geoffm@EBay.Sun.COM (Geoff Miller) (01/18/91)
From: geoffm@EBay.Sun.COM (Geoff Miller) In article <1991Jan16.013121.9797@cbnews.att.com> MEDELMA@CMS.CC.WAYNE.EDU (Michael Edelman) writes: >There's been a fair bit of discussion lately regarding FAE weapons, and >on last night's news I saw films of these weapons in action. >It looks like the bombs are first detonated radially to mix the fuel; >the resultant cloud of gas is more-or-less toroidal in shape. About a >second later the cloud is detonated, resulting in a fireball and a large >shockwave. I saw the same film. I was impressed with the tremendous power of these weapons, but I don't understand how the fuel can be dispersed by the preliminary explosion without being detonated. What kind of mechanism prevents premature detonation? Geoff -+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+- Geoff Miller + + + + + + + + Sun Microsystems geoffm@purplehaze.EBay.sun.com + + + + + + + + Milpitas, California -+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-
denbeste@uunet.UU.NET (Steven Den Beste) (01/18/91)
From: etnibsd!denbeste@uunet.UU.NET (Steven Den Beste) This kind of explosion seems to go completely against the philosophy which prevailed in the invention of the "blockbuster" bomb of WW-II. The concept went like this: A conventional surface explosion is very inefficient, since most of the power of the explosive goes into producing a shockwave. The blockbuster bomb was enormous, 6000 pounds or more, and had a delayed fuse and an armored nose. When it was dropped, it would hit the ground hard and keep going, burrowing down a hundred feet, and only then would it explode. This gave the explosion excellent "tamping", and almost all of the power of the explosion went directly into a shock wave in the ground. As a result, instead of merely breaking windows it shook all the buildings (or whatever) completely apart. Hence their nickname "earth-quake bombs". Does the gain from not carrying oxidizer in the bomb make up for the loss inherent in an atmospheric detonation?
cirby@vaxb.acs.unt.edu (((((C.Irby))))) (01/19/91)
From: cirby@vaxb.acs.unt.edu (((((C.Irby))))) In article <1991Jan18.003251.8296@cbnews.att.com>, etnibsd!denbeste@uunet.UU.NET (Steven Den Beste) writes: > The blockbuster bomb was enormous, 6000 pounds or more, and had a delayed > fuse and an armored nose. When it was dropped, it would hit the ground > hard and keep going, burrowing down a hundred feet, and only then would > it explode. This gave the explosion excellent "tamping", and almost all > of the power of the explosion went directly into a shock wave in > the ground. As a result, instead of merely breaking windows it shook > all the buildings (or whatever) completely apart. Hence their nickname > "earth-quake bombs". You're referring to Barnes Wallis' famous "Tallboy" and Grand Slam" bombs. They were designed for use against hard targets, such as bridges, submarine pens, and bunkers. The most interesting effect was the "trapdoor." The bomb made a big enough underground hole that the building would often fall right into the crater... We don't need bombs this big any more (12,000 and 22,000 pounds), since we can drop a precision-guided munition down an elevator shaft if we want (as evidenced by the video this morning (Jan. 18)). > Does the gain from not carrying oxidizer in the bomb make up for the loss > inherent in an atmospheric detonation? Fuel-Air Munitions aren't designed to work against hard targets. They work best versus widely-dispersed soft and medium targets, like infantry, light buildings, and storage areas. The overpressures involved (someone mentioned the 300 psi figure) will easily destroy a non-hardened building, and will kill any unprotected person (and I'd wager that the shock wave would have a shot at breaking any tank you'll find...) -- *C Irby Bitnet: cirby@untvax * "Admiration is for poets and for *Internet: cirby@vaxa.acs.unt.edu * dairy cows, Bobby!" ************************************
oplinger@thor.crd.ge.com (B. S. Oplinger) (01/19/91)
From: oplinger@thor.crd.ge.com (B. S. Oplinger) A previous poster asks (while describing ww2 blockbuster bombs): >Does the gain from not carrying oxidizer in the bomb make up for the loss >inherent in an atmospheric detonation? Think of it this way (deliberately simple): A normal bomb explodes with an effect of x, because only y% (some small amount) goes in a direction that is useful (the rest is lost going up). Now if you can spread the explosive material out so that for each little bomb, the same (100-y)% energy goes the 'wrong way', you will gain because some of that lost energy isn't lost, because the bomblet next to it pushes back and the net effect is to strengthen the blast. The nice part about using a fuel (which needs its own oxydizer) instead of an explosive (which will ignite on its own) is that the fuels used are liquid and disperse quite evenly. This idea is used to create the current fragmentation (bad choice of name, can't remember correct one) bombs, which are actually many small bombs and can be used to completely strip a chunk of forest of everything above ground for a much larger area than the same weight conventional (iron) bomb would. -- brian oplinger@crd.ge.com <#include standard.disclaimer>
mmm@uunet.UU.NET (01/21/91)
From: <ames!ames!claris!portal!cup.portal.com!mmm@uunet.UU.NET> WRT the effectiveness of an explosion in air vs. the "Blockbuster", it has been my understanding that what knocks down buildings is not so much the initial blast, but the rush of air into the vacuum created following a blast, in which case an explosion in air would probably be preferable. Can anyone confirm/refute the vacuum theory?
bame@hubble.sde.hp.com (Paul Bame) (01/22/91)
From: Paul Bame <bame@hubble.sde.hp.com> >From: geoffm@EBay.Sun.COM (Geoff Miller) > > but I don't understand how the fuel can be > dispersed by the preliminary explosion without being detonated. > What kind of mechanism prevents premature detonation? I also saw the FAE bomb film. It appears the first (bursting) explosion is of the "cool" variety, maybe something fast like ammonium nitrate - maybe also confined so that it's spent by the time it's container breaks. Remember that fuel-air fuels (say, gasoline) contain no oxidizer and would be difficult or impossible to ignite until dispersed. The cloud was ignited at the leading edge by something slow and hot, maybe regular gunpowder. Just speculating... -Paul "Spice is the Variety of Life" bame@hpfcbig.sde.hp.com N0KCL
disc3c1@jetson.uh.edu (01/23/91)
From: disc3c1@jetson.uh.edu In article <1991Jan21.035620.3877@cbnews.att.com>, ames!ames!claris!portal!cup.portal.com!mmm@uunet.UU.NET writes: > From: <ames!ames!claris!portal!cup.portal.com!mmm@uunet.UU.NET> > WRT the effectiveness of an explosion in air vs. the "Blockbuster", > it has been my understanding that what knocks down buildings is not > so much the initial blast, but the rush of air into the vacuum created > following a blast, in which case an explosion in air would probably be > preferable. Can anyone confirm/refute the vacuum theory? Bombs such as the CBU-72 FAE work on the principle of a "Overpressure" bomb This weapon contains a mixture of 3 heavier than air gases. When the bomb lands, the gases are released onto the air, forming an explosive mixture. A Delayed action fuse ignites the mixture, which causes the contaminated air to burn! As well as incinerating everything, the burning gases expand instantly In open air this is sufficient to set off mines and flatten soft objects such as men! The effect in an enclosed area is much bigger though. The "shock wave of gases" will knock down walls, floor and roof of the structure. The result in underground structures (such as a Sub Pen) is total destruction.. Bomb's such as this, are mainly dropped onto Builings, and have an effect (not as great as buildings) on Sub Pens, Hangars, Bunkers, and oil Platforms.. While they do have a small (small when comparing to the Exocet) effect on ships.. I hope that cleared it up a bit for you, I have seen a film a a building being blown to bits by a CBU-72 FAE bomb. In Slow motion you can see the "shock wave" of expanding gases, as it slowly rips through the building..nothing was left afterwards.. ************************************************** * The Iron Eagle : Sterling * * Sysop of - : Aviation * * Fightertown, USA : Sciences * * (713)868-4372 : 11625 Martindale Rd * * 24oo : Houston, TX 77048 * * Baud Rate Only! : USA * **************************************************
