Flying trampoline

I casually mentioned our storm destroyed trampoline in a piece about wind-throw and firewood. But I didn't go into detail. Like everyone and their dog, we bought a trampoline in the 00s when Dau.I and Dau.II were tweens. It seemed like fun and it came with more safety features than some which were sold in an unregulated market. The upright poles were sheathed in foam tubes and supported a child-proof safety net. The tubular-steel circular frame and the steel springs were covered by foam-filled water-proof mats. We also implemented a strict [boo-hoo no fun] policy of one bouncing body at a time. At the same time, on a different trampoline,  one of the neffies lost half a front tooth . . . embedded in the skull of a pal who was bouncing up as neffie was coming down.  A year earlier a niece had bounced off a trampoline and sustained a compound fracture in her arm. And my then boss's neighbour's boy had broken his neck and died having launched at his trampoline from the roof of the garden shed. Anyway, here it is, in its heyday with three tweens for scale:

What could possibly go wrong??  Well nothing even close to those harrowing accidents. One morning I got up and glanced into the haggard then stopped a rubbed my eyes because the trampoline wasn't there as usual at the bottom of the haggard. It's not like you could miss it!  I rounded the corner of the shed and saw it, all bend out of shape, at the Top of the haggard. During the night, which had been windy but not Storm Force, the trampoline took off like a flying squirrel and sailed 40m up a 1:10 slope until it whacked a pine tree. 10m further West, it would have taken the lid off our 16ft touring caravan = spare bedroom. 

I was a Navy brat, I knew about windage [The force of the wind on a stationary object]. I had therefore weighted down the tubular steel base of the apparatus with eight [8] 4in = 100mm solid concrete blocks. Which everbode kno is 8 x 22.5 = 180kg. But that's pffft nothing when the surface of the trampoline [not including the contribution of the safety netting] is 20 sq.m. and the wind is, say, 60km/h. We had that trampoline for several years, and the winds had been much stronger than The Last Night of the Trampoline. The key factors must have been a) the direction of the wind funnelling through the screen of trees to the South b) something something resonance: where the precise speed of wind bounced the whole disc off its blocks and set it off uphill.  

Don't do this at home kids! Forget trampoline tether kits. Only go trampolining somewhere you can sue the owner's ass if something goes wrong. But even then the compo really won't cover the damage.