BR7 wrote:I did. Everything I found indicates that Talos missiles used semi-active terminal guidance from the start, the only exception being a dedicated nuclear-armed version where the additional precision was deemed unnecessary. The only Bumblebee missiles that relied on beam-riding alone were very short ranged. If you know of anything different, could you link it or explain it in more detail?
Let me give you an example of how to generate a pencil beam that has very limited spread and is only a few millimeters across using WW2 technology.
We take a standard dish antenna and mount it slightly assymetically so that the center of rotation of the disk is slightly off the axis of that disk assembly. Now, when that dish is rotated the beam will sweep in a circle around the axis of the disk assembly. If we take the center of the divergent beam generated by that assembly, it sweeps in a circle around the axis of the disk assembly. Now, this is the clever bit. If the distance between that circle and the axis of the disk assembly is less than the radius of the beam generated by the radar at that particular distance, a tiny area on the center of rotation of the disk assembly will be constantly illuminated. The areas outside that spot at the center will only be illuminated at the time the disk actually directs the beam into those areas. So, the spot in the center will receive the full power of the radar (because it is constantly illuminated) while those areas outside the spot will, on average, receive less energy (because they are illuminated only part of the time). The slower the disk spins, the greater that differential, the faster it spins, the less that differential. Also a disk with a high degree of eccentricity will generate a tighter beam than one with a lower degree of eccentricity.
To simulate this, get a sheet of paper and roll it into a cone (the proportions of the cone don't matter but start with a long, thin one and experiment). That simulates the radar beam generated by the set. Now, get a knitting needle and tape it to the inside surface of the cone so that its aligned with the axis of the cone. Now, hold the knitting needle by the end at the small end of the paper cone and rotate said needle. You'll see the beam sweep around the axis represented by the needle. You've just generated a literally needle thin pencil beam that's independent of the size and shape of the paper cone. Try it will all sorts of different paper cones and you'll see how it all fits together. This technique is called conical scanning and was first used in 1941. It's still used today even though its long obsolete. Beam riders used to use conical scanning radars because they are very suitable for that application.
This is what I meant with my earlier comment about not knowing enough. All the maths and so on being quoted is fine, but it simply isn't relevent. There is a whole portfolio of techniques (mechanical and electronic) that can be used to generate pencil beams, all of the modern ones being highly classified. People literally spend their entire careers developing ways of generating tighter and more energetic beams from the equipment we have available. The shift to phased array radars opened up whole new areas of possibilities for that work, none of which one is going to read about in the open press for a very, very long time (one of the reasons why AEGIS ships were/are equipped with specialized spoogs is to hide what the SPY-1 radars can actually do).
Simon Jester wrote:It's almost enough to make me beat myself into good enough shape to join the Navy and become a radar technician; I would like to know what the hell is going on here.
The problem is that if you do know what's going on, there are about only twelve people in the world you can tell about it
Even teh people who operate AEGIS and SPY-1 systems have only a limited knowledge of what's going on (mostly it's process knowledge; to handle situation X you employ procedure Y). If you're really fascinated by this kind of thing, the best way to get involved is to get hired by the companies that design the equipment. Essentially that's Lockheed-Martin, Raytheon, BAE Systems and Thales. If you really want to go that way, contact me privately and we'll talk about it. Warning, before you do get in, you will be subject to a remarkably tight background check.
By the way, sonar systems are fun as well, oddly, one of the leading expert companies there is BAE Systems Australia. Virtually all the modern sonar systems built by Thales these days are based on Australian-developed technology. In VERY general terms sonars use much the same technology and employ the same techniques as fire control radars.
But you've triggered my inner experimental physicist's love of impressive gadgets, especially ones with performance characteristics that appear* to be violating Maxwell's Laws for fun and profit.
As you can see from the description of conical scanning (say again, a very old, very crude and long-obsolete way of dealing with this problem) we're not violating any laws, we've just engineered solutions that evade or exploit those laws. That's why, for sheer shits and giggles, engineering beats pure science any day. Anybody can create a new scientific law but an impressive shiny toy (especially if it costs a billion dollars or so) is really something.
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- PeZook
(For example, back in Armageddon, a baldrick was slowly cooked by being painted from thousands of radar sets; something along those lines does not so strain credulity, yet maintains the same continuity and battle details.) Just my $0.02, from a bemused fan of the story...
