The Effect of Airplane Fuel-Line Design on Vapor Lock

The study of fuel flow in gravity-feed systems, which has hitherto been confined to flow through simple orifices, has been extended to include the measurement of flow through systems of various designs. The results of this study indicate that variations in the cross-sectional area of the feed lines from that at the tank outlet may have a marked effect on the vapor-locking tendency. Constrictions in the line and increases in cross-sectional area along the direction of flow are particularly liable to cause trouble from vapor lock. Experiments with commercial carbureters show that weathering of the gasoline in the carbureter float-bowl reduces the vapor-locking tendency of the fuel and, under certain conditions, may even cause an increase in the flow through the jet.