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There has been a substantial increase in the number of successful African Americans. However, many students, especially African American males, continue to encounter numerous academic obstacles. This chapter focuses on the factors (e.g., social, academic, personal, and familial) that African American males often have to navigate throughout their PreK-12 schooling. Hindrances, such as poverty, lack of academic readiness, poor school experiences, teacher quality, and peer influences, often negatively impact the academic progress of these students and their access to higher level or gifted instruction. In this chapter, the authors discuss strategies that best counter these factors and support and supplement gifted black boys’ educational experiences. Additionally, educational practice and policy recommendations are provided.

THERE are many aeronautical engineers whose specialised knowledge does not include that of airscrews, and who nevertheless have occasion to make preliminary estimates in which some understanding of the properties of an airscrew is desirable. To these the most important quantities are frequently the diameter and efficiency appropriate to a given set of working conditions, and the static thrust.

In this chapter, we discuss teaching physical education to Black male students in urban schools. We present a brief account of the history and status of physical education and specifically examine school physical education, particularly for Black male students in urban geographical contexts. We also offer strategies to counter the narrative of Black male school failure and present strategies for addressing the needs of urban teachers and Black male students.

FOR the past twenty‐five years inventors and engineers have laboured to design and perfect an airscrew in which pitch change is accomplished automatically by the action of natural forces to which any operating airscrew is subject. Millions of dollars and extensive efforts in this country and abroad have gone into this quest which produced some unusual designs in the past, but has provided aviation today with the practical realization of feasible automatic airscrews. Controllable airscrew designs featuring simple construction and operation have undergone a similar development period. Many factors have influenced this development; such as considerations of cost, mechanical refinement and the state of small aeroplane and engine performance, which in the past would not always have benefited greatly from variable pitch. Today, the advantages automatic and controllable airscrews hold for performance and desirability of the small and medium planes, which are expected to be used widely, warrant thoughtful consideration.

Fig. 2 shows a blade carried by a head of the kind described in Specification. 435,818. The root of the blade comprises a steel tube 32 provided with a fairing 33, Fig. 3, which is a sliding fit over supporting arm 30 and is rotatable to vary the blade pitch. The outer end of tube 32 is secured to blade spar proper 34. The blade is anchored to the hub by a torsionally resilient tie rod 35 screwed at its outer end into spar 34 and secured by a nut and tapered collet device 36. At the inner end rod 35 is secured into arm 30 and secured by a screwed plug and taper pin assembly 37. The blade is of lancet shape and is arranged so that axis B—B of the spar intersects the flapping and drag pivot axes and in the normal mean position of the blade intersects the axis of rotation at the mean centre of oscillation F of the blade pitch control gear. The masses and aerofoil sections of the blade are such that the centres of mass and mean centres of pressure of all the sections lie along axis B—B. The construction of the blade is such that the “ neutral torsional axis,” defined as the locus of points in the chord at which an applied vertical thrust produces equal degrees of flexure of the leading and trailing edges, is at or slightly in front of the axis B—B. In the latter case increase in lift tends to decrease the angle of incidence of the blade as is shown in Fig. 6 wherein C is the centre of pressure, L the lift force, and 0 the neutral torsional axis. In either arrangement aerofoil sections having a stable centre of pressure travel may be employed. In order to bring the neutral axis forward, the nose portion of the blade, in the case of hollow stressed‐skin construction, may be reinforced by additional layers of material or may comprise material having a higher modulus of elasticity than the remainder. In order to compensate the resulting forward movement of the centre of mass, a small amount of non‐structural mass may bo incorporated in the blade. In one form in which the neutral torsional axis is coincident with the B—B axis, the blade comprises a spar and an aerofoil‐shaped fairing of material of the synthetic resin or plastic group of which the modulus of elasticity is so much lower than that of the spar as not to relieve the latter appreciably of its loads. Fig. 7 shows the method of construction of such a blade comprising a steel spar having a moulded fairing. A first mould comprises upper and lower dies 1, 2 and an interposed core 3. Spar 4 is located by pegs 5 and by rows of spaced raised points 6, and is also fluted to key the moulding. Steel wires 8, 9 are strung in the spaces forming the leading and trailing edges. The blade is formed with a solid nose and with internal ribs 10 and webs 11, the latter being produced by slots formed in the upper side of core die 3. After moulding as shown, dies 2 and 3 are removed, pegs 5 cut off, countersunk, and plugged, Fig. 9, and a lower die 13 placed in position and heat applied to unite the lower skin to ribs 10 and to seal the trailing edge. A suitable plastic material is stated to be “ plastic glass.”

Means for securing fabric to a wing or the like comprises a rib or similar member having an up‐right limb a, Fig. 2, of U‐section and horizontal flanges b with downturned ends d, the limb a being traversed at intervals by eyelets such as c, rivets or the like, around which the fabric securing cord/ is passed as shown in Fig. 1 so that the fabric is pulled down partially into the concavity in the virtue of their' nature or construction numerous small perforations or interstices spaced substantially uniformly over the area so as virtually to render the area uniformly porous to air. Perforations or interstices of the order of 420 per square inch are stated to be suitable to give the desired porosity. As shown, an aero‐engine 3 drives a centrifugal blower 5 to suck air through the wing covering, ducts 7, 6 having guide vanes 8, and exhaust it above the fuselage. Passages are formed in the wing beneath the covering and are provided with valves 13 operable together or severally. According to the first Provisional Specification, porous fabric may be stretched over closely perforated sheet‐metal.

The various British Standards for aluminium and aluminium alloy ingots and castings have now been combined into a single schedule, which has just been published as B.S. 1490: 1949, Aluminium and aluminium alloy ingots and castings for general engineering purposes.

THE use of the variable‐pitch airscrew has to‐day become commonplace. Its wide application permits certain facts derived from experience to be postulated and leads to new development problems.