This report covers the most common airfoils used for aircraft in the speed range that most of use build in.
Extracted from: NACA REPORT No.233
THE AERODYNAMIC CHARACTERISTICS OF SEVEN FREQUENTLY USED WING SECTIONS AT FULL REYNOLDS NUMBER
By MAX M. MUNK and ELTON W. MILLER
Langley Memorial Aeronautical Laboratory
This report contains the aerodynamic properties of the wing sections, U.S.A. 35 A, U.S.A. 35 B, Clark Y, and Gottingen 387, as determined at various Reynolds Numbers up to an approximately full scale value in the variable density wind tunnel of the National Advisory Committee for Aeronautics.
It is show that the characteristics of the wings investigated are affected greatly and in a somewhat erratic manner by variation of the Reynolds Number. In general there is a small increase in maximum lift and an appreciable decrease in drag at all lifts.
The tests described in this report were made in the variable density wind tunnel of the National Advisory Committee for Aeronautics. The construction of this tunnel, the features particular to it: and the reasons for providing such features will be the subject of another report.
Since the effective linear model size is equal to the actual model size multiplied by the ratio of the test density to the normal density of air, full scale values of the Reynolds Number are obtained in the variable density wind tunnel with moderate wind speeds on models of ordinary size by compressing the air to about twenty times its normal density (or normal pressure).
The present tests are among the first made in the variable density wind tunnel, and, as might be expected from the newness of the work, there are certain runs and individual readings which do not appear to check with the remaining data.
Owing to the general interest in these data and their probable value to airplane designers, it has been decided to make the data immediately available in the present form and to give more complete and more accurate data in some future report or reports. The general effect of the Reynolds Number and the characteristics of the various airfoils at large Reynolds Number are considered to be given with reasonable accuracy by these data.
METHOD OF TEST
The models were smoothly cutting of duralumin in rectangular form, 30-inch span and 5 inch chord, with equal and parallel sections along the span, The span of the models, 30-inches, is one-half of the throat diameter of the wind tunnel. In the tests each model was fastened to the tunne1 balance by means of thin wires and a vertical shielded bar extending across the tunne1 in rear of the model. A skid rigidly connected with the model bias hinged to this bar, so that the angle of attack could be changed during the tests by moving the bar up or down.
Each model was investigated through a range of angles of attack at an approximately constant pressure of the air circulating in the wind tunnel. This pressure was increased in steps and each time the test repeated.
In the same way the resistance of the wires and of other auxiliary parts was determined. This Iatter test includes the slight forces exerted by the air flow on the balances directly, in consequence of small leakages between the test room, the balance room, and the return channel.