Hush House
Hush houses – like the one above – are enclosed, noise-suppressing facilities used to test fighter jet engines. Should a fire occur, eight tanks release the chemical Halon to put it out. Efforts have now been finalized to use a new agent known as Novec. The move will have a considerable impact toward personnel safety and the environment, and will be cost-effective and save time. (U. S. Air Force photo/ Sue Sapp)