From Frank Fahy, Institute of Sound and Vibration Research
In the article “The shape of wings to come” Paul Marks gives the impression that the so-called “airframe noise” generated by aircraft landing in a “dirty” configuration (high-lift surfaces deployed and landing gear down) is caused by vibration of the structure (13 December 2003, p 28). But the vibrating structure radiates a negligible amount of sound compared with noise from the interaction between turbulent flow and the surface of the structure – especially thin trailing edges and corners of flaps. The noise would occur even if the structure were totally rigid, as one can demonstrate by blowing strongly across the edge of a thin plate, or even a fingertip.
Southampton, UK
