cmf258@cck.cov.ac.uk (J. Mellor) (02/12/91)
From: cmf258@cck.cov.ac.uk (J. Mellor) One of my house mates has just finished reading 'footfall' by Niven and Pournelle. Since he hasn't any access to the net he's asked me to post this request for him. It basically was an orbital device containing tens of thousands of depleted uranium or High Carbon Steel bars, these 'bars' had elementary guidance (Just enough to recognise a tank) and were then released from orbit to fall on those unfortunates below. These bars would also be explosive so that they would explode on contact with a hard object. [mod.note: Sounds like "Project Thor." It was one of Jerry Pournelle's favorites. - Bill ] Now his Question is, Would these 'bars' (Smart or Iron) be of any use against the Republican Guards if say dropped from 40-50000 Ft some engineering chappies worked out that they would(assuming 0 air resistance) fall about 400 m/sec and hit with the force of about 1000 KJ. His questions - How many could a B52 carry ? - How Effective would they be?
dnwiebe@cis.ohio-state.edu (Dan N Wiebe) (02/13/91)
From: dnwiebe@cis.ohio-state.edu (Dan N Wiebe) *** PLAUSIBLE HEARSAY WARNING *** The way I heard it, these orbital crowbars were based on the concept of hypervelocity. They were intended to hit the target at a speed faster than the speed at which sound travels in whatever material the crowbar is made of--so that the bar is "fed" into the target faster than the deforming impact shock wave can climb back out. In effect, or so I hear, while this phenomenon is in progress (the bar slows down rapidly, of course, once it hits the target), the bar can be considered infinitely hard--that is, harder than the armor against which it is being used. My source used the familiar "knife through butter" phrase. The problem lies in accelerating the rod to hypervelocity speeds in the first place; I think that's probably why they're put in orbit (18 miles per second or some such ungodly speed) and then deflected onto a target, rather than being dropped from a B-52. I don't know what the speed of sound in steel is, but I'd guess it's more than 400 m/sec. Another problem would be guidance. Unless you used one heck of a shove to deflect the thing from orbit, it'd come in at a pretty flat angle, following a trajectory probably several hundred miles long. Acquiring a tank-sized target through several hundred miles of atmosphere while you're moving eighteen miles every second would be challenging, to say the least, without even bothering with reentry ionization problems, which, due to the required speed, would probably continue pretty much up till impact. If you could solve those two problems, though, tacking an explosive charge on the rod would seem to be gilding the lily, so to speak. Disclaimer: the stuff in the first paragraph is pretty much a paraphrase of things I heard from somebody who has a doctorate in physics and ought to know. The rest of it is personal speculation on my part. Plug: Footfall is a wonderful book, as is Lucifer's Hammer and most of the other Niven/Pournelle books. (Other than being a Niven freak, I'm not connected with either of them in any way.) Shalom, Dan Wiebe dnw@rsch.oclc.org
aws@uunet.UU.NET (Allen W. Sherzer) (02/15/91)
From: mailrus!sharkey!hela!iti.org!aws@uunet.UU.NET (Allen W. Sherzer) In article <1991Feb13.032640.27454@cbnews.att.com> dnwiebe@cis.ohio-state.edu (Dan N Wiebe) writes: >The way I heard it, these orbital crowbars were based on the concept of >hypervelocity.... [description deleted] A weapon like this is in the works today. It is called the Hyper Velocity Missile (HVM) and LTV is the prime. HVM is a chunk of depleted uranium accelerated to mach 5 or so and then slams into a tank. A friend is doing simulation of the tracker and he recently described one of the test runs to me. They lined up four tanks side by side and launched one of these things into the side of tank #1. The missile went through all four tanks like the proverbial knife through butter. They thought that the crew of a fifth tank *might* have survived. Allen [mod.note: Not much of a test if you ask me... side armor on tanks is pretty flimsy, and not the most likely target. - Bill ] -- +-----------------------------------------------------------------------------+ |Allen Sherzer |A MESSAGE FROM THE ANTI-WAR MOVEMENT TO THE PEOPLE OF KUWAIT: | |aws@iti.org | "If rape is inevitable, enjoy it!" | +-----------------------------------------------------------------------------+
mullermb@mentor.cc.purdue.edu (Mark Muller) (02/19/91)
From: mullermb@mentor.cc.purdue.edu (Mark Muller) In article <1991Feb18.051806.8964@cbnews.att.com> john%ghostwheel.unm.edu@ariel.unm.edu (John Prentice) writes: [discussion of LTV's kinetic kill missile and demo deleted] > >Sorry, I don't quite believe this. By mach 5 I assume you mean >5 times the speed of sound in air, so mach 5 means about 1.5 km/sec. That >is the very, very low end of the hypervelocity regime. I am skeptical >that you can get a penetrator to go through a tank at that velocity. It >might penetrate to the interior if you have thin enough armor, but I doubt >seriously it would survive intact enough to ever get out again. Think >about it, the interior of a tank is the ultimate spaced armor! To be >honest, I am not all THAT confident you would even penetrate into the first >tank in the real world against good modern armor such as the Soviets have. >However, I wouldn't care to test that theory by sitting in the tank and having >you fire this at me, but I would probably be willing to sit in the second >tank. > However, Mach 5 is also about the velocity of the penetrator from a current M1A1 tank (I saw a chart in an issue of Armor Magazine about a year ago that had muzzle velocities of tank guns, with the 120mm gun in the M1A1 being at about 5000 fps, which equates to Mach 4.5) which should kill current Soviet tanks quite well. I say this since the 120mm is supposed to be an improvement over the 105mm gun, which, according to the Isrealis, had no problem penetrating with Syrian T-72's in Lebanon. Of course, one could say that T-74's and T-80's have much improved armor, in both quality and quantity, but this is hard to tell, and unlikely to be as significant that many people would have you believe (if desired, I could discuss this subject in more depth). Of course, in the case of tank rounds, by the time they impact their targets, there speed is reduced by aerodynamic drag, whereas the missile would possibly still be getting thrust from it engine. A lot of penetration, however, has to do not with absolute velocity, but with the energy concentration of the impact, which is simply the total kinetic energy per unit area of the impact. Thus if the missile is long and heavy, its penetration at an impact of Mach 5 could possibly surpass that of the typical tank gun penetrator. [mod.note: One advantage of such a missile would be that it would allow the use of longer penetrators than could be fired from a tank gun. (The tremendous acceleration in a gun limits the length the penetrator can be; the missile would probably have substantially lower acceleration). Penetration is approximately proportional to the length of the penetrator, so one might expect better performance from such missiles than one could get from a gun with the same velocity. - Bill ] ******************************************************************************* * Mark Muller Aeronautics and Astronautics Engineering * * Undergraduate Purdue University * *******************************************************************************