Abstract: The impact angle of a small caliber projectile is determined by accurately measuring the orientation angle of the projectile in flight and modeling epicyclical flight of the projectile. To measure the orientation angle, a projectile is fired along a trajectory within a test gantry. One or more sets of cameras captures images of the projectile in flight. The images are processed using computer vision to measure the position and orientation angle at each station. Calibration of the test equipment prior to the test firing of the projectile, allows for determination of these points in the 3d space of the test fixture. Aeroballistic models are fit to the orientation history. From these models, an impact angle is extrapolated.

Abstract: A try square with a blade extending perpendicularly from the stock and a pivotal tab housed at the end of the stock opposite the blade, the purpose of the tab being to lie within the stock when the square is put against surfaces to check if they lie at 90° and to project from the stock and lie coplanar with the blade during scribing. The projecting tab supports the stock during this operation.