Droplets of pig's blood were dropped onto paper at different angles to the horizontal to produce blood stains. Impact velocities varied from 1.82 to 5.76 m/sec, drop size from 3.7 to 5.0 mm in diameter, and the surface sloped at angles between 22.7 degrees and 90 degrees to the horizontal. From the data a single equation relating stain size to drop size and velocity for all impact angles was produced; ab = 111.74 (Re(1/2)We(1/4))(0.75)D(o)D(o) + 0.00084 with R(2) = 0.88, where a is the stain width, b the stain length, Re the Reynolds number, and We the Weber number. A second equation related the number of spines, N, to drop size, velocity, and surface slope for all impact angles as N = 0.76 We(0.5) sin(3)theta with R(2) = 0.9, where theta is the impact angle. Combining these equations the impact velocity can be determined and hence the position of the stain's source.

Trinitrotoluene (TNT) equivalency depends on knowing the relative strength of different explosives compared to TNT. However, most past work has been carried out only using spherical charges, whereas most military ammunition is cylindrical in shape. It is known that in certain directions, cylindrical charges give an enhanced blast close in when compared to that of spherical charges. This paper examines data for cylindrical explosive charges from the literature for Composition B and pentolite and then describes experimental work carried out on cylindrical PE4 charges. Analysis of the free air experimental and literature data shows that close into the curved side of a cylindrical charge it is possible to predict the peak pressure using an equation of the form Peak pressure = K mass/distance 3 , where K is an explosive dependent constant; 2695 Pa m 3 kg À1 for Composition B, 2498 Pa m 3 kg À1 for pentolite and 2565 Pa m 3 kg À1 for PE4, for length to diameter ratios of between 2 : 1 and 10 : 1. For a scaled distance (distance/mass 1/3 ) of less than 3.5 m kg À1/3 , the results are very accurate. This means that, provided data for cylindrical charges of TNT is obtained, a simple method of determining the TNT equivalency of a cylindrical charge, perpendicular to the curved surface is given by TNT equivalence = K explosive /K TNT . For a more accurate prediction at a scaled distance of greater than 3.5 m kg À1/3 a cubic equation of the form Peak pressure = K 1 Z À3 + K 2 Z À2 + K 3 Z À1 has been found to apply where Z = distance/mass 1/3 and the coefficients K 1 , K 2 and K 3 depend on the explosive type.

This paper discusses the effects of thickness, mass per unit area, sett, yarn linear density and twist of calico fabrics (100% cotton, plain woven) on the morphology of passive bloodstains. Horse blood was dropped vertically onto three calico fabrics with different mass per unit areas (85.1 g/m², 163.5 g/m² and 224.6 g/m²). Six different impact velocities were used (1.7 ms-1 , 2.9 ms-1 , 4.1 ms-1 , 4.9 ms-1 , 5.1 ms-1 and 5.4 ms-1). The dry bloodstains were largest on the calico with the lightest mass per unit area. The low yarn linear density and large inter-yarn spaces meant that the blood could wick into the yarns from all directions and along the intra-yarn spaces. The calico with the middle mass per unit area had the smallest mean dry bloodstain area for four out of the six velocities. The twist level for this calico was greater than for the calicos with a heavier or lighter mass per unit area. This reduced the amount of wicking which occurred along the yarns due to the tighter yarn structure. The calico with the heaviest mass per unit area had the highest yarn linear density resulting in a thicker fabric, so the blood could not as easily penetrate into the fabric. This resulted in a thicker wet blood layer remaining on the fabric surface, where it gradually wicked vertically into the yarns under gravity. Less wicking along the yarns occurred, resulting in a smaller bloodstain than on the fabric with the lightest mass per unit area. The correlation between impact velocity and mean dry bloodstain area was greater for the calicos with the medium and heaviest mass per unit area than for the calico with the

peak overpressure and impulse exceeded that of the primary shock wave for scaled distances, Z = R/M 1/3 ! 3.9 m kg À1/3 , where M is the mass in kg and R the distance from the charge in m. It was found possible to predict the primary peak overpressure, P, at all distances in the axial direction, for a constant length to diameter ratio, using P = 3075 Z À3 À1732 Z À2 + 305 Z À1 . Close in the primary peak overpressure is proportional to M/R 3 in the axial direction. It was not possible to predict the secondary peak overpressure with the data obtained. The total impulse from both shock waves, I, in the axial direction can be predicted using I = 746(M 2/3 /R) 3 À708(M 2/3 /R) 2 + 306(M 2/3 /R).