Vapor Trail or Shock Wave?

[GrizzlyMike]

Newbie Here...First Post. I was searching the net for an aviation forum to ask a question and it looked like this would be the place to ask.

I am an amateur photographer and hit a few airshows every year. During a Superhornet demo at the Cleveland Airshow I noticed a small cone forming on the canpoy area of the F18 as it executed a high speed pass and it grew larger and moved towards the rear before the pilot pulled up. It all happened over about 2 seconds. I assume this is a shock front preceeding supersonic transition or am I totally wrong?

Thanks

 

[Ryoukai]

Doesn't have to be supersonic to make one of those nifty clouds.
Getchya learn on!
Getchya learn on...again.

Edit: I assume that's your picture up there. Nice work. What kind of camera/lens are you using?

 

[GrizzlyMike]

OK..thanks


I took the shot using a Canon 10D and Canon 400 2.8.

 

[Brett327]

Generally, you are not going to get any supersonic speeds at an airshow - lots on restrictions on that and people generally frown upon having their windows broken. Like Ryoukai said, you can get all kinds of vapes in all kinds of situations, especially if the relative humidity is high. Areas of low pressure cause the vapor to condense and form vapes. Now, my jet only goes supersonic at MRT going downhill, so I'm not familiar with the particulars of the Hornet, but I'm sure someone who is can give you the details as to what you're seeing in your pic.

Brett

 

[Road Program]

Grizzly...

Yeah, what those guys said. Doesn't have to be supersonic or approaching those speeds to see conning like that.

BTW...mind if I use that as my background on my comp?

 

[Steve Wilkins]

BTW...mind if I use that as my background on my comp?

Property of Airwarriors.com now. Pay the Webmaster here: https://www.paypal.com/cgi-bin/webscr

 

[SteveG75]

What you are seeing is localized areas of transonic (i.e. exactly Mach 1.0) flow over areas of low pressure. This is causing localized shock waves.

After 15 years, that aero degree finally payed off.

BTW: Notice the stores loading on that jet. NONE. No stores, no pylons, nothing. The Hornet cannot go supersonic in level flight with any darag unlike the Tomcat. Hence the term, "world's slowest supersonic fighter".

 

[Texan]

BTW: Notice the stores loading on that jet. NONE. No stores, no pylons, nothing. The Hornet cannot go supersonic in level flight with any darag unlike the Tomcat. Hence the term, "world's slowest supersonic fighter".

Is that cannot or should not?

-Texan

 

[JD81]

Pretty sure it cannot hit mach 1.0 with the pylons and stores. The pylons are canted at like 3 degrees pointing outboard of the centerline, which make serious drag. I think this had to do with weapons seperation problems with pylons aligned on the aircraft's centerline, at least thats what I found from some research. Not sure if anyone can verify this.

Josh

 

[ea6bflyr]

Meat,
With talk like that it's no wonder you get all the babes. Is that what they mean when they say "talk dirty to me" ???
ea6bflyr

What you are seeing is localized areas of transonic (i.e. exactly Mach 1.0) flow over areas of low pressure. This is causing localized shock waves.

 

[petescheu]

OK..thanks


I took the shot using a Canon 10D and Canon 400 2.8.

Canon 400 2.8?? That thing probably cost almost as much as the jet did, crap. I know my 100-400 put me in the hurt locker for quite some time. Great shot...

 

[Schnugg]

Shock wave story: I was flying at about 500 feet and mach 1.2 on a bug on the tacts range in an F-14A on a Topgun sortie. In the SE corner of R-2301 Supersonic flight is authorized.

In any case, we start to decell once the knock it off, my pilot pulls back out of Zone 5 to mil and we get tossed quite forcefully forward into our harnesses. What a decell. I look back into the cockpit from looking over my shoulder towards our six and see what looks like a crack in the canopy. Scared the crap out of me for second before I realized it was the shock wave of compressed air. I could actually see it like a wrinkle in the air and it moved forward as we decellerated. The air was too dry for flashes of vapes, but the shock wave was right there, even cast a shadow.

Never saw it quite that obvious again. Cool stuff. And they pay me to do this...

 

[GrizzlyMike]

Grizzly...

Yeah, what those guys said. Doesn't have to be supersonic or approaching those speeds to see conning like that.

BTW...mind if I use that as my background on my comp?

Go ahead if you want. I have some high res shots from last years show at my web site. The airshow gallery is here.. http://www.phototracks.net/HFGallery.htm . This is just a hobby and I dont sell images. The Blue Angels were here last year. I will post some of the F18 Superhornet Demo images when I get them processed.

 

[GrizzlyMike]

What you are seeing is localized areas of transonic (i.e. exactly Mach 1.0) flow over areas of low pressure. This is causing localized shock waves.

After 15 years, that aero degree finally payed off.

BTW: Notice the stores loading on that jet. NONE. No stores, no pylons, nothing. The Hornet cannot go supersonic in level flight with any darag unlike the Tomcat. Hence the term, "world's slowest supersonic fighter".

Thanks for the info.

 

[GrizzlyMike]

Canon 400 2.8?? That thing probably cost almost as much as the jet did, crap. I know my 100-400 put me in the hurt locker for quite some time. Great shot...

I was lucky to find one used on E-Bay 3 years ago and negotiated a good deal. The IS model is like $7,000 new but I got it for $3K. The guy selling it was a photo journalist and it had a lot of dings and wear on it but the glass is in prime condition. It's an awesome airshow and wildlife lens.