From: skunk-works-digest-owner@pmihwy.com To: skunk-works-digest@pmihwy.com Subject: Skunk Works Digest V6 #11 Reply-To: skunk-works-digest@pmihwy.com Errors-To: skunk-works-digest-owner@pmihwy.com Precedence: Skunk Works Digest Wednesday, 29 January 1997 Volume 06 : Number 011 In this issue: Re: your mail Re: A12 fuel additive Re: A12 fuel additive Re: Re: Low Visibility Paint Re: A12 fuel additive Re: drag F-117's Re: your mail Re: A12 fuel additive Have Glass Re: A couple of short messages... Re: A12 fuel additive Contrails Re: RAM covered helmets eject-eject-eject Re: RAM covered helmets 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: Brad Hitch Date: Mon, 27 Jan 1997 20:28:01 -0700 (MST) Subject: Re: your mail > > > > > So, is there a simple was to express the increase in drag? > > The basic equation is the following: > > D = (1/2) * Rho * S * (v^2) * Cd > > Where: > D = Drag > Rho = Density of the atmosphere > S = Surface area of the wing > v = Velocity of the airplane > Cd = Coeffiente of Drag. This is function of Angle of Attack, Mach > number, Reynolds Number, and Airfoil Geometry. > One has to be careful to specify exactly what area the Cd refers to. In general one uses the planform area of the wing since this is a fairly readily available number or at least easily approximated. To say surface area is confusing since you get stuff like "wetted surface area? twice the planform area?," etc. The point is that you could use any area you like to reduce your drag data in the form of a Cd so that you HAVE to EXPLICITLY and UNAMBIGUOUSLY SPECIFY what area you used. If you're lucky you might even pick one that has a modicum of significance to the physics of the problem. ------------------------------ From: Jim Conrad Date: Mon, 27 Jan 1997 22:57:00 -0500 (EST) Subject: Re: A12 fuel additive At 11:33 AM 1/25/97 +0000, jwp@lubrizol.com wrote: >This got me wondering if there has been any progress in fuel additives >to reduce the visibility of condensation trails. Was this also a >problem with the high flying U-2 and A-12/SR-71? The recent photos of >the "doughnut on a rope" type contrail indicate that the contrail may be >a major problem during daylight flights of a "stealthy" aircraft. Their was an article in Aviation Week in the last year or so that addressed this issue with the B-2. I can't remember exactly how they were going to deal with it but they had a plan. <:><:><:><:><:><:><:><:><:><:><:><:><:><:><:><:><:><:><:><:><:><:><:><:> <:> Jim Conrad - Ocean View Communications - jjc@infi.net <:> <:> 757-490-8127 Office - 757-587-8251 Fax - 757-473-6740 Pager <:> <:><:><:><:><:><:><:><:><:><:><:><:><:><:><:><:><:><:><:><:><:><:><:><:> ------------------------------ From: Brett Davidson Date: Tue, 28 Jan 1997 17:58:06 +1300 (NZDT) Subject: Re: A12 fuel additive On Mon, 27 Jan 1997, Jim Conrad wrote: > >the "doughnut on a rope" type contrail indicate that the contrail may be > >a major problem during daylight flights of a "stealthy" aircraft. > > Their was an article in Aviation Week in the last year or so that addressed > this issue with the B-2. I can't remember exactly how they were going to > deal with it but they had a plan. Don't know exactly, but I've heard that the additives that have been used in the past are highly toxic or corrosive. One alternative that has been proposed is to ionise the exhaust: the vapour droplets would then repel each other and the contrail would disipate more quickly. Electrostatic techniques have also been proposed as a means of smoothing the airflow over wings and reducing drag. These may be used on the B-2 perhaps? Some UFO nuts have had their VCRs interfered with as B-2s fly overhead at low altitude and of course have thought that it was due to the alien-derived antigravity drive... Actually, if it has such a detectable effect, it doesn't sound very stealthy. - --Brett ------------------------------ From: Edward_R._Hotchkiss@atlmug.org (Edward R. Hotchkiss) Date: 28 Jan 1997 03:09:23 GMT Subject: Re: If I remember correctly from my automotive days, it doubles. My 280Z has an aerodynamic drag limited speed of 130 mph. /Ed Hotchkiss/ ------------------------------ From: Edward_R._Hotchkiss@atlmug.org (Edward R. Hotchkiss) Date: 28 Jan 1997 03:12:53 GMT Subject: