Engineering topics
Publications and source records attributed to Schrenk, O.
Flight-test data and wind-tunnel data on suction profiles are substantially in agreement. The lift values found in the model test can be actually flown and used as a basis for the design. To visualize the action of the suction, the flow conditions with and without suction on the upper surface were photographed; figures 12 to 15 are sections of the film.
The approximation method described makes possible lift-distribution computations in a few minutes. Comparison with an exact method shows satisfactory agreement. The method is of greater applicability than the exact method and includes also the important case of the wing with end plates.
This paper reports on 4-component balance measurements with and without angle of sideslip made on an airfoil with end plate at one tip. In addition, pressure distribution measurements on the end plate served as a basis for the determination of the forces on the end plate and for the bending moments.
The present report collects the investigations of the past years which, while not as yet intended for use in construction, show different possibilities for the building of a suction-type wing and at the same time present some basic explanations concerning the problem of suction. Experiments and results with a thick wing profile are detailed as well as boundary layer removal by suction and sink action. Experiments with flap profiles are also included.
We will here report on the effects of coarsely roughening not only the pressure side but also the suction or upper side of airfoils, as the first group of a larger series of experiments.
Ackeret began systematic polar measurements on Joukowsky wing sections, which were occasionally conducted in the wind tunnel. Under these conditions a considerable number of wing sections were tested during the last four years and the tests are now more or less concluded.
Our attempts to improve the properties of airfoils by removing the boundary layer by suction, go back to 1922. The object of the suction is chiefly to prevent the detachment of the boundary layer from the surface of the airfoil. At large angles of attack, such detachment prevents the attainment of the great lift promised by the theory, besides greatly increasing the drag, especially of thick airfoils. This report gives results of those experiments.
The first group of a large series of contemplated experiments on the effect of roughness was intended to show the effect of great roughness on airfoils of various sizes and attitudes.