I got this link of SF Fleet Week '07 forwarded to me. According to the photographer, this guy is going about 700mph (nearly mach 1 for the conditions) at 20msl! You can actually see the shock waves forming!

That is a great composition, however I would question its authenticity.

A skilled Photoshop technician, nontheless.

gb

Looks cool but not buying it. Even the blues wouldn't get cleared for a pass like that at that speed. Even if the rooster tail is real, that can occur well before 700kts.

I have a friend that works for the FAA and he was watching the practice for the next days show a Cleveland's Burke Lakefront Airport, and watched one of them intentionally go between two of the highrises knife-edge. He talked to him when they landed and he (the pilot) thought it was pretty funny.
He lost all respect for the Blue Angels after that.

And just what is the purpose to spend our taxes in the form of defense funds to allow the egos of these jocks to get their jollies.

Back in the "old days", the mid '70's, the Blue Angles dropped into Pendleton (PDT). When they came in they dropped through a solid cloud layer without any talking to the PDT controllers. The controller who was telling me about it was incensed and said he filed a report. He claimed that he very nearly lost his job over criticizing and filing a report. Basically, he said he was told was that they could do just about anything they wanted as long as their command didn't have a problem with it. The FAA didn't have anything to say about it. Later, I think he was one of those who lost his job anyway because of the strike. I'm pretty good with PhotoShop and tend to think the photo is real, maybe not 700 kts. though.

I have seen shock waves in the test section of supersonic wind tunnels and they look just like this. The change in refraction is noticeable. 700 kts? Who cares? It's still tres cool, as is that shimmering stream of taxpayers dollars exiting the afterburner.

Here's what happens when you get the real shockwaves, not lines edited in.


http://au.youtube.com/watch?v=CAG6H9M6gZo


Was at a military firing range so no damage to civilian property.

I'm on the fence regarding its authenticity. EXIF says 1/2000 sec at F5.6, image at 300 dpi, but you can forge EXIF tags.

I'd say it's real only because I tend to believe people are too lazy to fake something like this.

Sitting next to the engine in a commercial airliner, I've seen the change in refractive index near the engine inlet. It only extends outward six inches or so, but it isn't hard to see when lighting is right. This makes me think that the fighter could definitely produce a "mirage". I'm just not sure about how far it would extend. I be the closer to mach one the larger the effect.
tom

Its real. Seen that from the cockpit and from a sailboat in the bay. He is up around .98M or around 700mph.

The shockwave always forms first at the nose of my PA11 when approaching the mach numbers.

If it is real, I'll bet those two sailors standing on the bow of that boat looking away shit their pants when the noise got to them!!!

I had the pleasure of many a cropduster trying to tear the cab off my tractor as a young man. You know they're around, but you never expect it when those dirty dogs sneak up on you.

gb

What about you guys with constant speed props. If you flatten out the prop and run rpm way up, you can get close to the speed of sound at the tips. Have any of you noticed any optical refraction patterns near the tips?
tom

I have noticed contrails (??) coming off the tips, doing a runup when the temp/dewpoint spread is real close. About as close as I can come...

Eric

If the photo is not doctored then at what stage of the speed process do you get the lines? It would have to be before because if you've watched the F111 the damage bill round the Bay would have been in the tens of millions.

My understanding of gas dynamics and compressible fluid flow is basic at best, but after digging around in the little used areas of my head here is my best explanation of what is happening.

The F/A18 is actually flying in the transonic region; close to but not at the speed of sound. As it gets close to Mach 1 the localized airflow in certain spots exceeds the speed of sound, due to the shape of the airplane, and forms a shock wave. As the shock wave moves out away from its source and into undisturbed air it can propagate in all directions and dissipate. This happens from about Mach 0.7 to Mach 1 and is considered the transonic regime.

If the pilot would quit babying the plane and really pour the coal to it, a shock wave would form ahead of the plane eventually moving back and attaching to the nose as the speed increased. Now the whole plane is moving at Mach 1 or faster so the shockwave does not dissipate in the free air and you hear a sonic boom.

What you actually seeing in the picture is a change in the air's index of refraction (the way it bends light) caused by a nearly instantaneous pressure/density change across the wave. There even appears to be an ever-so-slight Prandtl-Glauert cloud (the slightly foggy area behind the lower shockwaves)! If it were more humid the cloud would probably be more obvious.

Would you look at that! I pulled a pile of crap out of my ass and made it look somewhat believable!

I'll eat crow for my skepticism on this one, looking through the guys album it would appear that he got a whole sequence of shots like this - and as Zane pointed out I can't imagine anyone with the time and inclination to doctor all of them. The other thing is that I misread his speed - 700 mph, not kts. mph I would believe as that is something less than 600kts. Those numbers make sense for a Hornet making a trans-sonic pass.

Hello Guys:

It is funny what a small world we live in. I had just been reading this thread before attending a party this past weekend (no libations invloved of course), and a friend started telling me a story of when he and his wife were returning from a tour of the wine country and got caught on the
Golden Gate Bridge in a traffic jam and observed the blue anges coming under the bridge.

Apparently this is an annual event, the boats do line up every year to watch the show and they do a 700 mph pass (just under the speed of sound) between the boats and under the bridge.

I would guess the picture is authentic!

Regards, Larry

The show in the bay is called fleet week.
Every year(oct.) I think,the Navy brings out the heavy iron.I have seen the blues from the bay bridge,at car level,VERY cool. Check it out if your in the bay(s.f.)area around that time.

Did anyone watch the video link at the bottom of that page? I think it would be hard to fake these, and they mirror the stills. See http://www.youtube.com/watch?v=K7rAUu8djZ4

MTV