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Saturday 8th 41F. A storm, with powerful winds, is forecast for Denmark tomorrow afternoon and evening. With 60+ mph gusts promised for our area.So I have taken the remaining telescopes off the mounting and stored them safely. The dome has been cleared and the shutters have been rotated upwind to the SW. Where the worst wind is forecast by the DMI.
The dome shutters now have eight, spaced spring clamps right up to the zenith. Two G-cramps are helping to hold them firmly shut apart from the usual, sliding door bolts at the bottom.
I have secured the top of the dome down to the massive pier using long, ratchet straps. These were hooked between heavy eye-bolts fixed through the zenith, triple thickness, dome cross-board. With the ratchet straps running down to hooks under the 18mm/ 3/4" cladding of the upper, telescope pier.
The heavy mounting, plus 56' feet of 4x4" pier timbers, plus 3/4" cladding, plus four, buried, pyramidal, concrete, carport anchors will take quite some lifting! So I hope the dome itself will now be completely safe from lifting. It already has eight, permanent disks overlapping the base ring. The disks are mounted on the steering wheel brackets held down to the octagonal building's, 2" x 8" top ring. So the ratchet strapping is really just extra insurance.
Domes are not renowned for lifting but can burst open. They have no horizontal surfaces to cause lift. The worst thing which can happen is a dome opening up so that it can be inflated by the wind. This will be likely to blow panels off the dome leading to serious failure and damage. Hence the deliberate, upwind direction of the shutters. Rather than risking them being ripped off by downwind suction.
Somebody online had their entire dome fly off the walls when they [foolishly] opened the doors facing into the wind! I am glad my access doors face south and I can enter the dome from below. It wouldn't be half as much fun to enter from the veranda doors which face west. I only open one half of my double doors on the ground floor. The potential is there should I want both doors open but there is plenty of room to get in via one.
I have now cleared the observatory of all loose items and covered the big mounting with a giant, leaf collection bag. I don't mind if it doesn't blow remotely as hard as forecast. I haven't lost anything by being prepared. We suffered some roof damage in a "once in a century" storm about 20 years ago. So know the power of the wind. Better to be safe than sorry. I can potter around today. Ensuring everything is as safe as possible before the wind picks up.
Domes are not renowned for lifting but can burst open. They have no horizontal surfaces to cause lift. The worst thing which can happen is a dome opening up so that it can be inflated by the wind. This will be likely to blow panels off the dome leading to serious failure and damage. Hence the deliberate, upwind direction of the shutters. Rather than risking them being ripped off by downwind suction.
Somebody online had their entire dome fly off the walls when they [foolishly] opened the doors facing into the wind! I am glad my access doors face south and I can enter the dome from below. It wouldn't be half as much fun to enter from the veranda doors which face west. I only open one half of my double doors on the ground floor. The potential is there should I want both doors open but there is plenty of room to get in via one.
I have now cleared the observatory of all loose items and covered the big mounting with a giant, leaf collection bag. I don't mind if it doesn't blow remotely as hard as forecast. I haven't lost anything by being prepared. We suffered some roof damage in a "once in a century" storm about 20 years ago. So know the power of the wind. Better to be safe than sorry. I can potter around today. Ensuring everything is as safe as possible before the wind picks up.
There is nothing downwind except trees, fields and forest. We are protected, to some extent, by a shelter belt of trees to the west. Though this belt does not extend quite far enough to the SW. Which leaves us potentially exposed. Thankfully our own garden has been much better furnished with trees and bushes to the SW over the 20 intervening years. Though the boundary trees look a bit tall and spindly in their bare winter clothing. They should all help to take the edge off the worst gusts.
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