I am not sure if you have noticed but this has not been Corvette weather lately. One cold January morning I decided to exercise my computer mouse by scouting around the web looking for bits of CCA history that I had not seen before. It turned out to be a very interesting morning. I stumbled onto a copy of the Corvette News from 1958 at the GM Heritage Center. It was a quarterly magazine published by GM and Volume 2, Number 3, contained an article on the CCA as well as information on the upcoming 1959 Corvette models. There is too much information to cover all of it. But, if you would like to see the full issue of the magazine, it is located here.
For me, a very interesting thing was spotting pictures of the timing equipment that the CCA developed in 1957. We have a written record of the progress of the development from club meeting minutes but I had never seen a picture of the system, let alone pictures of the system in actual operation. I have already covered some of this material in the CCA's closed Facebook group. If you have seen that post, please keep reading because there will be additional cool information here. In fact, I will start out with some details from the magazine that have nothing to do with timing equipment.
A significant portion of the magazine was dedicated to providing information on the 1959 Corvette which was the next thing coming at that point. I recommend going to the magazine link above to get those details because I will not have room here to cover them. Thankfully, the GM Heritage Center has also scanned a rich collection of their other historical documents. The GM Heritage Center did an excellent job of scanning the originals and both medium, and high resolution PDF copies are available. Fair warning, a GM fan can spend hours here.
According to the club minutes, the CCA provided timing and scoring support at Marlboro, Andrews AFB, and for the Greater Metropolitan Area Sports Car Council in addition to numerous autocross events. The timing equipment appears to have been powered off of 110V AC provided through extension cords. Photo B is another view of the timing equipment showing the display. The five vertical slots contained decade counters that provided the numerical readout.
The cabinet would have contained a stable oscillator that generated pulses. The start and finish line sensors were photo electric devices that could start and stop the oscillator pulses from going to the decade counter displays. Crossing the starting line would enable the pulses to be sent to the counters. The counters themselves were cascaded together allowing a "full" counter on the right containing a count of nine to pass a single pulse to the next counter on the left when it received the 10th pulse. It would also reset the full counter back to zero. With five decade counters they were able to count up to 99,999 pulses before it would roll over back to zero.
There was probably a switch selectable divider on the output of the oscillator that would allow selecting the pulse rate going to the decade counters. By carefully setting the frequency of the oscillator and applying the selectable divider they would have been able to cover a wide range of time measurement with pretty good accuracy. The display would easily be able to show time in seconds from 9.9999 to 9999.9 by adjusting the divider. For a typical autocross course like we use today they could have set the divider to read up to 99.999 seconds. In fact, if pulses were only sent to the counter array every second from the divider they could have measured more than 27 hours with 1 second accuracy so it would have even worked as a timer at the Rolex 24-Hours!
The timing system still would have been very basic compared to what we are using today in the club. For example you could only time a single vehicle. There was no ability to do split timing. You could only measure the time for one car on a drag strip or road course and you could not have more than one car at a time running an autocross course.
By the way, those are vacuum tubes on the back of the decade counter. No transistors, integrated circuits, or anything solid state in those days.
It was also interesting to see the photo detectors that were used to tell when a vehicle crossed the start and finish line seen in photos C and D.
The principle was very much the same as we use today, sixty years later. The car would break a light beam sending the signal that it had crossed the line. The system would use two boxes. One contained a light source and the other a photo sensitive detector. But the similarity ends there. The 1958 version would have been sensitive to light level changes. They could have potentially had problems with background light changes like the sun coming out from behind a cloud and they certainly would have had problems in the rain. Our current photo sensors take advantage of using very narrow spectrum light from an ultraviolet laser diode rather simply looking for a level change in white light. In addition the laser light is not a steady signal like turning on a regular light bulb. It is modulated with a particular pattern that the photo detector expects to see. This means that you could take another ultraviolet light source (like the sun) and it could not interfere with detecting that the light beam had been broken by a passing car.
Technology certainly has advanced in the past sixty years. We now have the capability of not only displaying your autocross time on your cell phone but the times of all the competitors as well. Imagine what the CCA members above, sitting in their chairs around that big equipment cabinet, would have thought if they had seen what we can do today!
Still, the CCA can be proud of the fact that the club was making major contributions to motorsports in the Nations Capital area in 1958. No other club or organization (including the SCCA) had the capability of providing their own electronic timing system in those days.
Jon Thorn
Corvette Courier Editor
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