Report discussing the 6-foot-4-inch wind tunnel and its auxiliary equipment has proven itself capable of continuous and reliable output of data. The real value of the tunnel will increase as experience is gained in checking the observed tunnel performance against full-scale performance. Such has been the case of the 8- by 8-foot tunnel, and for that reason the comparison in the calibration tests have been presented.

This report presents a description of the rules, history and new technical innovations in the Deutsch de la Meurthe Cup race of 1934.

Report discussing model tests prove the feasibility of enhancing the aerodynamic qualities of wing-fuselage fillets by appropriate design of fuselage and wing roots. Abrupt changes from maximum fuselage height to wing chord must be avoided and every longitudinal section of fuselage and wing roots must be so faired and arranged as to preserve the original lift distribution of the continuous wing. Adapting the fuselage to the curvilinear circulation of the wing affords further improvement. The polars of such arrangements are almost the same as those of the "wing alone," thus voiding the superiority of the high-wing type airplane known with conventional design.

From Summary: "This report presents the results of wind tunnel tests of a wing in combination with each of three sizes of Fowler flap. The purpose of the investigation was to determine the aerodynamic characteristics as affected by flap chord and position, the air loads on the flaps, and the effect of flaps on the downwash."

"This paper presents the results of wind-tunnel tests of several airfoils of low aspect ratio. The airfoils included three circular Clark Y airfoils with different amounts of dihedral, two Clark Y airfoils with slots in their portions, and three flat-plate airfoils. Lift, drag, and pitching-moment characteristics of the slotted airfoils with slots open and closed; pitching moment characteristics of one of the slotted airfoils with slots open and closed; and lift characteristics of the flat-plate airfoils are included" (p. 1).

From Summary: "The results of a wind-tunnel investigation of the NACA 23012, the NACA 23021, and the Clark Y airfoils, each equipped with a cambered external-airfoil flap, are presented in this report. The purpose of the research was to determine the relative merit of the various airfoils in combination with the cambered flap and to investigate the use of the flap as a combined lateral-control and high-lift device."

"The main purpose of this investigation is to make available to the designer useful information with regard to the aerodynamic drag of various types of flying-boat hull models. The present report is the first in a series covering investigation in this field. Through close cooperation between hydrodynamics and aerodynamics divisions it is hoped that results leading to improvements in hull design obtained" (p. 1).

"The tests described in this report were made as part of an investigation of the spinning characteristics of the F4B-2 airplane conducted at the request of the Bureau of Aeronautics, Navy Department" (p. 1).

This report presents a detailed analysis and history of the construction and operation of the aeronautical laboratory of the Stockholm Technical Institute. Engines and balances are discussed and experimental results are also given.

Report presents the results of a study made to determine the air-flow characteristics around finned cylinders. Air-flow distribution is given for a smooth cylinder, for a finned cylinder having several fin spacings and fin widths, and for a cylinder with several types of baffle with various entrance and exit shapes. The results of these tests show: that flow characteristics around a cylinder are not so critical to changes in fin width as they are to fin spacing; that the entrance of the baffle has a marked influence on its efficiency; that properly designed baffles increase the air flow over the rear of the cylinder; and that these tests check those of heat-transfer tests in the choice of the best baffle.

From Summary: "A description of the test methods used at the National Bureau of Standards for determining the characteristics of aircraft compasses is given. The methods described are particularly applicable to compasses in which mineral oil is used as the damping liquid. Data on the viscosity and density of certain mineral oils used in United States Navy aircraft compasses are presented. Results of flight tests are presented."

Report presenting an analysis of a wing brace with a small auxiliary strut, which is attached to the wing spar at the upper end. The design is quite effective but has some difficult analysis problems. The report is broken into two parts; one is a theoretical investigation and one is an experimental investigation.

Report includes the National Advisory Committee for Aeronautics letter of submittal to the President, Congressional report, summaries of the committee's activities and research accomplished, bibliographies, and financial report.

