An Airfoil Spanning an Open Jet

Proceeding from the fundamental problem on the mutual relation of a wing and free boundaries the distribution of the circulation is determined for an airfoil spanning an open jet of rectangular section at different aspect ratios, and then for an open jet of circular section. The solution is obtained by means of a Fourier series and computations have been performed for different values of the variables. The second part describes the experiments performed for the purpose of proving the theory. The results confirm the theory. In conclusion it defines the induced drag of a wing extending across an open jet and compares it with the drag of a monoplane having a span equal to the jet width at equal total lift.