Further remarks on Ettling and car fires

In my post Muehlenkamp’s Ettling imposture, I explained why the experiments of Bruce Ettling offer no support whatsoever for Roberto Muehlenkamp’s delusions regarding the challenges involved in carrying out mass cremation. Muehlenkamp has responded with a long missive that takes on a disorganized caricature of of the argument which I advanced. Observing Muehlenkamp’s repetitive spamming of the same defective arguments while ignoring the actual thrust of his opponents’ reasoning, I’m reminded of Lermontov’s description of Grushnitsky: “Он не отвечает на ваши возражения, он вас не слушает. Только что вы остановитесь, он начинает длинную тираду, по-видимому имеющую какую-то связь с тем, что вы сказали, но которая в самом деле есть только продолжение его собственной речи.” Muehlenkamp, however, lacks Grushnitsky’s good qualities.

The one point in Muehlenkamp’s meanderings that deserves a reply is that of whether the external combustibles in Ettling’s experiments played a significant role in the partial cremation, or whether – as Muehlenkamp suggests – the different results of Ettling’s two experiments show the dramatic influence of “bringing the grid in the right position.”

Muehlankamp states that “in Ettling’s experiments, the external fuel didn’t contribute significantly to the cremation of his animals, as shown by the fact that the 150-pound ewe lost only 20% of its mass/weight to the fire.” This argument reveals that Muehlenkamp doesn’t know the contents of Ettling’s paper, although he’s been citing it for years, and it’s barely over a page long. With the 150 pound ewe experimental conditions were completely different – different model of car, smaller amount of gasoline, the car windows and doors were shut and the fire left to smoulder until the heat broke a window, allowing for increased oxygen supply, and finally the fire was extinguished rather than being allowed to burn itself out. In light of these dramatic differences, it’s evident that Muehlenkamp’s argument in favor of the claim that the external fuel didn’t contribute significantly is unfounded.

Muehlenkamp has even argued that Ettling’s experiments demonstrate the “importance of bringing the grid into the right position” – yet the positioning of the body was identical in both of Ettling’s experiments, namely on its back on the front seat. Thus, Ettling carried out two experiments with different results. Factors A, B, C, and D were altered between the experiments, while factor E was left constant. From these data, Muehlenkamp deduces that factor E (namely the “positioning of the grid”) is responsible for the difference between the results. Is there really any need to explain why this is wrong?

How much fuel is involved in a car fire?

How large was the supply of combustibles for Ettling’s car fires? They fall into two parts: the fuel contained in the materials out of which the car’s interior was made, and the added gasoline. The easy part is the added gasoline. In the case of the 170 pound ewe, in which the fire was allowed to burn freely, there were 11 quarts of gasoline. Applying Muehlenkamp’s numbers for the energy content of various fuels (without any claim that they are correct), this is the equivalent of some 55 kilograms of wood.

What about the combustibles that make up the car’s interior – what is their energy content? Here’s a paper on car fires which describes some relevant experiments:

onthefir

Three full-scale experiments on passenger cars were carried out on inexpensive, ordinary medium-size cars manufactured in the late 1970s.
[…]
The total heat released during the experiments was 3.0–3.9 GJ.

Another paper gives considerably more detail:

2193-0414-2-5

The paper reveals, among other things, that the main variables we have to consider are the weight of the car and date of manufacture. (For the role of curb weight, see figure 10 of the paper.) Here we are somewhat hampered by a lack of particulars, but can still get a rough idea. The car in question was a Plymouth, but the specific model is not given in Ettling’s paper. Here and here we find numbers for the curb weights of Plymouth models from the 1950s and 1960s. As one can easily see, most Plymouth models were mid-sided and larger, while a few fell into the compact category, but none in the small or mini categories (see table 1 of the paper for the classifications). Tables 12-19 of the paper give the heat release data by weight classification.

Concerning year of manufacture, there is less data than one would like concerning car fires in vehicles of early model years. Figure 11 of the paper states that average energy release for 1970s model cars was 3.4 GJ. Unfortunately there is a lack of information available for earlier models.

All in all, given the curb weight of Plymouth vehicles it is relatively conservative to estimate the energy released from the car’s interior combustibles in Ettling’s experiment with the 170 pound ewe at 3 GJ. Muehlenkamp uses different figures at different points for the energy content of wood, but if we adopt his sometimes value of 3,843.48 kCal/kg, this translates to 186 kilograms of wood. To this must be added the energy from the gasoline – equivalent in energy content to some 55 kgs of wood.

In summary: car fires involve large amounts of combustibles. A study based on a car fire absolutely cannot show the practicality of mass cremation with limited quantities of fuel. The fuel supply in Ettling’s experiments, measured in terms of kilograms of seasoned wood with equivalent energy content, was most likely hundreds of kilograms. Nevertheless, Ettling’s experiments fell far short of attaining complete cremation. It is the height of hypocrisy for Roberto Muehlenkamp, who believes that the ewes in Ettling’s experiments should have been able to cremate themselves completely without the use of any external fuel beyond that needed for initial ignition, to rely on Ettling’s experiments in making his case for the ease with which mass cremation can be carried out.