anatomy of a burnt out blitz

[Tony Wheeler]

Amongst the many CMPs photographed by Keith and I as kids in the early 1970's was this C60L sawmill crane. 40 years later it's still there, albeit in a rather sorry state after the 2008 Black Saturday bushfires. I dropped in recently to inspect the burnt out wreck, and found the damage it had sustained quite interesting. Although parked in a cleared area some distance from the treeline, it was nonetheless subjected to intense radiant heat - sufficient to melt the carby, cause windscreen glass to soften and droop, and solder to flow down the radiator. Steel parts absorbed tremendous radiant heat - the springs becoming soft enough to sag under vehicle weight, and even the LH windscreen frame to sag under its own weight - suggesting the entire vehicle was literally red hot! Interestingly though, some non-metal materials inside the cab, including sections of wiring insulation and fuel hose, were barely even charred. Presumably these were shielded from direct radiant heat from the treeline.

[Tony Wheeler]

Some more pics of the heat damage, and one of the brick timber drying kiln in which 13 people, including 4 children, took refuge from the firestorm while the old Chev glowed red hot a few metres away! Fortunately they all escaped unharmed - unlike 3 of their neighbours, who sadly were amongst the 173 souls who perished that day.

[Keith Webb]

I reckon the heat from the burning tyres would have helped the springs to sag. Those were horrific fires. It was such a hot windy day, around 46C at my place.

I once photographed a Ford CMP in the Adelaide Hills which had been through a bushfire with very similar results.

[Tony Wheeler]

Originally Posted by Keith Webb

I reckon the heat from the burning tyres would have helped the springs to sag.

Possibly, although I believe radiant heat from the treeline would have been sufficient on its own, judging by the molten carby (approx 500C) and the softened windscreen glass (approx 800C). Steel at 800C is cherry red to orange, which would explain the LH windscreen frame sagging under its own weight.

Another blitz a few miles up the road was a long way from the treeline, and that one suffered minimal damage (see pics). Only one tyre ignited, and the heat from that only melted the steering wheel. I suspect tyres probably burn too slow to heat steel red hot - unlike the burning forest, which is pumping out gigawatts of IR radiation. Kinda like a giant bar radiator - distance is all important!

I'm aware of at least four CMPs destroyed in these fires, I wonder how many others there were...