The laboratory instruments, which we often constructed with makeshift means, gave encouraging results and showed that they could satisfactorily meet the required conditions. By limiting ourselves to the employment of hot wires of 0.05 mm (0.002 in.) diameter, we obtained instruments which faithfully followed all the wind fluctuations of over 0.1 second and even much more rapid variations without any very great error.Nearly all airplane and engine constructors have experimented with devices for diminishing the noise of engines. Various types of silencers ( Schneebeli, Ad Astra, Skribechk, etc.) ... Fig. l gives the sound diagram for an automobile engine.
|Title||:||NACA TM 264|
|Author||:||E. Huguenard, A. Magnan, A. Planiol, United States. National Advisory Committee for Aeronautics|