Design and Development of a Novel Launch System with Energetic Materials for Unstable Free-Flight Testing

Abstract

Characterizing the behavior of highly unstable bodies in flight presents a variety of engineering challenges. Free-flight testing with scale models provides an efficient and economical solution to this problem. This test method requires a means of launching the test model, undamaged, at the desired velocity. The objective of this research was to develop a launch system which incorporates the use of energetic materials for free-flight testing of a model flight vehicle of predetermined mass and dimensions. A high-low pressure gun system was selected for the launcher design, as this system is capable of launching relatively high masses in the velocity range of interest while retaining the necessary reliability and repeatability for useful free-flight testing. This research effort covers the entire process of the design, development, and construction of a novel launch system that makes use of energetic materials for the launch propellant. The energetic material used in this research was double-base smokeless propellant. An analysis of the selected propellant was conducted to determine the relevant physical and chemical properties. These were used in the development of an internal ballistics model created in MATLAB. The purposes of this model were to inform the launcher design process and make predictive velocity estimates for future work. Propellant cartridges specific to this research and procedures for their production were developed and tested. High-speed cameras were utilized for the acquisition of velocity data and also proved useful in observing the dynamics of the launch event during iterations of the launcher design process. The launch system’s potential for use with other data acquisition methods were also investigated. These included infrared motion capture cameras and an in-chamber pressure transducer. The series of test launches conducted with the completed launcher achieved the required velocity for the given mass of the flight model and resulted in a mean velocity within 0.16 m/s of the target velocity with a standard deviation of 1.77 m/s. Further refinement of the internal ballistics model with data from other acquisition systems could provide increased predictive capability, leading to a more efficient response to changes in the mass and required velocity of the flight vehicle model.