Hush kit
Hush Kit is the name of a retrofittable device for soundproofing older turbofan engines that only have a low bypass ratio.
principle
The main source of noise from these engines is usually the sharp separation of the fast hot gases from the core engine from the environment. In the attached jacket, the hot gas is mixed with the outside air by means of a special device, thus reducing the sharp differences in speed.
Modern turbofan engines meet the noise regulations much more easily, since the higher bypass flow component, which has a lower speed than the gas flow of the core engine, envelops the hot gases in such a way that the noise is significantly reduced.
Since April 1, 2002, civil jet aircraft types throughout the EU have only been granted take-off and landing permits if the aircraft type in question can prove that it has been approved for noise in accordance with Chapter 3 of the ICAO regulations "Annex 16". According to this, jet aircraft that were registered before 1977 (aircraft according to Chapter 2) no longer have take-off and landing permits in the EU. However, it is possible for some aircraft types to meet the conditions for Chapter 3 by retrofitting a hush kit. However, this condition is bought at the cost of a loss of engine power.
Affected by these regulations and retrofittable with Hush Kits are, for example, the Boeing 727 and the Boeing 737-200 with JT8D engines from Pratt & Whitney or the Tupolew Tu-154 .
See also
Web links
Individual evidence
- ↑ Regulation using the example of Frankfurt Airport ( Memento of the original dated December 22, 2010 in the Internet Archive ) Info: The archive link was inserted automatically and has not yet been checked. Please check the original and archive link according to the instructions and then remove this notice.
