Jack J. Shrager

A review of all literature published since 1964 relating to helicopter vortex systems nd wake turbulence was made. The results of this review are evaluated and summarized, and conclusions are drawn relative to that review. The documents are grouped in general catergories, and this is further supplemented by an annotated bibliography and authors index. Also incorporated in the review is a comparative analysis of rotary-wing versus fixed-wing circulation intensity time-history.

Consumer Product Safety Commission

The purpose of this notice is to promulgate the Standard for the flammability of Children's Sleepwear.

D.A. Kourtides, J.A. Parker, C.L. Segal

Aromatic polybenzimidazole (PBI) foams in the density range of 24-80 kg/m3 produced by controlled thermal cross linking of the prepolymer have been developed and shown to have excellent thermophysocal properties, fire resistance and low smoke evolution when exposed to heat or flame; they also retain their mechanical properties up to 473 degree K without any significant degradation. In addition to superior thermal properties, these foams maintain a high degree of flexibility, a good modulus to weight ratio as well as a high strength to weight relationship. Consequently, these combinations of excellent thermal and mechanical properties make this foam an attractive candidate for aircraft fire barriers and space shuttle thermal insulation where the combination of low weight and high temperature insulation is critical.

This paper describes the relationship between prepolymer purity, processing parameters and additives to the thermophysical properties of these foams. Studies included the addition of surefactants and fibers and variations in the cure and postcure schedules. It was determined that foam properties were effected by differences in prepolymer purity, curing schedule and the presence of solid additives in the foam. A direct relationship between the amount of fiber, additive and resultant foam density was established. High temperature compressive performance was improved by postcuriing at 800 degree K. Surfactant additives were found to improve the uniformity of cell size. Foams were characterized as to their ambient and high temperature compressive strength and modulus, density, porosity, thermal conductivity and efficiency and other thermal properties.

Studies were conducted to determine the effect of prepolymer purity on foam properties with the aim of utilizing low cost prepolymers to produce these foams. It was concluded that foams made from prepolymer having an ortho-diamine purity of 95% had approximately the same properties as foams made from higher purity and cost prepolymer.

Stephen L. Imbrogno, Thomas Rust, Jr

Engine-core exhaust emissions were measured on a low-time JT8D-11 strength in both high-smoke and low-smoke configurations. Changing from the high-smoke to the low-smoke configuration considerably reduced the visible smoke, 55 to 90 percent, as measured using the Society of Automotive Engineers (SAE) smoke numbers. Carbon monoxide was reduced by up to 40 percent. Total unburned hydrocarbons were reduced by 40 percent at idle power, while the production of oxides of nitrogen was increased by 60 percent at the high power setting. These percentages are absolute with no consideration for time in mode, according to the Environmental Protection Agency (EPA) landing/takeoff cycle.

T.Z. Harmathy

Fire safety as provided for by present building codes is examined critically and the characteristics of building fires are reviewed. A new design approach is suggested.