Will JetBlue’s Vortex Generator noise reduction be heard?

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JetBlue retrofitting planes with vortex generators

Press Release not specific as the Noise Reduction

Community Groups Point to Significant Lower Decibels

Lufthansa not as Aggressive

As with many press statements, what is said is frequently less important than what is unsaid.  JetBlue announces that it is spending “less than $1million” on technology that will reduce noise on landings. That’s a message which will please the communities who live under the aircraft landing patterns near airport.

What is unsaid is the specific noise reduction, usually measured in a metric called “decibels.” That number likely would be of interest to the stockholders and the financial world. An investment of $1,000,000 should have some return in revenue or some soft benefit. Lowering of the noise generated by JetBlue’s aircraft may create good will among those residents in these impact areas.

ANAC, an airport noise group concerned about noise from Logan Airport in Boston, Massachusetts, is an advocate of a requirement that all airplanes serving BOS must be retrofitted with vortex generators. A320Whine, a website (not clear who the sponsor may be) makes the following assertions:

Airbus’s A320 family of aircraft, the A318, A319 A320 and A321, makes an annoying wailing noise while on arrival to airports. This unpleasant noise, known as the Airbus or A320 whine, occurs between 7- 30 miles from landing before lowering flaps or landing gear. The noise is caused by air passing over circular vent holes under the wing, similar to wind blowing over a bottle– just on a much larger scale. These annoying wailing tones can be heard on the ground and add an extra 2-11dB of noise to the plane, above the sound of the engines.

The A320 whine can be eliminated by mounting a small air deflector, a vortex generator, upstream of the 2 vents on each wing. The vortex generator was developed by Lufthansa and German Aerospace Centre(DLR) after research of many years. Airbus sells these as a retrofit and calls them “FOPP ( Fuel Tank Over Pressure equalization Ports) air deflectors.”

Lufthansa, Europe’s second largest carrier, retrofitted 157 of their A320 family aircraft with the vortex generators, and required it on all new deliveries since February 2014. Air France made an early commitment similar to Lufthansa. After public pressure in the UK, British Airways and easyJet have committed to timeline for installing the modification on their A320 family fleets by June of 2016.

*NEW*United Airlines is the first US Carrier that committed to installing the fix. Installation of the Vortex Generators will begin in 2017.

US Airlines and number of A320 aircraft in fleet

 

A319

A320

A321

Total

A320’s
% of fleet

With VG

Total US majors

316

487

244

1047

97

Allegiant

11

16

0

27

34%

12

American

125

54

187

366

38%

unk

Delta

57

69

5

131

16%

5

Frontier

28

24

10

62

100%

14

Jet Blue

0

130

29

159

72%

24

Spirit

29

45

13

87

100%

33

United

56

97

153

21%

0

Virgin

10

52

0

62

100%

9

US airline A320 fleet mix -updated 07/2016
Source: http://www.airfleets.net

Average of 6dB of “Extra“ Noise

The airbus whine is perceived on the ground up to 30 miles away from the runway. A simple upgrade can eliminate the whine up to 9dB.

All Airbus A320’s made after 2014 have the A320 whine “fix” installed as standard equipment.  To retrofit the Airbus FOPP air deflectors takes 2 people a total of 10 man hours. The modification can be installed during routine aircraft maintenance but for safety reasons the wing’s fuel tanks will need to be partially defueled, which occurs when the plane undergoes a more rigorous maintenance.  The air deflectors are installed in front of the (2) Fuel Over Pressure Protector (FOPP) cavities on each wing and involves the removal and re-installation of the FOPPs. Some quoted estimates in the US are between $3-5k per plane for hardware and labor. European carriers who have performed the retrofit report total price can be $10-20k per plane. A new A320 costs $97 Million.

Lufthansa, cited by Whine as the developer of the vortex generator, has its own statement of the benefits of its retrofit on its website :

“At the beginning of 2014, Lufthansa was the first airline worldwide to start operations with an Airbus A320 equipped with noise-reducing vortex generators, thus setting an industry standard. Aircraft with vortex generators are up to 4 decibels quieter during the approach phase. In the meantime, the Group has retrofitted all aircraft of the A320 family operated by Lufthansa and SWISS with these vortex generators. The retrofit of Austrian Airlines’ A320 family is expected to be completed in 2019.