Re: Low Visibility Paint I joke that the paint job on my car is a stealth job. It is a weathered (dead paint) blue. Given an overcast day, I have to remember to turn on my lights to keep from getting into accidents. /Ed/ ------------------------------ From: Wei-Jen Su Date: Tue, 28 Jan 1997 13:19:56 -0500 (EST) Subject: Re: A12 fuel additive On Mon, 27 Jan 1997, Jim Conrad wrote: > > Their was an article in Aviation Week in the last year or so that addressed > this issue with the B-2. I can't remember exactly how they were going to > deal with it but they had a plan. > What I remember from AW&ST. They mention that the B-2 has a contrails warning system. Similary to stall warning, when there is about to form contrails, it start giving the pilot a warning signal. BTW, I found that F-117 pilot use helmet coated with RAM and special stealthy flying suit. Any comment?? May the Force be with you Su Wei-Jen E-mails: wsu02@utopia.poly.edu wjs@webspan.net "My dad used to fly the same aircraft that I am flying right now" B-52 pilot ------------------------------ From: Lee Date: Tue, 28 Jan 1997 13:27:19 -0700 Subject: Re: drag At 09:39 PM 1/27/97 -0500, Wei-Jen Su wrote: > If you wants to know more, I can keep going forever... Replay me >if you wants to know more. Thanks, that's exactly what I needed and it only provoked one question. Is the formula for total drag or only drag over the airfoil? Lee __ __ _ Utah Karting Champion (1991 1992 1993) __ _ - ~~ l ~-_ "Karting is the purest form of motor @~~ ------+--------~----____ racing." --- Ayrton Senna (1960-1994) @==/~_~\===|=~======|===/~_~\~~-, http://www.wasatch.com/~racer \ ( (_) ) \_______| ( (_) )__ , send mailto: racer@wasatch.com >~~\___/~~~~~~~~~~~~~~~~\___/~ 1987 Fiero GT Metallic Blue, CS ------------------------------ From: patrick@e-z.net Date: Tue, 28 Jan 1997 13:31:20 -0800 Subject: F-117's Wei-Jen Su wrote: > > BTW, I found that F-117 pilot use helmet coated with RAM and > special stealthy flying suit. Any comment?? > >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> The Lockheed literature claim that the pilots helmet could be noticed in RCS testing. But I believe that the vapor deposition of a metallic coating on the canopy glass resolves this problem. Enough of the radar signal is now reflected off of the glass to reduce the signature to a an acceptable level. If this is true, a pilot "dressed in RAM" would not be necessary. If one examines the photos available of 117 operations there appears to be no evidence of anything but standard issue flight suits and helmets being used. And in my observations they still use the same standard issue gear at Holloman today. But this does not rule out the possibility any special testing of such items. I use to believe these aircraft where equipped with a special dispenser that added a chemical to the exhaust stream which negated any vapor trails that may be produced in flight. But I cannot find any evidence to support this. patrick cullumber patrick@e-z.net ------------------------------ From: Mary Shafer Date: Tue, 28 Jan 1997 17:40:27 -0500 (EST) Subject: Re: your mail In general, the surface area, S, is defined as being the product of the span and the mean aerodynamic chord, b and c_bar (or mac) respectively. However, for aircraft, these numbers are usually based on an early set of drawings and are not actually measurements of the aircraft as built. If the original poster is trying to do some sort of ratio (as indicated by the use of "increase), it may well be that some of the terms, particularly S, may cancel out (S/S=1). I don't remember the original request so I can't really say. 