From: skunk-works-digest-owner@mail.orst.edu To: skunk-works-digest@mail.orst.edu Subject: Skunk Works Digest V5 #429 Reply-To: skunk-works-digest@mail.orst.edu Errors-To: skunk-works-digest-owner@mail.orst.edu Precedence: bulk Skunk Works Digest Wednesday, 20 September 1995 Volume 05 : Number 429 In this issue: Re: Jet Engines Sailboats (was Re: Jet Engines) Engines Re: SR71-Kelly comments Re: Sailboats (was Re: Jet Engines) NOT F-117/U-2/C-130s on carriers UAV Biot - Savart & Induced Drag Moon Missiles Re: F-117/U-2/C-130s on carriers Moon Missiles (RE:) [none] Re: GPS Re: GPS- comments and a question Re: UAV Re: F-117/U-2/C-130s on carriers Re: your mail Re: F-117/U-2/C-130s on carriers 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: Nick Barnes Date: Wed, 20 Sep 1995 09:37:28 +0100 Subject: Re: Jet Engines > From: "R. Lee Hawkins" > Date: Tue, 19 Sep 1995 12:03:20 -0400 > Subject: Re: Jet Engines > > In your message dated: Mon, 18 Sep 1995 20:52:42 CDT you write: > > > >This raises a question in my mind about the maximum speed of the airframe, > >since the maximum speed of a boat is 1.3 * (the square root of the length of > >the boat), does the same axiom hold true for an aircraft. > > Actually, it's 1.3 * sqr(waterline distance) in *general*. For some > designs, it can be as high as 1.6 * sqr(waterline distance). Bzzt. My bad dimensionality detector just went off. Can someone explain how this formula is derived, so those of us who don't choose to work in nanoparsecs per fortnight (or whatever) can figure out the constant for themselves? Nick Barnes, speaking for himself ------------------------------ From: "George" Date: Tue, 19 Sep 95 22:09:33 -0400 Subject: Sailboats (was Re: Jet Engines) >From: dougt@u011.oh.vp.com (Doug Tiffany) >Date: Mon, 18 Sep 95 15:28:34 EDT >Subject: Re: Jet Engines much deleted >That almost seems like a sailboat that can exceed the speed of the >wind. It's obvious that I'm not thinking correctly on this one (This >one of many :-) ). Sailboats can easily exceed the speed of the wind, as most sailboats get their thrust from wind traveling over their airfoil-shaped sail to generate lift perpendicular to the sail, rather than being pushed by the wind (as in a square-sail). I'd draw a few diagrams, but ASCII is hard. This also explains tacking, or the ability to sail into the wind and make progress, the boat sails 45 degrees into the wind, the sail is at a moderate angle of attack wrt to wind, the projection of the sail's thrust onto the course of the boat is small, but enough to get forward movement, into the wind. As far as subsonic combustion pushing a jet to supersonic speeds, it must be the nozzles! george ------------------------------ From: Charles_E._Smith.wbst200@xerox.com Date: Wed, 20 Sep 1995 04:25:37 PDT Subject: Engines A few clarifications: The flow at the end of the combustion chamber, not the nozzle, cannot exceed Mach 1. (Due to thermodynamic restrictions.) The exit of the turbine goes into a mixing chamber(for a fan) and is then accelerated through a Laval-type nozzle. Engines today use variable-area mixers to maximize efficiency. The terms VAT and FAT are descriptions of which type of internal area control engines use. VAT`s use vanes to vary turbine area. FAT`a are fixed area, usually followed by somewhat sophisitcated mixers. (All this applies to low compression "fighter" type engines, as opposed to high compression transport types.) And yes, I forget who to thank but thanks for the correction.... rocket nozzles become UNDERexpanded as back pressure decreases! Sailboats: My nacra will exceed the wind speed, but not always. It depends on heel angle, (which affects Biot-Savart, and gives a vertical component to thrust), and drag which spikes till the hulls plane. I run a weather helm so as the wind goes up the rudders create lots `o drag. I once considered doing a computational model of the system, but after discussing it with my friends we all decided it probably impossible to get reaslistic results. Chuck ------------------------------ From: mangan@Kodak.COM (Paul Mangan) Date: Wed, 20 Sep 95 07:34:50 EDT Subject: Re: SR71-Kelly comments Originally from me: > > I also received my copy of Bell Aircraft Since 1935 and they have > pictures of their U2 equivalent in there. I think they called it > the DS-188( I'll recheck that). Neat piece of equipment. It I checked on this and I was wrong(same