Archived posting to the Leica Users Group, 2013/12/12

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Subject: [Leica] IMG: From Long Ago
From: jhnichols at (Jim Nichols)
Date: Thu, 12 Dec 2013 16:19:11 -0600

As a young engineer, my first assignment was to calculate the nozzle 
plate shapes for a flexible plate nozzle for the AEDC 16-Ft Transonic 
Wind Tunnel, then under construction.  The shapes had to vary from a 
simple contraction to a Mach 1.6 contour, and the process had to be done 
by 16 pairs of jacks, without over stressing the steel plates.  And, 
other than the basic supersonic shapes calculated by folks at Cal-Tech, 
it was all done on Friden and Marchant desk calculators.

To move the jacks from contour to contour, a series of steps were chosen 
that stayed within stress limits, as determined from curvature 
calculations. These steps were then stored in L-shaped pegs on a 
mechanical memory drum, with the shapes transferred to cam-driven 
readers and fed to vacuum-tube amplifiers which supplied the driving 
signals to the ball-bearing screw jacks.

Bear in mind that this was all done in the early 1950s.

This photo, taken from my technical report, shows the mechanical memory 
drum and the console which contained the drum drive system, the transfer 
plate, and the individual jack amplifiers.  The console and system were 
designed to our specs and provided by an engineering company whose name 
does not come to mind after 60 years.

Memory has come a long way since then. :-)

Jim Nichols
Tullahoma, TN USA

Replies: Reply from bill at (Bill Grimwood) ([Leica] IMG: From Long Ago)