So I was filtering through twitter and was really confused by this:

It just didn’t seem real. Did everyone get put in the box?

Yes. Yes they did.

I couldn’t stop laughing at how many people got shoved into the box.

There’s a 3 minute video how what happened at the bottom of the sbnation link here.

I am almost every time put in a trance whilst spectating an aircraft/jet takeoff . There is always something interesting in the occurrence that makes me go nuts!

And this time around, there are these series of rings that one can see in the exhaust plume of a jet engine when it takes off ( usually when the afterburner is on).

I had no clue about the phenomenon nor did I know how to express it in ‘search engine’ terms to find a match.

But upon discussion with some of friends, I was shown this video of a space shuttle launch that seemed to produce a similar pattern.

Hmm.. Interesting

Shock Diamonds

These set of rings/disks that are formed in the exhaust plume are known as Shock Diamonds or Mach discs ( and by many more names ).

And usually occurs at low altitudes when the pressure of the exhaust plume is lower than the atmospheric pressure.

How does it form ?

Since the atmospheric pressure is higher than the exhaust, it will squeeze it inward. This compresses the exhaust increasing its pressure.

The increased pressure also instills a increased temperature.

As a result, ignites any excess fuel present in the exhaust making it burn. It is this burning that makes the shock diamond glow.


The pressure is now more than the atmospheric pressure, and the exhaust gases start to expand out.

Over time, the process of compression and expansion repeats itself until the exhaust pressure becomes the same as the ambient atmospheric pressure.

In other words, the flow will repeatedly contract and expand while gradually equalizing the pressure difference between the exhaust and the atmosphere.

The same occurs in rocket engines as well.

What if?

What if the atmospheric pressure is less than the exhaust plume ( like at higher altitudes ), would we still see shock diamonds ?

Yup, we would! And here’s a picture of it too ( The Bell X-1 at speeds close to Mach 1 )

The same phenomenon as discussed above occurs except that the cycle starts with the exhaust gases expanding to atmospheric pressure first.

Did you enjoy this post?

There is an extensive explanation of shock diamonds given by shock waves which this post does not cover.

And this beckons the start of Supersonic Fluid Dynamics - a marvelous field of its own. If this captivated you, it is definitely worth a google.



A fluidic oscillator is a device with no moving parts that sprays a fluid from side to side. The animations above illustrate how they work. A nozzle funnels a fluid jet through a chamber with two feedback channels. When the jet sweeps close to one side of the chamber, part of the fluid is directed along the feedback channel and back toward the inlet. That flow feeds into a recirculating separation bubble in the middle of the chamber. As that bubble grows, it pushes the jet back toward the other feedback channel, continuing the cycle. Many automobiles use fluidic oscillators in their windshield washer sprays. Check out the award-winning full video from the Gallery of Fluid Motion.  (Image credit: M. Sieber et al., source)


Skyacht One

Designed by SottoStudios in collaboration with Embraer Executive Jets, Skyacht One is probably the most luxurious private jet in the world.

Inspired by a 1939 custom yacht, the exclusive aircraft combines state-of-the-art technology with the hand-made luxury of the past to create what the studio calls “a yacht that can fly”.

Trimmed in mahogany, the navigation-themed interiors comprise 5 sumptuous cabin zones, including an extravagant master suite with walk-in shower, a conference room, and a dining area. Fitted with adjustable lighting, the generous main cabin features a Chesterfield sofa and a cocktail bar.

Here, in sprite form, the first round matchups of the 2015 nhl Stanley Cup playoffs.  Teams with home-ice are in their home sprites, and aways for the rest.  Should be great!

Suck, Squeeze, Bang and Blow - That’s how a jet engine works!

It sucks in air from the surrounding,

squeezes it up with the compressor, 

and when fuel is added and ignited, the bang occurs. 

The air is blown out the back  and this produces Thrust.

And no, I am not oversimplifying things. It is really that Simple. ;)

Happy Halloween!

PC: nasa, bbc, imgur,worldofwarplanes.

EDIT: This principle can also be used to understand how your car engine works as well. 

Lasers are a great way to deliver a lot of energy very quickly. In this animation, you see a jet of water get struck by a pulse from a powerful X-ray laser. The energy from that laser pulse gets absorbed by the water in a matter of picoseconds - that’s trillionths of a second. All that energy in so little time makes the water vaporize explosively. It’s this vapor explosion that breaks the jet in two. As the vapor expands outward, it forces water from the jet into a thin film that forms a cone. The conical film bends back on itself until it strikes the jet and coalesces. For more, check out this video of a similar experiment that looked at laser impacts on droplets. (Image credit: C. Stan et al., from Supplementary Movie 5; via Gizmodo)