 Welcome to this learning object, Angles of Impact. In bloodstain pattern analysis, the angle of impact is the acute angle relative to the plane of the target at which a drop of blood strikes a target. The overall shape of the stain defines the angle of impact. A circular stain indicates an angle that is more perpendicular, such as 80 or 90 degrees. The more elliptical the shape of the stain, the more acute is the angle of impact. As you can see in these images, the higher the angle of impact, the more circular the resulting stain will be. The lower the angle, the more elongated and elliptical the stain will be. When a blood droplet strikes a smooth surface at a 90 degree angle, the resulting stain will be circular. The spines, satellites and scallops will occur in a moderate to even pattern around the stain. There will be very little difference in stain shape for angles of impact between 60 and 90 degrees. When a drop of blood strikes a smooth surface at an 80 degree angle, the stain will be circular as it was with a 90 degree angle of impact. Again, the spines, satellites and scallops will occur moderately and evenly around the stain. Directionality from right to left is only starting to become evident. In the case of a 70 degree angle of impact, the resulting stain will be less circular. The spines, satellites and scallops will again be visible around the stain. Directionality from right to left is increasingly evident. When the angle of impact is 60 degrees, the resulting blood stain begins to elongate. The spines, satellites and scallops will occur more moderately around the stain, focusing on the side opposite the angle of impact. Directionality from right to left is more pronounced. The elongation of a blood stain becomes more apparent when the angle of impact is 50 degrees. The stains, spines, satellites and scallops focus on the side opposite the angle of impact. Directionality from right to left is starting to become more evident. When the angle of impact is 40 degrees, the elongation of the resulting stain becomes even more apparent than it was at 50 degrees. The spines, satellites and scallops will be more visible on the side of the stain opposite the angle of impact. Directionality from right to left is very evident. A blood stain becomes even more elliptical when the angle of impact is 30 degrees. The spines, satellites and scallops continue to focus on the side of the stain opposite the angle of impact. In this elliptical stain, the direction of travel for the satellite spatter often matches that of the parent stain. Directionality from right to left continues to become more evident. A 20 degree angle of impact results in a blood stain that is significantly more elliptical than a stain from a 30 degree angle. The spines, satellites, spatter and scallops will be more visible and will continue to focus on the side opposite the angle of impact. Directionality from right to left is clearly evident. Finally, when a blood droplet strikes a smooth surface at a 10 degree angle, the resulting stain becomes more and more elliptical. The spines, satellites, spatter and scallops occur more and more around the stain, focusing on the side opposite the angle of impact and indicating directionality. Remember, the overall shape of the stain defines the angle of impact. A circular stain indicates an angle that is more perpendicular. When the angle of impact is between 70 and 90 degrees, the stain, spines, scallops and satellites may be evident around the parent stain. Directionality is not clear here and it is important to use caution when trying to determine it. The more elliptical or elongated shape, the more acute the angle of impact is. As the angle of impact decreases, one side of the stain will show greater evidence of spines, scallops and satellites. When the angle of impact is between 40 and 70 degrees, the nature of the outflow of blood is likely to create a number of spines, scallops and satellites spatter that are oriented to one side of the stain. The spines and satellite stains make directionality quite evident. In impact angles that are less than 40 degrees, the resulting stains are much more elliptical. The outflow of blood travels almost exclusively along the leading edge of the collapsing droplet. Such an impact is likely to create a single spine and a satellite stain. In these elliptical stains, the direction of travel for the satellites better often matches that of the parent stain. As you can see in these images, the higher the angle of impact, the more circular the stain. Likewise, the lower the angle, the more elongated and elliptical the resulting stain will be. You have completed this activity. Angles of impact.