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.

A performance analysis is given to determine whether bondary-layer control by suction might reduce the minimum take-off distance of a four- or five-place airplane. Results indicate that boudary-layer control might be effective in improving the take-off characteristics of this type airplane having wing loading of 10 or more pounds per square foot and aspect ratios of 10 or more.

The landing of a simplified airplane structure, consisting of a uniform beam for the wings, a concentrated mass for the fuselage, and a linear spring for the landing gear, is analyzed exactly and is compared with several approximate solutions. The approximate solutions which neglect elasticity in the determination of landing-gear reaction but consider elasticity in computations of stresses give results of good accuracy and indicate that drop tests in which rigid masses are used may be a satisfactory approach to the landing problem.