The faster you go, the further aft the spike shifts. On the p-38 when the spike reached the far aft of the wing, it would lift the tail up causing transonic dives that ripped the tail off. On the x-1 Chuck Yeager watched the spike shift back into his ailerons and could barely hold control at mach .88. At mach .94 the spike hit the elevator and made it completely uncontrollable. The secret was to make the entire elevator movable with no tabs or hinges to get caught in the spike. Solving the ailerons was done by making the movable elevator work as elevons so that ailerons werent needed in transonic. Once you go fast enough (past mach 1) the spike is completely behind the aircraft and it flies smoothly again.
Nice one, that a perpendicular presure wave, it seems to be learning forward but its perpendiculsr to the surface at its point of origion, looks awsome
A very good aircraft to see this phenomena on is a Folker F28 - the shock happens just aft of the wing leading edge and is visible down most the span. Best observed if the sun is in front of the aircraft.
The Fokker F-28, a very good aircraft indeed for observing this. Because of its hypercritical airfoil, it suffered less at critical mach number than most passenger aircraft, and therefore could be safely taken deeper into shock-waves-on-the-wing territory than most. I was present when two pilots took this to the limit and beyond. I never found out if their comments that this was their last day with that airline (overheard on the destination jetway) were the inspiration or the expected result of their exploit. The account of that memorable flight is recorded in ruclips.net/video/E5_bV4lT5Pw/видео.html
@@gavinvalentino6002 Make sure it is dry weather aloft. These aircraft can be really dicey in icing conditions. The shock wave deposits ice aft of the de-icing equipment in the wing, leading to build up, leading to disaster.
Otta see what a 757 running full out has for micro shock wave. This super plane likely could get through sound barrier completely. Years ago, when flying AA 757 that was running hard to get time back, the person in the window seat said the same thing. Looked like “heat waves” many spots on cowl, and wing.
@@johnross6314 I've seen those micro shock waves on the 757 on short-hauls in the tropics, where the condensation makes them more obvious. It has the same supercritical airfoil as the 767 pictured in the video. Certainly it should remain controllable through the Critical Mach Number, and it has a better chance of punching through the CMN than the widebody 767.
I observed similar on the wing of a 737 one time. Took videos of it on my phone and showed to a friend of mine who is an aero engineer. He said the same thing. Density change, trans-sonic region, very cool!
It's caused by air flowing faster over the wings of the 737 than the ambient air, meaning that the air over the top of the aerofoil is moving faster than mach 1.0, but the plane isn't necessarily. It's a really cool effect.
@@bobjohn2000 Not necessarily. It may be something simpler, like two regions with different temperatures that causes the simple phenomenon of light refraction.
@@YuriRosas_ - Nope, densities. While density differences due to temperature can cause visual distortion, that’s not what’s happening here. Temperature would not produce one well defined distortion, that’s a normal shockwave due to the airflow abruptly transitioning from local supersonic flow to subsonic.
@@christianlabanca5377 Yes, I know. Cause and effect. "It's really windy outside." "How do you know? You're inside." "Because I can see through the window that tree is about to be blown down."
Thankyou……. I saw this phenomenon on a Qantas 747-238B about 40-45 years ago and I could only describe it as looking like a thin jet of heat wobble or like a thin strip of cellophane protruding up from the engine nacelle and no one, not even engineers could tell from my description what it was, the closest they came was to say perhaps it was a form of St Elmo’s fire but I’ve seen that and that’s not what it was……. You have solved a 45 year old mystery for me 😊 By the way, my Dad worked for Qantas and so did I and I moved on to other companies but spent 37 years in aviation and this old mystery gets solved by a RUclips video LOL
When I flew the MD80, we could feel buffeting from transonic flow at the engine pylons at around M.82 all the way up in the cockpit. Back it off to M.78 or so and it would stop. Thanks for posting this, what a cool video!
Pretty common to see along the span of any aircraft flying at high-subsonic Mach and with the light at your back. There, it appears as a thin, linear shadow near the surface and along the span at or near mid-chord, dancing fore-and-aft somewhat. Pretty cool...thanks for posting!
Except it is. But also isn't. Totally what's going on. But something nearly all the people in here need to remember is it's normal. Even visible on skydiving planes that are nowhere near M1.0.
Captain was probably a commuter and had a flight home to catch! That’s a nice shockwave, it forms because the air forced over the engine lip is accelerated.
The prevatanater frop coalinator was designed to prevent this, but as you can see the overwhelming friction from the air hyperblurrifies and surrounds 3.7° photoneutems.
