4. Similarity rules

The flight tests required for aircraft certification in icing conditions are very costly and generally do not allow :

• develop and optimize protection systems;

• cover all icing conditions likely to be encountered during commercial aircraft operations.

Tests are therefore carried out in icing wind tunnels. Since the size of the wind tunnels does not allow 1:1 scale tests to be carried out, reduced-scale models are used, for which it is necessary to define similarity rules (rules enabling the same behavior to be obtained at both scales)