It provides a means to measure and display the lift or drag on a set of models consisting of two different sized cylinders and a hydrofoil. The balance assembly is an articulated parallelogram, linked to a load cell. The parallelogram resists bending moments so that only the force on the model is transmitted to the load cell. The balance assembly is mounted on a carrier that runs along the rails of the Flume. The display unit displays the force measured by the load cell. This unit is hung on the flume.