Call me silly but I've been a jet engine mechanical engineer for almost three decades. The aluminum leading-edge ring on the jet engine, nacelle, that happens to be a Pratt Whitney, has anti-ice, which is engine bleed air. You can't pump bleed air into the nacelle without having a place for it to go. You're simply seeing engine bleed air dumping out of one of several ports, or holes, located in different sections of the nacelle. While the air being dumped overboard may be transonic, the aircraft, especially on initial descent, is nowhere near transonic. The 767 has a cruise of between Mach .82 and Mach .84. It definitely doesn't accelerate above those numbers on decent as the autopilot/autothrottle is pulled back damn near to the stops. Decent is in the mid Mach .70's
At the risk of sounding stupid.... So, is what the video shows a transonic shockwave? Why isn't the bleed air being sucked into the engine? Is the bleed air spilling out because the engines are at or near idle and not pulling as much air in? Thanks.
- So riddle me this: Why are they operating the intake anti-ice in completely clear air? Your answer doesn’t make sense for several reasons, that being chief among them. You’re also incorrect on the descent profile, we don’t slow down to descend, you descend at at speed at or close to cruise, until you transition to indicated airspeed, usually in the just below FL300. Also, 767 Econ cruise isn’t that fast. Both the 757 and 767 were built after the 70s oil crisis, and cruised slower than earlier generations of airliners for greater efficiency; Mach 0.80 is a more typical cruise speed. The 767 is definitely slower than earlier wide-bodies. The DC-10 cruised at M.83, the long bodied L-1011’s at M.84, and the B-747 was the speed demon at M.86. Yes, they could all go faster (Mmo on the L-1011 was M.90), but that’s now where we cruise or descend for efficiency. www.boeing.com/farnborough2014/pdf/BCA/bck-767_5_13_2014.pdf
@@bradcrosier1332 the same reason they they keep engine anti-ice and engine ignitors on an take off, even in clear air conditions. Procedures... They are put in place for a reason, i.e., it has probably iced in clear-air at some point in the past. Aviation doesn't do things willy nilly. No gray areas. Black. White. Simple...
@@hook2442 - You clearly have ZERO idea what you are talking about! We DO NOT have the anti-ice on during takeoff in clear air conditions! If you really had any understanding of what you’re talking about, you’d know that extracting bleed air for the engine anti-ice reduces the power available on takeoff. If there are icing conditions, absolutely it is used - but not in clear air for no reason! I have over thirty years experience operating turbojet transport aircraft similar to the B-767 (including its sister aircraft, the B-757). Feel free to look me up in the FAA airman registery, I’m right there. It’s online and free. Let’s see evidence of your credentials. amsrvs.registry.faa.gov/airmeninquiry/
I once witnessed a transonic shockwave on the wing of the CRJ as it made a fast descend from altitude for landing. I was sitting next to the window looking down at about 50% chord. I first felt the transonic shockwave as a very slight rumble through the seat which caused me to look outside. The light angle allowed the shockwave to appear and it danced back and forth just below the window, and sometime disappeared. Every time it appeared, there was rumble vibration that was associated with it.
a friend of mine who flew b-17's over germany in wwII went on to fly fighter jets in korean war said the first time he approached speed of sound the plane was shakey and controlls were stiff, then when he passed the speed of sound all of a sudden the plane was riding like a cadillac and handling smooth as silk
Remember watching this phenomenon over the wing on 727s back in the day, esp when descending. Was fun and interesting to observe where they would form and move.
Pretty cool to think that if you manipulate geometry and air in a certain configuration you can make a lense or distortion with the light passing through.
Neat!. I've also seen, at the right angle, light from the sun get distorted over the low pressure over the wing and cast the equivalent of a shadow over the entire length of the wing... right there, a line dancing and slightly changing shapes as you cruise along and high speed... very mesmerizing.
I subscribed immediately after reading the most concise description I’ve seen to date. It told me what to look for, exactly where I could see it, and a very relatable presentation of the physics at play during this phenomenon.
I think it’s a normal effect that at some points of surfaces of wings, fuselage ect. some local airflow is faster than speed of sound even if the hole plane is slower what we definitely have here with an subsonic flyin’ 767.
Shock waves and aircraft controls is tricky business. The SR-71 has a movable (almost 3 feet) cone at the engine intake to control the position of the shock wave so that the air is always enters sub sonic if I understand that correctly.
Great video. I get a kick out of uninformed journalists and talking heads on TV that say, 'the Blue Angels demonstrated supersonic flight when they made this pass in front of the crowd on Sunday...' They point to a pic with the saucer shaped pressure wave perpendicular to the aircraft visible due to condensation of moisture in the ambient air.
The air velocity flowing over the engine inlet, is almost approaching the local speed of sound (critical Mach number - Mach Crit.) This causes a sudden compression of the airflow, thus forming some sort of "barrier" perpendicular to the airflow.
