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

Good

[Aighearach]

It's pretty cool looking too. And who wants exploding tomatoes, or hearing loss?

Re:Good

[PolygamousRanchKid]

And who wants exploding tomatoes, or hearing loss?

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

If they dive too low

[Quakeulf]

They'll get anti-aired. Guile doesn't have that many great jump-in options and should be playing the safe downback-game.

Re: Huh?

[Dutchy Wutchy]

Maybe the modifications to the F-18 are only expected to fly quietly under certain conditions and perhaps fly poorly. The X-59 may be designed to test flight profiles required for commercial aircraft.

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).

It's not small

[stealth_finger]

It's not small, it's thin!

Much hubris in the announcement...

[Bearhouse]

From the link:

NASA’s newest experimental aircraft, designed with quiet supersonic technology and intended to help open a new era in faster-than-sound air travel over land, will forever be known in the history books as the X-59 QueSST. The U.S. Air Force, which is the government entity responsible for assigning X-number designations and the popular name associated with the aircraft, officially informed NASA of their decision on June 26.

“For everyone working on this important project, this is great news and we’re thrilled with the designation,” said Jaiwon Shin, NASA’s associate administrator for aeronautics. “I’m confident that the contributions the X-59 QueSST will make to our nation and the world will ensure its place among the greatest NASA X-planes ever flown,” Shin said.

"among the greatest?"...nope, don't think so...

or "Low-Flight Flight Demonstrator"

[tomxor]

or "Low-Flight Flight Demonstrator"

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

Re:Huh?

[stealth_finger]

Speak for yourself, monkey boy. I go to India and Japan a couple times a year. I could definitely use flights that get me there fast enough that my body clock can be more or less in sync with local time.

Doesn't matter how long it takes to get there, that place will still be the same amount of hours before or behind only it will be even worse because you'll just be even more out of whack.

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.

Re:Sonic booms are not caused by crossing the barr

[Anonymous Coward]

The state of trespassing is caused by my stepping into your property without your permission. You're just arguing the imprecision of the English language now.

Re:Huh?

[vtcodger]

I agree that flying across the Pacific is very tedious. Hated it myself. But consider that the heavily traveled route from West Coast North America to East Asia is (or can be) almost entirely over water and could be flown at supersonic speeds with a short subsonic segment at each end. That's what Concorde did across the North Atlantic My understanding is that It isn't done that way because its really hard to design an aircraft that can carry enough fuel to travel 10000km at supersonic speeds and also carry passengers and freight. The SR-71 Blackbird -- basically a huge titanium can with two engines and a LOT of fuel -- required in-air refueling to make long distance flights. The Wikipedia article on the SR-71 highlights a lot of other design issues with the real supersonic aircraft one might like to have when faced with a 20 hour flight from Los Angeles to Singapore or Mumbai. https://en.wikipedia.org/wiki/...

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."

Re:Scope creep

[Chris Mattern]

National AIR and Space Administration, Einstein. It has nothing to do with space, but everything to do with air.

Re:Scope creep

[CrimsonAvenger]

Trump, reign these people in.

Rein. If you can't spell it, don't use it....

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

[Anonymous Coward]

I think your numbers are not correct. I suspect that the 14 miles per gallon are already per passenger, as well as the 104 for the 787 Or was that supposed to be 0.115 gallons per customer per mile?

7,635 nmi to burn 33,384 gallons is 0.228 nautical miles per Gallon, or 66 nmi per passenger per gallon for 290 passengers.

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]

Report: https://www.flightglobal.com/F...

Re:Still not economical

[MtViewGuy]

I agree, especially on the Concorde. The Concorde used Rolls-Royce Olympus 593 _turbojets_, which were notoriously fuel-inefficient and noisy at the same time.

But we've come a LONG way since the Concorde was designed in the 1960's. Thanks to modern computational fluid dynamics, we now know how the sonic boom happens, and by carefully shaping the entire plane itself, we can reduce sonic booms to a tiny fraction of what the Concorde generated.

Personally, I believe we may soon see an corporate jet SST seating about 20 passengers that will fly at Mach 1.6 maximum and go as far as 6,000 nautical miles. Why impose the Mach 1.6 limit? First of all, at Mach 1.6, the structural heating will be quite a bit lower than on the Concorde, and as such that will allow the use of a lot more composite structural parts, which will dramatically cut the production cost of the plane (titanium and high-temperature stainless steels are very expensive to make), not to mention lower fuel burn. Secondly, with only a Mach 1.6 top speed, that makes it easier to design the airframe to drastically reduce the sonic boom, since the pressure wave buildup that causes the sonic boom is far lower than at Mach 2.0. Finally, with the Mach 1.6 top speed, we can use a new generation of variable cycle turbofan engines that will need far lower levels of reheat (afterburner) operation at top speed, which means way lower fuel consumption even at top speed.

Re:Still not economical

[squiggleslash]

Holy shit, I'm going to start flying a Boeing 787 to work every day, the fuel savings over my 30mpg Corolla will be enormous!

Re:Still not economical

[ceoyoyo]

Edit #2: a lot *worse* than a train.

Apologies, American-style MPG fuel economy is the reciprocal of the L/km we use.

Re:Still not economical

[Solandri]

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

Yes it is a fair to compare a modern subsonic airliner to Concorde.

Subsonic airliners have gotten much more fuel efficient since the 1970s by switching to higher bypass ratios. Basically, instead of the engine operating as a turbojet and blasting air out the back to push the plane forward, part of the power generated by the engines (more than 90% in modern designs) is diverted to spin ducted propellers, which push air back to push the plane forward. This is why so many commuter planes "still" use propellers - their engines are actually jet engines (instead of piston engines), but they drive a large unducted propeller and derive almost none of their thrust from shooting air out the back.

