Some cool aerodynamic stuff: Shockwave Shadow Photo

So recently I discovered (thanks to a cool captain I was with) that you could actually see the shadow from the shock wave (from the separation of the supersonic flow vs subsonic air flow) that forms on an aircraft's wing at high speed in the right conditions.

From what I've read you can see this due to how light is diffracted as it passes through the shock wave if the conditions are right. I've been trying to capture it for the last few weeks but the conditions just weren't right until earlier today on a reposition flight while we were heading to the Southwestern part of the US. We were cruising at Mach .92 at 43,000 ft when I snapped these photos. The quality isn't that great due to the glare off the wing from the early morning light but you can see it clearly here.

Anyways figured that this was pretty cool and that most aviation enthusiasts here in the transportation section would appreciate seeing this so I figured it was worth sharing.

That's interesting. I'm guessing that it moves toward the front of the wing when you slow down?

What type of aircraft? I don't believe commercial airliners fly at that speed.

I am near LB can I catch a ride?

PhotosGuy wrote in post #13609341
That's interesting. I'm guessing that it moves toward the front of the wing when you slow down?

Yep. It'll move forward as you slow and further aft as your speed increases. Here's a little diagram I found on wiki to show what you're seeing: http://en.wikipedia.or​g …:FAA-8083-3A_Fig_15-9.png

DaveKosiba wrote in post #13609359
What type of aircraft? I don't believe commercial airliners fly at that speed.

It's a Cessna Citation X. The only airliner that's still flying today that comes close to that is a 747-400 I believe. Though I think the 727 got pretty fast but not sure how fast.

sigma pi wrote in post #13610033
I am near LB can I catch a ride?

Hah not an option unfortunately. Plus our planes are all over the place and I just happen to live in LB.

Given the speed of sound is approx. 768 mph, and a 727-200 cruises at 537 mph (0.7 mach) and the 747-400 max cruise speed is 0.76 mach, I'd be surprised if I saw shock waves on the wing of one of those while I was in the passenger seat.

At 0.92 mach your Citation X would be at or very near its spec maximum velocity (depending on windspeed of course) and must be approaching the speed of sound in order for you to see the shock waves. So that is very cool and so much faster than I've ever been.

I don't know much about planes, or how fast a commercial airliner could go, but I do love seeing the condensation trails over the wing when I look out the window (obviously what I've seen is not the same as you), but seeing that always makes me think about my Fluid Dynamics and Thermal Design classes back in college.

Cool shots of a phenomenon that occurs on more airplanes than you think. Airflow goes supersonic over most airfoils without the airplane itself going supersonic speeds. Air travels faster over the top of the wing and can show a shockwave about mid wing approx .82mach, which is the speed of most airliners. The faster you travel the farther back on the wing the shock wave appears until at supersonic when it's at the trailing edge of the wing. You may not recognize the shockwave outside an airliner, and the compression is also a function of speed, altitude, temperature, etc.

I hate to disagree with the above post but your speeds are way too slow. The 727's cruise was .81 with a max of .90, but to save fuel they normally didn't fly that fast every time. (I know a few pilots who did fly over .90 many times in the 727.) The 747 typically flies at .84M (just listen to the "Speedbirds" from British Airways when they announce their intentions when crossing the Atlantic). The maximum speeds of the 747-100 thru 300 was .86 while the 747-400 and above is .92. Typical cruise speeds are .84 and .85 respectively.

I fly the 757, 767, GV and G550 and typically fly at .80-.83 in the Boeing and .83-.85 in the Gulfstream. The Citation X is a wicked fast airplane itself - looks fast even parked on the ramp!

doubleo6point9 wrote in post #13610242
Yep. It'll move forward as you slow and further aft as your speed increases. Here's a little diagram I found on wiki to show what you're seeing: http://en.wikipedia.or​g …:FAA-8083-3A_Fig_15-9.png

It's a Cessna Citation X. The only airliner that's still flying today that comes close to that is a 747-400 I believe. Though I think the 727 got pretty fast but not sure how fast.