page) The X-16 was the U2 look alike. The X-16 was actually ordered by the Government (28 units). When Kelly Johnson heard about it he was so furious that he built a plane to compete but the Government said "too late". He wouldn't take no for answer and even though the X-16 contract was already awarded he persisted and presented the Gov. and CIA with the U2. The CIA became involved and the X-16 was cancelled. Bell Aircraft had already built a special building to house the construction of the X-16 and was in the process of building the first unit. The D188 was fancy VTOL fighter. Really sharp. > was being built about the same time that my dad was going back and > forth between The Skunk Works and Bell Aircraft(where he was employed). > > They also had a picture of the 4 fanned XV22 in there and talked about > how it was short lived due to a crash in August of 1966. I saw it > crash. After it hit the first time one of the rear fans sped up and > twisted the rear section of the craft over 180 degrees. I helped the > pilots get out as the crash truck came in from Bell Aircraft/Niagara > Falls Airport. The crash site was on Hoover road in an open field > on the Hoover Dairy property. The significance was that it was only > a few feet from High Tension lines. I took photos of it and then > had my camera taken away from me. Luckily I new several of the big > shots there and they took it away from the security people and gave > it back. > Paul > mangan@kodak.com > ------------------------------ From: hendefd@tech.duc.auburn.edu (Frank Henderson) Date: Wed, 20 Sep 1995 07:30:11 -0500 Subject: Re: Sailboats (was Re: Jet Engines) NOT Is there ANY chance we can take this fascinating discussion to email or an appropriate group? ObSkunk: I hope to be moving down to Sarasota, FL soon. Is there any good aircraft (SR's U2's ...) places down there? # Frank Henderson | Div. of Univ. Computing # Network Services /0\ Security Administrator # X-500/Gopher Manager \_______[|(.)|]_______/ # Auburn University o ++ 0 ++ o hendefd@mail.auburn.edu ------------------------------ From: clarence@spooky.chinalake.navy.mil (Clarence Dent) Date: Wed, 20 Sep 1995 08:28:09 -0800 Subject: F-117/U-2/C-130s on carriers Su Wei-Jen wrote: >> I have a picture of a U-2 that landed on a carrier at sea. I also have >> seen a picture of a C-130 that landed on the deck of a carrier (how else >> did it get there?). I think the C-17 could do it with the right wind > > I saw a video of a C-130 landing in a carrier... scary!!! If the >pilot make a big mistake, it will be catastrofic... I think that is one >of the reason that they don't do that no more (for security reason) > > May the Force be with you > > Su Wei-Jen > wsu02@barney.poly.edu I think it depends on the size and importance of the load the C-130 would be carrying. Helicopters can carry say a new engine for a tomcat slung underneath for a short distance, but not a long one. In most parts of the world, a C-141 could transport the engine to a nearby airfield and then a helicopter could ferry it over to the carrier, but in times of war, things have to move much more quickly. A C-130 could almost but not quite carry the entire aircraft (engines, wings, fuselage, etc) in pieces, little alone just an engine and deliver it directly to the carrier in need. As long as the deck is completely clear, the wingspan of the C-130 aircraft clears easily. Since it would only need to be on the deck for a matter of minutes to unload, such an event could easily occur. Although, the pilot would have to be *very* good and confident!... Remember, the C-130 is one of those aircraft that can reverse the pitch of the propellors and virtually stop on a dime. The trick is getting enough speed and lift to get off again... Clarence@spooky.chinalake.navy.mil "Jet Noise: The sound of a paycheck" ------------------------------ From: dougt@u011.oh.vp.com (Doug Tiffany) Date: Wed, 20 Sep 95 11:54:42 EDT Subject: UAV I found this item at Popular Mechanics (http://popularmechanics.com) and was wondering if this was one of the UAV's that have made the thread here: (Desperate attempt to get back on topic) Tech Update Of The Day: September 20, 1995 Bloodhound of Chemical Warfare WASHINGTON, DC -- Alerting our troops to chemical-weapon attacks, an ultrasensitive toxin detector may soon fly aboard an unmanned air vehicle. No bigger than a shoebox, the Surface Acoustic Wave