A summary of published information on braking friction coefficients is presented. An analysis is included which indicates that the magnitude of the friction coefficient available will affect the technique required for obtaining the shortest ground run only under extreme conditions. In this connection, technique refers to the choice between utilizing air drag and ground friction through choice of attitude. The analysis further shows that the landing attitude is almost never the attitude for the shortest ground run. A chart is presented for rapid estimation of ground-run. A chart is presented for rapid estimation of ground-run distance for any set of values of friction coefficient, airplane attitude, initial drag weight ratio, and initial velocity. Sample studies are presented for high- and low-wing loadings.

Reproductions of reports, some declassified, of research done at Langley Memorial Aeronautical Laboratory during World War II. The order of reports does not represent when they were chronologically issued. Reference to the original version of each report is included.

An investigation has been conducted to determine the effects of vertical-tail location and size on the subsonic aerodynamic characteristics of a model having a triangular wing. The wing had an aspect ratio of 3, an NACA 0003.5-63 section in the streamwise direction, and plain, trailing-edge ailerons. The wing was attached to the fuselage in either a mid or high position and an unswept horizontal tail was located on the fuselage center line. Two vertical tails were tested which had areas of 26.7 or 20.3 percent of the wing area. Each vertical tail was equipped with a rudder and had a geometric aspect ratio of 1.5, a taper ratio of 0.16, and 54 degrees of sweepback of the leading edge. Each vertical tail was tested at two different tail lengths. The wind-tunnel tests were conducted at a Reynolds number of 2.5 milMon at Mach numbers from 0.25 to 0.95.

1. Considerations of safety and accuracy limit the rate of descent used in the landing approach to about 25 feet per second.

An investigation was made to determine the effects of boundary-layer control on the landing performance characteristics of a liaison type of airplane having a payload of 1500 pounds and a flight duration of 5 hours. The aspect ratio was varied from 5 to 15, the wing span from 30 to 100 feet, and the brake horsepower from 300 to 1200. The use of boundary-layer control caused reduction in total landing distance (25 to 40 percent), ground-run distance, gliding speed, and stalling speed whereas sinking speed was increased only slightly.