Cost-effective optoelectronic system to measure the projectile velocity in high-velocity impact testing of aircraft and spacecraft structural elements

Abstract

We present a microcontrolled optoelectronic system to measure online the average velocity of a projectile impacting on aircraft and spacecraft structures. The projectile velocity can vary in the range from subsonic to supersonic. The implemented optical system is based on three optical barriers that are crossed by the projectiles before impacting on the structural elements. A simple optoelectronic prototype is constructed and tested. The flight times among the three optical barriers are obtained by the microcontroller system. The measured velocity accuracy in test conditions is better than 1%. A high-brightness liquid crystal display is used to show messages of the system configuration and also the measured projectile velocity. To ensure safety in the experimental impact tests, serial RS-232 communication can be used to monitor this information using a remote computer. The system is highly robust since it is able to measure projectile velocity even when an optical barrier is missed by failure in either the optical transmitter or the receptor.