Model Car Fire Investigation
A young male was having some difficulty starting his pull-start model car. He had heard that loosening the glow plug 1/4 turn would make it easier to start, presumably by reducing the compression in the engine. As schematically illustrated below, the young man was allegedly sitting on a step with the model car between his legs on a doormat and a half-full, 1-gallon can of methanol-nitro fuel about 1-foot to the left of his left leg.
Allegedly, the methanol-nitro fueled car started after the glow plug was loosened 1/4 turn and then ran for about 2-5 minutes before the glow plug blew out of the engine and sprayed the young man with methanol-nitro fuel causing burns, predominantly on the inside of the full length of the young man's legs. He was wearing full-length jeans.
At some point, the 1-gallon fuel can exploded, but the fuel can was allegedly not between his legs, but on the ground to the side of his left foot. The burns were most severe on the inside of the young man's legs and there were no documented burns on the outside of his left leg or left foot where the 1-gallon fuel can was alleged to be sitting.
Chemaxx was hired to investigate and reconstruct this incident.
The first effort at reconstruction involved the loosened glow plug. Using an exemplar model car, numerous attempts were made to loosen a glow plug and document the glow plug flying out of the engine and the subsequent spray of fuel. However, each and every time the glow plug was loosened, the engine would die before even a 1/2 turn could be achieved, as shown in the video below.
In the above video, the glow plug igniter was left on to provide every opportunity for the engine to keep running. However, even in that configuration, the engine quickly stopped.
It should be noted that at least 5 full (360-degree) turns of the glow plug are needed to remove the glow plug from the engine. The fact that the engine stopped after less than 1/2 turn, presumably due to loss of compression, was highly inconsistent with the young man's version of events. It was possible to start an engine with the glow plug 1/4 turn loose, but any further loosening quickly stopped the engine each and every time.
Attempts were also made to explode the 1-gallon methanol-nitro fuel can that was allegedly half full of fuel. Many variables were tested, including less fuel, more fuel, higher percentages of nitro, sealed and non-sealed, external fires, etc. For example, the video below shows a sealed, half-full, 1-gallon fuel can on its side with the spout down in an external fire. The top blows off with a spray of fire, but there was no explosion of the fuel can. Not one fuel can explosion was achieved in spite of the many attempts and the very severe circumstances that were tested.
Finally, Astroturf and other doormats were tested for flammability. Every doormat material tested was readily flammable and it was unimaginable that a half-full, 1-gallon can of methanol-nitro fuel could explode right next to the doormat and have the doormat show no evidence of fire. The model car was allegedly sitting on the doormat and one of the rear tires was seriously burned, but there was no documented evidence of any doormat burns. For example, the video below shows Astroturf burning after the ignition of a small amount of fuel that was placed on the doormat.
The idea that a half-full, 1-gallon can of methanol-nitro fuel can explode right next to a doormat and burn a rear tire on the model car sitting on the doormat, but not leave ample visible of evidence of fire on the doormat itself, was adamantly contradicted by the experimental testing.
In summary, while there was little doubt that the young man was burned, each and every attempt to experimentally reconstruct the alleged events that led to those burns, failed. The case settled prior to trial.
Dr. Fox has a Ph.D. in Physical Chemistry and is a Certified Fire & Explosion Investigator who specializes in complex industrial chemical accidents and consumer-related chemical accidents. He specializes in the reconstruction and understanding of unusual chemical accidents, fires and explosions.
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