Monday, January 11, 2016

Will F-35s mean more noise?

Attracting an F-35 fighter jet program to Joe Foss Field could turn up the volume over parts of Sioux Falls.

The South Dakota Air National Guard's 114th Fighter Wing is among 18 units nationally that are vying to become a home base for the military's fifth-generation fighter jets. The U.S. Air Force is expected to choose two sites in 2017 with the aircraft arriving in 2021.

According to the military, the noise from an F-35 is generally comparable to the F-16 jets currently used at Joe Foss. Studies have shown the takeoff noise is almost equal. F-35s are slightly louder at 1,000 feet, but quieter at 1,500 feet.

The Sioux Falls Chamber of Commerce says securing an F-35 presence would be an economic win with potential to bring 45 new jobs to the city.

But other communities have resisted the programs, arguing the noise would create a nuisance. When the U.S. Air Force selected Burlington, Vt., as home for 18 of the newer, more powerful jets, residents challenged the decision in court. The City of Valparaiso, Fla. also filed suit over noise concerns.

Colonel Russ Walz, of the 114th Fighter Wing in Sioux Falls said noise concerns have been overblown in other parts of the country.

Walz said engine size isn't the only factor in what nearby populations hear. Flight patterns, paths and elevation have an impact as well.  The flight path won't change, Walz said. The city also has rules limiting aviation noise outside of the immediate area of the airfield to 65 decibels on the ground.

A 12-gauge shotgun blast, by comparison, is about 165 decibels and a snowmobile or motorcycle can register around 100 decibels.

Any increase in engine noise from the F-35s would be counteracted by altering ascent and descent angles and approach speeds, Walz said.

“We’ll adjust our flight profile. We basically climb out at a higher angle, lower air speed, to get to higher altitude quicker so that we can mitigate the noise,” he said.

An official noise impact study would be done if Sioux Falls is selected. The review would look at specific details of the region’s land uses and topography.

Tony Reiss said he regularly hears F-16s from his home near 21st Street and Main Avenue, even though most takeoffs and approaches to the airfield are to the north. A bigger jet engine “could get quite noisy," he said. He's concerned that elected leaders have endorsed the jets without a formal analysis of the noise impact.

“The mayor and city councilors are out cheering – and I’m all for bringing them in and additional economic opportunity to Sioux Falls – but that might be one area they haven’t thought of yet,” he said.

The Skyline Heights neighborhood northwest of the airfield is among the most affected by noise. Jets routinely roar over the rural subdivision, annoying some. But the issue of jet noise has never been a topic of complaint at neighborhood association meetings, said President John Lavendar.

“Sometimes they get kind of low. When I’m out in the yard weeding or something, you look up and you can see the pilot sitting in the cockpit. I’ve waved a couple times,” he said. “They’re fun to watch for me.”

Just to the north, developers are trying to turn 93 acres into a mixed-use neighborhood with a hotel resort. They don't expect quiet, considering there’s a truck stop and interstate highways within ear shot.

“We’re going to have a few live-work situations out there, maybe an apartment building … but they don’t usually fly at night when people are home sleeping,” said Dawn Aspaas, a development partner behind the Redstone Village edition.

Walz said night and evening flights are irregular. Typically, the 114th Fighter Wing flies four days a week in the morning and afternoon and one weekend a month during monthly guard drills.

“Those are things that we do to be respectful of our neighbors. We’re all members of our community. We’re always going to do everything that we can to be respectful and still get our mission accomplished,” he said.

How does an F-35A compared to an F-16 PW-220?

F-16 ~103 dBs
F-35 ~111 dBs

Arrival @ 1,000 feet
F-16 ~90 dBs
F-35 ~93 dBs

Low approach @ 1,500 feet
F-16 ~103 dBs
F-35 ~89 dBs

@ 2,000 feet
F-16 ~75 dBs
F-35 ~79 dBs

How loud is that?

Lowest audible sound: 0 dBs
A whisper from six feet: 30 dBs
A jackhammer from 50 feet: 95 dBs
Level at which long exposure may result in hearing loss: 95 dBs
A snowmobile or motorcycle: 100 dBs
A rock amplifier from five feet: 120 dBs
Level at which pain begins: 125 dBs
12 Gauge Shotgun Blast: 165 dBs
Death of hearing tissue: 180 dBs
Loudest sound possible: 194 dBs

Source: National Hearing Conservation Association 

Article and photo:

No comments: