flow, despite the easy starting, easy scavenging, low mechanical losses, and freedom from knock, renders the quiescent-chamber engine unattractive for aircraft-engine use. P, eport No. 57 I, Pressure Distribution Over a Rectangular Airfoil with a Partial-Span Split Flap, by Carl J. Wenzinger and Thomas A. Harris. 12 pages, diagrams, 23. 5 X 29 cms. Washington, Superintendent of Documents, I936. Price ten cents. Pressure-distribution tests of a Clark Y wing model with a partial-span split flap were made to determine the distribution of air loads over both the wing and the flap. The model was used in conjunction with a reflection plane in the N.A.C.A. 7-by Io-foot wind tunnel. The 2o-per cent.-chord split flap extended over the inboard 6o per cent. of the senti-span. The tests were made at various flap deflections up to 45 ° and covered a range of angles of attack from zero lift to approximately maximum lift for each flap deflection.
The results are given as airfoil section, or rib, pressure diagrams for the wing with flap neutral. Increments of airfoil section pressures are given for various amounts of flap deflection so that combined wing and flap section pressure diagrams may be obtained by a simple addition. Calculated coefficients of section loads and moments and of wing loads and moments are also given for the wing and flap combination and for the flap alone.
It was found that deflecting a partial-span split flap affected the pressures and the section normal-force and pitching-moment coefficients over the entire wing span. The flap loads and moments were almost constant over the span of the partial-span flap for a given angle of attack and flap deflection. The maximum normal-force and hinge-moment coefficients were about the same for the partialspan split flap of the present tests as for a full-span split flap previously tested.