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NASA Captures Unprecedented Images of Supersonic Shockwaves (phys.org)

Posted by BeauHD on from the I-just-found-a-new-wallpaper dept.

As NASA looks into developing planes that can fly faster than sound without creating "sonic booms," the space agency has captured unprecedented photos of the interaction of shockwaves from two supersonic aircraft. Phys.Org reports: When an aircraft crosses that threshold -- around 1,225 kilometers (760 miles) per hour at sea level -- it produces waves from the pressure it puts on the air around it, which merge to cause the ear-splitting sound. In an intricate maneuver by "rock star" pilots at NASA's Armstrong Flight Research Center in California, two supersonic T-38 jets flew just 30 feet (nine meters) apart below another plane waiting to photograph them with an advanced, high-speed camera, the agency said. The rendezvous -- at an altitude of around 30,000 feet -- yielded mesmerizing images of the shockwaves emanating from both planes. You can view all of the photos via NASA.

37 comments

  1. Awesome by JustAnotherOldGuy · · Score: 2

    Awesome stuff, and some precision flying was needed too.

    --
    Just cruising through this digital world at 33 1/3 rpm...
    1. Re: Awesome by Anonymous Coward · · Score: 0

      That interaction makes a well known pattern but NASA is silent on the subject.

    2. Re: Awesome by Anonymous Coward · · Score: 0

      You know whatâ(TM)s awesome, when MDMA kicks in...

      2am here holy shit and I choose to comment on Slashdot zzz

    3. Re: Awesome by Anonymous Coward · · Score: 0

      Then CHiPs pulled them over and issued tickets

    4. Re:Awesome by Anonymous Coward · · Score: 1

      FTA, "they were Rockstars" in reference to the pilots who were 30 ft apart at supersonic speeds

      Funny, not like many rock stars that I have heard about, I wonder if the pilots where drunk and snorting tons of coke?

    5. Re: Awesome by Anonymous Coward · · Score: 0

      Please elaborate?

    6. Re:Awesome by Anonymous Coward · · Score: 0

      bruce dickinson

    7. Re: Awesome by Anonymous Coward · · Score: 0

      What the *fuck* are you talking about

    8. Re: Awesome by Anonymous Coward · · Score: 0

      LOL

      This devolved so quickly
      Actually thought my question was being answered for a second

  2. Gas Dyamics by Zuckrow by 140Mandak262Jamuna · · Score: 3, Insightful
    Remember seeing Schlieren pictures while doing the gas dynamics I course back in college.

    The formula P by Po = ( 1 + (gamma - 1)/gamma * M^2) ^ (( gamma - 1)/gamma) I will never forget. Brain cells spent memorizing that formula are frozen for ever, can never be repurposed to do anything else, even if I have do earthly reason to calculate the total pressure in a supersonic flow ever again! The last Gas Dynamics examn I sat for was 32 years ago!

    --
    sed -e 's/Chuck Norris/Rajnikant/g' joke > fact
    1. Re:Gas Dyamics by Zuckrow by fazig · · Score: 1
      This in particular is not my field of expertise, but I do work in measurement engineering where I design prototypes for new instruments. And I have a general interest in methods that allow us to visualize phenomenon like these.

      Schlieren is what came to my mind as well. The article however does not mention this method. Instead they write:

      In an intricate maneuver by "rock star" pilots at NASA's Armstrong Flight Research Center in California, two supersonic T-38 jets flew just 30 feet (nine meters) apart below another plane waiting to photograph them with an advanced, high-speed camera, the agency said.

      Source: https://phys.org/news/2019-03-...

      Besides of mentioning that advanced high-speed camera they do not disclose the rest of the setup they used. Does this mean that the need for a dedicated light source (replaced by the sun) and a parabolic mirror can be eliminated these days? Well, at least when it comes to performing measurements on these scales.
      Modern high-speed cameras are already able to pick up shock waves from explosions, which was a big audience favourite on shows like Mythbusters.
      It's good to see things progress and getting simpler.

