This report is concerned with the importance of the flat-top lift curve as a factor contributing to safety and control at low speed. An analysis of existing airfoil data indicated definite relations between the shape of the lift curve and certain section dimensions. The shape of the lift curve at maximum lift appears to be of sufficient importance to justify additional investigation with the view of developing a section with satisfactory efficiency and moment characteristics.

An investigation was conducted to determine the injection lag, duration of injection, and spray start and cut-off characteristics of a fuel injection system operated on an engine and injecting fuel into the atmosphere. The results indicated that for the injection system investigated, the injection lag, in crank degrees, decreased with increase in engine speed for a constant quantity of fuel discharged, but was not affected at constant engine speed by varying the fuel quantity from approximately one-half to full load fuel quantity.