Manometer for recording air speed

If it is desired to record the pressure difference given a gauge, the manometer must answer the following conditions: 1) It must respond quickly so that all speed variations will be correctly recorded; 2) It must not be affected by rectilinear or curvelinear accelerations. Hence, movable parts must be counterbalanced. An instrument which met these criteria is discussed as well as details of construction

Triplane tests

These experiments were carried out to determine the aerodynamic characteristics of various triplanes, which differed in the relative positions of the wings and, more especially, in the stagger, and in the shape of the wing sections. The tests were restricted to such dispositions as appeared constructively adapted to the plan form considered. Four different sets of wings were used in these tests, three of which had the same cross-section but differed in aspect ratio and in area. The tests were made at an air velocity of about 30 m.p.s. (98.4 ft/sec.) in the large wind tunnel. Results are given in tabular and graphical form

Wing resistance near the ground

In the present treatise, a convenient method will be indicated, which makes it possible to determine the polar curve of an airplane at short distances from the ground by a simple short calculation, when the polar curve is known for flight in unlimited space

The Effect of the Nature of Surfaces on Resistance as Tested on Struts

The chief concern was to measure the variations of resistance brought about by the nature of the surface of the struts. The struts were spanned with aviation linen, and then covered with one coat of varnish. The top surface was not perfectly smooth after this treatment, being slightly rough owing to the threads and raised fibers of the fabric. The results of the measurements of the surfaces are shown by the dotted lines of the curves plotted in several figures. The resistance is given in terms of the characteristic value. Next, the surface was altered by the removal of any roughness on it by means of filing with sandpaper. The measurements of surfaces thus treated gave values represented by extended lines. The increase of resistance with increasing characteristic value, more or less marked in the first series of measurements, was no longer observable. Resistance always decreases with the increase of characteristic value, excepting in the case of strut 7, which shows a slight tendency to rise again. The reasons for this phenomenon have not yet been fully explained

:Theoretical investigation of the effect of the ailerons on the wing of an airplane

The present work investigates, on the basis of Prandtl's wing theory, the form of the lift distribution when the ailerons are deflected in opposite directions. An ideal fluid and a wing with a rectangular form are assumed. The moments must not cause any rotation of the wing or any deviation from the rectilinear motion

Air-flow Experiments

This report describes the apparatus used to take air-flow photographs. The photographs show chiefly the spiral course of the lines of flow near the tip of the wing. They constitute therefore a visual presentation of the phenomena covered by airfoil theory

Contribution to the mutual interference of wing and propeller

The change of induced wing drag due to the field of flow of the propeller was analyzed quantitatively. The field of flow of the propeller is represented by a uniform distribution of sinks over the propeller disk area, whose strength is determined by the increase in speed in the slipstream. The superposition of this sink flow on the basic flow reproduces the actual field of flow outside of the slipstream with close approximation

New Data on the Laws of Fluid Resistance

Thus far, all attempts at the quantitative determination of drag, on the basis of the theory of viscous fluids, have met with but slight success. For this reason, whenever a more accurate knowledge of the drag is desirable, it must be determined by experiment. Here, a few experimental results are given on the drag of a cylinder exposed to a stream of air at right angles to its axis. It is shown that the drag depends on the absolute dimensions of the body and the velocity and viscosity of the fluid in a much more complex manner than has heretofore been supposed

The Aachen Wind-tunnel Balance

A description of the balance in the Aachen wind-tunnel