The air screw was driven by an engine powered by a chemical exothermic reaction—oxidation of a hydrocarbon fluid called “gas,” which it was not. If you think this unlikely, I assure you that it was unlikely even then. The method was woefully inefficient. A flier was not only likely to run out of gas with nothing around him but ocean, but also this temperamental engine often coughed and quit. Embarrassing. Sometimes fatal.