jgd@Dixie.Com (John G. DeArmond) (01/23/91)
From: jgd@Dixie.Com (John G. DeArmond) cirby@vaxb.acs.unt.edu (((((C.Irby))))) writes: >Fuel-Air Munitions aren't designed to work against hard targets. They >work best versus widely-dispersed soft and medium targets, like infantry, >light buildings, and storage areas. The overpressures involved (someone >mentioned the 300 psi figure) will easily destroy a non-hardened building, >and will kill any unprotected person (and I'd wager that the shock wave >would have a shot at breaking any tank you'll find...) I'm not sure of the overpressure capability of FAEs but it takes a surprisingly small overpressure to do tremendous damage. Again referencing "The Effects of Nuclear Weapons" (and assuming that the FAE explosion would generate an overpressure similiar to a nuke.), 1 psi of overpressure will destroy a frame house, 2 psi will destroy a brick house, 3 psi will damage/tilt a cast concrete house and 4 to 6 psi will lift and move lathes, turn over trucks, smash school busses into the pavement and generally reek havoc. 3 to 5 psi will blow down telephone poles and steel towers. The book has some rather graphic pictures of tests performed in the desert during atmospheric testing. I would think that somewhere in the range of 5 to 7 PSI would probably at least tip a tank and maybe roll it over. John -- John De Armond, WD4OQC | "Purveyors of speed to the Trade" (tm) Rapid Deployment System, Inc. | Home of the Nidgets (tm) Marietta, Ga | {emory,uunet}!rsiatl!jgd |"Politically InCorrect.. And damn proud of it
ahahma@utu.fi (Arno Hahma) (01/24/91)
From: ahahma@utu.fi (Arno Hahma) In article <1991Jan23.035540.4193@cbnews.att.com> jgd@Dixie.Com (John G. DeArmond) writes: >the pavement and generally reek havoc. 3 to 5 psi will blow down telephone >poles and steel towers. The book has some rather graphic pictures of >tests performed in the desert during atmospheric testing. I would think >that somewhere in the range of 5 to 7 PSI would probably at least tip >a tank and maybe roll it over. A typical FAE bomb with no aluminum will produce an overpressure of about 20 to 30 bars, that is, about 140 to 210 PSI inside the fuel-air cloud. This is more than enough to damage even concrete bunkers. The pressure impulse/unit mass (for an ethylene or propylene oxide FAE) is about 5 to 7 times that of PETN, i.e. you'll need roughly 5 to 7 times more PETN to achieve the same, average pressure effect. The peak pressure produced will be many times higher with PETN, but it also lasts only for a very short time. If you manage to use hydrocarbons to make a FAE, then the ratio will be even more than 1 to 5..7. ArNO 2
mst@relay.EU.net (Markus Stumptner) (01/27/91)
From: vexpert!mst@relay.EU.net (Markus Stumptner) Status: R >From article <1991Jan23.035405.3978@cbnews.att.com>, by disc3c1@jetson.uh.edu: > Bombs such as the CBU-72 FAE work on the principle of a "Overpressure" bomb > [...] > Bomb's such as this, are mainly dropped onto Builings, and have > an effect (not as great as buildings) on Sub Pens, Hangars, Bunkers, > and oil Platforms.. While they do have a small (small when comparing > to the Exocet) effect on ships.. > > I hope that cleared it up a bit for you, I have seen a film > a a building being blown to bits by a CBU-72 FAE bomb. In Slow motion > you can see the "shock wave" of expanding gases, as it slowly rips > through the building..nothing was left afterwards.. I seem to remember they also work well against tanks, since even if the tank withstands the pressure, the crew inside is killed. I do not know whether this has been mentioned before, but my father told me that this is not a new idea. The Germans used warheads of that kind in their "Nebelwerfer" rocket projectiles on the Eastern Front in WWII. Allegedly they stopped this after a short time, since the Soviets threatened to retaliate with gas attacks. Markus Stumptner mst@vexpert.dbai.tuwien.ac.at Technical University of Vienna vexpert!mst@uunet.uu.net Paniglg. 16, A-1040 Vienna, Austria ...mcsun!vexpert!mst