Chemical Agent Detector (SAWCAD) can sniff out particles numbering only a few parts per trillion. The Naval Research Laboratory led in the de-velopment of the device. Hunter unmanned air vehicle would carry SAWCAD chemical-weapons sensor. SAWCAD features an array of piezoelectric surfaces thinly coated with different polymers, each engineered to bond with a particular chemical agent. When a toxic agent contacts the coating, it disrupts an acoustic wave that's constantly beamed across the surface. The disruption has a characteristic signature that reveals the type and amount of toxin encountered. - -- A hundred years from now, it will not matter what kind of house I live in, how much is in my bank account, or what kind of car I drive, but the world may be a different place because I was important in the life of a child. Douglas J. Tiffany dougt@u011.oh.vp.com Varco-Pruden Buildings Van Wert, Ohio ------------------------------ From: Charles_E._Smith.wbst200@xerox.com Date: Wed, 20 Sep 1995 09:14:02 PDT Subject: Biot - Savart & Induced Drag In response to several email requests I will post this of topic reply. Biot Savart is the relationship which is used to determine the downwash at a particular spot along the span of a finite wing. As I`m sure you al know, the wingtip vortices create a downwash. The net effect of this is to reduce the effective angle of attack to a value less than the angle the wing makes with the aircraft`s velocity. The net effect rears its head as induced drag. This is where the engineers get a little chuckle. The term "induced" is not due to the fact that the wing "induces" something to happen, but that when someone went to explain this phenomina (Prandtl, if memory serves) the Biot-Savart law for induction in wires in a magnetic field yeilded the explanation. So the term "induced " come from the EM concept of induction! An intersting aside. The higher the aspect ratio, the less the downwash. The less the downwash, the lower the geometric angle of attack before stalling. This explains why most airfoils fall off at around 15 deg. in 2D data, but aircraft can fly at such high nose-up attitudes. Sailplane pilots have to pay a price for the performance of the long, skinney wings. The wings will stall at small nose-up pitch displacements. (slow , constant alt. deceleration.) A Cherokee will (AR about 6) will fly with the nose way up! Chuck Smith "Aerospace Engineer to the Stars" ------------------------------ From: "Terry Colvin" Date: Wed, 20 Sep 95 11:03:52 EST Subject: Moon Missiles Forwarded from SPACE TECH list: ______________________________ Forward Header __________________________________ Date: 18 Sep 1995 15:59:01 -0700 From: John Schilling Subject: Moon missiles Bruce Lewis writes: >saundrsg@qlink.queensu.ca (Graydon) wrote: >>Assuming cylinders fifty miles long by twenty miles in diameter, that's >>roughly 80 km by 32 km dia, for an approximate volume of 64 340 _cubic >>kilometers_. One cubic kilometer is a billion cubic meters; multiply by >>specific gravity to get billions of tons per cubic kilometer. Call it >>five; five billion times 64 340 is about 32 _tera_tons, 32 000 000 000 >>000 000 kg. >> >>Every nuke on the planet won't move that rock quickly. The moon is a >>_terrible_ place to get the gazillion kg of deuterium required to build >>the many, many very big H-bombs required to even think about moving such a >>rock. Nor are there a bunch of Apollo asteroids in that size range. >Okay, make it main group planetoids and antimatter bombs, then. >Or elfin magic, for all I care. The point isn't "how it's done", it's >"what can BE done should it ever happen." Postulate any necessary >technology you like: the point is, _what could Earth do to defend itself >against an attack from space?