Wow! The airplane has caught up with its own sound waves and is compressing them to form the boundary region to supersonic flight. This shock wave destroyed the first airplanes that dared to go this fast in the early development of faster airplanes in the 1930s during the "streamlining craze" to make planes go faster. It was Chuck Yeager, who in 1947--who was first to break through that boundary with sustained super sonic flight that did not destroy the aircraft. The compression waves change the refractive index of air that makes the shockwave visible to the eye. Amazing! I have never thought to look for it, but now I will! Awesome!
I think it might be a shear zone due to being an engine nacelle. The boundary layer is being pushed along with the plane but the engine intake is vacuuming in an enormous amount of air just in front of it. I think you’re seeing through an edge but I’ll bet it circles the engine inlet.
That's a very interesting thought. It's not what you describe and I'll explain why, but it does in fact circle the nacelle, and also appears on all sorts of places around the aircraft surface like a circle around the nose and along the middle of the wings. The air is accelerating over the curved surface by being forced suddenly out of the way, and as the aircraft approaches speeds close to sound, some areas of the aircraft have localized airflows that briefly jump into transonic speed. The sound waves cannot exceed that speed exactly where it crosses over to transonic speeds, so the waves pile up in a compressed cone at that precise speed. The vacuuming phenomenon is not far off from reality, and it would not be the case when the aircraft is at cruising speeds. The air pressure is actually going up as the inlet cone, nacelle, and incoming air all compress air ahead of the first stage compressor blades. In fact, if there was a vacuum, that would be really bad because the compressor stages would have to get the air back up to ambient pressure and then compress it from there. Very inefficient. Instead the air is squeezed by the surrounding surfaces as a free compression stage. And actually any shear in the nacelle could lead to compressor stalls, so nacelles are thicker and round to prevent shear inside the nacelle. Shearing boundaries are never that well defined. Shearing is full of vortices and very, very turbulent and messy, with it getting messier when it's more energetic. If there was shearing from a powerful suction from the engine, it would also be on the inside of the nacelle, beginning at the leading edge or behind it on the inside, and then form a funnel shape inside the nacelle with turbulent flow in a ring around the nacelle interior surface, and smooth flow entering the center. Picture a thin nacelle shape, and then picture it pointed inward, and then picture it pointed so far in that it was just a flat plate with a hole in it. The air entering in the hole is clean and the air around it is turbulent. The shear zone begins at the edge of the hole and goes inside. If the suction was higher, the shear wouldn't go outside the hole, it would just get more turbulent and intense. But it never goes past the sharpest edge of surface. This is the exact reason subsonic aircraft are round, actually.
For the dummies: the aircraft might have reached Critical Mach Number. Although, the aircraft is not supersonic, the flow over it is supersonic. Thus, the shockwave was observed.
Whenever I had a window seat just behind the wing, I always wondered why the scenery directly below always looked a bit blurry. Originally I thought it was imperfections in the window but I now know it's due to turbulence produced the the exhaust of the gas turbine that's at the core of the engine.
It’s the compressed water vapor in the air which distorts the natural pressure wave giving a visual clue to the compression/decompression zones at the juncture point.
Seen on the wing of a 747 cruising at altitude, too. In fact most airliners have a visible shock wave visible SOMEWHERE on the wings or engine nacelles, when at cruise altitude and cruise speed.
You're seeing a distortion in the air, caused by a backup of fluids, backing up around a disruption in the laminar flow. The distortion is created by seeing this backup during sub-sonic flight. Visual distortion is caused by liquid and build-up of molecules, hydrogen, oxygen, miniature amounts of water vapor, creating this sub-sonic bubble. If the aircraft was travelling above Mach 1 at altitude, this laminar flow disruption would change dramatically, or move to another location of the airplane.. however, it would be virtually impossible for a commercial airliner to travel supersonic, due to the design of the engines, and the shape of the inefficient wing. The plane would likely come apart due to massive overspeed friction, causing total in-air breakup.. but that's a whole different topic. Good catch on the video!
At first I thought it was accelerated air being sucked into the jet like that point on the cowling that is dangerous to walk past when an engine is running on the ground...good to find out what it really is. Great post.
One attempt to explain: Imagine a bar with a D profile laid on it's side, flat side down, and being propelled through the air like a wing. The air that goes over the top "wants" to meet back up with the air that flows underneath. Let's say this profile is 1.5x longer over the top than the flat bottom side. This means the air going over the top must travel 1.5 times as far as the air going underneath, or corollary to that, 1.5 times faster. If the speed of sound in the air you're in is 700mph, and you are traveling at 500mph, the air flowing over the top of your D-shaped "wing" needs to go 750mph, but it can't. So, there's a shock front formed where the air exceeds 700mph, and a large turbulent/low pressure zone where other air attempts to fill the places where oncoming air can't make it in time.
