Very interesting indeed. I can remember using glider trailers (panel size as viewed from above, 9m x 2m) and moving them around in a complex pattern, once a minute, in a paddock adjacent to the start point feature (a bridge).
But then, I can almost remember back to when they sent observers out to each turning point to lie on their backs and observe the gliders rounding the TPs. For the DDSC members reading this, there is (was?) a picture in the bunkhouse of a gliding competition grid launch in progress, and the 'ground clock' can be seen in the photo. Another thing just came to mind. Why have a ground clock, when the start and finish line observers were taking your start and finish times? It was to prevent the cheat going round the first TP before coming back and crossing (and photographing) the start line, then going to the second TP. When there was no time imprint on the photos, this was quite possible to do. Pam From: aus-soaring-boun...@lists.internode.on.net [mailto:aus-soaring-boun...@lists.internode.on.net] On Behalf Of gstev...@bigpond.com Sent: Thursday, 11 August 2011 12:02 AM To: Discussion of issues relating to Soaring in Australia. Subject: Re: [Aus-soaring] Ground Clocks - a little bit of history Hi Terry, Verrrry interesting. I gave Max a call earlier tonight, and you are right! Are you aware that he has built two of these infernal devices? He told me building the Horsham one kept him amused for "weeks". His memories of the whole thing are now a bit vague, but he obviously remembers the bits that proved to be challenge - valves and controllers and such like, all built from scratch! He has no photos, and all the surviving components were consigned to the tip/recyclers about 12 months ago. It would seem that the scenario was much as you described! Max was the builder and Wally Wallington provided the design concepts - based on the Binary Theory you have referenced. Camera clocks were just appearing on the scene at this point in time, and Max intimated that they (and by inference, due to time required to phase out an older system), and the conventional start gate method were used for the actual scoring of the competition that year. Pick a date in the early eighties, rather than late seventies as you have suggested, for this competition. Max found that this particular project did not achieve its aim, due to the fact that the panels, as constructed, were too small, and thus could not be definitively photographed with the cameras in use at the time - Kodak Instamatics almost invariably - from 1000 m above terrain. The panels were square, and the size was either 2.5m or 3.0 m to a side - Max couldn't quite ping it off the top of his head! .... pun? .... groan! The material used for the panel cladding was mini-orb steel sheeting. Total cost to build the system was "about $1000.00". The 2nd Ground Clock that he built was for the WGC in Benalla. Once again Wally Wallington (who was the Contest Director), provided the concepts, and Max then did the work to put these concepts into reality. It would seem that this clock is basically as described in the April '83 edition of AG. Max told me that he provided a brief (one page?), description of the system in the WGC notes of the time . If anybody has a copy of the document, please do download it to this site . The essential changes here over the Horsham design were the increase in panel size to 20 m X 3 m, and the construction of the panels out of fabric. These panels could be opened and closed by sliding them along supporting side wires. Three people could operate the system. Again, it would appear that in the reality, all start times were taken from the on board camera clocks, and the ground clock was not used, except in a back-up situation, such as when the camera clock had failed to record a start - a pilot finger problem always - he didn't press the right buttons - as a camera failure would mean no record at all, of anything - bad luck buddy - zero points for the day! I suggest that it would be very possible - almost a sure thing - to get grant money to build a replica of this device at the Gliding Museum (and a sure way of slowing down the kids after they have run the panel sheets in and out a few times), if the Museum Directors choose to take the idea onboard. I suspect that Max would be delighted to act as Project Director (if asked), but of course on the proviso that he was given total authority and control. Cheers, Gary ----- Original Message ----- From: Terry Neumann <mailto:tfneum...@internode.on.net> To: Discussion of issues relating to Soaring in Australia. <mailto:aus-soaring@lists.internode.on.net> Sent: Wednesday, August 10, 2011 10:26 AM Subject: Re: [Aus-soaring] Ground Clocks - a little bit of history Max Hedt invented and constructed a ground clock for use at Horsham Week comps back in the last century - (very late 70's perhaps??) As I recall - and it was back a while now - it used a system of displaying the time using binary notation. It was impressive in its complexity and brilliant in its design and construction. The system used a master electronic contraption (computer?) called FRED* to command (either open or close) a number of large blocks or frames of horizontal shutters like those in a venetian blind. This was achieved by a compressed air driven piston on each individual frame extending or retracting as commanded by FRED and swinging the shutters in much the same way as a swell box on a large pipe organ. If the shutters on a particular frame were closed, it appeared as a solid block and represented the binary digit 1. Blocks which were open appeared largely transparent from the air and represented the binary number 0. The whole contraption was large enough - several hundreds of square metres in area - to be photographed with sufficient definition from the start height, and later to be decoded as an actual starting time by the verifier, possibly Max himself or the late Geoff Champlain. To be at the site itself when the thing was in operation was a mind blowing experience with the petrol driven air compressor and FRED in the midst of the multiple frame assemblies supporting the shutters. Every so often the sequence would change, the shutters on some frames would close - others would clang open - all with mechanical sounds, accompanied by that of compressed air energising the pistons or venting from then. It's possible that wildlife at Horsham still avoid that area ;-) It must have taken hundreds of hours to design and build. I often wonder what happened to it; there must be photos of this somewhere. Incidently, you can see how a binary clock operates, and what it looks like here <http://www.kwista.com/for-fun/binary-clock-online/> Quite fascinating. Regards TN E & OE * FRED is/was an acronym which has been used elsewhere in scientific and electronic literature. Google can be your friend if you don't know what it stands for but would really like to ..... ;-) Most electronic enthusiasts have a FRED or two in their collection. _____ _______________________________________________ Aus-soaring mailing list Aus-soaring@lists.internode.on.net To check or change subscription details, visit: http://lists.internode.on.net/mailman/listinfo/aus-soaring
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