On the Sunday night, I’ll freely admit that I was making propane explosions in an empty part of the HA campsite. This basically involved heating small (190gram) butane gas cylinders up until the seal on the can failed, releasing all the butane in one fell swoop, which then ignited in a fireball of about 2 cubic metres, and lasted for a second or so.
I’m going to make a number of assumptions, all of which will skew the results in Peters favour.
The explosions took place no closer than 10 metres to peters marquee, probably more like 15 – 20 metres.
1 mole of butane weighs 58.0grams, and this can liberate up to 425 kilowatts of energy, so the full 190 grams would, given perfect conditions liberate 3.2 x 425 kw or 1360 kilowatts, or for those of us more familiar with 1 bar fires, 1360 of them on, for 1 second.
Now if we assume all the energy released was concentrated into a single point in space, and that /all of it was transmitted by radiation, linearally in all directions, and none of it was absorbed by the medium it passed through (ie. Air), then Peters marquee at 10 metres, can be taken to stand on the border of a sphere 10 metres in diameter, the formula for the surface area of a sphere is 4X pi X the radius of the sphere, all squared, or;-
4 * 3.14 * 10 squared, or 15575 square metres.
So it therefore stands that each square metre of the sphere radius 10 metres felt 1360/15575 watts per square metre, or about 87 watts per square metre, for 1 second.
It is for this reason, and for observations made at the time (ie the marquee didn’t appear to be on fire, scorched, or melted) that I firmly believe that my actions were not to blame for the damage to Peters marquee and / or car.
There was a large bonfure lit by the squad of guys camping behind Peters marquee on one of the evenings, and a sustained heat source would be much more likely to cause the damage to which Peter has referred. However, as i do not know what they were burning, i can't offer any specific energy loadings.
I'm more than happy to bury any hatchet, at any time.