Path: utzoo!utgpu!news-server.csri.toronto.edu!bonnie.concordia.ca!uunet!lll-winken!sun-barr!newstop!sun!amdcad!amdcad!military From: ab3o+@andrew.cmu.edu (Allan Bourdius) Newsgroups: sci.military Subject: Re: Shooting Down Cruise Missiles Message-ID: <1991Apr29.052626.6132@amd.com> Date: 28 Apr 91 14:37:40 GMT Sender: military@amd.com Organization: Advanced Micro Devices, Inc. Lines: 86 Approved: military@amd.com From: Allan Bourdius >Periodically, it corrects the >inertial "fix" by comparing a simple terrain map (altitude only) with >measurements from a radar altimeter. It then corrects its inertial >"fix" and continues to the next "map correction area", etc. Depending >on the quality of the inertial nav unit, only a few areas along the >way will need to be terrain mapped. Actually, the guidance system is probably *a lot* more complex then we are led to believe. In an unclassified briefing I got at my NROTC unit, the briefers told us that the Tomahawk is capable of avoiding objects that it didn't know was in its flight path (like a recently built building). Also, the Tomahawk can discriminate between individual buildings that are close together as to which one to hit. Chances are that the TERCOM guidance is used significantly more than for just checking the inertial track. >Now consider the special nature of cruise missile flight planning. >There's no point in conserving fuel. The weapon is only for use against >stationary targets, so there's no hurry. There's no reason to take the >shortest path to the target! Finally, let's speculate that making up >terrain maps is a lot of work, especially under the time pressure that >preceded the outbreak of hostilities in the Gulf. Well, I'm sure that a Tomahawk could attack a moving target, provided it wasn't going too fast. After all, variants of the missile are designed to strike warships. A BGM-109D, the sub-munition variant, would probably be the best against a moving target. Unfortunately, you couldn't reprogram the missile in flight so you'd have to go by something like a train schedule in order to hit your target! There would be a point in conserving fuel if you are going to fire a -109D that possesses the capability to hit something like four different targets (3 with bomblets, 1 with a terminal dive). Terrain maps take a great deal of time to make and program into the missile (from my understanding), but the radar mapmaking and missile targeting probably began on August 3--5 1/2 months before the war started. They had *plenty* of time to target and guide the Tomahawks. >If a Tomahawk is ever observed, the point of observation is a very likely >place to shoot down future missiles. This is a definite weakness in the >weapons system. Since the pulse jet engine probably makes a characteristic >noise, human observers can be taught to report the passage of the missiles. >Air defence radars can then be concentrated in these areas. Once detected, >Tomahawk is vulnerable to conventional techniques, like interceptors and >tactical antiaircraft missiles; it's not even supersonic. The Tomahawk has a turbofan engine, not a pulse jet. I think that the last thing built with a pulse jet was the US V-1 clone, the Loon. The entire theory behind the TLAM and TERCOM guidance is the principle of *avoiding* enemy air defenses. I should think that's why targeting takes so long. It's pretty much impossible to defend everywhere, so you can fly your missiles around all the defenses, theoretically. Human observers would probably be next to useless for a couple of reasons: 1) by the time you hear the missile (I think they're pretty quiet) and see it and can report it, it will likely have changed course or will be far enough away already; 2) They fly low enough to get lost in radar ground-clutter so that after a civilian "tip" came in, the missiles would still be damn hard to find. How are you going to "concentrate" your air defense radars so quickly? Radars tend to be big and bulky and take a while to move (take the phased-array radars used with the Patriot for example). The whole point of the TERCOM guidance is to fly the missile *around* radar envelopes. Also, you can launch your Tomahawk from almost anywhere. A Tomahawk fired from off the southern tip of Greece could strike Baghdad with about 200-300 miles of range left over. Supersonic speed matters little. If it was supersonic, it would make more noise and have a much shorter range. The TLAM also flies 50-100 feet off the ground--maneuvering at supersonic speeds at that height, even for an unmanned aircraft, is highly risky to say the least. The poor performance of the Iraqi defenses against TLAM's and other events (like the fact that Mathias Rust flew a Cessna (a much bigger and slower target than a TLAM) into Moscow undetected) prove that the cruise missile is a very difficult target to engage, no matter how complex and sophisticated your air defenses are. Granted, all this is mostly speculation and informed guessing, but the cruise missile is probably a lot less vulnerable than many people believe. -- Allan Bourdius [MIDN 3/C (Marine Option)/Brother, Phi Kappa Theta Fraternity] ab3o+@andrew.cmu.edu or Box 4719, 5125 Margaret Morrison St., Pgh., PA 15213 The opinions in this post/mail are only those of the author, nobody else.