Your explanation is excellent except for one small essentially insignificant aspect... The extremely popular "Equal transit time" theory is no longer an accurate explanation. It's not your fault that it was told to you. It is a very common misconception. In fact, I think I learned it from a book 20 years ago myself. The air over the top doesn't actually need or want to meet up with the air under the bottom. The curvature of the upper surface accelerates the airflow resulting in low pressure/"lift" (due to Bernoulli effect) which also creates downwash off the trailing edge of the wing. Your explanation of how the acceleration aspect of Bernoulli effect causes the shockwave is excellent.
@@StratMatt777 "The air over the top doesn't actually need or want to meet up with the air under the bottom. " *Some* air will always want to fill that spot where the upper surface flow is disturbed, and fluid dynamics, inertia, reynolds number, too early to brain but yeah, it's not really the 'air buddy system' but it's close enough for 99.99% of explanations.
I've seen them on the wing of a 747. The wave is a little weird to watch, they shift forward or backward fairly slowly. Until you realize just how fast that wing is moving forward,
But that’s what happens, a high point of pressure along the fuselage but most importantly the wings. That’s why the horizontal tail is so important at these speeds. It controls the pressure points along the entire airframe as speed enters the transonic range. The tail experiences the same issues as the main wing with its own shock wave. That’s why it’s both so large in area and an inverted airfoil.
I don't think I've ever actually see this phenomenon myself. I've been on plenty of flights over or near the wing/engines... guess I just haven't had the right conditions. Awesome video of it.
This is not the aircraft flying close to supersonic but rather the airflow at the leading edge of the inlet accelerating to near sonic speed as it passes. The inlet cowl is kind of shaped like a small airfoil and inside the inlet is a low pressure zone that would/could create an small zone of near supersonic airflow. I'm sure there is an engineer that can explain this better than I.
The faster you go, the further aft the spike shifts. On the p-38 when the spike reached the far aft of the wing, it would lift the tail up causing transonic dives that ripped the tail off. On the x-1 Chuck Yeager watched the spike shift back into his ailerons and could barely hold control at mach .88. At mach .94 the spike hit the elevator and made it completely uncontrollable. The secret was to make the entire elevator movable with no tabs or hinges to get caught in the spike. Solving the ailerons was done by making the movable elevator work as elevons so that ailerons werent needed in transonic. Once you go fast enough (past mach 1) the spike is completely behind the aircraft and it flies smoothly again.
I was just going to point this out. You beat me to it lol
Thus, the T-38, F-104, and SR-71.
Swept wing also made a huge difference in controllability too.
I think he wrote about this in his autobiography.....Laurie
I always forget how much of a monster the P-38 was…
Nice one, that a perpendicular presure wave, it seems to be learning forward but its perpendiculsr to the surface at its point of origion, looks awsome
John Michael Twist hahaha thanks to my lesson about intake wave formations some weeks ago:)
That's normal.
@@Radio_Flakes very funny
Transonic airflow around the engine nacelles...good eye!
@@Radio_Flakes dude, im not even criticizing you, why are you so defensive
A very good aircraft to see this phenomena on is a Folker F28 - the shock happens just aft of the wing leading edge and is visible down most the span. Best observed if the sun is in front of the aircraft.
The Fokker F-28, a very good aircraft indeed for observing this. Because of its hypercritical airfoil, it suffered less at critical mach number than most passenger aircraft, and therefore could be safely taken deeper into shock-waves-on-the-wing territory than most. I was present when two pilots took this to the limit and beyond. I never found out if their comments that this was their last day with that airline (overheard on the destination jetway) were the inspiration or the expected result of their exploit. The account of that memorable flight is recorded in ruclips.net/video/E5_bV4lT5Pw/видео.html
Can I request one for my next American Airlines flight?
@@gavinvalentino6002 Make sure it is dry weather aloft. These aircraft can be really dicey in icing conditions. The shock wave deposits ice aft of the de-icing equipment in the wing, leading to build up, leading to disaster.
Otta see what a 757 running full out has for micro shock wave. This super plane likely could get through sound barrier completely. Years ago, when flying AA 757 that was running hard to get time back, the person in the window seat said the same thing. Looked like “heat waves” many spots on cowl, and wing.
@@johnross6314 I've seen those micro shock waves on the 757 on short-hauls in the tropics, where the condensation makes them more obvious. It has the same supercritical airfoil as the 767 pictured in the video. Certainly it should remain controllable through the Critical Mach Number, and it has a better chance of punching through the CMN than the widebody 767.
I observed similar on the wing of a 737 one time. Took videos of it on my phone and showed to a friend of mine who is an aero engineer. He said the same thing. Density change, trans-sonic region, very cool!
It's caused by air flowing faster over the wings of the 737 than the ambient air, meaning that the air over the top of the aerofoil is moving faster than mach 1.0, but the plane isn't necessarily. It's a really cool effect.
