Accession Number:



Study to Extend the Low Frequency Test Capability in the Main Chamber of the AFFDL Sonic Fatigue Facility.

Descriptive Note:

Final rept. Dec 69-Jan 71,

Corporate Author:


Report Date:


Pagination or Media Count:



The Horn Extension System will extend the frequency range of the siren bank in the Main Chamber of the AFFDL Sonic Fatigue Facility to 20 Hertz. Specifications for system design were developed based on a thorough acoustic, structural, and operational analysis. The entire system is constructed of aluminum. It is designed for infinite fatigue life at the full correlated siren power output of one megawatt. A Horn Extension Network, a Progressive Wave Test Section, and a Horn Termination comprise the system. The Horn Extension Network consists of 25 similar sections that form transitions from the annular cross section of a siren outlet to rectangles 125th the cross section of the Progressive Wave Test Section. Each transition section consists of three subsections. Two are castings and the third is a weldment. Three 6 x 12 x 5 foot long rectangular sections make up the Progressive Wave Test Section. These sections are made of aluminum sand-filled sandwich. The Horn Termination is similar construction. The system is made in sections to be bolted together. Maximum weight per section is 7500 pounds. All sections can be readily handled by a forklift. This report describes a low frequency horn extension system that was designed and developed for specific application in the Main Test Chamber of the AFFDL Sonic Fatigue Facility. However, much of the analytical content could be applied by acoustical engineers to general horn design studies of similar scope. From a structural standpoint the design was intended to withstand sound pressure levels normally encountered only in special high intensity acoustic test facilities.

Subject Categories:

  • Test Facilities, Equipment and Methods
  • Acoustics
  • Mechanics

Distribution Statement: