Data Acquisition System for a Handgun Dynamometer
Abstract In the fields of competition shooting and handgun engineering, it is highly desirable to be able to properly assess and measure handgun recoil. If recoil could be measured, it would be useful to the competition shooter in his continuous quest to evaluate modifications for his equipment and methods. The engineer would benefit since the results of measured testing would quantify the reaction forces present allowing proper stress analysis and the ability to calibrate FEA models. The objective of this project was to design and develop a device capable of measuring recoil forces on multiple independent axes. The device will respond and measure only on the axis the load is applied to. It was determined that the most cost effective way to meet the design specifications was to utilize strain gage based transducer technology. A custom multiple axes Dynamometer was designed, fabricated and interfaced with the Smith & Wesson CATS (Computer Aided Testing System) data collection system. The system was calibrated and tested with a model 4013TSW pistol and the results were graphed. The results showed peak values of 950 lb. for the horizontal recoil force, 125 ft-lb. for the recoil moment, and 24 ft-lb. for the rifling torque. Taking factors into consideration, these values are close to the expected values. The Dynamometer exhibited ringing at about 310 Hz. due to its natural frequency and required filtering to properly observe the load profile. When low-pass filtered at 100 Hz., the load profile stood out, but the amplitude was attenuated. The net result was that peak values were observed in the standard data, while the load profile and gun signature could be identified in the filtered data. The device was found to be useful for qualitative analysis, but was deemed inadequate for impact and high frequency applications. The Dynamometer could be improved with efforts made to raise the natural frequency and advanced filtering techniques.