A ducted bypass turbofan is not possible with a supersonic aircraft because the airflow through the engine also needs to be supersonic, meaning propellers (which rely on generating low air pressure on one side) don't work. You have to rely on the turbine blades compressing the air, which is pretty much what a turbojet does, so there's no point doing a bypass. And the only way to fly at supersonic speeds is to blast air out the back of the engine.

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.

They use a helluva lot more fuel (per passenger mile) when flying supersonic. That they use more fuel than a regular airliner while flying subsonic is another negative, not a mitigating factor.

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.

Re:Still not economical

[tlhIngan]

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.

The big problem with Concorde was the noise. That limited the routes it could fly. When Concorde was designed, 19 airlines were lining up at the chance to buy one. They knew that getting from point A to point B quicker was worth the extra cost (which meant higher ticket prices and more profit).

However, the noise the Concorde makes made it impossible to do overland flights that everyone wanted, which is why it was limited to New York to London routes over water. Had it been quieter and able to do New York to LA and other routes, that would be far more appealing.

And yes, people would pay for the privilege - imagine going from LA to New York, conducting your business, then flying back from New York to LA in time to see the kids to bed. What would've been a 3 day business trip got compressed to 1. (Or 2 day whirlwind tour).

Re:Still not economical

[willy_me]

You are correct that supersonic flights will never be more economical - but that is only if you ignore time. Time is tricky to evaluate because everyone will have a different opinion on how valuable it is.

Ignoring the obvious error of mpg per passenger, this simple assessment does not differentiate between the different stages of flight. It matters because the majority of fuel is used at takeoff. Once at the desired velocity and altitude it takes considerably less fuel to maintain said velocity and altitude. As a result, planes that operate at very high altitude, where there is little resistance, can travel long distances with different economies then more traditional planes.

There is a niche market for flights where time is expensive, distances are long, and overall mass required for transport is small. Not being able to fly supersonic over land is a major hurdle that must be overcome in order to make such planes a reality. The other is maintenance cost - the real reason why the concord was retired.

Re:Still not economical

[rocket rancher]

The actual fuel efficiency ratio is on the order 4:1, not 17:1. You have factored in the number of passengers twice, for some reason, creating the erroneous 17:1 ratio. Fuel cost can be off-set by an increase in the number of passengers, which in turn is enabled by the increase in the number of routes that can be flown, which is what this project is all about. The only routes that the Concorde could fly at Mach or above had to be over water, which limited the number of potential routes, which in turn severely constrained the number of potential passengers. The lack of routes killed Concorde and nothing else.

The fifty year old Concorde had a max speed just north of Mach 2. Assuming no increase in performance in the last half century (unreasonable, I know, but I'm deliberately low-balling to make a point) imagine the demand if a route to Moscow from London opened up with a flight time of one hour. To Dubai in under three hours? or to Beijing in four? Bicoastal elites in the US are a huge potential market. LAX or SFO to JFK in less than two hours instead of nearly six? LAX to JFK is the third busiest air route in the US. London to Dubai is the fourth busiest air route in Europe. Each of these two routes had more passengers in 2015 than the Concorde flew in it's entire 34 year operational history. I hope you are beginning to get the big picture. Even if maintenance costs were as high as you assert (they aren't, but again, I'm being deliberately pessimistic to prove a point) the increased passenger base would still insure a more than healthy profit margin and a quick ROI.

Re:Still not economical

[MtViewGuy]

Actually, Rolls-Royce spent a lot of time evolving the Olympus turbojet so it could run in full reheat for long periods of time--a feat that was thought to be almost impossible.

But we've come a long way in engine technology since then. The GE YF120 showed how much engine technology has evolved since the time of the Olympus Mk. 593; something similar could become available for the SST corporate jet I mentioned, especially since at a maximum of Mach 1.6 the engine may need very little reheat operation, which means way lower fuel burn compared to the Okympus Mk. 593.

Re:Huh?

[AmiMoJo]

I think I'd be less tired if I didn't have to spend 12 hours on an airplane, especially in an economy class seat.

Unfortunately supersonic transport is likely to be insanely expensive.

Copyright violation

[Errol backfiring]

Since this is Texas, the NASA will probably be sued for the copyright violation of silence.

Low-Flight

[PPH]

How low? The article wasn't clear on this.

HOW does this make it more economical?

[damn_registrars]

The article says it will make it more economical, but doesn't say a word about how. What aspect of the NASA testing addresses that? Another thread here mentions that engines are better now then they were when Concorde was designed - and undoubtedly they are - but the article implies that this testing for reduction of the sonic boom somehow makes supersonic travel more economical and it does not give any indication of why that would be true.

Re:HOW does this make it more economical?

[ceoyoyo]

Concorde could only fly two or three routes because of the ban on flying supersonic over land, and even then it generally had to do some combination of flying a longer route that was more over water and flying subsonic at the beginning and end of the route. Flying subsonic in a supersonic aircraft drinks fuel and takes longer.

Longer flights mean less efficient utilization of the aircraft, more fuel is more fuel, and limited routes means the research and manufacturing costs are spread over fewer aircraft.

Re:HOW does this make it more economical?

[rkordmaa]

Supersonic airliner that can't fly over land is a very uneconomical thing to have. This addresses the problem.

Re:Sonic booms are not caused by crossing the barr

[AmiMoJo]

You could interpret that "when" as meaning "once it enters supersonic flight". Maybe there is less room for interpretation in American English.

The cows will be thrilled

[nospam007]

...and maybe also deaf.

Re:Scope creep

[cellocgw]

Trump, reign these people in.

Rein. If you can't spell it, don't use it.

Dunno - the original seems to describe his fundamental plan pretty accuractely.

Re:Huh?

[x_t0ken_407]

The awesomeness of that video cannot be overstated...