bxr307@csc.anu.oz (09/04/90)
From: bxr307@csc.anu.oz In article <1990Sep2.061150.3728@cbnews.att.com>, FQV@PSUVM.PSU.EDU (jim bowers) writes: > > > From: jim bowers <FQV@PSUVM.PSU.EDU> > > In article <1990Aug31.030929.24575@cbnews.att.com>, sysmgr@KING.ENG.UMD.EDU > (Doug Mohney) says: > An antitank missle guided by laser designator would enable the missle > launch point and the tracker to be widely seperated and this would > be a distinct advantage. So why don't they have a ground based version > of the Hellfire?????? > Jim But there is! The US Army has tested on several occasions such a weapon. My memory tells me that it was tested mounted on the back of a light utility ("pickup" in USspeak :-) truck and had either twin or single rails. However they decided not to adopt it immediately instead placing it on the back burner for the moment. It was intended to arm the RDF and light divisions giving them commonality of ammunition with the air support elements (AH64) that were intended to be with them. Additionally the Swedes have adopted a similar weapon on a single rail tripod as a coast defence weapon. It is called the RBS-15 (I think from memory) and is intended for the close in defence of the Fjords. While the idea of seperating the launcher from the guidance system is good in theory in practice it leads to several problems. If the missile cannot actually "see" the laser designator's "spot" of light before launch there has to be some sort of pre-programmed flight pattern to enable it to get to a point where it can see it and home in on it. So if you place your launcher below a hill where it is in dead ground its great because its protected. However both you and the designating unit has to know where each other is (not exactly however a fairly good idea would help) so that the missile when commanded to fire would be able to be sent in the right direction at least. In addition with a laser designated missile how do you have more than one missile in flight at one time? Each has to be designated and as far as I know the wavelength of the Laser homing head is set, so you cannot have multiple designators using different wavelengths to guide different missiles. This plus a desire to prevent interference between different firing units, as well the time of flight for each round would decrease your rate of fire considerably (in fact as the missiles are lot bigger, heavier and less "handy" than TOW rounds in their launch tubes, I would think the rate of reloading would also decrease your rate of fire again). Many 2nd generation ATGW's which used wire guided systems had this "off-mount" facility. They found that while it was good in theory, in practice it increased the "minimum range" of the system (usually doubling it) as the missile had to be gathered into the line of sight of the operator. The further off the line of flight the operator was placed usually the greater the "minimum range" became. However they found a way to decrease the "minimum range" was to place your operator forward of the launch point, nearly in line with the line-of-flight of the missile so that it flew over his head and could then be quickly gathered into his line of sight. The British in their FV438 ATGW missile carrying version of the FV432 APC which used Swingfire missiles made use of this facility and had an off-mount guidance system. They also had a handy little periscope which could be extended about 6 feet above the vehicle allowing it to remain in dead ground and still keep its fire lane under observation without exposing the vehicle. Now that might be a better solution for a Hellfire equipped vehicle, simply having a periscope which had the laser emiter in its head extending perhaps 10-20 feet overhead? Brian Ross