Hah not an option unfortunately. Plus our planes are all over the place and I just happen to live in LB.

oooo I dont think I would fit in that plane actually
https://photography-on-the.net …?p=12683668&pos​tcount=101

Last year, I was on an Airways (USAirways) 757 in a window seat. Right as the last rays of light were shining above the horizon, I spotted this exact phenomenon. Not the shadow, but the actual prism effect that's created by the pressure differences. It danced about mid chord of the wing, extending about a foot above the wing surface. I watched it for a good five minutes, in complete awe. I had to think to myself; of all the people that fly daily, less than 1% of them even have an idea of what's going on out on and around those wings.

FotoPilot wrote in post #13610569
Cool shots of a phenomenon that occurs on more airplanes than you think. Airflow goes supersonic over most airfoils without the airplane itself going supersonic speeds. Air travels faster over the top of the wing and can show a shockwave about mid wing approx .82mach, which is the speed of most airliners. The faster you travel the farther back on the wing the shock wave appears until at supersonic when it's at the trailing edge of the wing. You may not recognize the shockwave outside an airliner, and the compression is also a function of speed, altitude, temperature, etc.

I hate to disagree with the above post but your speeds are way too slow. The 727's cruise was .81 with a max of .90, but to save fuel they normally didn't fly that fast every time. (I know a few pilots who did fly over .90 many times in the 727.) The 747 typically flies at .84M (just listen to the "Speedbirds" from British Airways when they announce their intentions when crossing the Atlantic). The maximum speeds of the 747-100 thru 300 was .86 while the 747-400 and above is .92. Typical cruise speeds are .84 and .85 respectively.

I fly the 757, 767, GV and G550 and typically fly at .80-.83 in the Boeing and .83-.85 in the Gulfstream. The Citation X is a wicked fast airplane itself - looks fast even parked on the ramp!

Thanks for enlightening me, I had forgotten that air speed over the wing can approach supersonic speeds. I also didn't know commercial airliners were that fast.

^^ No worries, and I apologize if I sounded condescending. It's all good info out there

FotoPilot wrote in post #13612606
I fly the 757, 767, GV and G550 and typically fly at .80-.83 in the Boeing and .83-.85 in the Gulfstream. The Citation X is a wicked fast airplane itself - looks fast even parked on the ramp!

^^ No worries, and I apologize if I sounded condescending. It's all good info out there

Thanks for posting up the additional info to clarify. Are you flying both the 757/767 and Gulfstreams for the same company and at the same time? Haha I know how you feel about the X. I used to pump jet fuel for the QS ones back in the day and never imagined that I would get to fly one. I also never imagined that it would be economical for the X to fly a sustained .90-.92 across the country like it does!

sigma pi wrote in post #13610829
oooo I dont think I would fit in that plane actually
https://photography-on-the.net …?p=12683668&pos​tcount=101

Hah yeah that wouldn't work out too well. But I guarantee you the leg room more than makes up for it.

tfaudree wrote in post #13611391
Last year, I was on an Airways (USAirways) 757 in a window seat. Right as the last rays of light were shining above the horizon, I spotted this exact phenomenon. Not the shadow, but the actual prism effect that's created by the pressure differences. It danced about mid chord of the wing, extending about a foot above the wing surface. I watched it for a good five minutes, in complete awe. I had to think to myself; of all the people that fly daily, less than 1% of them even have an idea of what's going on out on and around those wings.

It's amazing to see that. I saw a photo of one posted on the internet but I wasn't sure how legit that was. Going to have to try and catch a shot of the actual prism next time I see one.

DaveKosiba wrote in post #13611720
Thanks for enlightening me, I had forgotten that air speed over the wing can approach supersonic speeds. I also didn't know commercial airliners were that fast.

The 747 is a lot faster than most people would think. Hell I didn't know it could cruise that fast until our assistant Chief Pilot once told me that they had some issues with their HF radios while making a North Atlantic crossing so they ended up piggy backing on a 747 that was also making the crossing in order to make their position reports.

doubleo6point9 wrote in post #13612989
Thanks for posting up the additional info to clarify. Are you flying both the 757/767 and Gulfstreams for the same company and at the same time?

Yes I am. Only two type ratings, but really like 4 different airplanes, all in one company.

I've seen this happen on commercial flights.

doubleo6point9 wrote in post #13612989
Hah yeah that wouldn't work out too well. But I guarantee you the leg room more than makes up for it.

Touche!

are you flying out of the "Toyota Terminal"?