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In partnership with NASA, the Lockheed Martin Skunk Works team is solving one of the most persistent challenges of supersonic flight – the sonic boom. NASA awarded Lockheed Martin Skunk Works a contract in February 2016 for the preliminary design of X-59, designed to reduce a sonic boom to a gentle thump.

In 2018, Lockheed Martin Skunk Works was selected for the design, build and flight test of the Low-Boom Flight Demonstrator (LBFD). The X-59 aircraft will collect community response data on the acceptability of the quiet sonic boom generated by our design, helping NASA establish an acceptable commercial supersonic noise standard to overturn current regulations banning supersonic travel over land. This would open the door to an entirely new global market for aircraft manufacturers, enabling passengers to travel anywhere in the world in half the time it takes today.

X-59 is designed to cruise at 55,000 feet at a speed of about 940 mph and create a sound about as loud as a car door closing, 75 Perceived Level decibel (PLdB), instead of a sonic boom.

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Paul F.
Probably... though it's the first I've heard of this particular project.
There are several aircraft makers in the last decade or so that have flirted with the idea of a 21st century supersonic passenger aircraft. Other than operational costs like fuel, the biggest stopping point has been routes they'd be allowed to fly. If a demonstrator project like this can open up routes, and the problems of fuel and maintenance costs can be managed.... we'll have a second generation of supersonic transport!

My idea has always been, "drive it HIGHER". Thanks to the inverse-square law, and thinner air, sonic booms from altitudes above 100,000 feet would be similarly greatly reduced. Of course, flying at 100,000 feet brings its own set of problems...

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Will Collier

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Paul F.
Probably... though it's the first I've heard of this particular project.
There are several aircraft makers in the last decade or so that have flirted with the idea of a 21st century supersonic passenger aircraft. Other than operational costs like fuel, the biggest stopping point has been routes they'd be allowed to fly. If a demonstrator project like this can open up routes, and the problems of fuel and maintenance costs can be managed.... we'll have a second generation of supersonic transport!

My idea has always been, "drive it HIGHER". Thanks to the inverse-square law, and thinner air, sonic booms from altitudes above 100,000 feet would be similarly greatly reduced. Of course, flying at 100,000 feet brings its own set of problems...

Besides which, while a sonic boom is not nothing, but it's far from the only noise a high-powered jet makes. Take it from somebody who's lived near fighter jets for about the last 25 years, they don't have to be supersonic to be really loud on takeoff and landing....

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mrlynn

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Will Collier

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Paul F.
Probably... though it's the first I've heard of this particular project.
There are several aircraft makers in the last decade or so that have flirted with the idea of a 21st century supersonic passenger aircraft. Other than operational costs like fuel, the biggest stopping point has been routes they'd be allowed to fly. If a demonstrator project like this can open up routes, and the problems of fuel and maintenance costs can be managed.... we'll have a second generation of supersonic transport!

My idea has always been, "drive it HIGHER". Thanks to the inverse-square law, and thinner air, sonic booms from altitudes above 100,000 feet would be similarly greatly reduced. Of course, flying at 100,000 feet brings its own set of problems...

Besides which, while a sonic boom is not nothing, but it's far from the only noise a high-powered jet makes. Take it from somebody who's lived near fighter jets for about the last 25 years, they don't have to be supersonic to be really loud on takeoff and landing....

Any reason why supersonic passenger planes couldn't have subsonic modes for take-off, landing, and low-level flight?

/Mr Lynn

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space-time
We had MIGs go supersonic over my hometown (200k) all the time.

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Will Collier

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Paul F.
Probably... though it's the first I've heard of this particular project.
There are several aircraft makers in the last decade or so that have flirted with the idea of a 21st century supersonic passenger aircraft. Other than operational costs like fuel, the biggest stopping point has been routes they'd be allowed to fly. If a demonstrator project like this can open up routes, and the problems of fuel and maintenance costs can be managed.... we'll have a second generation of supersonic transport!

My idea has always been, "drive it HIGHER". Thanks to the inverse-square law, and thinner air, sonic booms from altitudes above 100,000 feet would be similarly greatly reduced. Of course, flying at 100,000 feet brings its own set of problems...

Besides which, while a sonic boom is not nothing, but it's far from the only noise a high-powered jet makes. Take it from somebody who's lived near fighter jets for about the last 25 years, they don't have to be supersonic to be really loud on takeoff and landing....

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JoeH

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Will Collier

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Paul F.
Probably... though it's the first I've heard of this particular project.
There are several aircraft makers in the last decade or so that have flirted with the idea of a 21st century supersonic passenger aircraft. Other than operational costs like fuel, the biggest stopping point has been routes they'd be allowed to fly. If a demonstrator project like this can open up routes, and the problems of fuel and maintenance costs can be managed.... we'll have a second generation of supersonic transport!