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.... On Mon, 27 Jan 1997, Brad Hitch wrote: > > > > > > > > So, is there a simple was to express the increase in drag? > > > > The basic equation is the following: > > > > D = (1/2) * Rho * S * (v^2) * Cd > > > > Where: > > D = Drag > > Rho = Density of the atmosphere > > S = Surface area of the wing > > v = Velocity of the airplane > > Cd = Coeffiente of Drag. This is function of Angle of Attack, Mach > > number, Reynolds Number, and Airfoil Geometry. > > > > One has to be careful to specify exactly what area the Cd refers to. In > general one uses the planform area of the wing since this is a fairly > readily available number or at least easily approximated. To say surface > area is confusing since you get stuff like "wetted surface area? twice > the planform area?," etc. The point is that you could use any area you > like to reduce your drag data in the form of a Cd so that you HAVE to > EXPLICITLY and UNAMBIGUOUSLY SPECIFY what area you used. If you're lucky > you might even pick one that has a modicum of significance to the physics > of the problem. > ------------------------------ From: larry@ichips.intel.com Date: Tue, 28 Jan 1997 15:39:42 -0800 Subject: Re: A12 fuel additive >An article on Stone's blackbird page > >http://www.thepoint.net/~jstone/blackbird.html > >contains an article (The U-2's Intended Successor: Project Oxcart, >1956-1968) which mentions that one of Lockheed's breakthroughs on the >A-12 was the use of a cesium containing fuel additive which reduces the >radar return from the afterburner plume. Yes, this was interesting. Also read in the hypothetical case of a plasma surrounding a vehicle (hypersonic airplane, UFO, whatever) and how you could see it but not have it register on radar. It would be interesting to know the physics here. I recall that the RCS handbook had a chapter on radar interaction with plasmas. Seeding the relatively low temperature (as plasmas go) of a jet (turbojet,rocket) exhaust with elements from the alkalai family to create a lower temperature plasma was relatively new in the A-12's day, as I think it dates back to 1958. It has been done for power generation as well as to increase the speed of the flow using MHD techniques. >This got me wondering if there has been any progress in fuel additives >to reduce the visibility of condensation trails. Yes, this has been done. It works. > Was this also a >problem with the high flying U-2 and A-12/SR-71? I believe the U-2 and SR pick altitudes where there is no contrail being left. > The recent photos of >the "doughnut on a rope" type contrail indicate that the contrail may be >a major problem during daylight flights of a "stealthy" aircraft. Or, perhaps just the setting of the throat in the inlet. In other words, as the throat is opened, the flow becomes more stable. There have been problems with wind tunnels that pulse near transonic speeds, given a model in the throat of the tunnel, whose cross section chokes the flow. I believe the slotted throat wind tunnel was created to solve this problem. >I remember work being done by the Air Force a long time ago on fuel >additives that reduce the droplet size in the contrail and make it >"invisible". The most effective materials I heard of were very >corrosive to the engines and were probably never used. That's why it wasn't added to the fuel, but sprayed in the exhaust of the engine. It of course needed its own corrosion proof tank. There may be some information about this in Jay Millers B-2 datagraph. I recall seeing a picture of a KC-135 test aircraft that had been fitted with the spray hardware, somewhere. > BTW, I found that F-117 pilot use helmet coated with RAM and >special stealthy flying suit. Any comment?? Yes, but the F-117A pilot is not allowed to wear the suit outside the aircraft! Sorry, I couldn't resist! Actually there have been some fairly interesting science fiction stories, I recall one from Analog magazine in the past year, about this very thing. A suit that made one invisible. The way the suit worked, was that the suit was covered with millions of nodes, display processors, and routing networks and processors, that did the following: 1. Capture visual light levels as input. 2. Route the captured visual light levels to the appropriate display processors. 3. Display on the surface of the suit, compensating for wrinkles and operational movements of the person enclosed within, the appropriate hologram of the scene, visible through that display plane, to mask the volume of the person underneath. 4. A display plane that works in all applicable light levels, and is compatible with 1,2, and 3. 5. Low power requirements for all of 1-4, and life support capability for the enclosed person, as well as interfaces for human input sensors. 