_ Good lord, this is getting ridiculous. Whatever technology the loonies (I can think of no better term) used to move the rocks in the first place, Earth can use to move them again. Earth has an industrial base orders of magnitude greater than anything we are going to see in space in the next century or two, it has access to every technology the spacers have, and it now has a very powerful motive to devote whatever resources it takes to accomplish the job. *And*, it has an easier task in that, unless they wait to the last minute, the delta-V needed to make the rock miss Earth will be substantially less than the delta-V required to set it on collision course to begin with. It is trivially true that if we postulate a space colony with an arbitrarily large population and industrial base, equipped with arbitrary technologies, we can develop attacks that the United States of America circa 1995 will not be able to stop. This seems to be the point you are trying to make. Big F*cking Deal. The United States of America, circa 1995, has no space colonies. Any nation which, in the future, *does* have space colonies, will also have capabilities that USA-1995 does not have. At the very least, almost by definition, a whole lot of spaceships. If the colony can make lots of nukes, so can the mother country. If the colony has antimatter bomb technology, so does the mother country. If the colony has elfin magic capable of relocating asteroids, the mother country has whole armies of elf magicians who will relocate the moon into a close (~0.05AU) solar orbit, bake it until the pesky loonies are chunks of amorphous carbon, and then put it back where it belongs, decorating the night sky. Attacking the mother country is *not* a viable strategy for a secessionist colony, unless we make grossly unrealistic assumptions regarding the relative capabilities of colony and homeworld. - -- *John Schilling * "You can have Peace, * *Member:AIAA,NRA,ACLU,SAS,LP * or you can have Freedom. * *University of Southern California * Don't ever count on having both * *Aerospace Engineering Department * at the same time." * *schillin@spock.usc.edu * - Robert A. Heinlein * *(213)-740-5311 or 747-2527 * Finger for PGP public key * ------------------------------ From: Mary Shafer Date: Wed, 20 Sep 1995 14:59:35 -0400 (EDT) Subject: Re: F-117/U-2/C-130s on carriers I've got the video tape of the C-130 going onto and off of the carrier. It's my understanding that this was an experiment and the aircraft was as light as they could make it. The QSRA (Quiet Short-Haul Research Aircraft), a modified Bison, also landed and took off from a carrier. No wires, no catapult. They really meant that "S". The QSRA had USB (upper surface blown) flaps, which is how it worked. Regards, Mary Mary Shafer DoD #0362 KotFR shafer@ursa-major.spdcc.com URL http://www.dfrc.nasa.gov/People/Shafer/mary.html Some days it don't come easy/And some days it don't come hard Some days it don't come at all/And these are the days that never end.... ------------------------------ From: dougt@u011.oh.vp.com (Doug Tiffany) Date: Wed, 20 Sep 95 15:35:17 EDT Subject: Moon Missiles (RE:) As long as you're giving profound statements, maybe you can tell us how this applies to Lockheed? > Precedence: bulk > > Forwarded from SPACE TECH list: > ______________________________ Forward Header __________________________________ > Date: 18 Sep 1995 15:59:01 -0700 > From: John Schilling > Subject: Moon missiles > > Bruce Lewis writes: > > >saundrsg@qlink.queensu.ca (Graydon) wrote: > > > Attacking the mother country is *not* a viable strategy for a secessionist > colony, unless we make grossly unrealistic assumptions regarding the > relative capabilities of colony and homeworld. > > > -- > *John Schilling * "You can have Peace, * > *Member:AIAA,NRA,ACLU,SAS,LP * or you can have Freedom. * > *University of Southern California * Don't ever count on having both * > *Aerospace Engineering Department * at the same time." * > *schillin@spock.usc.edu * - Robert A. Heinlein * > *(213)-740-5311 or 747-2527 * Finger for PGP public key * > - -- A hundred years from now, it will not matter what kind of house I live in, how much is in my bank account, or what kind of car I drive, but the world may be a different place because I was important in the life of a child. Douglas J. Tiffany dougt@u011.oh.vp.com Varco-Pruden Buildings Van Wert, Ohio ------------------------------ From: dovergar@nyx10.cs.du.edu (dennis overgard) Date: Wed, 20 Sep 95 13:46:00 MDT Subject: [none] NAME: Dennis Overgard From dovergar Wed Sep 20 07:10:09 1995 Return-Path: Received: by nyx10.cs.du.edu (4.1/SMI-4.1) id AA05224; Wed, 20 Sep 95 07:10:09 MDT Date: Wed, 20 Sep 95 07:10:09 MDT From: dovergar (dennis overgard) Message-Id: <9509201310.AA05224@nyx10.cs.du.edu> X-Disclaimer: Nyx is a public access Unix system run by the University of Denver. The University has neither control over nor responsibility for the opinions or correct identity of users. To: skunk-works@mail Subject: arresting hooks The arresting hooks