A hush house is an enclosed, noise-suppressed facility used for testing

aircraft An aircraft is a vehicle that is able to fly by gaining support from the air. It 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 ...

systems, including

propulsion Propulsion is the generation of force by any combination of pushing or pulling to modify the translational motion of an object, which is typically a rigid body (or an articulated rigid body) but may also concern a fluid. The term is derived from ...

mechanics Mechanics (from Ancient Greek: μηχανική, ''mēkhanikḗ'', "of machines") is the area of mathematics and physics concerned with the relationships between force, matter, and motion among physical objects. Forces applied to objects r ...

electronics The field of electronics is a branch of physics and electrical engineering that deals with the emission, behaviour and effects of electrons using electronic devices. Electronics uses active devices to control electron flow by amplification ...

pneumatics Pneumatics (from Greek ‘wind, breath’) is a branch of engineering that makes use of gas or pressurized air. Pneumatic systems used in industry are commonly powered by compressed air or compressed inert gases. A centrally located and elec ...

, and others. Installed or uninstalled

jet engines A jet engine is a type of reaction engine discharging a fast-moving jet of heated gas (usually air) that generates thrust by jet propulsion. While this broad definition can include rocket, water jet, and hybrid propulsion, the term typicall ...

can be run under actual load conditions.

Testing

A hush house is large enough to accommodate an entire manned or unmanned aircraft. Some facilities are also equipped to test additional capabilities such as weight and balance, night vision and low lighting, water intrusion, heat soaking, and wind evaluation. Jet engines can be run while installed in the aircraft, which must be restrained by holdback devices to resist the engine thrust. Uninstalled engines (without the aircraft) can be tested while held in place by thrust frames. The air intake and exhaust systems of indoor engine test cells and hush houses are designed to block the transmission of noise, while optimizing the engine air flows. The engine exhaust, after having been thoroughly mixed with cooling air, is generally discharged through a vertical stack. The gas path incorporates acoustic damping panels (often containing fibrous insulation protected from gas stream erosion by metal mesh) to reduce the sound energy of the gas stream and attenuate the noise transmitted to the surrounding outdoor area. Because the engine exhaust flow is "augmented" with a relatively large flow of cooling air induced by a

Venturi effect The Venturi effect is the reduction in fluid pressure that results when a fluid flows through a constricted section (or choke) of a pipe. The Venturi effect is named after its discoverer, the 18th century Italian physicist, Giovanni Battista V ...

into the exhaust silencing system, the exhaust muffler of an indoor test facility is generally referred to as an augmenter tube, although the term "detuner" is commonly used in the UK. Some outdoor run-up facilities used to test aircraft engines (installed or uninstalled) may also be outfitted with noise control structures, called Ground Run-Up Enclosures.

Examples

Marine Corps Air Station Miramar Marine Corps Air Station Miramar (MCAS Miramar) , formerly Naval Auxiliary Air Station (NAAS) Miramar and Naval Air Station (NAS) Miramar, is a United States Marine Corps installation that is home to the 3rd Marine Aircraft Wing, which is the av ...

San Diego San Diego ( , ; ) is a city on the Pacific Ocean coast of Southern California located immediately adjacent to the Mexico–United States border. With a 2020 population of 1,386,932, it is the List of United States cities by population, eigh ...

California *

Marine Corps Air Station Iwakuni is a United States Marine Corps air station located in the Nishiki river delta, southeast of Iwakuni Station in the city of Iwakuni, Yamaguchi Prefecture, Japan. History The Japanese government bought a large portion of what is today MCAS I ...

Japan Japan ( ja, 日本, or , and formally , ''Nihonkoku'') is an island country in East Asia. It is situated in the northwest Pacific Ocean, and is bordered on the west by the Sea of Japan, while extending from the Sea of Okhotsk in the north ...

Naval Air Station Jacksonville Naval Air Station Jacksonville (NAS Jacksonville) is a large naval air station located approximately eight miles (13 km) south of the central business district of Jacksonville, Florida, United States., effective 2007-10-25 Location NAS Jack ...

Jacksonville, Florida Jacksonville is a city located on the Atlantic coast of northeast Florida, the most populous city proper in the state and is the largest city by area in the contiguous United States as of 2020. It is the seat of Duval County, with which the ...

Naval Air Station Joint Reserve Base Fort Worth Naval Air Station Joint Reserve Base Fort Worth (abbreviated NAS JRB Fort Worth) includes Carswell Field, a military airbase located west of the central business district of Fort Worth, in Tarrant County, Texas, United States. This military a ...

Fort Worth, Texas Fort Worth is the fifth-largest city in the U.S. state of Texas and the 13th-largest city in the United States. It is the county seat of Tarrant County, covering nearly into four other counties: Denton, Johnson, Parker, and Wise. According ...

Naval Air Station Oceana Naval Air Station (NAS) Oceana or NAS Oceana is a United States Navy Naval Air Station located in Virginia Beach, Virginia. Nowadays, the station is located on 23.9 km2. It has total of 250 aircraft deployed and buildings valued at $800 mil ...

Virginia Beach, Virginia Virginia Beach is an independent city located on the southeastern coast of the Commonwealth of Virginia in the United States. The population was 459,470 at the 2020 census. Although mostly suburban in character, it is the most populous city ...

Naval Air Station Patuxent River Naval Air Station Patuxent River , also known as NAS Pax River, is a United States naval air station located in St. Mary’s County, Maryland, on the Chesapeake Bay near the mouth of the Patuxent River. It is home to Headquarters, Naval Air Sys ...

Maryland Maryland ( ) is a state in the Mid-Atlantic region of the United States. It shares borders with Virginia, West Virginia, and the District of Columbia to its south and west; Pennsylvania to its north; and Delaware and the Atlantic Ocean to ...

References

{{reflist Aircraft noise reduction Aviation infrastructure