My idea has always been, "drive it HIGHER". Thanks to the inverse-square law, and thinner air, sonic booms from altitudes above 100,000 feet would be similarly greatly reduced. Of course, flying at 100,000 feet brings its own set of problems...

Besides which, while a sonic boom is not nothing, but it's far from the only noise a high-powered jet makes. Take it from somebody who's lived near fighter jets for about the last 25 years, they don't have to be supersonic to be really loud on takeoff and landing....

They can be loud enough just flying over. There is an ANG unit in Westfield flying F-15C's. They fly over this area regularly at least 10,000 feet up and are definitely a loud rumble. Occasionally they do training at lower altitudes, that is very loud.

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Will Collier

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space-time
We had MIGs go supersonic over my hometown (200k) all the time.

Where was that?

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space-time
We had MIGs go supersonic over my hometown (200k) all the time.

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Ombligo
The double sonic booms (one from the nose, one from the wings) was how I knew the Space Shuttle was landing. The approach was over my house and something like 80,000 feet. The thing had to do a serious dive to get from that altitude at my house to ground level at Kennedy - about 100 miles away.

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Will Collier

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mrlynn

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Will Collier

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Paul F.
Probably... though it's the first I've heard of this particular project.
There are several aircraft makers in the last decade or so that have flirted with the idea of a 21st century supersonic passenger aircraft. Other than operational costs like fuel, the biggest stopping point has been routes they'd be allowed to fly. If a demonstrator project like this can open up routes, and the problems of fuel and maintenance costs can be managed.... we'll have a second generation of supersonic transport!

My idea has always been, "drive it HIGHER". Thanks to the inverse-square law, and thinner air, sonic booms from altitudes above 100,000 feet would be similarly greatly reduced. Of course, flying at 100,000 feet brings its own set of problems...

Besides which, while a sonic boom is not nothing, but it's far from the only noise a high-powered jet makes. Take it from somebody who's lived near fighter jets for about the last 25 years, they don't have to be supersonic to be really loud on takeoff and landing....

Any reason why supersonic passenger planes couldn't have subsonic modes for take-off, landing, and low-level flight?

/Mr Lynn

No, because they certainly will be subsonic in those flight modes. Besides the obvious safety issues, because the speed of sound is higher at lower altitudes and thus it takes more energy and fuel to go supersonic, even military high speed jets rarely get above the Mach under, say 20,000 feet except in dire circumstances.

There's a supersonic corridor above the Appalachian Mountains north of Atlanta for F-22 flight tests. It avoids populated areas, but if you're in south Cobb County, you still know when one takes off or lands.

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mrlynn

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Will Collier

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mrlynn

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Will Collier

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Paul F.
Probably... though it's the first I've heard of this particular project.
There are several aircraft makers in the last decade or so that have flirted with the idea of a 21st century supersonic passenger aircraft. Other than operational costs like fuel, the biggest stopping point has been routes they'd be allowed to fly. If a demonstrator project like this can open up routes, and the problems of fuel and maintenance costs can be managed.... we'll have a second generation of supersonic transport!

My idea has always been, "drive it HIGHER". Thanks to the inverse-square law, and thinner air, sonic booms from altitudes above 100,000 feet would be similarly greatly reduced. Of course, flying at 100,000 feet brings its own set of problems...

Besides which, while a sonic boom is not nothing, but it's far from the only noise a high-powered jet makes. Take it from somebody who's lived near fighter jets for about the last 25 years, they don't have to be supersonic to be really loud on takeoff and landing....

Any reason why supersonic passenger planes couldn't have subsonic modes for take-off, landing, and low-level flight?

/Mr Lynn

No, because they certainly will be subsonic in those flight modes. Besides the obvious safety issues, because the speed of sound is higher at lower altitudes and thus it takes more energy and fuel to go supersonic, even military high speed jets rarely get above the Mach under, say 20,000 feet except in dire circumstances.

There's a supersonic corridor above the Appalachian Mountains north of Atlanta for F-22 flight tests. It avoids populated areas, but if you're in south Cobb County, you still know when one takes off or lands.

I meant, any reason why SSTs couldn't use engines that were quiet at low (subsonic) speeds?

/Mr Lynn

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Thrift Store Scott

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mrlynn

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Will Collier

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mrlynn

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Will Collier

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Paul F.
Probably... though it's the first I've heard of this particular project.
There are several aircraft makers in the last decade or so that have flirted with the idea of a 21st century supersonic passenger aircraft. Other than operational costs like fuel, the biggest stopping point has been routes they'd be allowed to fly. If a demonstrator project like this can open up routes, and the problems of fuel and maintenance costs can be managed.... we'll have a second generation of supersonic transport!

My idea has always been, "drive it HIGHER". Thanks to the inverse-square law, and thinner air, sonic booms from altitudes above 100,000 feet would be similarly greatly reduced. Of course, flying at 100,000 feet brings its own set of problems...