@@bobjohn2000 Not necessarily. It may be something simpler, like two regions with different temperatures that causes the simple phenomenon of light refraction.
@@YuriRosas_ - Nope, densities. While density differences due to temperature can cause visual distortion, that’s not what’s happening here. Temperature would not produce one well defined distortion, that’s a normal shockwave due to the airflow abruptly transitioning from local supersonic flow to subsonic.
Well, today I was made aware of this phenomenon, thanks for posting. There's a science to everything.
Almost… everything :)
Friend: "You can't 'see' compressed air!"
Me: Shows him Pressure Waves caught on video.
Blow his mind with Schlerinen imaging
Technically you're seeing the discontinuity, not the compressed air
@@christianlabanca5377 Yes, I know. Cause and effect.
"It's really windy outside."
"How do you know? You're inside."
"Because I can see through the window that tree is about to be blown down."
@@SternLX " Back To Reality "
... wait Dorothy, that tornado looks kinda real
... have you seen Toto ?
... they stopped holding concerts
Your friend is probably a "climate change" fanatic as well.
I need to start paying closer attention when I have a window seat. That was cool, and I have probably seen it before, but never knew it.
Thankyou……. I saw this phenomenon on a Qantas 747-238B about 40-45 years ago and I could only describe it as looking like a thin jet of heat wobble or like a thin strip of cellophane protruding up from the engine nacelle and no one, not even engineers could tell from my description what it was, the closest they came was to say perhaps it was a form of St Elmo’s fire but I’ve seen that and that’s not what it was……. You have solved a 45 year old mystery for me 😊
By the way, my Dad worked for Qantas and so did I and I moved on to other companies but spent 37 years in aviation and this old mystery gets solved by a RUclips video LOL
Thank you for posting! I’ve seen this on the wing before too. Most folks never notice this stuff.
I remember being able to see that on the upper wing surface of a 727, there would be a light shadow as well.
The shadow is a good way to see them.
Yes. I've seen it dance around on a 737 wing surface. fascinating.
727 is/was one of the loudest aircraft for its capability
When I flew the MD80, we could feel buffeting from transonic flow at the engine pylons at around M.82 all the way up in the cockpit.
Back it off to M.78 or so and it would stop.
Thanks for posting this, what a cool video!
No thanks for posting this.
What crap.. Most modern Jets run at 0.84 Mach.... Don't the engineers figure it out the md80 only flys smooth at Mach 0.78??
@@sarahconner9433 in what way is the md80 a modern jet to you
@@camhackett44 ? More words ??; I don't understand??
Pretty common to see along the span of any aircraft flying at high-subsonic Mach and with the light at your back. There, it appears as a thin, linear shadow near the surface and along the span at or near mid-chord, dancing fore-and-aft somewhat. Pretty cool...thanks for posting!
Seeing shockwaves form in transonic fight is absolutely awesome
I love non-clickbait stuff like this. Keep it up man! And nice observation. I would’ve missed that.
Except it is. But also isn't.
Totally what's going on. But something nearly all the people in here need to remember is it's normal. Even visible on skydiving planes that are nowhere near M1.0.
That looks more like a warp in the fabric of the time-space continuum, but that's just me. :)
Doorway for the Foo Fighters.
Warped Space Time
... Continuing to Continue
An eddy in the space time continuum.
That engine is about to hit Jake Gyllenhaal's bed
at 88 mph :)
Had to watch the video a couple of times ... but finally saw it !
Fantastic !!
Captain was probably a commuter and had a flight home to catch! That’s a nice shockwave, it forms because the air forced over the engine lip is accelerated.
nice! with all the flying i had done(707, CV990, DC-10 ) i had never seen this effect.
That is a great spot and really cool. A good visual demonstration of the phenomena.
WOOW! That is amazing video! I have never tought that it's possible to see it by naked eye...!
this is awesome. i'm glad i'm not an airplane physicist, and i'm more glad there are qualified people who are.
The prevatanater frop coalinator was designed to prevent this, but as you can see the overwhelming friction from the air hyperblurrifies and surrounds 3.7° photoneutems.
Call me silly but I've been a jet engine mechanical engineer for almost three decades. The aluminum leading-edge ring on the jet engine, nacelle, that happens to be a Pratt Whitney, has anti-ice, which is engine bleed air.
You can't pump bleed air into the nacelle without having a place for it to go.
You're simply seeing engine bleed air dumping out of one of several ports, or holes, located in different sections of the nacelle. While the air being dumped overboard may be transonic, the aircraft, especially on initial descent, is nowhere near transonic.
The 767 has a cruise of between Mach .82 and Mach .84.
