The Anonymous Widower

Analogue Computing at the Science Museum

There were reports in the papers this week about James Lovell selling the checklist that he used to correctly setup the lunar module to get them back home.

What is always missed out in these discussions, is that all of the calculations for the Apollo moon landings were done on a simulator, built using two PACE 231R analgue computers linked together.

At the Science Museum, they did have Lord Kelvin’s differential analyser, but although it was impressive, with lots of impressive engineering and brass gears, there was little to indicate, what this type of machine grew into by the 1960s. Without analogue computers to solve the complicated dynamics of the moon landings, the Americans wouldn’t have been able to get there when they did. Digital computing didn’t have the capability to match a PACE 231R to solve the simultaneous differential equations involved until the mid 1970s.

I was lucky enough to work with a PACE 231R and there are pictures of the one I used here.

There doesn’t appear to be a working PACE 231R anywhere in the world.  But to get one to work would be a lot easier than say to get an early digital machine working.  An analogue computer is basically a peg board that links a series of amplifiers together.  Now I know that these amplifiers are thermionic valve and not transistor, but a typical machine would have a hundred or so of them. And as they use something very akin to  1960s audio technology, finding someone to fix them would not be difficult. Our machine at ICI Plastics in Welwyn Garden City, was carefully looked after by one Eddie Kniter, a Pole, who walked his way to Switzerland to escape the Nazis.

I wonder if the Science Museum has one of these machines in its reserve collection. Getting it working, would really show kids how differential equations are useful in real  life.

Returning to Apollo, I remember that the magazine, Simulation, published by Simulation Councils Inc., had a detailed description in one issue of all the simulators and simulations done in connection with the project.

I’d love to get hold of a copy.

November 26, 2011 - Posted by | Computing, News, Transport/Travel | ,

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