Sound Barrier Story Fact or Fiction???????????

[Jack Cook]

I recently got this from a friend. The picture is bogus has it's a painting by artist Dru Blair, The story is highly questionable has it describes a F-18 but the movie is Ok but how fast is it going. Maybe one of our AF wixers like jcw or Randy can answer that.
http://home.swbell.net/weaversc/jet.html

[RareBear]

I have seen several variations on this video sequence. The effect is real, and happens as the plane passes the speed of sound, at sea level about 762 mph. If I recall correctly, as the aircraft approaches Mach 1, the pressure wave is ahead of the aircraft; but as the plane passes Mach 1, the wave moves aft of the plane, and the resulting pressure change produces a cloud of condensation around the aircraft.

The painting on the left is pure fantasy.

Regards,

Walt

[Ollie]

That's a F-14!!

[TimAPNY]

That is a great cameraman. Anyone who has tried to flim a Mach pass, it is not easy.

[Randy Haskin]

A couple points:

1) The video is of an F-14, not an F/A-18.

2) Mach 1 is dependant *only* on temperature, so it is only 750-ish MPH at sea level on a "standard day", at 29.92", etc.

3) A visual shock cone is not an indicator of being on/near/through the sound barrier. All it means is that there is sufficient moisture in the air and drop in pressure for condensation to form. That can happen at 200 knots in the pattern just as easily as it can at M=1.0. The faster you get, the more that condensation vapor is going to appear like a cone.

4) If a jet is flown low and fast over water, the engines *do* kick up roostertails. It's not as impressive as in the painting, but I have a video of the Reno ANG shining their a$$es out overa lake and it's very impressive...and dangerous....and illegal....

[leo]

That is a painting, "Tomcat" by Dru Blair.
Although I have seen several speed of sound or "close" passes over water, never have I seen plune like that, tho the water DOES get churned up a bit!

Leo

[bdk]

I recently got this from a friend. The picture is bogus has it's a painting by artist Dru Blair, The story is highly questionable has it describes a F-18 but the movie is Ok but how fast is it going. Maybe one of our AF wixers like jcw or Randy can answer that.
http://home.swbell.net/weaversc/jet.html

If the aircraft is truly supersonic, there should be a shockwave at the nose. I suspect the aircraft is subsonic and what you are seeing are the local shock waves from the thicker part of the body as the air accelerates around. These shock waves are where the drag rise begins occurring in the transonic range.

The condensation of water vapor can be caused by the pressure change associated with moving through the air, not necessarily with supersonic flight. You see this on landing in airliners as vortices from the flaps and wingtips- far from supersonic.

Hopefully we have some real experts in aerodynamics out there that can answer this definitively.

[Randy Haskin]

Hopefully we have some real experts in aerodynamics out there that can answer this definitively.

Real life experience isn't good enough? Gotta have a degree on your wall to have a valid opinion?

[Tony]

Squadron Leader Andy Green RAF exceeding the speed of sound at an altitude of about 6"

Rule Brittania




Photo copyright Andrew Graves

http://www.andrewgraves.biz/ssc_stuff/SSC_pics.htm

[bdk]

Real life experience isn't good enough? Gotta have a degree on your wall to have a valid opinion?

Yikes! That was not what I meant. Now you're putting me on the defensive.

Your response did not address whether or not THIS aircraft was exceeding the speed of sound, only that one could see vapor at lower speeds.

Sometimes the powers of observation can be deceiving though, even to those with degrees. Frequently the correct answer is not the most obvious one.

Anyone ever seen a white tornado before?

[RMAllnutt]

I've seen a Panavia Tornado covered in snow once.... does that count?

Richard

[Cvairwerks]

You guys need to closely read the text. It is physically impossible for the aircraft to be in the position that he describes for him to hear the shock wave and get the picture. (which I wasn't able to see). The audiable portion of the shock wave isn't going to be heard by the photographer until the aircraft is PAST him.....no way is he ever going to hear any portion of a shock wave from in front of the aircraft.

[airnutz]

cvairworks...good point! About a month ago Randy Haskin wrote a
very detailed explaination of what occours with "percieved" viewing and
photography of "sound barrier breakage". I wouldn't ask Randy to
re-explain..when all we have to do is "click" his name and dig thru
his posts.

[HarvardIV]

Hey guys:

It looks looks to be fake, because the frames appear to be speeding up during the shock wave event, and going back to normal speed after the event. It looks like somebody actually photographed parts of it, and then spliced in lot of frames.

Chris

[Jack Cook]

That photo sorta looks like a farmer in Nebraska running his tractor and plowing his field.
BTW I check Dru Blair's painting never won the World 2000 photo contest although their is such a contest.