Tech Tuesday: Amazing Schlieren Imaging of Bullet in Flight
Every Tuesday an interesting technical feature is posted on the Applied Ballistics Facebook Page. For today’s 4/23/24 “Tech Tuesday”, a fascinating video of a bullet in flight was posted. This Schlieren video illustrates a 6mm 109gr Berger LRHT bullet traveling at 3163 FPS. The stunning video reveals the bullet shockwave and the turbulent wake. Check it out:
About the Schlieren Imaging Process — What It Shows
Schlieren Imaging is a way of making airflow features visible. You can clearly see the compression (shock) wave at the front of the bullet. A compression wave is formed when the air has to move faster than the speed of sound to get out of the way, which is certainly the case for this bullet which is moving about 2.5 times the speed of sound (Mach 2.5). That shock wave is the ‘snap’ you hear when bullets fly past you if/when you’re downrange. Also, compressing the air into a shockwave takes energy, and that energy comes directly out of the forward velocity of your bullet and gets converted into heat and noise as the shock wave forms and dissipates. The turbulent wake at the base of the bullet shows where/how base drag applies. The third and smallest component of drag for a supersonic bullet is skin friction drag, which is a viscous boundary layer effect, and is the least visible in this image.
Above is a second Schlieren imaging video. This shows a 6mm 109gr Berger LRHT bullet at ~2800 fps as fired from a PRS rifle at the Applied Ballistics Lab. Bryan Litz notes: “You can clearly see the compression (shock) wave at the front of the bullet. A compression wave is formed when the air has to move faster than the speed of sound to get out of the way, which is certainly the case for this bullet which is moving about 2.5 times the speed of sound (Mach 2.5).”
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