Ian Smith, a design engineer at Flymo, demonstrates the principal components in a hover lawnmower and explains how they work. We see how airflow is created to allow the mower to hover over the grass, and how the design means the grass cuttings are at the same time sucked into a grass box. We also see a safety test which the mower must pass.
The class could discuss the necessary properties of each lawnmower component, such as the blade (resistance to brittle fracture), the grass basket (light weight, low cost to form), and the impeller (stiffness/rigidity, uniform weight distribution, ease of manufacture). They should explain why the selected materials are a better choice for each component than possible alternatives.