Overfly measurements revealed that the vortex generators are able to eliminate two unpleasant tones and thereby lower the aircraft’s total noise level on approach by up to four decibels at distances between 17 and 10 kilometers from the runway. Thus the Lufthansa Group has realized a key objective of the “Alliance for More Noise Protection”, a joint initiative of the Lufthansa Group, Fraport, the airline association BARIG, DFS, the Airport and Region Forum (FFR), and the government of the State of Hesse.

Retrofitting the existing fleet

The Lufthansa Group is also retrofitting older aircraft in its fleet with noise-reducing technologies. In this connection the Group is working closely with the German Aerospace Center (DLR) and the various aircraft manufacturers.

At the beginning of 2014, Lufthansa was the first airline worldwide to start operations with an Airbus A320 equipped with noise-reducing vortex generators, thus setting an industry standard. Aircraft with vortex generators are up to 4 decibels quieter during the approach phase. In the meantime, the Group has retrofitted all aircraft of the A320 family operated by Lufthansa and SWISS with these vortex generators. The retrofit of Austrian Airlines’ A320 family is expected to be completed in 2019.

Overfly measurements revealed that the vortex generators are able to eliminate two unpleasant tones and thereby lower the aircraft’s total noise level on approach by up to four decibels at distances between 17 and 10 kilometers from the runway. Thus the Lufthansa Group has realized a key objective of the “Alliance for More Noise Protection”, a joint initiative of the Lufthansa Group, Fraport, the airline association BARIG, DFS, the Airport and Region Forum (FFR), and the government of the State of Hesse.

Airbus A320 audio tests

A320 audio tests with and without vortex generators on the final approach at Frankfurt Airport from the Offenbach-Lauterborn monitoring point.

[the underscored text is linked the recording of the aircraft noise as it lands.]

Without vortex generators

With vortex generators

A320 audio tests with and without vortex generators on the final approach at Munich Airport from the Massenhausen monitoring point.

Without vortex generators

With vortex generators


A 2014 Aviation Week article Lufthansa’s A320 VGs – look close…er, closer was even less positive about the noise reduction

The VGs on the A320 have a very specific purpose. They reduce noise on final approach by up to 2dB by eliminating two annoying tones caused by air flowing over circular fuel-tank pressure equalization vents under the wing – like blowing across the mouth of a bottle, Lufthansa says. The VG creates a vortex in front of the vent and prevent the noise. Quite clever, actually.


Major European Airbus operators take steps to avoid A320 whistle noise nuisance

 

 

A 2018 article states:

Late last year, Lufthansa became the first airline to start retrofitting vortex generators, which generate an air vortex over the vents to effectively prevent the annoying tones. According to measurements taken by the airline and DLR, the component can also reduce the overall noise level of the aircraft when landing by up to four decibels at distances of between 10 and 17 kilometres away from the airport


The ultimate purpose for this review is to provide a more accurate expectation for what the vortex generator’s impact. As the Lufthansa audio tape indicates, there is a qualitative difference in the diminution of the annoying “whistle” character caused by the air blowing over the Fuel Over Pressure Protector cavities (similar to when one blows over a bottle mouth).

Decibels are the engineering measurement of noise; a difference of 4 decibels may not result in individuals’ perception of the level of the sound. Psychoacoustics is the scientific study of sound perception. More specifically, it is the branch of science studying the psychological and physiological responses associated with sound (including speech and music) The ear is one of the most subjective of the senses; a sample of persons hearing a noise will rank their observations, but the graph of their individual perceptions will not cluster in a tight group.

Expectations of a 6 decibel improvement are not supported by the Lufthansa numbers. The perceptions of the benefit may not meet these expectations. JetBlue should be commended for their investment and HOPEFULLY the vortex generators will be positively recognized by the affected citizens.

 

 

 

 

 

 

https://youtu.be/0sHATdmDqc8



 

 

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1 Comment on "Will JetBlue’s Vortex Generator noise reduction be heard?"

  1. Nice Innovation … Much Appreciated :)

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