Desenvolvimento de bancada de testes estáticos para motores-foguete

Abstract

This study addresses the development of a low-cost static test bench for obtaining the thrust curve of rocket engines. The project consists of a static test table prototype, which is basically composed of an ESP8266 microcontroller (Wemos D1 mini development board), a 100 kg load cell, an HX711 converter and a micro-SD adapter. The load cell produces a small electrical signal proportional to the force applied to it. The HX711 chip, in turn, amplifies the signal, which is read by the microcontroller. The microcontroller then records the data on the micro-SD card for later analysis. The data reading frequency and reading resolution obtained with this equipment are, respectively, 90 Hz and 0.04 N. An object of known weight was used to calibrate the bench. Then, two validation tests were carried out. The first test used several objects of known weight that were compared with measurements obtained by the static test table. The biggest difference between the results was 0.03 N. The second test consisted of burning three rocket motors, resulting in the reading of the thrust curve of each one. This test demonstrated that the equipment operates as designed. The difference of the project is the search for an affordable and simple solution allowing its application in different locations, including places without access to the electricity grid, as it can operate on a battery. The project also aims to increase safety in static tests and promote safe practices in experimentation with rocket models.