8.1.20 Secure and rapid load/unload of OTAs onto the GEM.

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Back to the easy load/unload of OTAs on the big GEM. I have found some square, aluminium tubing and closely matching channel section. I'm hoping to have a short channel fixed to the ends of the saddle. The open side of both channels will face upwards when the saddle is pointed at the pole. Though I may opt for only a top channel. There being no need for a lower one provided a secure fixing is available at the bottom.

The square tubing will be fitted onto the OTAs at saddle length spacing. A central slot, at the top of the saddle, for a bolt or pin on the OTAs, will provide lateral location at the top. While a clearance hole at the lower end of the saddle will allow a bolt on the OTA to easily drop through. A lower wing nut will secure the OTA immovably. This being within easy reach of the observatory floor. A rounded, or "projectile" nose on the bottom bolt will aid insertion.

Earlier folded refractor fixing ideas used a wing nut [or even two] at both top and bottom. The top one was always well beyond reach, even with a stepladder. It made fitting and removal of the telescopes extremely dangerous. Particularly in the dark!

I tried pairs of widely spaced slots for location without a channel and this was a nightmare to locate from the ground. It is essential to be able to easily hook the weight and bulk of the OTA instantly onto the top of the saddle without climbing a stepladder.

It is dangerous with long and heavy OTAs to try to mount them with the saddle at any other angle. I have tried repeatedly and came very close to disaster several times! Large refractor objectives don't bounce well when they start falling from 10-11 feet above the ground on the end of a long and very top-heavy tube!  While the sheer bulk of the equally heavy, folding refractor framework provided surprisingly few useful handholds. Despite the heavy objective being slightly lower, the balance point didn't help.

Fortunately I shall now have the 3x4 pulley system. Instead of relying on brute, manual force to lift my OTAs out of doors. There is still a load on the pulling rope for one hand but this is manageable when wearing rubber gloves. A habit I have learned to use whenever I am manhandling OTAs and heavy telescope mounting parts.

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