ONERA micronewton thrust balance: Analytical modelling and parametric analysis

A mechanical model that describes the behavior and performance of the ONERA micronewton thrust balance is presented. The balance is based on the pendulum principle and it makes use of capacitive and accelerometric sensors in order to detect the thrust. The model makes it possible to understand the influence of the different parameters on the balance performance. Consequently, it is possible to optimize the performance of the current version of the balance, and to lead the design of future versions. The assumptions of the model are confirmed by the agreement between its predictions and the experimental data. This analytical noise-modelling approach is not specific to the ONERA balance and it may be of significant interest for the micropropulsion community because it leads to the individuation of the noise limits of the instrument and it shows the possibilities of improvement.