NASA To Test 'Quiet' Supersonic Flights Over Texas (cnn.com)

NASA announced it will publicly demonstrate a quiet supersonic aircraft near the coastal resort city of Galveston, Texas, to ensure that its prototype really will be barely audible when it crosses the sound barrier. CNN reports: If NASA's experimental project -- formerly known as the X-plane or "Low-Flight Flight Demonstrator" but recently renamed X-59 QueSST -- works, it should help make supersonic flight more economical. From November, NASA will use supersonic F/A-18 Hornet jets over Galveston to mimic the sonic profile of the X-59 while a group of around 500 residents document the noise levels -- if there are any. By performing dives at the speed of sound, the jets will produce two types of sonic boom in order to truly determine the sound they produce on the ground.

According to NASA, Galveston was chosen as the testing area as it's located near the Gulf of Mexico, allowing the fighter jets keep louder sonic booms out to sea, while hurling quieter sonic "thumps" into the city. The secret to the plane's noise-reducing ability is its uniquely shaped structure, designed so that supersonic shockwaves don't build up into powerful sonic booms.

Comments

Re:Huh?

[rednip]

I had to read that again as well. I'd guess that the F-18 (perhaps modified) is expected to make a sound wave similar to what's been modeled, but only under specific conditions. e.g. diving once already above the speed of sound. This is a survey to see if it's really at an acceptable level.

Re:Huh?

[Anonymous Coward]

You should read the articles. They give some more insight.

Looks like the modified F/A-18 are able to produce the needed effect only performing dives, not in normal straight flight. They are anyway modified fighters, and the modification looks quite expensive it's common for a prototype to cost way more than the final product it's being used to test).

The final object will allow testing in straight flight and pose basis for further development towards applying the technology to actual transportation airplanes, which are much bigger than a fighter jet and cost relatively less.

I'd add that it looks like this technology requires costs to be cut down also using economies of scale, which, past history proves, is difficult for supersonic flights, since most people don't actually need such fast transfers. The few that actually need them can pay the premium. Most probably it will be applied to corporate jets and specialised military transports before big airliners.

Sonic booms are not caused by crossing the barrier

[students]

"its prototype really will be barely audible when it crosses the sound barrier."

Sonic booms are caused by going faster than the speed of sound. They are not caused by reaching the speed of sound. This is why the boom is a potential problem - it is heard along the entire supersonic flight path, not just at the beginning.

Re:Scope creep

[Anonymous Coward]

*sigh*

The first A in NASA stands for Aeronautics (The study, design & manufacturing of flying machines).

Re:Good

[PolygamousRanchKid]

And who wants exploding tomatoes, or hearing loss?

"Where's the kaboom? There was supposed to be an Earth-shattering kaboom!"

or "Low-Flight Flight Demonstrator"

[tomxor]

or "Low-Flight Flight Demonstrator"

So... it's a Low Flight Flight Demonstrator Demonstration?

Re:Huh?

[Luckyo]

If you can't afford first class, and your complaint specifies that you're not talking about first class seating, you're not going to be able to afford this kind of travel.

Re:Huh?

[mikael]

Current jets can make sonic booms. That's due to the shape of the aircraft and the wings so that there are two sonic booms due to areas of high air pressure. They can reduce that by a small amount by making minor changes to the airframe and wings:

https://www.youtube.com/watch?...

With the X-59, they completely redesign the airframe and wings so that the pressure waves cancel each other out rather than reinforce each other.

I Can't believe it...

[Dantoo]

I'm stunned. Shocked. Is this even possible? I never believed this could happen in my lifetime.

Galveston is a resort these days?

The Sonic Fart Engine.

[geekmux]

"The secret to the plane's noise-reducing ability is its uniquely shaped structure, designed so that supersonic shockwaves don't build up into powerful sonic booms."

Why did my childish mind translate this as NASAs new Sonic Fart Engine, equipped with titanium SBD valve technology?

(Spectator)"Sir, is this plane fast?"

(Captain Texas, US Air Force) "Quicker than a sonic fart in high wind, yes, Ma'am."

Still not economical

[Pollux]

It should help make supersonic flight more economical.

Supersonic flight still will not be more economical. As this video by Wendover Productions explains, the biggest cost of supersonic flights is the fuel. The Concorde flies 14 miles per gallon of fuel, while the Boeing 787 flies 104 miles per gallon. Also consider the Concorde only carried 128 passengers, while the 787-9 can carry 290. Doing the math, on a 3,470 mile flight from New York to London, a Concorde would consume 1.936 gallons of fuel per passenger, while a 787-9 would consume only 0.115 gallons per customer. That's almost 17 times greater fuel efficiency.

And that's not even beginning to mention the much higher building and maintenance costs of supersonic planes and engines.

Permitting cross-continental flights with a supersonic plane isn't going to matter one bit in the economics of supersonic flight.

Re:Still not economical

[Anubis IV]

The Concorde flies 14 miles per gallon of fuel, while the Boeing 787 flies 104 miles per gallon. Also consider the Concorde only carried 128 passengers, while the 787-9 can carry 290. Doing the math, on a 3,470 mile flight from New York to London, a Concorde would consume 1.936 gallons of fuel per passenger, while a 787-9 would consume only 0.115 gallons per customer.

You’ve misunderstood the fuel economy numbers you quoted, which should have been readily apparent as soon as you tried to suggest that a Concorde got similar fuel economy (14 mpg) to an older car. The original numbers you gave were already on a miles per gallon per passenger basis, so dividing them again by the number of passengers gives you a useless number.

Re:Still not economical

[ceoyoyo]

That's not exactly a fair comparison. A 1970's era subsonic airliner would use a lot more fuel than the 787 as well.

This report puts Concorde per passenger fuel consumption at about twice a 707, four times a contemporary 747, essentially the same as a business jet and a lot better than a train.

One of the reasons why Concorde was so expensive was that there were only a few built, to fly very specific routes that were mostly over water, and even so, there were generally fairly long subsonic legs at the beginning and end. Those are expensive because supersonic aircraft tend to drink fuel when flying subsonic, and if you have to do it at the end of your flight you have to carry all that extra fuel all the way.

Opening up more routes to supersonic aircraft would make them a LOT more economical. Barring some groundbreaking innovation, supersonic would still be more expensive than subsonic, but not by nearly as much as the Concorde was.

Re:Still not economical

[ceoyoyo]

Turbofans are not propellers. Turbofans work fine on supersonic aircraft, and are installed on many military jets. You generally wouldn't use a high bypass tubofan, and might even go with a turbojet for a plane that flies mostly supersonic because low-bypass and turbojets get more efficient at high speed. There has also been a lot of development in turbojets and low bypass turbofans since the 1970s. This is demonstrated by the super cruise capabilities of fifth generation fighters.