Hush house
Encyclopedia
Aircraft
An aircraft is a vehicle that is able to fly by gaining support from the air, or, in general, the atmosphere of a planet. An aircraft counters the force of gravity by using either static lift or by using the dynamic lift of an airfoil, or in a few cases the downward thrust from jet engines.Although...
jet engine
Jet engine
A jet engine is a reaction engine that discharges a fast moving jet to generate thrust by jet propulsion and in accordance with Newton's laws of motion. This broad definition of jet engines includes turbojets, turbofans, rockets, ramjets, pulse jets...
testing facility for the testing of installed or uninstalled jet engines under actual load conditions.
Jet engines and aircraft can be tested either indoors or outdoors.
- Indoor engine test cells are facilities designed for testing engines removed from an aircraft (referred to as "uninstalled engines"). The engines in such facilities are generally suspended from overhead thrust frames.
- A hush house is wide enough to accommodate an entire aircraft so that the engine can be run while installed in the aircraft. Uninstalled engines secured to thrust frames can also be tested in most hush houses.
- The air intake and exhaust systems of indoor test cells and hush houses are designed to optimize the engine air flows, and to discharge the cooled jet exhaust through a vertical stack. The intake and exhaust systems have silencers to reduce noise transmitted to the surrounding outdoor area.
- Outdoor run-up areas are facilities where engines are tested outdoors while mounted on thrust stands, or where engines are tested outdoors while installed in an aircraft. They may, or may not, include provisions for noise control. The photograph shows a type of outdoor test facility called a "run-up pen" that is surrounded by a barrier to reduce noise in the surrounding area. While such facilities are much louder than enclosed, indoor hush houses, they are the only practical noise suppression option for run-up testing of larger multi-engine aircraft such as airliners.