How close was this F-18 to breaking the sound barrier?

I snagged this photo at the Rockford IL Airshow earlier today and I am curious to know just how close he was....

Nice shot but I don't think the vapour cone has anything to do with the sound barrier and more to do with atmospheric conditions at the time.
But I may be wrong

If this is at an airshow they aren't allowed to.

Yeah I really don't know either, for what its worth no other plane, F-4, F-15, F-16 that was there developed a cone like this entire day.

did it make a loud boom?

It never passed the speed of sound, as xMClass pointed out, that is something that is not allowed in civilian airspace. I am more curious as to how close he got to that barrier..

CTP wrote in post #10644321
It never passed the speed of sound, as xMClass pointed out, that is something that is not allowed in civilian airspace. I am more curious as to how close he got to that barrier..

Not allowed and not done are two different things. . . .

Could you imagine the damage done if he broke the sound barrier at that low of an altitude? Have you ever seen the episode of Mythbusters where they tried it out with the Blue Angels? It was awesome

Scatterbrained wrote in post #10644394
Not allowed and not done are two different things. . . .

Good point

CTP wrote in post #10644263
I snagged this photo at the Rockford IL Airshow earlier today and I am curious to know just how close he was....

I have an even better photo that was take right before this one and of course there is a light tower blocking part of the plane.

Not enough information to answer that question. The vapor you saw is not caused by a supersonic shockwave, but rather by a sudden drop in air pressure behind a non-supersonic pressure wave created by the aircraft pushing its way through the air.
Details here:
http://en.wikipedia.or​g …%80%93Glauert_s​ingularity

However, if you could visualize the shockwave off the nose of the aircraft, you COULD estimate the mach number.. formula and online-calculator here.
http://www.grc.nasa.go​v …-12/airplane/oblique.ht​ml
For fun, pretend that WAS the shock wave.. it gives you a speed of about M1.7 or so..

Nice image, i know that the CAA limit in the UK for high speed pass is 0.95 Mach

Rick1930 wrote in post #10644795
Not enough information to answer that question. The vapor you saw is not caused by a supersonic shockwave, but rather by a sudden drop in air pressure behind a non-supersonic pressure wave created by the aircraft pushing its way through the air.
Details here:
http://en.wikipedia.or​g …%80%93Glauert_s​ingularity

However, if you could visualize the shockwave off the nose of the aircraft, you COULD estimate the mach number.. formula and online-calculator here.
http://www.grc.nasa.go​v …-12/airplane/oblique.ht​ml
For fun, pretend that WAS the shock wave.. it gives you a speed of about M1.7 or so..

The info I was looking for, thanks for the help!

The 18 pilot at our show says he does .96!

Rick1930 wrote in post #10644795
Not enough information to answer that question. The vapor you saw is not caused by a supersonic shockwave, but rather by a sudden drop in air pressure behind a non-supersonic pressure wave created by the aircraft pushing its way through the air.
Details here:
http://en.wikipedia.or​g …%80%93Glauert_s​ingularity

However, if you could visualize the shockwave off the nose of the aircraft, you COULD estimate the mach number.. formula and online-calculator here.
http://www.grc.nasa.go​v …-12/airplane/oblique.ht​ml
For fun, pretend that WAS the shock wave.. it gives you a speed of about M1.7 or so..

Nice formula

Well I have bad news for all of you guys (lol). The Sound Barrier is broken at nearly all airshows, and airports every day!!. If you are ever near an A/C that breaks the barrier ENTIRELY then you will hear two distinct booms, not one. That's is because the front of the A/C breaks first followed by the rear of the A/C. The barrier is visible either partially or entirely on many speed runs.

Props rountinely break the sound barrier and so do many winged surfaces, during high speed turns. If you have ever seen schlieren photography of a bullet or off of the wings of a fast moving jet, you can see the beginnings of the pressure wave coming off of the flight surfaces. Beleive it or not it is very difficult for A/C to break the barrier completely at low levels. The actual speed needed is a varible, not a constant depending on altitude, air pressure, temp etc. The Blue Angels and the T-Birds flirt with the SoS all the time and I have been present when it was broken (partially) by BA#5 over SF Bay. It broke a few boat windows, and ruptured a few ear drums within a 150 yard range of the plane.

The pilot got his ass chewed but good. What happened? Tail wind during the High speed pass. Jet engines break the SoS all the time, but it is contained within the airframe and engine cowling. Anyone ever seen small tornado looking critters coming from the front of the engine? Creeps me out.