Note presenting the von Kármán-Millikan theory of laminar boundary layers as applied to the laminar boundary layer about an elliptical cylinder on which boundary-layer and pressure-distribution measurements. Good agreement is obtained between calculated and experimental results, meaning that the method may be generally applied to the laminar boundary layer about any body provided that an experimentally determined pressure distribution is available.

This report analyzes the action of a cantilever T beam with a tension flange so thin it can only carry tensile stresses.

"The paper beings with a brief discussion on the origin of the bending stresses in cantilever box beams under torsion. A critical survey of existing theory is followed by a summary of design formulas; this summary is based on the most complete solution published but omits all refinements considered unnecessary at the present state of development. Strain-gage tests made by NACA to obtained some experimental verification of the formulas are described next. Finally, the formulas are applied to a series of box beams previously static-tested by the U.S. Army Air Corps; the results show that the bending stresses due to torsion are responsible to a large extent for the free-edge type of failure frequently experienced in these tests" (p. 1).

Circular presenting a description of the Boulton Paul P.71A, which is a new type of two-engine biplane. Details of the design, fuel tanks, materials, fuselage, passenger seating, tail, and flying qualities are provided.

"A method is presented for calculating the aerodynamic forces on a moncylane wing, taking into account the elastic twisting of the wing due to these forces. The lift distribution along the span is calculated by the formulas of Amstutz as a function of the geometrical characteristics of the wing and of the twist at stations 60 and 90 percent of the semispan. The twist for a given lift distribution is calculated by means of influence lines" (p. 1).

"This report gives the results of tests in the NACA full-scale and variable-density tunnels of a new wing section, the NACA 23012, which is one of the more promising of an extended series of related airfoils recently developed. The tests were made at several values of the Reynolds number between 1,000,000 and 8,000,000. The new airfoil develops a reasonably high maximum lift and a low profile drag, which results in an unusually high value of the speed-range index. In addition, the pitching-moment coefficient is very small" (p. 435).

"Fuel injected into a spherical bomb filled with air at a desired density and temperature could be ignited with a spark a few thousandths of a second after injection, an interval comparable with the ignition lag in fuel-injection engines. The effect of several variables on the extent and rate of combustion was investigated: time intervals between injection and ignition of fuel of 0.003 to 0.06 second and one of 5 minutes; initial air temperatures of 100 degrees C. to 250 degrees C.; initial air densities equivalent to 5, 10, and 15 absolute atmospheres pressure at 100 degrees C.; and air-fuel ratios of 5 to 25" (p. 107).

"Comparative tests were made on seven conventional Pitot-static tubes to determine their static, dynamic, and resultant errors. The effect of varying the dynamic opening, static opening, wall thickness, and inner-tube diameter was investigated. Pressure-distribution measurements showing stem and tip effects were also made. A tentative design for a standard Pitot-static tube for use in measuring air velocity is submitted" (p. 1).

"Simultaneous air-flow photographs and pressure-distribution measurements have been made of the NACA 4412 airfoil at high speeds in order to determine the physical nature of the compressibility bubble. The flow photographs were obtained by the Schlieren method and the pressures were simultaneously measured for 54 stations on the 5-inch-chord wing by means of a multiple-tube photographic manometer. Pressure-measurement results and typical Schlieren photographs are presented" (p. 1).

In this paper there is presented a deflection formula for single-span beams of constant section subjected to combined axial and transverse loads of the types commonly encountered in airplane design. The form of the equation is obtainable by dimensional analysis. Tables and curves of the non dimensional coefficients are appended to facilitate the use of the formula. The equation is applied to the determination of the spring constant of a beam. Tables and curves are presented to show the variation of the spring constant with changes in the axial load and position along the beam.

The 6.C.1 balance is the first fully automatic balance assuring a continuous and simultaneous record of the aerodynamic characteristics of an airfoil in a wind tunnel. Because of the rapidity of the measurements a complete polar (six components) requires only about three minutes of wind, that is to say, of motive power, which is of interest for wind tunnels with high efficiency factors and may lead to the economical design of large size wind tunnels.