6. A zipper compatible with 1-5. ------------------------------ From: habu@why.net (habu) Date: Tue, 28 Jan 1997 21:25:50 -0800 Subject: Have Glass Does anyone have any details on a program called "Have Glass", supposedly an F-16 RCS reduction program? Also there was evidently a similar program for F/A-18s called "Glass Hornet". I've seen these mention in World Air Power Journal, Vol. 26. Now that Lockheed builds F-16s, I guess this is on topic... Greg Fieser ------------------------------ From: habu@why.net (habu) Date: Tue, 28 Jan 1997 21:28:26 -0800 Subject: Re: A couple of short messages... John Stone wrote: > > The deal is you have to take all of them, and pay shipping from KY! > John, Any idea what shipping would be to Dallas? (assuming you haven't already sold them...) Please reply to gregd@cambertx.com - my IPS (why.net) *sucks* and I can only get on about every third day...geez, I might as well be on AOL... Thanks, Greg ------------------------------ From: dadams@netcom.com (Dean Adams) Date: Tue, 28 Jan 1997 23:41:42 -0800 (PST) Subject: Re: A12 fuel additive > BTW, I found that F-117 pilot use helmet coated with RAM and > special stealthy flying suit. Any comment?? > Sounds like another one of those tall tales. I'm surprised they could even keep a straight face with the "stealthy flying suit" bit! As someone already mentioned, the F-117 has a special coating on the canopy glass to prevent the usual cockpit RCS problems. ------------------------------ From: Matt Starnes Date: Wed, 29 Jan 1997 09:15:28 -0600 Subject: Contrails In order for a contrail to appear, do certain atmospheric conditions have to be present? I'm just curious because I was sitting out the other day and saw single contrails, double contrails, etc,. Thanks alot. ------------------------------ From: gregd@cambertx.com (Greg Fieser) Date: Wed, 29 Jan 97 09:14:01 PST Subject: Re: RAM covered helmets Yes, it is true that special canopy coatings have been developed to reduce unwanted radar reflections from within the cockpit (including the pilot's head), but I believe Su Wei-Jen is referring to the highly classified study known as "Senior Silk", conducted by the DRD (Department of Redundancy Department) in an effort to reduce the RCS of a pilot *after* ejection! This included RAM covered flight suits and helmets, and special faceted flight boots. Even the shape of the pilot relief tube was optimized for stealth... These "Senior Silk Suits" are also designed to protect the pilot when ejecting at Mach 10 at 200,000 ft. I have heard that the parachute canopy was also constructed of a special material and had a very unusual (large, black, triangular) shape. Senior Silk was preceded by another, rather unsuccessful and very unpopular program known only as "Have Guillotine"... ------------------------------------- Greg Fieser 1/29/97 gregd@cambertx.com 9:14:01 AM (aka habu@why.net) ------------------------------------- ------------------------------ From: "John P.McElwain" Date: Wed, 29 Jan 1997 15:25:37 -0500 Subject: eject-eject-eject Hi Folks: My son subscribed me to this newsletter because I'm a retired pilot and he thought I'd enjoy it.Though the subject is interesting I'm personally obsessed with floatplanes and flying boats.He didn't,however,bother to record the procedure for de-subscribing.Can anyone help me? "Have Guillotine" indeed.Keep the oily side down,now. Regards, John McElwain ------------------------------ From: Brett Davidson Date: Thu, 30 Jan 1997 10:18:50 +1300 (NZDT) Subject: Re: RAM covered helmets On Wed, 29 Jan 1997, Greg Fieser wrote: > the RCS of a pilot *after* ejection! This included RAM covered > flight suits and helmets, and special faceted flight boots. Even > the shape of the pilot relief tube was optimized for stealth... > > These "Senior Silk Suits" are also designed to protect the pilot > when ejecting at Mach 10 at 200,000 ft. I have heard that the etc.... Ah yes, reminds me of of the project I had heard about, code named "Extract Mickey".. but I'm not allowed to talk about that. - --Brett ------------------------------ End of Skunk Works Digest V6 #11 ******************************** To subscribe to skunk-works-digest, send the command: subscribe skunk-works-digest in the body of a message to "majordomo@pmihwy.com". 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