OT: Navigation Aids (was Long term data storage) (was: Disasters

I beg to differ. The Luftwaffe had a very good radio navigation system mostly in place at the start of the war, a development of the Lorenz Blind Landing system (essentially a VHF Aural Range or VAR) called " Knickebein" (Crooked Leg). Knickebein was used to allow Luftwaffe aircraft to navigate with considerable accuracy over England, and made night bombing worth the effort. It was detected and (ultimately) jammed, and was essentially unuseable after July 1940. A constant race (The "Battle of the Beams") went on between British Scientific Intelligence trying to figure out what new radio navaids were being developed and used, and means to jam them, and the Germans trying to come up with replacements for navaids that were compromised or jammed. A replacement for the jammed Knickebein system was instrumental in the destruction of Coventry. "Pathfinder" aircraft of KG100 using the then new "X-Gerat" system marked the target with incendiary devices so that the recently de-Knickebeined main force could locate and bomb the target. This took place by night, so visual navigation was not being depended on. This is certainly true. The RAF heirarchy were still of the opinion that it was possible to navigate accurately at night by astronomical means, in the same way that ships did. This was ultimately proven to be wishful thinking, but the attitude delayed the introduction of navaids like Gee and Oboe for some time. Useful by day, but the Germans found that bombing during the day was perilous in the extreme, an experience shared by the US Air Force over Germany somewhat later. At night landmarks have little practical use. Unless they are on fire of course. Interestingly, the Coventry raid was made during a full moon, and anecdotal reports from Luftwaffe aircrew suggests that they could probably have found the target visually, particularly after it was well alight. Much of this was detailed in a BBC TV series called "The Secret War", and in a book of the same name. Another book by the then head of British Scientific Intelligence, R.V. Jones "Most Secret War" goes in more depth into this and other fascinating things. To get us back on topic, there is considerable time given in these sources to the means used to crack the codes generated by the German Enigma and Geheimschreiber encrypting machines. Arguably the first true electronic computer, Colossus, was built specifically to deal with the Geheimschreiber, and had contributions to it's design by the legendary Alan Turing himself.. The book "The Ultra Secret" goes into the whole business of the Enigma codes, and the breaking of them, which aided the Allies enormously throughout the war. I tried to name my first VAX "Colossus" in it's honour, (and because of it's SIZE - it's a 6000) but was foiled by the 6 character limit in VMS/Decnet host names. So I had to settle for ENIGMA. Cheers Geoff Roberts Computer Systems Manager Saint Mark's College, Port Pirie, South Australia geoffrob(a)stmarks.pp.catholic.edu.au