This report records observations and recommendations resulting from an inspection trip to representative aircraft manufacturing establishments and repair stations. This inspection was made for the Navy Department and was specifically in reference to gluing practice at the various places visited. The period of the visits was between November 23, 1926 and February 16, 1927.

In order to experimentally study the conditions leading to ice formation on aircraft surfaces, an aircraft was equipped with small auxiliary surfaces and aerodynamic shapes similar to struts, wires, Pitot heads, etc. This airplane was flown at an altitude where a temperature of 32 F was encountered, at such times as cloud formations could be found at the coincident altitude. Here it was discovered that ice formed rapidly in regard to quantity, character, shape, and rapidity of formation.

This note describes tests of the drag due to a Wright "Whirlwind" (J-5) radial air-cooled engine mounted on a cabin type airplane. The tests were made in the 20-foot Propeller Research Tunnel of the National Advisory Committee for Aeronautics. The drag was obtained with three different types of exhaust stacks: Short individual stacks, a circular cross section collector ring, and a streamline cross section collector ring.

This report presents the results of an investigation of the rolling and yawing moments due to ailerons of various chords and spans on two airfoils having the Clark Y and U. S. A. 27 wing sections. Some attention is devoted to a study of the effect of scale on rolling and yawing moments and to the effect of slightly rounding the wing tips. The results apply to level flight with the wing chord set at an angle of attack of +4 degrees and to conditions of zero pitch, zero yaw, and zero roll of the airplane. It is planned later to extend the investigation to other attitudes for monoplane and biplane combinations. The work was conducted in the 10 foot wind tunnel of the Bureau of Standards on models of 60-inch span and 10-inch chord. (author).

This investigation was conducted by the National Advisory Committee for Aeronautics at Langley Field, Va., at the request of the Army Air Corps, for the purpose of comparing the full scale lift and drag characteristics of an airplane equipped with several sets of wings of commonly used airfoil sections. A Sperry Messenger Airplane with wings of R.A.F.-15, U.S.A.-5, U.S.A.-27, and Gottingen 387 airfoil sections was flown and the lift and drag characteristics of the airplane with each set of wings were determined by means of glide tests. The results are presented in tabular and curve form.

"This investigation of the pressure distribution on the tail surfaces of a pursuit airplane in violent maneuvers was conducted for the purpose of determining the maximum loads likely to be encountered on these surfaces in flight. The information is a part of that needed for a revision of existing loading specifications to bring these into closer agreement with the actual flight conditions. A standard F6C-4 airplane was used and the pressure distribution over the right horizontal and complete vertical tail surfaces was recorded throughout violent maneuvers. The results show that the existing loading specifications do not conform satisfactorily to the loadings existent in critical conditions, and in some cases were exceeded by the loads obtained" (p. 539).

"An adjustable blade metal propeller was tested at five different angle settings, forming a series varying in pitch. The propeller was mounted on a VE-7 airplane in the twenty-foot propeller research tunnel of the National Advisory Committee for Aeronautics. The efficiencies were found to be from 4 to 7 per cent higher than those of standard wood propellers operating under the same conditions. The results are given in convenient form for use in selecting propellers for aircraft" (p. 521).

With an unsymmetrical wing and a rotating Magnus cylinder, the lift is produced by the superposition of parallel and circulatory flows. An explanation of the circulatory flow is furnished by the boundary-layer theory of Prandtl and the consequent vortex formation. According to this explanation, it must evidently be possible to increase the circulation either by increasing the size of the stronger (lower) vortex or by decreasing the size of the weaker (upper) vortex.

"The most important aerodynamical qualities that should be aimed at in wind tunnel design, are as follows: 1) constant and parallel direction of flow; 2) uniform velocity across all sections; 3) absence of turbulent motion; 4) constant velocity of flow. The above-mentioned qualities are all realized in a high degree in the Gottingen type of wind tunnel, with a parallel portion before the working section, the cross section of which is steadily reduced. It is shown in what follows, that the system can be applied to other wind tunnels, such as the N.P.L. or Eiffel type" (p. 1).

Since 1922 the further development of the glider has consisted of a very gradual and arduous improvement in regards to air resistance, weight, strength and maneuverability. This report provides an in-depth examination of these improvements.

The problem of noise in aircraft is considered and some solutions are presented. The primary sources of sound explored included the engine and the propeller and some ways of insulating passengers from the noise are provided.

Having been designed as a long range aircraft, it carries 6200 liters of fuel and 280 liters of oil and has three propeller groups, each with a 180 HP Hispano-Suiza engine capable of 230 HP. Details of the design, wings, ailerons, fuselage, fuel tanks, landing gear, characteristics, performances, tests, drawings, and photographs are provided.

Brief summary of the habitat, habits, food and economic status, measurements, subfamilies, and subgenera of genera Sorex and Microsorex.