The Story Behind the Photo:

February: Planes, Trains, or Automobiles

by Steven McKeen

Having trained police officers in high-speed driving at the WSP Academy Track while a police officer, I really like driving fast.  I also like fast motorcycles and boats.  Well times change and we move on to different events and interests.  Still liking fast vehicles, I am now a bystander and found that I really enjoy photographing airshows.  The power in some of these aircraft is nothing short of amazing and a blast to experience.

A goal I have had in photographing aircraft, was to capture a vapor cone on a jet.  I have taken thousands of photos at many airshows and have not had the right conditions to capture the photo at all shows.  A little bit of luck also plays a very important role in getting the “Right” photo.  The weather has to be just right, the plane has to be flying the right direction, the plane has to create the cone at the right place to capture a good photo, the lighting has to be in the right place. Then if everything lines up, you hope your focus is correct and your high-speed shutter is clicking at just the right time to sync at the exact moment.  Since this action is very high speed, a shutter capture just prior to, or after, will cause you to miss the shot.  Keep in mind, that these planes only perform this action a couple of times at the most at each air show.

It took four years to capture this photo.

Here is an explanation of how vapor cones are made: The vapour cones are created by a shockwave that is generated by the aircraft as it picks up speed. The shock waves are the physical effects of the aircraft travelling so fast through air. Awe-inspiring photographs of fast jets surrounded by split-second shockwave aren’t evidence of a plane breaking the sound barrier That, we’re often told in excitable captions, is a sonic boom. Except, it isn’t – or at least, not quite. What you’re seeing is a physical effect that takes place as an aircraft approaches the speed of sound, but it’s not the sonic boom itself.

As aircraft design has become more sophisticated, planes have become more streamlined, and faster – and begun to do things to the air around them that they just weren’t able to do when they were slower and more cumbersome. And the mystery shockwaves that surround, low, fast-flying planes as they approach and then pass the sound barrier are proof that the air starts to do some very strange things at such speeds.

So what are these mystery vapor cones?

The conditions that create the vapor cone all lead toward the breaking of the sound barrier – but the cones are usually photographed at speeds just below the speed of sound.  Flying so close to the ground, the air is denser and creates more friction and drag – and, anyway, pilots are banned from breaking the sound barrier over land. You can do it over the sea, but you can’t do it over the land. 

The shock waves are the physical effects of the aircraft travelling so fast through air, especially if it’s moist and warm, and affecting the air around it.Moreover, capturing the shockwaves created when an aircraft passes the speed of sound are incredibly difficult – they’re much harder to pick up with the naked eye.

The vapor cones are created by a shockwave that is generated by the aircraft as it picks up speed. The shock waves are the physical effects of the aircraft travelling so fast through air. As the aircraft picks up speed and approaches the speed of sound – around 767mph (1,234km/h) at sea level – shockwaves form around the aircraft. Across these shockwaves there is ‘discontinuity’ in the local air pressure and temperature. This causes the air to lose its capacity to hold water and condensation starts to form, creating the vapor cone. “If you see a vapor cone, you’ve got a shockwave, because you’ve got a change in pressure and temperature”.

Many of the best pictures of this phenomenon feature aircraft flown by the US Navy; no accident, given that the warm, moist air close to the surface of the sea can help amplify the effect.

It’s a trick commonly performed by F-A/18 Hornet fighter-bombers, the mainstay of the US Navy’s carrier fleets. The Hornet is also used by the Blue Angels aerobatic team, and these pilots are adept at performing maneuvers that creates these vapor cones – also known as ‘shock collars’ or ‘shock eggs’. Moreover, they’re often done next to an aircraft carrier or out to sea, with trained US Navy photographers close to hand – taking a split-second picture of a jet travelling at 600mph (960km/h) is not something you’re likely to capture in crystal-clear detail on your smartphone.

The air travelling around the wing can accelerate – and that can break the sound barrier .

Just to make things more complicated, the vapor cones are often the most dramatic when they take place in what’s called ‘transonic’ flight – that’s when some of the air flowing around the aircraft is flowing at above the speed of sound, and some of it below.

“The aircraft isn’t necessarily travelling faster than the speed of sound, but the air travelling over the wing is accelerated and locally breaks the sound barrier”.

Ultimately, he says, you need to have the right climactic conditions – the kind of warm moist air that aircraft operating off carriers can find easier than most. Then, get a nearby cameraman who really knows what they’re doing and voila – you’ve captured, on camera, the dramatic vapour cloud that so many of us think is the split-second spectacle of a sonic boom.

Here are the photos from the high-speed drive showing how fast it changes and how the lighting is critical.  On the last two photos, you can see the plane was heading towards the sun, blowing out the photo.  Everything lined up just right for the third photo and 4 years of waiting paid off.