It definitely doesn't accelerate above those numbers on decent as the autopilot/autothrottle is pulled back damn near to the stops. Decent is in the mid Mach .70's
At the risk of sounding stupid.... So, is what the video shows a transonic shockwave? Why isn't the bleed air being sucked into the engine? Is the bleed air spilling out because the engines are at or near idle and not pulling as much air in? Thanks.
- So riddle me this: Why are they operating the intake anti-ice in completely clear air? Your answer doesn’t make sense for several reasons, that being chief among them.
You’re also incorrect on the descent profile, we don’t slow down to descend, you descend at at speed at or close to cruise, until you transition to indicated airspeed, usually in the just below FL300.
Also, 767 Econ cruise isn’t that fast. Both the 757 and 767 were built after the 70s oil crisis, and cruised slower than earlier generations of airliners for greater efficiency; Mach 0.80 is a more typical cruise speed. The 767 is definitely slower than earlier wide-bodies. The DC-10 cruised at M.83, the long bodied L-1011’s at M.84, and the B-747 was the speed demon at M.86. Yes, they could all go faster (Mmo on the L-1011 was M.90), but that’s now where we cruise or descend for efficiency.
www.boeing.com/farnborough2014/pdf/BCA/bck-767_5_13_2014.pdf
@@bradcrosier1332 the same reason they they keep engine anti-ice and engine ignitors on an take off, even in clear air conditions.
Procedures...
They are put in place for a reason, i.e., it has probably iced in clear-air at some point in the past. Aviation doesn't do things willy nilly. No gray areas. Black. White. Simple...
@@hook2442 - You clearly have ZERO idea what you are talking about!
We DO NOT have the anti-ice on during takeoff in clear air conditions! If you really had any understanding of what you’re talking about, you’d know that extracting bleed air for the engine anti-ice reduces the power available on takeoff. If there are icing conditions, absolutely it is used - but not in clear air for no reason!
I have over thirty years experience operating turbojet transport aircraft similar to the B-767 (including its sister aircraft, the B-757). Feel free to look me up in the FAA airman registery, I’m right there. It’s online and free. Let’s see evidence of your credentials.
amsrvs.registry.faa.gov/airmeninquiry/
I once witnessed a transonic shockwave on the wing of the CRJ as it made a fast descend from altitude for landing. I was sitting next to the window looking down at about 50% chord. I first felt the transonic shockwave as a very slight rumble through the seat which caused me to look outside. The light angle allowed the shockwave to appear and it danced back and forth just below the window, and sometime disappeared. Every time it appeared, there was rumble vibration that was associated with it.
I did not know about this phenomenon until your post. Thanks.
My mother could make a shoe do that.
That’s goddamn funny I don’t care who you are.
😂
Initially I was expecting this to be a typical vapour cloud formation on winglets.
But I'm glad I was wrong.
Short video, to the point, no BS, clean camera.
Good Video. Liked.
That's amazing! Good spotting, and filming!
Thank you, for both the video and the in-depth explanation.
a friend of mine who flew b-17's over germany in wwII went on to fly fighter jets in korean war said the first time he approached speed of sound the plane was shakey and controlls were stiff, then when he passed the speed of sound all of a sudden the plane was riding like a cadillac and handling smooth as silk
Remember watching this phenomenon over the wing on 727s back in the day, esp when descending. Was fun and interesting to observe where they would form and move.
Wow! Thank you for this. I will look for this and point this out. I've only ever seen that in photographs. So cool thanks.
Pretty cool to think that if you manipulate geometry and air in a certain configuration you can make a lense or distortion with the light passing through.
Neat!.
I've also seen, at the right angle, light from the sun get distorted over the low pressure over the wing and cast the equivalent of a shadow over the entire length of the wing... right there, a line dancing and slightly changing shapes as you cruise along and high speed... very mesmerizing.
came here expecting a P-G cloud, left extremely satisfied. a+ would watch 100 more times
ruclips.net/video/bELu-if5ckU/видео.html old, im certain outdated, but a good basic intro
Happy Nacelle and good cheer to you all this holiday season.
Sometimes I see two standing shockwaves over the wings and engines, one in the front of the wing and the other in the back!
I subscribed immediately after reading the most concise description I’ve seen to date. It told me what to look for, exactly where I could see it, and a very relatable presentation of the physics at play during this phenomenon.
Absolutely ! I saw it many years ago on the wing of a Boeing 707 ...
That was the Gremlin on the wing, the one Kirk saw in "Nightmare at 20,000 Feet"
Excellent description. Thank you.
Looks kind of like a heat wave. Neat looking.
I think it’s a normal effect that at some points of surfaces of wings, fuselage ect. some local airflow is faster than speed of sound even if the hole plane is slower what we definitely have here with an subsonic flyin’ 767.
oh well this popped up out of nowhere. That's so cool!