    2. Re:Gas Dyamics by Zuckrow by religionofpeas · · Score: 2, Informative

      2nd link says this: "The images were captured during the fourth phase of Air-to-Air Background Oriented Schlieren flights, or AirBOS"

    3. Re:Gas Dyamics by Zuckrow by Anonymous Coward · · Score: 0

      Schlieren is a technique to make deformations caused by diffraction that aren't obvious to the naked eye visible. The jets were photographed with a high speed camera from above, so there was a background of land or sea with quite a lot of detail in it. I expect the deformations can be found by comparing the background in subsequent images taken by a high resolution high speed camera. That would make the visualisation technique similar to InSAR.

    4. Re:Gas Dyamics by Zuckrow by fazig · · Score: 2
      I guess I've got to check all links, thank you.

      BOS is an optical density visualization technique, belonging to the same family as schlieren photography, shadowgraphy or interferometry. In contrast to these older techniques, BOS uses correlation techniques on a background dot pattern to quantitatively characterize compressible and thermal flows with good spatial and temporal resolution. The main advantages of this technique, the experimental simplicity and the robustness of correlation-based digital analysis, mean that it is widely used, and variant versions are reviewed in the article.

      Source: https://link.springer.com/arti...

      Or for those who are not inclined to refuse Wikipedia as a source:

      Background-oriented schlieren (BOS) is a novel technique for flow visualization of density gradients in fluids using the Gladstone–Dale relation between density and refractive index of the fluid. BOS simplifies the visualization process by eliminating the need for the use of expensive mirrors, lasers and knife-edges. In its simplest form, BOS makes use of simple background patterns of the form of a randomly generated dot-pattern, an inexpensive strobe light source and a high speed digital camera.

      Source: https://en.wikipedia.org/wiki/...

      Google schoolar places the earliest mention of this method into 2001, which is not that new: https://iopscience.iop.org/art...

  3. Ear-splitting sound by PPH · · Score: 3, Insightful

    Please. Stop already. I've heard plenty of sonic booms and I'd be hard pressed to describe them as 'ear-splitting'. If you live in the mid-west, Florida or other areas, thunderstorms create far higher sound pressure levels. And do more damage to windows and structures as well.

    If we can't get the highly suggestible people over the idea that sonic booms are intolerably loud, because they have been told they are, we will never develop supersonic aircraft.

    --
    Have gnu, will travel.
    1. Re:Ear-splitting sound by Anonymous Coward · · Score: 2, Informative

      I've heard plenty of sonic booms and I'd be hard pressed to describe them as 'ear-splitting'.

      You must have been far, far away from the sonic booms. I lived about 15 miles from a former military air base. Jet jocks were often goofing around and busting the sound barrier. The noise is LOUD and startling!

    2. Re:Ear-splitting sound by Anonymous Coward · · Score: 0

      "If we can't get the highly suggestible people over the idea that sonic booms are intolerably loud," - Full stop. This person is a moron. They need their skull split and deafened, and it's clear they have no idea what they're talking about.

    3. Re:Ear-splitting sound by geggam · · Score: 1

      When I was a kid fighter jets would occasionally create a sonic boom over the small town I grew up in. As a kid I thought this was cool as hell.

      A few times they were low enough it felt like light thunder

    4. Re:Ear-splitting sound by Anonymous Coward · · Score: 0

      Almost got killed driving on a mountain road when a hot dog dropped a boom from not more than 500 feet altitude AGL Almost wrecked the care I was driving because it was so loud I thought I already had! (and you don't want to lose control going along the side of a cliff).
      Called the local base to complain. If you don't have the tail number...GTFO. Right, like I'm going to see that at > mach1 right overhead.
      They said they have a policy of no flying under 2500 feet. Didn't mention that I live at 2200 feet above sea level. Definitions matter!

    5. Re:Ear-splitting sound by Anonymous Coward · · Score: 0

      When I was a child (maybe 6th grade), I had a walk home of around a mile (uphill... the way to the bus stop was naturally downhill - don't be weird).

      One day, we were shown "The Day After" as the Cold War was on, and I don't need to tell you that many of us were terrified. I may need to tell you that it was about a post-nuclear apocalypse... accurate or not, it did scare us (destroyed civilization, slow death by radiation, fighting over emaciated rats to eat, all that).

