Shockwave Shadows in Ultra Slow Motion (Bullet Schlieren) - Smarter Every Day 203

Hello, Thank you posting this. I'm a bit late to the party. I see some similarities between the wavefields you show in this video and seismic waves propagating from a controlled source into the ground. I wonder, however, what the 3D wave propagation looks like for these experiments. The use of a single mirror means that one of the horizontal axes is collapsed. Not that I expect you to repeat this experiment (of course!), but if you had another mirror underneath the projectile you could see the wave propagation in both horizontal axes. You could then construct a composite image of the 3D wave propagation.

Ohad Barak

Great video :)

What about a prince Ruperts drop? They make a sound right?

Nathan Steadman

Yes please!

Andrew Phillips

Do you think you could record someone cracking a whip with this set up?

Nathan Steadman

Yeah, I remember. But I have no clue how to do it :D

This really made my brain think. This was one of the best videos I’ve seen from you in a long time. Wow! I remember learning this back in physics, but seeing it on sub sonic and supersonic bullets was super cool. Well done sir!

Nathan Steadman

I've suggested this before :)

Emory Stagmer(VAXHeadroom)

Wow, very cool images. That leads to 2 interesting topics for me, which you might find interesting to deal with in videos: 1.) When the militarys started to increase plane speed to sonic speed, they experienced a lot of plane losses, because aerodynamics changes at supersonic speed and typical aerodynamicly built planes can't be flewn at supersonic speed. So what are the differences? What changes and why? 2.) There is some really fascinating stuff about how Schlieren-Optics work. Its Fourier-Optics. So basically lenses transform 2D images into 2D fourier representations of the images and back. With the knife edge (or spot) used in schlieren optics, you actually create a 2D high pass filter in spatial domain, removing the spatial frequency 0 out of the image before retransforming it into image domain. Its not that complicated to explain, but I guess, with the right setting, it really can be fun to play around with different "filters".

Stefan Schloesser

That blew my mind! :D I wonder if each of the spikes on the sub-sonic bullet could cause a sonic boom. Gosh I would love to see a Schlieren imagery of a falcon heavy booster touching down with the three sonic booms it causes. :D

Great video! Loved the energy. I watched this with my 2nd grader and kindergartener. I paused the video a few times and had them point out details on the screen so I could explain it a bit more. When you were talking to the professor, and he started saying some words, I was like "OH! Trans-sonic region!" :) I'm pretty sure the exact transonic region/speeds depends on the specific object and how it accelerates the air around it. Modern planes tend to stay away from transonic flight (either above, or below, never in)...at least that is what I was taught in my couple weeks informal course from a genius.

Jeff Dzado

I love it!! The spikes on the subsonic bullet result from the same phenomena as the vapor cone on a transonic aircraft!

Whit

that was epic: love the ending: "if you are not...... what is wrong with you!"

That was a fun one. Granted, they all are. But still. :)

Workbench

Nice! Thank you again.

Dustin Ohman

Rayleigh-Plesset makes me happy.

Smarter Every Day

Another awesome vid of yours was the bullet fired underwater...with Rayleigh-Plesset cavitation awesomeness. :-)

Neuroskynet

Nice! Travelling homeward on a tram and this pops up, so will watch it now. Thanks.

Daniel Turner