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National Advisory Committee for Aeronautics, Technical Notes - An Analytical Investigation of Effect of High Lift Flaps on Takeoff of Flight Airplanes

The present trend toward the use of light (personal-owner-type)
aircraft in farming and ranching activities and the indication that
nearness to centers of population is important to the success of airport
operation make it increasingly desirable that the personal airplane be
able to take off in short distances from poorly prepared airfield sur-
faces. Since very little reduction in take-off distance is obtained
from the flaps now in use on light airplanes, even though very effective
high-lift flaps are in use on some military and transport aircraft, it
seems likely that much can'be done to improve take~off by Judicious
selection of high-lift—device arrangements.

Take—off distances and the corresponding lift coefficients have
been determined for a hypothetical transport airplane employing flaps
(reference 1) and for a liaison-type airplane using boundary—layer con—
trol (reference 2), but the problem of take-off for light airplanes
equipped with high-lift devices has not been dealt with adequately.
(Boundary—layer control in its present phase of development is considered
impractical for personal aircraft and is not considered in this analysis.)

This report covers three phases of investigation of the problem of
improving take-off performance by the use of flaps. The first part is
concerned with the determination of the optimum lift coefficient for
take—off for airplanes having loadings representative of personal air-
craft and flying from field surfaces encountered in personal—aircraft
operation. The analysis is made for airplanes carrying four people and
enough fuel and oil for 5 hours' flight at 65 percent of full power.
Power loading, span loading, aspect ratio, and drag coefficient are
varied sufficiently to deterndne the effect of the variables on take-
off performance, and for each given set of conditions the lift coeffi—
cient and the velocity are determined for the minimum distance to take
off and climb to 50 feet.