Physicists at BYU may have fixed the challenging issue of exceptionally loud airplane toilets. The quirks of vacuum-assisted flushing mechanisms at high altitudes have made finding a workable solution to this persistent problem more difficult than it sounds, but through the scientific method (and plenty of trial and error), airplane lavatories could soon be just a bit quieter.
The flush of an airplane toilet is notoriously loud. Even in the heydays of the Boeing 727, when engine noise made it difficult to hear water running in the bathroom sink, the shriek of the vacuum-assisted toilet could be earsplitting. There is much less ambient cabin noise on modern passenger planes, but the toilet flush hasn’t gotten any quieter over the years.
“Airline companies have always had standards for the toilet noise, but they’ve never met those and there has never been much pressure to do so,” Brigham Young University Professor of Mechanical Engineering Scott Sommerfeldt said in a release announcing a potential breakthrough on that front. “Now with the reduced cabin sound levels, the sound of the toilet flushing is more noticeable and customers are pushing back.”
Sommerfeldt and colleague, Professor of Physics Kent Gee say they may have found a solution to the previously unsolvable challenge of piercing inflight toilet noise. According to the researchers, getting a typical lavatory toilet to flush with limited water requires a partial vacuum, which at an altitude of nearly 40,0000 feet can move air at nearly half-the-speed-of-sound.
The team of BYU scientists spent two years researching the problem and after several prototypes, thousands of flushes and no fewer than three published studies, the physics and acoustics experts came up with an airplane toilet that creates about half the decibels of airplane toilets currently in use today. The researchers say the secret was adding additional piping to increase the distance between the toilet bowl and the flush valve and making the pipe attachment at the bowl more of a gradual bend as opposed to a sharp 90-degree angle.
Because the new toilets require aircraft lavatories to undergo a hefty bit of reengineering to accommodate the new equipment, passengers won’t be able to enjoy a more peaceful restroom experience anytime soon. When new quieter patent-pending toilets finally become standard equipment on passenger planes, however, there may be at least one unheralded benefit for families.
“It’s a great mix between physics and engineering,” researcher Michael Rose, the lead author on the team’s latest publication in Proceedings of Meetings on Acoustics wrote. “The toilet is much quieter and now kids won’t think they’re going to get sucked out.”
This is apparently a real concern for parents traveling with small children.
“People have told us they don’t want their kids to be scared to use the bathroom on a flight,” Gee concurred. “So, we’ve used good physics to solve the problem.”
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