Don't Trust the Crane

Now here is a blog that has almost nothing to do with ham radio.  Almost. I dare you to read to the end if you like math, and even if you don't like math.

One of my day jobs is welding and building gates, railings, metal art, etc.  Lately I've been spending much more time on software, communications, and various hi-tech endeavors, but I still go out and do an occasional metal project if I get in the mood.

Today I received a phone call from someone who said that a railing that I had built years ago was in need of repair. Hmm.  Yep, after many years, railings tend to need paint, but if the welds were pretty good, then it usually only takes some paint to make the railing look like new.

I did not expect to see this:

This is what happens when a large and heavy object falls from about 20 feet onto a piece of 30mm steel RHS.  Looks fairly well crushed, eh?  In this case, a crane on the back of a truck was lowering a large solar water tank from a roof for replacement.  Clearly the straps holding the tank were not adequately secured, and down came the tank at 32 feet per second squared...or 9.8 m/sec^2 if you remember high school physics.

The tank probably weighs in at about 120 lbs.  That is food for thought..more on that in a second.  Here is what the tank looks like on the ground.

The tank smashed the windshield on the crane truck. WHAM!

So what does this have to do with ham radio?  Not much, but I was thinking about who, in their hobby might have to deal with the risk of falling objects.  Artists? No.  Clay modelers? Unlikely.  Chess players? Highly unlikely.  However, we amateur radio operators do tend to put things up in the air and occasional are up above the ground ourselves.  Fortunately, no one was anywhere near the tank when it fell from 20 feet or so.  For fun, let's figure out the forces involved. To help, I visited the site:

https://www.engineeringtoolbox.com/impact-force-d_1780.html

From the formulas available on that site, I figured as follows, and I apologize for working in metric, but it's what I have been using for about 20 years, so here we are:

E = (60kg weight of the tank) (9.81m/s^2 acceleration of gravity) (7 meters of falling distance)

   =4120.20 Joules

now we calculate the Force involved, and it is A LOT !

Fmax = 2 (4120.2 Joules)/0.02m (impact distance of 2cm from the ground)

          = 412 kilo Newtons

And how much is that? Well round it off to 92,621 pound - feet of force.  That's a lot.

And what does this have to do with Ham Radio?  Well next time you climb that tower, be sure that your ground crew is not anywhere under you in case you drop a tool, an antenna element, a tool bag, or even a machine screw.  Certainly you want to make sure that you are firmly belted to the tower; that's a given. 73 for now, Mark 4x1ks