Design study for noise tests on laminar flow fin

Abstract

The study deals mainly with engineering problems associated with the introduction of a noise generating facility on 'Lincoln' aircraft R.F.342 for the purpose of studying the effect of high intensity sound pressure levels at both random and discrete frequencies on the laminar flow fin currently being tested in this aircraft. The frequencies selected as representative of both turbulent boundary layer and propulsion system disturbances lie within the band. 200 to 2000 c.p.s. with an upper limit of 1200 c.p.s. for discrete work. Required sound pressure level at the fin surface is estimated to be 130 db. Conclusions are that the project is feasible but with the reservation that certain estimated figures and effects will require to be confirmed by a test programme prior to mounting the full-scale experiment.