Besides which, while a sonic boom is not nothing, but it's far from the only noise a high-powered jet makes. Take it from somebody who's lived near fighter jets for about the last 25 years, they don't have to be supersonic to be really loud on takeoff and landing....

Any reason why supersonic passenger planes couldn't have subsonic modes for take-off, landing, and low-level flight?

/Mr Lynn

No, because they certainly will be subsonic in those flight modes. Besides the obvious safety issues, because the speed of sound is higher at lower altitudes and thus it takes more energy and fuel to go supersonic, even military high speed jets rarely get above the Mach under, say 20,000 feet except in dire circumstances.

There's a supersonic corridor above the Appalachian Mountains north of Atlanta for F-22 flight tests. It avoids populated areas, but if you're in south Cobb County, you still know when one takes off or lands.

I meant, any reason why SSTs couldn't use engines that were quiet at low (subsonic) speeds?

/Mr Lynn

A sonic boom is when an object travels faster than the speed of sound which causes a cone-shaped shock wave to radiate backwards from the object, that shock wave exhibits a concussive effect when it reaches the ground. The engines themselves play no direct part in a sonic boom.

Aircraft engines today are dramatically quieter than they were when the Concorde was designed so they're not really the problem, the sonic boom itself is.

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freeradical
Prop aircraft can be very loud.

I understand that the tips of the propellers on the TU-95 have a supersonic linear velocity.

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Carnos Jax
To possibly shed some additional light on the situation with some educated speculation on my part, while engines have dramatically improved in efficiency since the days of the Concord, part of the reason why it (and many fighters today) are loud during takeoff, is due to the use of afterburners. And the reason they use these is because those engines tend to be pure turbojets or low bypass turbofans. Such engines are best for supersonic air speeds. But they can’t produce as much thrust as the high bypass turbofans used on today’s airliners. Then again high bypass turbofans are no good for supersonic travel.. there may need to be some innovation in this area. Maybe some kind of hybrid design that route air through the core of the engine only as the speed increases.

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Truly game-changing breakthroughs in US fighter engines are nearly in hand. After more than a decade of labor by Air Force Research Laboratory and engine-makers Pratt & Whitney and General Electric Aviation, increases in speed and range, reduced dependency on tankers, and a menu of new tactics are just some of the advantages coming in the next few years.

By 2021, engineers are expected to have built and tested flightworthy engines that could, for example, give new fighters 30 percent more range than they have today, produce enough spare power to fire directed energy weapons, or run cool enough to improve stealth. Besides those advantages, new engines could provide great benefit to the F-35 strike fighter, allowing it to sustain high-speed flight at treetop altitudes, something it can’t do today. The work is advanced enough that, given a green light, a new development program with a short execution time line could be launched and start producing new power plants by the early 2020s.

So significant are the improvements that the new engine technology effort has been exempt from recent budget cuts, to quicken the pace that the new power plants can be deployed in the inventory.

“We’ve gained tremendous insight from our experience designing engines for the F-22 and the F-35, which are truly a generation ahead,” said Pratt & Whitney’s James Kenyon, senior director of advanced programs and technology, in a 2016 news release. Subsequent development—funded by the Air Force, Navy, and in-house—have yielded “tremendous progress” since 2012 and “we’re eager to move into the next phase of adaptive engine development,” he said.

That next phase is the Adaptive Engine Transition Program, or AETP, a five-year project that began last summer with $1 billion contracts each to Pratt & Whitney and General Electric Aviation. It will refine and mature technologies developed in the Adaptive Engine Technology Development program, launched in 2012 and concluding this year.

The term “adaptive” refers to an engine that can change its internal geometry to be efficient in a variety of missions and flight conditions.

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Article Accelerator

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freeradical
Prop aircraft can be very loud.

I understand that the tips of the propellers on the TU-95 have a supersonic linear velocity.

I hope not. That would be a dangerous condition.

[tinyurl.com] (links to wikipedia)
[en.wikipedia.org]

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Bixby
I've always thought this was highly informative and engaging video on landing the space shuttle: https://www.youtube.com/watch?v=Jb4prVsXkZU

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mrlynn
Thanks Carnos Jax and freeradical, for addressing my question (which was in response to Will Collier's point that, besides sonic boom, SSTs would be too loud at and near airports).

The answer is clearly some kind of hybrid engine(s) that could switch from low-speed high-speed modes. As I recall, a British company was working on a combination turbo-fan and ramjet to address these concerns.

Or an SST could conceivably carry two kinds of engines, which of course would add a lot of weight.

/Mr Lynn

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JoeH
Actually quite true.

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Ombligo
The Tu-95 had a passenger version, the Tu-114 which was used by Aeroflot. It used the same engines, with the same noise. No noise-canceling headphones either.