Kuryakin "HA!!" U.N.C.L.E. Network Services Ruby kuryakin@uncle.net Galactic Gumshoe It's hotter than Heater in Hooterville. ------------------------------ From: Kathryn & Andreas Gehrs-Pahl Date: Fri, 19 May 1995 18:09:04 -0400 (EDT) Subject: Hollywood -- and Skunk Works planes I would like to contribute some less serious material to the list, concerning our favorite aircraft and how they are featured in tv and the movies -- not including documentaries like "The Secret Vigil", etc. I have here a little list, sorted by aircraft type, with some remarks: 1) U-2 series of aircraft: a) TV-series "Quantum Leap": in one episode (don't know the title), Sam (Dr. Samuel Becker, the hero) 'leaps' into Edward Lee Oswald (the _suspected_ assassin of John F. Kennedy), while Oswald is stationed at Atsugi, Japan (!). He works in some sort of US Army radar operator room, when a U-2 (a U-2R or TR-1A is briefly shown) comes in from "above 90,000 ft.", apparently from a CIA mission over the USSR or China. :) b) TV-film "Call to Glory" -- apparently also a tv-series (?): the movie recounts the events surrounding the 'Cuban Missile Crisis' from the point of view of an USAF U-2 pilot and his family, including the shooting down of Maj. Rudolph Anderson over Cuba. -- Very nice flying (T-38) and U-2 (U-2R though) scenes. Best U-2 movie so far (if you ignore the usual 'family drama' parts). 2) SR-71 series of aircraft: a) Movie "D.A.R.Y.L." -- a "Data Analyzing Robot, Young Life form" :) escapes after 'lots of adventures' and steals an SR-71A, which he flies 'home', where he ejects, while the bad USAF guys remotely destroy the Blackbird. Disney-style movie. -- The SR-71A appears to be the 'Contractors Bird' (article 2006, serial '64-17955') taxiing and starting from Palmdale. Cockpit shots etc. are of course pure Hollywood. b) Movie "Final Approach" -- an SR-71 pilot, flying a very fast 'low level' training mission (?) crashes. -- During the rest of the movie (99%) he is dead and argues with a psychoanalyst (the devil ?) about what had happened to him. -- Forget it! 3) F-117 series of aircraft: a) TV-film "Night Rider 2000", part of the "Action Pack" series: some sort of "Mad Max" environment in the US southwest. Includes a crashed F-117A, not recovered by the USAF, because the land it lays on is a sacred Indian burial ground. During this movie, a car, looking like an F-117-cockpit on wheels, is also featured. -- The F-117A mock-up is acceptable (but the car stinks). b) Movie "Interceptor": Terrorists try to steal an C-5 Galaxy, transporting two "mind controlled" F-117A, but are stopped by another F-117 pilot, who is on board as a passenger, supported by the female C-5 pilot. -- This flick not only features F-117As with folding wings, starting out of the back of the Galaxy, unfolding the wings in free-fall and then dog fighting each other -- the real funny part is the way the terrorists come on board the Galaxy! They crawl through the aerial refueling boom of their fake tanker, cutting a hole through the top of the C-5. -- Big joke! c) Movie "The Philadelphia Experiment 2": Our hero, stranded from the 1940s 'Philadelphia Experiment' in the 1990s, is thrown into the 1990s of a parallel world, where the Nazis won W.W.II. The reason they won is, because the son (?) of a German mad scientist in the 'real' 1990s repeated a modified 'Philadelphia Experiment' with the goal of transporting things from one place instantaneous to another place (beam me up Scotty). He chooses to use an F-117A, flying alone, non-stop, and unrefueled from the USA to Germany (Wiesbaden!), carrying a nuclear weapon, as a demonstration object. He succeeds in transporting the F-117 to Germany, but also moves it back in time to the 1940s. So the Nazis, presented with this gift from the future, sending the F-117A, now called 'Phoenix' (with German W.W.II markings) back to the USA to bomb Washington. They not only have fuel for the F-117, they also find out how to fly it and how to detonate the nuclear device! (And of course that ends the war in favor of the Nazis). The mock-up of the 'trans-continental-range, nuclear armed F-117A' is good, and looks interesting with fake Wehrmacht Luftwaffe markings. But it gets blown up, what ultimately restores the normal time line. -- Totally unrealistic, but fun. Any comments or additional information is more than welcome. - -- Andreas - --- --- Andreas & Kathryn Gehrs-Pahl E-Mail: schnars@ais.org 313 West Court St. #305 or: gpahl@raptor.csc.flint.umich.edu Flint, MI 48502-1239 Tel: (810) 238-8469 WWW URL: http://www.umcc.umich.edu/~schnars/ - --- --- ------------------------------ From: larry@ichips.intel.com Date: Fri, 19 May 1995 17:29:36 -0700 Subject: Re: Air spike and linear aerospike engine Adrian Brown writes: > Just recently, there's been lots of talk about both the Linear >Aerospike engine in the X-33, and the "Air spike" concept. As a poor >,impoverished student, I can't afford to buy "Aviation Leak". As a >result, I don't get much information about the really new concepts. >>From the discussions here, they both sound very interesting, and I'd >really like to find out more about them. > > If anyone