      Anyway, I'm walking home from the bus stop thinking about it, I hear a couple of sonic booms. I'm convinced they're nukes going off, and I start running home, waiting for the flash. I don't see it, but I'm scrambling and crying for maybe ten minutes waiting to die before I can get home. Eventually I didn't die, but it is to this day the most emotionally exhausting thing I've ever experienced.

      Strangely, I do miss them still... never heard one loud enough that I thought it would shatter windows though.

    6. Re:Ear-splitting sound by PPH · · Score: 1

      One day, we were shown "The Day After"

      Question: Who showed you this? And what do you think their motives were, if any?

      When you show something like this to a kid, you have to be careful and provide some discussion afterwards so as no to freak them out. Unless that was the idea.

      waiting for the flash

      I think that by the time I was 12, I had seen some films of nuclear tests. And I knew that you saw the flash first. And then you counted the seconds until the boom to figure out how far away it was. Also a cool thing to do with lightning.

      never heard one loud enough that I thought it would shatter windows though.

      They can if you live near an air force base and they go Mach 1 at something like 1000' AGL. Which is either an emergency scramble or an asshole pilot that's about to be switched to CAS for the rest of their career.

      --
      Have gnu, will travel.
    7. Re:Ear-splitting sound by Anonymous Coward · · Score: 0

      "Ear-splitting sound"

      and

      Please. Stop already.

      Why do you care what some idiot reporter says, who isn't even willing to sign their name to their phys.org article?

      The actual NASA scientist, Matt Kamlet, used no such phrase.

      Can't we even discuss the actual science here anymore?
      The first comment to get modded up to +5 has to be about how stupid reporters talk like stupid reporters and make up shit that isn't true?

      It's very sad times when such a large percentage of the population just today discovering reporters don't know what they are doing is somehow "insightful", yet they won't remember that fact through tomorrow :(

    8. Re:Ear-splitting sound by Anonymous Coward · · Score: 0

      If i had a vote, super-sonic flight should be discouraged, no BANNED outside of military use. noise pollution is absurd in modern earth.

      If i had a vote, I also happen to feel that aircraft flights above a certain decibel level (ie commercial levels) should be drastically reduced, again noise pollution is absurd already through flight corridors, and basically any major city which does not have a water-directional-approach.

      Mass-Airplane flights are HORRIBLE for the encirclement as well, before even calculating for noise pollution.

      More trains, more vacation and more 'road trips'

    9. Re:Ear-splitting sound by Anonymous Coward · · Score: 0

      I live in the mid-west and fighter jets have been practicing overhead for a while now. Most of the time it just sounds like distant thunder, but a few times it felt like someone rammed their truck into the house. The floor felt like I was on a trampoline and someone jumped next to me. It was less like a sound and more like what I image a shockwave is like.

  4. These were presumably conventional by jd · · Score: 1

    You'd need to perform a similar set of experiments with waverider airfoils, where the planes essentially surf the shockwave, to get a comprehensive picture.

    --
    It's a small world and it smells funny; I'd buy another if it wasn't for the money; Take back what I paid (SoM)
    1. Re:These were presumably conventional by pavon · · Score: 2

      It is worth mentioning that these pictures were just a test of their improved imaging system, and not intended to provide any new information yet.

    2. Re:These were presumably conventional by Anonymous Coward · · Score: 0

      Oh good because I thought this whole thing was pretty pointless. A fluid is a fluid and there is no need to do these dangerous stunts.

  5. This is why I read Slashdot by pz · · Score: 1

    THESE sorts of articles are what I want to see on Slashdot. Not the latest reason we need to cater to the perceived slights against one group or another.

    I read the article. The photos are indeed magnificent. Makes me want to understand more about how they plan on mitigating sonic boom.

    --

    Put my fist through my alarm clock with its ding-dong death inside my ear. - The Blackjacks.
  6. Putin yawns by Anonymous Coward · · Score: 0

    Russians have already been there and done that. Their hypersonic maneuverable weapons are many decades ahead.

  7. LIght source? by Anonymous Coward · · Score: 0

    The images usually use a point light source and a mirror to magnify the pressure waves' very slight change in diffraction index to get the cool images. How would they achieve either while in flight? I've never heard of it being done before.