DETERMINATION OF AERODYNAMIC DRAG PARAMETERS OF SMALL IRREGULAR OBJECTS BY MEANS OF DROP TESTS

Drag coefficients were determined for various irregular objects such as glass fragments, stones, steel fragments, and spheres by means of drop tests for use in a mathematical model to correlate nuclear explosion blast experiments. Drop tests were also made on small laboratory animals and extrapolated to estimate the drag properties of man. A method was developed to estimate the average drag properties of man from his total surface area. (D.L.C.

A STUDY OF THE TISSUE RESPONSE TO STERILE DEPOSITS OF PARTICULATE MATERIAL

Thirty-seven sterile materials of common construction usage, common lubricants, and samples of wearing apparel were injected as finely divided particles into the subcutaneous soft tissues of guinea pigs, each in six different sites. At intervals of 3, 7, 14, 21, 30, 65, or 90 days, an inoculation site of each material was excised, in toto, fixed, and examined microscopically. In addition, ten selected materials were injected into the liver and spleen and deposited on the omentum and mesentery of four guinea pigs for each material type. At intervals of 7, 14, 21, and 30 days, one of each group of four animals was sacrificed and a block of tissue containing the inoculum was removed from the tissues and organs, fixed, and examined histologically. The majority of materials induced only a mild and delayed inflammatory response followed by encapsulation at the end of 14 days and a relatively inert fibrous nodule produced by the 2lst or 30th day. Copper particles incited a marked inflammatory response with abscess formation which persisted until the 90th day, although showing signs of subsiding at this time. Cudmium lesions were characterized by a peculiar zone of necrosis about the particle aggregate which persisted until the 60th day. Duraluminum of one type incited a pseudoneoplastic fibrous response. Axle grease, in the early stages, induced one of the most intense acute inflummations, in contrast to that produced by motor oil and ordinary lubricating grease, but the process had subsided and was fibrosed by the end of 30 days. (auth

THE OVERPRESSURE-DURATION RELATIONSHIP AND LETHALITY IN SMALL ANIMALS. Technical Progress Report

A total of 993 mice, rats, guinea pigs, and rabbits were exposed to sharp-rising overpressures of various short durations. They were mounted on a concrete pad above which high-explosive charges, ranging in weight from 0.50 oz to 64 lbs, were detonated. Pressure-time measurements were obtained with pencil- type and shock-tube piezo-electric gauges on the pad directly beneath the charges. The duration of the blast waves ranged from 0.40 to 6.8 msec. The LD/sub 50/ pressures were calculated for each species at the different pulse durations. In general, the pressures required to produce 50% lethality rose at the shorter durations. Combining the results of this study with those from previous shock- tube investigations made it possible to define the tolerance of four small-animal species to sharply rising overpressures as a function of pulse duration. (auth

MORTALITY IN SMALL ANIMALS EXPOSED IN A SHOCK TUBE TO "SHARP"-RISING OVERPRESSURES OF 3-4 MSEC DURATION. Technical Progress Report

A total of 661 animals was exposed to sharp''-rising overpressures of 3 to 4 msec duration using a shock tube of novel design which produced a pressure pulse similar to that obtained with high explosives. The reflected shock overpressures associated with 50% lethality were 29.0, rabbit, respectively. Other observations included the time of death in mortally wounded animals and gross pathological lesions likely to contribute to mortality. Selected data from the literature bearing upon the influence of overpressure and pulse duration on lethality were reviewed. These included pulse durations ranging from less than 1 msec to 8 sec. The critical pulse duration, that duration shorter than which the overpressures required for mortality increases sharply, was noted to depend upon animal size and to be of the order of many hundreds of microseconds to very few milliseconds for smaller'' animals and a few to many tens of milliseconds for larger'' animals. (auth

BLAST BIOLOGY--A STUDY OF THE PRIMARY AND TERTIARY EFFECTS OF BLAST IN OPEN UNDERGROUND PROTECTIVE SHELTERS

Dogs, pigs, rabbits, guinea pigs, and mice were exposed to nuclear detonatiors in two open underground pantitioned shelters. The shelters were of similar constructions and each was exposed to separate detonations. Each inner chamber filled through its own orifice; thus four separate pressure enviromments were obtained. An aerodynamic mound was placed over the escape hatch of each structure to determine its effect on the pressurecurve shape inside the chamber. In one test a sieve plate bolted across the top of the mound was evaluated. Wind protective baffles of solid plate and of heavy wire screen were installed in the shelters to compare primary and tertiary blast effects on dogs. The shelters also contained static and dynamic pressure gages, radiation detectors, telemetering devices, and, in one test, air-temperature measuring instruments, dustcollecting trays, and eight pigs for the biological assessment of thermal effects. One dog was severely injured from tertiary blast effects associated with a maximal dynamic pressure (Q) of 10.5 psi, and one was undamaged with a maximal Q of 2 psi. Primary blast effects resulting from peak overpressures of 30.3, 25.5, 9.5. and 4.1 psi were minimal. The mortality was 19 per cent of the mice exposed to a peak pressure of 30.3 psi and 5 and 3 per cent of the guinea pigs and mice exposed to a peak pressure of 25.5 psi. Many of the rabbits, guinea pigs, and mice sustained slight lung hemorrhages at maximum pressures of 25.5 and 30.3 psi. Eardrum perforation data for all species, except mice, were recorded. Following shot 2, thermal effects were noted. Animals of the groups saved for observation have died from ionizing-radiation effects. (auth