can help with information, especially about the "Air >spike" idea, please let me know. I'll try. Aerospikes are not the same as Airspikes. One use of a spike in a supersonic flow - aerospikes - a surface upon which to expand a flow - the action of a nozzle. Aerospike is an old term, as work on them occurred back in the 50's and 60's. An Aerospike is a type of nozzle for a jet (usually spoken of in rocket contexts) engine. Unlike traditional bell shaped nozzles, which are optimized for a specific altitude, aerospike nozzles are altitude compensating, therefore, they optimize thrust across altitude changes (climbing into orbit) better than standard bell nozzles. Therefore the interest in them for SSTO rockets. Now more uses of spikes. Physical or structural spike's are used in the design of supersonic vehicles to cause shock waves. These shock waves cause air to be denser, hotter and higher pressure as air flows through them. This is actually desired as shocks are therefore used for several purposes, such as to pressurize air going into an airbreathing engine's inlet or/and to optimize lift on the vehicle's lifting surface (waveriders). Airspike may be a new term, coined by the RPI researchers, I think. It refers to the effects of a spike in an airflow, namely a shock is generated as described above, but in this case the shock is caused by a non-structural spike, or one that appears to be made of air, if you will. The shock in an airspike is actually formed by a directed energy beam focused in front of the vehicle. The beam is so high in energy that it causes a detonation in the air at its focus point, which causes a shock wave to propogate outward from the detonation. However, an important function of these shocks, as I understand it, is not so much to propogate in front of the vehicle in the same path as the vehicle, but to propogate sideways and cause the air in front of the vehicle to move out of the way to the side. In this way they reduce the density of the air in front of the vehicle, to reduce heating effects at high Mach numbers, among other things. The vehicle is actually propelled by what is called a MHD Fan, or a Magneto-Hydro-Dynamic Fan (when you see MHD, think of the vector equation F = (J X B) (explained later)), and the shock performs an inlet function for the MHD fan. The shock moves most of the air mass immediately in front of the vehicle to the sides of the vehicle, opening a kind of tunnel in the air for the vehicle to pass through. Now that the shock has pushed much of the air along the sides of the vehicle, the vehicle will, through an additional power beam, get energy to turn the air into a plasma as it passes by the vehicle. This air-plasma flow is like an electric current, due to the plasma effects. It will have a certain current density (J). The vehicle will generate an appropriately oriented magnetic field (B) for the electrified air current to pass through. The MHD Fan action is caused by the (J X B) body force (F) on the electrified air stream. This causes the electrified air stream to curl or wirl about the vehicle as it passes by it, imparting a thrust, as a fan would. Therefore the name MHD Fan. So, there is no need for a physical fan to induce the flow. In fact, at high temperatures, you wouldn't want a physical fan. Why was a MHD Fan used? I think the exersize was to decouple many traditional hypersonic shapes from this exersize. In other words, show that hypersonic vehicles could be designed without following traditional hypersonic body design techniques. One could look at using these techniques with traditional hypersonic designs. I still have several questions about this design myself. I hope to obtain a technical paper about it, or talk to someone who can answer my questions. Larry ------------------------------ From: "Michael William Freeman" Date: Fri, 19 May 1995 23:36:13 -0400 (EDT) Subject: Silence -Roar- Silence > From: Evan Beeton > Date: Thu, 18 May 1995 17:32:41 -0400 (EDT) > Subject: Noisy Stuff > > Terry Colvin typed... > >Silence - WOOSH - silence. > > That's what it sounded like alright... seems I was mistaken about that. I > have received a few messages describing the same thing. I don't know much > about aircraft, so it seemed like something unusual. However, there > still is the fact that I haven't seen or heard any military aircraft > (besides helos) in this area since the late 80's when a C-130 flew into > FLL. And that was not at 2 in the morning, nor very low over a civilian > apartment complex. It's just too weird to pass off as routine. I had a simillar experience about a year ago. I live in the heart of a city, and at about 11pm, all is quiet, then a tremndous roar of a jet engine, then silence again. I don't think that the Air Farce is allowed to do low level flights over major populated areas. ------------------------------ End of Skunk Works Digest V5 #275 ********************************* To subscribe to skunk-works-digest, send the command: subscribe skunk-works-digest in the body of a message to "majordomo@mail.orst.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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