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[aprssig] Our Tornado

Dave dave at g8kbv.demon.co.uk
Fri Apr 6 12:53:16 UTC 2012


On 5 Apr 2012 at 10:52, Gregg Wonderly wrote:

> 
> On Apr 5, 2012, at 10:33 AM, Dave wrote:
> 
> > On 4 Apr 2012 at 12:48, Charles Blackburn wrote:
> > 
> >> texas yesterday..
> >> 
> >> what makes it more impressive is that some of those were apparently
> >> fully loaded..
> >> 
> >> charlie
> >> 
> > 
> > From the news footage shown over hear, those "fully loaded" box
> > trailers, when they landed, ended up suprisingly flat, for something
> > that was full.
> > 
> > Mind you, even an empty one of those weighs in at some 7+ tonne's
> > from memory?  You still wouldn't want one to land on you...
> > 
> > Empty or otherwise...
> 
> surface sq ft * .0027 * windspeed * windspeed == force in pounds of
> force.
> 
> 57' * 13.5' = ~670sqft
> assume 100mph wind
> 
> that presents a force of 20776 pounds or about 10 tons of force,
> clearly enough to push it across the ground.  Do some trig and you can
> figure out what the lift force is at a particular "tilt" of the
> trailer.  It's really easy for 100+ mph winds to lift semi trailers
> full of stuff, because of the nice flat surface of the trailer. 
> Lighter objects with less surface area would easily sit still and not
> move.
> 
> http://www.ehow.com/how_5814125_convert-wind-speed-pressure.html
> 
> Gregg Wonderly
> W5GGW
> 
> 

Hi.

I don't doubt the forces involved, just doubt from the pictures if the 
upside down flattened ones were full of goods when it hit.   Unless they 
were stuffed so full, that "stuff" couldn't move about, and it was 
strapped or chained down, I'd have expected the goods to have moved about 
and destroyed the box trailer while "in the air", so you would not get a 
nice neat flat-pack when it came back to ground.

The last time the news here said something about a Tornado hitting a 
small town in the UK, my first thought was that the RAF had lost one of 
their planes.

73.

Dave G0WBX
(listening to KC2MK, working into Europe on 17m.  Variable signal 
strengths.)



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