Shock waves and aircraft controls is tricky business.
The SR-71 has a movable (almost 3 feet) cone at the engine intake to control the position of the shock wave so that the air is always enters sub sonic if I understand that correctly.
Great video. I get a kick out of uninformed journalists and talking heads on TV that say, 'the Blue Angels demonstrated supersonic flight when they made this pass in front of the crowd on Sunday...' They point to a pic with the saucer shaped pressure wave perpendicular to the aircraft visible due to condensation of moisture in the ambient air.
The air velocity flowing over the engine inlet, is almost approaching the local speed of sound (critical Mach number - Mach Crit.) This causes a sudden compression of the airflow, thus forming some sort of "barrier" perpendicular to the airflow.
There's 40 seconds I'll never get back. Yep... I bailed early.
Interesting, never noticed that before.
I thought this would suck. It didn't! Thanks! I will try to improve my view on humanity.
One of the best detail ever recorded !
Very well spotted!!!!
I saw that one time on an a320. I wondered what it was called. Amazing how it bends light.
Great catch on video. Well done and explained.
Wow! The airplane has caught up with its own sound waves and is compressing them to form the boundary region to supersonic flight. This shock wave destroyed the first airplanes that dared to go this fast in the early development of faster airplanes in the 1930s during the "streamlining craze" to make planes go faster. It was Chuck Yeager, who in 1947--who was first to break through that boundary with sustained super sonic flight that did not destroy the aircraft. The compression waves change the refractive index of air that makes the shockwave visible to the eye. Amazing! I have never thought to look for it, but now I will! Awesome!
I was expecting a condensation cone in typical fashion, but this does seem like a pressure wave.
That’s shocking!
Well done for capturing a normal shock wave. Most people don't reliase that some parts of the aircraft are travelling faster than the actual speed.
I think it might be a shear zone due to being an engine nacelle. The boundary layer is being pushed along with the plane but the engine intake is vacuuming in an enormous amount of air just in front of it. I think you’re seeing through an edge but I’ll bet it circles the engine inlet.
That's a very interesting thought. It's not what you describe and I'll explain why, but it does in fact circle the nacelle, and also appears on all sorts of places around the aircraft surface like a circle around the nose and along the middle of the wings. The air is accelerating over the curved surface by being forced suddenly out of the way, and as the aircraft approaches speeds close to sound, some areas of the aircraft have localized airflows that briefly jump into transonic speed. The sound waves cannot exceed that speed exactly where it crosses over to transonic speeds, so the waves pile up in a compressed cone at that precise speed.
The vacuuming phenomenon is not far off from reality, and it would not be the case when the aircraft is at cruising speeds. The air pressure is actually going up as the inlet cone, nacelle, and incoming air all compress air ahead of the first stage compressor blades. In fact, if there was a vacuum, that would be really bad because the compressor stages would have to get the air back up to ambient pressure and then compress it from there. Very inefficient. Instead the air is squeezed by the surrounding surfaces as a free compression stage. And actually any shear in the nacelle could lead to compressor stalls, so nacelles are thicker and round to prevent shear inside the nacelle. Shearing boundaries are never that well defined. Shearing is full of vortices and very, very turbulent and messy, with it getting messier when it's more energetic. If there was shearing from a powerful suction from the engine, it would also be on the inside of the nacelle, beginning at the leading edge or behind it on the inside, and then form a funnel shape inside the nacelle with turbulent flow in a ring around the nacelle interior surface, and smooth flow entering the center. Picture a thin nacelle shape, and then picture it pointed inward, and then picture it pointed so far in that it was just a flat plate with a hole in it. The air entering in the hole is clean and the air around it is turbulent. The shear zone begins at the edge of the hole and goes inside. If the suction was higher, the shear wouldn't go outside the hole, it would just get more turbulent and intense. But it never goes past the sharpest edge of surface. This is the exact reason subsonic aircraft are round, actually.
That's bloody awesome
Saw this on a first generation 747. Local airspeed over some surfaces can be much faster than indicated airspeed.
Hey, there's the Red river!!
👍I'm watching for this next time💨
That is freaking awesome!
Well captured.
Awesome catch!
Pretty cool, nice observation
It appears to have a refractive lensing effect, in looking through it at the ground.
That is so cool you noticed that, good eye. (And I thought I was the only one who notice things like that ...lol)
For the dummies: the aircraft might have reached Critical Mach Number.
Although, the aircraft is not supersonic, the flow over it is supersonic. Thus, the shockwave was observed.
At least somebody studied hard. Thank you comment nation
Whenever I had a window seat just behind the wing, I always wondered why the scenery directly below always looked a bit blurry. Originally I thought it was imperfections in the window but I now know it's due to turbulence produced the the exhaust of the gas turbine that's at the core of the engine.
