Originally published at: NASA reveals secret supersonic airplane that quiets the sonic boom to a thump - Boing Boing
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So it would really only shave a couple hours off the normal flight time.
This gets to the main reason the Concorde never saw widespread success in the first place; the cost/benefit of the design just didn’t make sense even for longer flights over international waters. Most people who were rich enough to afford a ticket would opt to travel in comfort by flying first-class on a conventional airplane instead of cramming themselves aboard a death trap just to save a small amount of time.
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You will never feel so close to a billionaire as when you experience that gentle THUMP overhead.
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IDK how’s about NASA spend some time on making current jet engines quieter.
JFC they are loud AF. Signed anyone who lives within 15 miles of an airport.
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There’s been a ton of work on this problem, and the problem of noise associated with flight generally. And huge improvements over the last several decades, certainly on a per-flight basis.
Of course there is a much higher volume of flights now, and at the end of the day aviation is just a loud endeavor.
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This thing looks what I would expect for an X series plane, but how does any of this translate into a commercial aircraft? It reminds me of concept cars with suicide rear doors and no B pillars…sure it looks cool, but that sure as hell isn’t going to pass a side impact test. In this case it’s functional, but still not entirely practical.
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A part of that is the crap aerodynamics of the landing gear, with some nice baffles (and foils, etc) the sound can be reduced a decent amount. Unfortunately, it’s expensive, so it doesn’t get done.
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“Reveals”? “Secret”? Five years ago, I wrote a book that had images (CGI) and some details about this airplane…
As for “rattling windows and angering residents”, sonic booms do more than this. They literally break windows on the ground, and can rattle houses enough to cause cracks. It’s not just a nuisance, it’s expensive damage.
After the SSBD program ended, NASA published an excellent book about the history of research into sonic booms: what airplane shapes and speeds and altitudes and atmospheric conditions make them more or less intense, how much damage they do to property on the ground, and how an airplane could be shaped to minimize this intensity. The SSBD was a “quick and dirty” early experiment; an old F-5 fighter with a long bulge added to the nose and belly. (See also the F-15 that had a telescoping “Quiet Spike”). Those early tests were successful enough to justify the X-59, an airplane designed almost from scratch to be even better at this. (I say “almost” because it’s easy to spot some F-16 parts on there…). The SSBD book can be downloaded for free from NASA as an e-book or PDF:
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That’s an astonishing snoot for a plane!
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Yeah, it’s not the boom that doomed it, the real market for this kind of aircraft would be long-distance flights, at minimum trans-atlantic, preferably trans-pacific. Concorde iirc couldn’t single-stage hop from London to Austrialia, where that kind of speed would make a significant diference, or even Hong Kong without a refueling stop. Add to it the significant fuel per passenger mile costs, the limited seating (a friend who flew it said it was like paying twice the going rate for first class elsewhere while only getting the room from normal flight’s coach,) and then add the boom and it was never really going to make it. I’ve heard it said that the Internet and videoconferencing was the final nail in its coffin, but there never really was a market for “get there 20% faster for 200% the cost,” either for the carriers or the customers.
Now, if they can inprove the efficiency to at least be somewhat on par with high bypass turbofan busses carring 300+ passengers, without any significant increases in environmental impacts or passenger safety, then solving the boom problem might make a difference.
In the meanwhile, I expect that the stealth aircraft industry is making note of this and planning a new generation (6th gen?) of steathy aircraft that don’t make a sonic boom, just a harder to detect thud. That’s their market, and probably the real reason NASA is still pursuing a plane design that will, unless there’s serious breakthroughs, never see commercial passenger jet applications.
But our murder-machines, they’ll be very, very quiet.
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The X-59’s first flight is expected later in the year. Capable of reaching 925 miles per hour, the plane could fly from Los Angeles to New York City in less than three hours.
Blimey, America is large.
I’m reminded of the old joke…
Australian Farmer, “I can get into my car in the morning, drive all day, and still not have reached the edge of my property by evening.”
European Farmer, “Yeah, I used to have a car like that, too.”
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There are multiple companies working on supersonic business jets (SSBJs) and at least one (Boom) working on a supersonic commercial airliner. The kind of shape and analysis used on the design of the X-59 would benefit all those projects (although Boom claims that there’s enough of a market for their airplane even if they only fly trans-oceanic routes. I don’t think they’ll have much of a market one way or the other, but that’s a separate conversation).
The X-59 should, at the very least, trigger a change in laws that currently prohibit all supersonic flight over land (in the US and many other countries). I think it’s easy to argue that you should be allowed to fly supersonic over land if you can demonstrate that your airplane does not create a sonic boom that is strong enough to annoy people (or to break windows) on the ground.
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Pictured: the designer.
Sonic Boom Thump Boy
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Jet engines are getting quieter and quieter, a side effect of how better materials (and higher fuel prices and other factors) have allowed for wider and wider turbofans to make engines more and more efficient. When a modern airplane comes in to land, more than 50% of the noise comes from air blowing around the landing gear, around (and through the slots into) the flaps, etc., not from the engine.
… and NASA has researched this quite a bit. For example, they measured the noise made by a Gulfstream coming in to land, and then tested the noise-reducing impacts of things like more aerodynamic landing gear and seamless (flexible-surface) flaps.
The story of this project is quite remarkable, because they had to design and build a huge microphone array in the desert, then fly an airplane through a very specific spot while it was coming in to land with the engines at idle… not to mention, develop the computational tools to predict where sound would come from, to get sound source data from a large array of microphones… all that was first tested in a wind tunnel… super cool stuff.
Lots of cool data: (Feel free to scroll to the second half and just look at the pictures ;])
Slide deck, good overview of data and then “next steps” (testing a larger Gulfstream, testing airliner wind-tunnel models):
Data from larger gulfstream tested more recently:
Developing computer software that can predict all this, then applying those analysis methods to airliners:
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For one person. There is hardly enough room on that thing for your toothbrush.
When this highly compressed shockwave meets a human ear, it produces a loud boom, which does not occur when the plane breaks the sound barrier, but is rather a continuous effect that can be heard by anyone in a cone-shaped area beneath the plane, as long as it exceeds the speed of sound.
I need to go watch a video on how this works, because I can’t wrap my head around it. How can I only hear one boom, and then someone else a mile down the road hears a boom but at a different time but I didn’t hear that boom. I imagine if everyone lined up in a line and raised their hand as they heard the sound it would look like a wave, but still baffles me.
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yeah, i imagine it’s like an ocean wave with the plane at the crest, and you at the trailing trough. make the wall of that wave tall enough, and it will knock you down. now imagine the same with air, the windows of your house, and your eardrums.
( a slow wave you wouldn’t notice even if it’s tall. you’d just float up with it. a fast tall wave becomes a wall )
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I’m just trying to imagine this scaled up to something that can carry ~100 passengers (the Concorde held 92-120 according to Wikipedia) and it’s pretty hilarious. So much nose. Way too much nose to fit into existing airports.
This photo of a wind tunnel model really highlights HOW MUCH NOSE there is: Model Planes: Studying NASA’s Quiet Supersonic Aircraft Before It Flies - NASA
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Scale it up enough, and you could get passengers into the nose’s interior space. Stack 'em up and jam 'em in like cordwood. 
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DO NOT BOOP!!
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scale it up enough, and you get on the plane in new york and off again in london, all while it sits still at the airport. hmmm. maybe that’s called a bridge. 
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