NASA reveals secret supersonic airplane that quiets the sonic boom to a thump

It will fall afoul of the Nose Abatement Society.

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Faster quieter planes for a relative few versus in-home 3D virtual reality armchair-vacations/visits for all. :upside_down_face:

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Imagine a row of people floating on the water, with maybe 10 feet between each person. Imagine that, 30 feet away, a boat goes by, its path being parallel to the row of people. The boat is going fast enough to make a wake. At one point, you are hit by the boat’s wake. A second later, the next person is hit. A second after that, the person-after-that is hit. It’s the same thing with the airplane and its boom, except in 3D (imagine revolving the boat wake around the axis of the boat’s path, to make a 3D cone - like a Christmas tree lying horizontally - with the boat at the tip) and the wake is “sharp” enough to feel like a “pop” instead of a gentle up-and-down in pressure.

Edit: If you want to expand the analogy: If the boat were going more slowly than the speed of waves on the water surface, it would not make a wake, instead it would make concentric ripples that would radiate away from the boat in all directions like when you throw a pebble into a pond. If you’re floating on the water, you’d be able to start “sensing” the approach of this slow boat long before it goes by (if you know what ripples to “listen” for), so the pressure made by the boat on its way to you would be spread out over time. But if the boat is going faster than surface waves, then it makes a wake… and you notice no change whatsoever in the water until the boat is past and the wake hits you, all at once, compressing the pressure built up during the approach period into a single instant. Again, with an airplane, it’s the same thing: pressure waves in air, and the difference between hearing a subsonic plane coming… versus watching a supersonic plane fly silently by and then being hit by its shockwave and hearing the boom. Edit2: Illustration from NASA’s SSBD book that I mentioned in an earlier comment:

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Then why does the ground rumble 10 miles away when planes take off? At an average of one flight every minute over hours at a time you have a effing deafening explosion of noise pollution. At 10 miles out planes up at 2k ft are still noisy AF on the ground at 90 - 100db during throttle up.

I wonder if all this so-called research into engine noise is really just aimed at reducing levels for the passengers and NOT for anyone who lives near an airport.

I will personally fucking raise hell to prevent any such supersonic craft from airports near me come booms or thumps.

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Notice that (1) The research that I mentioned is not about engine noise, but about all the other sources of noise, which add up to a majority of noise during landing… and (2) I wrote “during LANDING”. (Yes, during takeoff, most noise is from the engines).

I think it pretty much goes without saying that supersonic airplanes are not supersonic during takeoff or landing. They will only make booms/thumps when flying tens of thousands of feet up.

On the one hand, I can’t argue with your subjective opinion that airliners are annoyingly loud. I can only say that (1) I’ve worked across the street from an airport for my whole career (since 2006) and jet noise never bothered me, and (2) If you look at the data, airliners are getting quieter - again, mostly as a side effect of using more fuel-efficient engines:

jetenginesar

Above: Noise requirements get stricter over time, and newly-certified airplanes get quieter in order to meet them. (Remember that decibels are logarithmic: Going down by ten decibels is effectively equivalent to cutting noise in half. Going from above +10 to below -20 means that a modern airliner is less than 1/8th as loud as an airliner from the mid-60s). Below: Despite the US population growing quite a bit, and the number of jetliner flights growing a LOT (as shown by the blue line), the number of people exposed to airliner noise above a certain level is less than 5% of what it was in 1975 (red line):

emplanements-noise-500px

Sources:

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“Emplanements”?

So next time I’m hiking in some remote location I’ll hear thumps in addition to the usual engine noise.

Great.

The whole point of the X-59 program is for NASA to learn whether such noise annoys people. So… Don’t complain to me, go complain to NASA! Especially if you live near one of the locations where they will be doing these tests. Link below to NASA’s plan to survey local communities.

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I know that complaints mean nothing. For the past 5 years I’ve been working on noise abatement issues in regards to NextGen and the noise pollution it brought to an airport near me. Quickly learned that the FAA and airport authorities value profits and getting as many airplanes through the system as they possibly can. Damn the residents in the way.

Forgive me if I don’t trust that NASA or whomever will do right for the people in the way who have nothing to do with a rich person’s taxi.

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I’m old enough I remember sonic booms before they were outlawed, as there was an AFB not too far away. I thought they were cool! I could see though as an adult that would get annoying right quick. Not to mention all the other downsides relating to animals.

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Fair enough. Thank you for your work, and I’m sorry it has been so frustrating, that sucks.

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I was at a Bowie Baysox baseball game this summer when I first heard a sonic boom. It was a clear day, so that ruled out thunder, and it was so loud that I stood up and started looking for smoke from an explosion. It turned out to have been from a fighter jet scrambled after a private flight went astray near DC. I didn’t know supersonic flight was illegal over land, but that would explain why it’s rare.

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Oh, it’s still legal for the military to go supersonic, so long as they’re above 30,000 feet or in special designated areas, like a certain national park not too far from where I live. Every so often the wind will be right and the windows will rattle. Even when they were only allowed offshore, as a calculus prof pointed out when the lecture hall windows rattled every morning at 8:15ish, the shock wave still propagates and can be felt/heard a long distance away.

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I need high speed rail like the one in Japan or Korea, not this. Also, this is not counting the boarding time, which is another shit show. This doesn’t make any economic sense anyway. Air travel is crowded, environmental polluting method.

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is the name of my 2nd album

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I thought the nail in the coffin for the Concorde was stricter pollution laws?

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On that train, all graphite and glitter
Undersea by rail
Ninety minutes from New York to Paris
(More leisure for artists everywhere)

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Reminds me of this

Saw a program where one of the engineers was describing how they came to choose this shape, as the earlier designs and models all made a big boom when passing through tunnels at speed, and if the driver went too fast, they’d shatter windows with a really loud one.

They understood it was ripples, and one noticed that kingfishers were able to enter still water with barely a splash or ripple. So the design of the front of the train is the same as a kingfisher’s head… and so, noticeably is this plane.

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I’m puzzled as to why NASA is actively helping the aviation industry to become even less sustainable.

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