on Air Force aircraft are used to prevent excursions off the end of runways. I once had the priveledge of belonging to an Air Force flying club and taking instruction at an ANG Base. The flight instructor was extremely firm about not landing short on the runway because the arresting cable at the runways end would rip the undercarriage off the Cessna 152 we were flying. An F-104 pilot I talked to at an airshow told me that the arresting hook on the 104 he was flying was for the same purpose. By the way, one of the most interesting experiences I had was when I was taking a lesson during a base inspection. The chief flight instructor, with me on board, attempted an "unauthorized" takeoff to test the flight ops personell. ( we didn't make it) Dennis Overgard ------------------------------ From: Marco Giaiotto Date: Wed, 20 Sep 1995 22:07:06 +0200 Subject: Re: GPS Hello everybody. I actually work with GPS receivers in flight test activity on Tornado and EF2000. I had to evaluate the possibilities of both military and civil system. I hope this can help. > [If someone has actually WORKED on the nuts and bolts of GPS, dive > in...] ... > >>Yes, there is only one GPS system, but this system has two levels of >>accuracy and security, military and civilian. > Yep. There is only one satellite constellation, but three frequencies, L1, L2 for "P" code and another for "C/A" code (P = Precision, C/A = Coarse/Acquisition). The C/A code is what is called "civil" GPS. It cannot have the same precision of the P code for a reason I will clarify but, when the "select availability" is off, i.e. the satellites don't inject a random jitter into the signal, can reach the precision of one metre for dynamic measurement. Using either method, the position is evaluated knowing the position of the received satellites and your distance from each of them. The distance is calculated using a very precise clock inside the receiver to evaluate the transmission delay of the satellite signals. When the select availability is on, the measurement can be corrected using a differential method: a static receiver has to be placed on ground, in a well known point, and acquires as many position samples as the on-board receiver. At this point we can procede in real time, transmitting the acquired signals to the aircraft, or in post-flight, processing both the acquired files and reconstructing the aircraft trajectory. In both cases we have to compute the position error of the fixed receiver, on a sample by sample basis (remember we know the position, so we can evaluate the error from the reading). From this error, we extract the range error of each satellite (introduced by the select availability). This error is what we apply to each sample of the on-board receiver to correct its readings. Using this method we remain inside the one-meter CEP. For static measurements (survey) aimed to establish a fixed point, we use the differential system with an already known position. With a two-hour survey, we can reach a ten-centimeter precision (!) > >>The military GPS signal requires a key-code which a soldier in the field puts >>into his GPS reciever and gets the famed 'down-to-the-foot' accuracy of the >>GPS. Not exactly: the receiver synchronizes the incoming signals by means of a pattern. This pattern is repeated continuously by the satellites. The true difference is that the C/A pattern is composed of 1024 bits and is transmitted at 1 MHz frequency, giving a duration of 1 ms. The P code pattern is transmitted at 10 MHz frequency, and repeats itself more or less every week. This is the reason for the name: the P receiver acquires and synchronizes the C/A code and, when it knows the time and, more or less, its position, switches to the P code. Here come the two frequencies: what the C/A code cannot take into account is the thickness of the ionized atmosphere, which varies during the day. Using two frequencies, due to the difference the signals are affected by a different delay and we can evaluate that delay, thus compensating the ionization. This can give a precision of half a metre in dynamic measurements. I have to stress that a C/A differential method may be more precise than the P code, but is very difficult to be applied in real time > >>Now, in a theater of war, > I Don't believe that the signal can be degraded for only certain areas. Of course >>such as the Iraq/Kwait area during the Gulf war... > My