It’s the compressed water vapor in the air which distorts the natural pressure wave giving a visual clue to the compression/decompression zones at the juncture point.
Negative, the the multiple explanations in the thread.
I had to force the definition to 1080p, maximise the screen and use a magnifying glass...I finally felt like a WW2 test pilot in a dive...
Great job capturing this on camera.
Wow, thanks for sharing, very interesting.
Very cool-- good catch!!
Seen on the wing of a 747 cruising at altitude, too. In fact most airliners have a visible shock wave visible SOMEWHERE on the wings or engine nacelles, when at cruise altitude and cruise speed.
This is very interesting. Thanks
That's pretty cool.
That's way total cool!
You're seeing a distortion in the air, caused by a backup of fluids, backing up around a disruption in the laminar flow. The distortion is created by seeing this backup during sub-sonic flight. Visual distortion is caused by liquid and build-up of molecules, hydrogen, oxygen, miniature amounts of water vapor, creating this sub-sonic bubble. If the aircraft was travelling above Mach 1 at altitude, this laminar flow disruption would change dramatically, or move to another location of the airplane.. however, it would be virtually impossible for a commercial airliner to travel supersonic, due to the design of the engines, and the shape of the inefficient wing. The plane would likely come apart due to massive overspeed friction, causing total in-air breakup.. but that's a whole different topic. Good catch on the video!
So cool to see
Fantastic video description! I wish more people included this much detail.
At first I thought it was accelerated air being sucked into the jet like that point on the cowling that is dangerous to walk past when an engine is running on the ground...good to find out what it really is. Great post.
Wow! Excellent! I had never seen this. Better than any graph!
I've seen that a few times but knew what it was... Kinda cool when you see it dance a wee bit! The light gotta be right though!
One attempt to explain:
Imagine a bar with a D profile laid on it's side, flat side down, and being propelled through the air like a wing. The air that goes over the top "wants" to meet back up with the air that flows underneath. Let's say this profile is 1.5x longer over the top than the flat bottom side. This means the air going over the top must travel 1.5 times as far as the air going underneath, or corollary to that, 1.5 times faster. If the speed of sound in the air you're in is 700mph, and you are traveling at 500mph, the air flowing over the top of your D-shaped "wing" needs to go 750mph, but it can't. So, there's a shock front formed where the air exceeds 700mph, and a large turbulent/low pressure zone where other air attempts to fill the places where oncoming air can't make it in time.
Nice attempt but can't understand 😂
Thank you.
Your explanation is excellent except for one small essentially insignificant aspect... The extremely popular "Equal transit time" theory is no longer an accurate explanation.
It's not your fault that it was told to you. It is a very common misconception. In fact, I think I learned it from a book 20 years ago myself.
The air over the top doesn't actually need or want to meet up with the air under the bottom.
The curvature of the upper surface accelerates the airflow resulting in low pressure/"lift" (due to Bernoulli effect) which also creates downwash off the trailing edge of the wing.
Your explanation of how the acceleration aspect of Bernoulli effect causes the shockwave is excellent.
@@StratMatt777 "The air over the top doesn't actually need or want to meet up with the air under the bottom. "
*Some* air will always want to fill that spot where the upper surface flow is disturbed, and fluid dynamics, inertia, reynolds number, too early to brain but yeah, it's not really the 'air buddy system' but it's close enough for 99.99% of explanations.
@@mfree80286 I agree. I honestly wasn't intending to be a judgmental prick! :)
Wow, that’s really cool.
Thanks RUclips algorithm 👍
That’s cool! So, the plane must have been relatively close to supersonic to create this…500-600 mph or so??
AWESOME, well caught thank you for posting this.
I've seen them on the wing of a 747. The wave is a little weird to watch, they shift forward or backward fairly slowly. Until you realize just how fast that wing is moving forward,
But that’s what happens, a high point of pressure along the fuselage but most importantly the wings. That’s why the horizontal tail is so important at these speeds. It controls the pressure points along the entire airframe as speed enters the transonic range. The tail experiences the same issues as the main wing with its own shock wave. That’s why it’s both so large in area and an inverted airfoil.
This is awesome!
I don't think I've ever actually see this phenomenon myself. I've been on plenty of flights over or near the wing/engines... guess I just haven't had the right conditions. Awesome video of it.
That's cool as hell.
That's so cool!
This is not the aircraft flying close to supersonic but rather the airflow at the leading edge of the inlet accelerating to near sonic speed as it passes. The inlet cowl is kind of shaped like a small airfoil and inside the inlet is a low pressure zone that would/could create an small zone of near supersonic airflow. I'm sure there is an engineer that can explain this better than I.
this blows my mind
Saw this over the wing of a 757 once. The shock wave actually cast a shadow on the wing.