Simple flight tests were made on ten conventional airplanes for the purpose of determining their action in two situations, which are generally thought to precede and lead to a large proportion of airplane crashes. These situations are when in an attempt to stretch the glide in a forced landing, the airplane is stalled, and when while taking off, particularly if taking off steeply, the engine fails at a low altitude.

"The effect of scale and turbulence on the lift and drag of five airfoils the NACA 0006, the NACA 0021, the Clark Y and the USA 35-A, and the USN PS6, have been investigated in the Variable Density Wind Tunnel of the NACA. Tests were made over a wide scale range for only two different conditions of turbulence. Because of the limited scope of the tests, no general conclusions have been drawn, but it is indicated that increasing either turbulence or scale eliminates the discontinuities in the lift curves for thick airfoils, and that the effects of increased turbulence on the profile drag of airfoils tend to become of small importance at very high Reynolds Numbers" (p. 1).

"Tests were conducted in the Variable Density Wind Tunnel of the NACA to determine the importance of the interference effects and drag of struts on a monoplane. Inclined struts were placed upon a Gottingen 387 airfoil in the lower surface positions and in two upper surface positions. Tests were made at values of Reynolds Number comparable with those obtained in flight. It was found that the interference drag of struts may be as great as the drag of the struts alone" (p. 1).

From Summary: "Logical analysis of a box wing necessitates the allowance for the contribution of the drag spars to the torsional strength of the structure. A rigorous analysis is available in the use of the Method of Least Work. The best logical method of analysis is that applying Prandtl's Membrane Analogy. The results so obtained vary by a negligible amount from those obtained by the rigorous method."

From Summary: "This report contains the lift, drag, and moment characteristics of tapered Clark Y, Gottingen 393, and USA 45 airfoils as obtained from tests made in the Variable Density Wind Tunnel of the NACA. The results are given at both low and high Reynolds Numbers to show scale effect and to provide data for use in airplane design."