understanding was that during DS a VERY SPECIAL set of circumstances > kicked in: > 1) "we" did not have enuf proper mil GPS receivers. > 2) We needed GPS BADLY, as one sand dune looks like the next > (to an outlander...). > 3) Intel indicated that Iraqi forces did not have GPS, either > version, in quantity. > > Soooooo > Selective Availability was TURNED OFF. ANYBODY got full mil > accuracy, which allowed the military to get, rapidly, and use > accurately, civil GPS receviers. > Select availability was off during DS, and allied forces were using civil Trimble GPS receivers I have two more thing to clarify: 1. How can the receiver clock be so precise ? 2. How is the position actually evaluated ? but this message is already too long. Should anybody be interested, send a mail to the list, and I will send a further message. In my opinion the list can stand one more message on this topic, provided it is of general interest. Regards, Marco ------------------------------ From: Marco Giaiotto Date: Wed, 20 Sep 1995 22:07:10 +0200 Subject: Re: GPS- comments and a question > >The former Soviet Union had a GPS- type of system as well, I understand. I believe it is called GLONASS, but i'm not so sure >I wonder if it is still operational. If it is, does anyone make a >GPS-type of receiver for it? Can it be used by civilians? There was a project to integrate it with th GPS/NAVSTAR, but nothing has been done as far as I know. The problem now is called "maintenance"... Regards ------------------------------ From: sschaper@pobox.com (Steve Schaper) Date: Wed, 20 Sep 1995 15:24:53 -0500 Subject: Re: UAV Interesting, sounds like it ought to be mounted on the exteriors of armored vehicles and ships as well. ------------------------------ From: sschaper@pobox.com (Steve Schaper) Date: Wed, 20 Sep 1995 15:27:09 -0500 Subject: Re: F-117/U-2/C-130s on carriers At 8:28 AM 9/20/95, Clarence Dent wrote: >have to be *very* good and confident!... Remember, the C-130 is one of >those aircraft that can reverse the pitch of the propellors and virtually >stop on a dime. The trick is getting enough speed and lift to get off >again... > >Clarence@spooky.chinalake.navy.mil > > >"Jet Noise: The sound of a paycheck" Sounds like they should carry rocket assists or something similar for getting back home. I'm new to the list, is your email address for real or a joke? (I know, I know, you could tell me, but then you'd have to kill me.) ------------------------------ From: BaDge Date: Wed, 20 Sep 1995 17:04:18 -0400 (EDT) Subject: Re: your mail On Wed, 20 Sep 1995, dennis overgard wrote: > were flying. An F-104 pilot I talked to at an airshow told me > that the arresting hook on the 104 he was flying was for the > same purpose. > By the way, one of the most interesting experiences I had was > when I was taking a lesson during a base inspection. The chief > flight instructor, with me on board, attempted an "unauthorized" > takeoff to test the flight ops personell. ( we didn't make it) > > Dennis Overgard Oh, man, talk about "arresting", as in cardiac. Made me nervous just reading about a 'test' like that. But don't leave us hanging...details, (beg, beg)?? See ya! regards, ________ BaDge ------------------------------ From: clarence@spooky.chinalake.navy.mil (Clarence Dent) Date: Wed, 20 Sep 1995 14:23:41 -0800 Subject: Re: F-117/U-2/C-130s on carriers >I've got the video tape of the C-130 going onto and off of the carrier. >It's my understanding that this was an experiment and the aircraft was as >light as they could make it. > >The QSRA (Quiet Short-Haul Research Aircraft), a modified Bison, also >landed and took off from a carrier. No wires, no catapult. They really >meant that "S". The QSRA had USB (upper surface blown) flaps, which >is how it worked. > >Regards, >Mary > I'm curious Mary, did they use the JATO rocket packs on takeoff? I saw the plane land, or maybe it was a still of it already on the carrier, but I had no additional info than that. I've been on carriers, and they are really wide, but not long. How much of the deck did the plane need to land? Do you think we could get a C-17 on a carrier? Clarence@spooky.chinalake.navy.mil "Jet Noise: The sound of a paycheck" ------------------------------ End of Skunk Works Digest V5 #429 ********************************* 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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