Trembler ignitions were particularly suitable for igniting these mixtures. The cars were powered by Continental engines, used Timken axles, Bijur starters, and Bosch ignitions. Most of the explosions were caused by firedamp ignitions followed by coal dust explosions. CD ignitions to some piston engined fighter aircraft. Natural factors affecting ignitions include lightning flashes, volcanoes, and seasonality. In 1924, Velie began installing Westinghouse electric ignitions in their cars. Reducing human-caused ignitions may be the most effective means of reducing unwanted wildfire. All the models had 4-cylinders, "Splitdorf" ignitions with disc clutch and first gear final drive. Ignitions can be either natural or anthropogenic. CD ignitions use step-up transformers. On October 27 the LAE was disabled to prevent inadvertent ignitions. A significant difference from modern ignitions is in the strength and number of sparks produced. The booster failed on the third flight, causing the loss of the DCSS before ignitions.