Initiated by the RLM (Reichsluftfahrministerium – Reich Aviation Ministry), the Mü18 "Meßkrähe" was an experimental flying wind-tunnel used to research aerofoil sections in undisturbed airflow.
The Krueger flaps developed for the Boeing 747 were constructed from fiberglass honeycomb material and were designed to be intentionally distorted into an aerofoil section on deployment.