Abstract
Landing gear is now well known to be a major source of aircraft noise. Several studies have also identified the importance of surface details in the noise generated by landing gears at high frequencies. However, the basic mechanisms of noise generation at lower frequencies are less well understood. In this study, we examine the effect of changes to the overall gear layout on the noise produced. 1/12th scale models containing only the wheels, axles and main struts have been studied using two nested, 48-microphone arrays in the closed-section Markham wind tunnel at Cambridge University. Local fairings have also been added to isolate and identify individual noise sources. Results indicate that shape and placement of the wheels can affect the overall noise level by at least 6dB on simplified four wheel models. Changes in geometry were also found to substantially affect high frequency sources close to the main oleo, suggesting that noise sources from conventional, fully dressed gears might be equally susceptible to small changes in the overall design.