MM>  MM> Mmm ... they developed an analog `differential analyser' at Rugby
MM>  MM> using Meccano - the British Boy's Own constructor kit of the day
MM>  MM> (and still in business, I discovered t'other day).  There's a
MM>  MM> working variation in the Auckland Museum of Transport and
MM>  MM> Technology, coincidently...

MM>  TV> One of the WW2 AA radar sets included a totally mechanical
MM>  TV> analog predictor computer made of wheels and rotating rods.
MM>  TV> The radar fed in several positions for the target and the computer
MM>  TV> derived height, speed and direction, then computed the aiming point
MM>  TV> for AA guns to put their shells where the target was *going to be*
MM>  TV> by the time the shells got all the way up there.
MM>  TV> Could give height commands to the fuze setter on guns not using
MM>  TV> proximity fuzes.
MM>  TV> It was quite accurate, but needed to be run in a temperature
controlled
MM>  TV> oil bath to avoid errors from thermal changes in the size of the
MM>  TV> precision wheels.

MM> And it sat in a green steel container on a trailer chassis - with
MM> a round brass `BTH' insigna on the outside.  

You peeked!  (But the BTH was inside.)   

It was, IIRC, Radar No4 Mk7.

MM> My father was deeply
MM> involved in the design of that device,  and remained unsatisfied
MM> with it until he passed on.
MM> By another coincidence,  there's one on display in the MOTAT
MM> museum here in Auckland,  and he used to get very upset and kick
MM> it when passing it in his final years...

Then your father was a true engineer.

MM>  TV> We had Facit ones - also quite acrobatic on occasion.

MM> There was a jumping carriage that moved as it carried numbers to
MM> the next column ? And backwards for square rooting ?

That's the way they all worked back then, AFAIK.

MM> Spectacular viewing...

And noise - they sometimes developed quite a catchy rhythm. . . 




Terry V.
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 þ MM 1.1 #0367 þ Multitasking: screw up several things at once!

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