The moment a bullet turns into a flashlight, filmed
[The Slo Mo Guys] captured something fascinating while filming firearms at 82,000 frames per second: a visible emission of light immediately preceding the impact of a bullet. The moment this happens is shown above, but if you want to skip to the point in the video where it happens, it all starts at [8:18].
The ability to capture ultra-slow motion allows us to see things that would otherwise happen far too quickly to notice, and there are quite a few visual spectacles throughout the video. We'll talk a bit about what's involved and what could happen.
Spotting anything unusual on the video replay is the essence of extreme slow motion filming.First of all, the clear blocks filmed are ballistic gel. These dense blocks are tough, resilient, and common in firearms testing because they reliably and consistently measure things like deformation, fragmentation, and bullet impact. It's possible to make homemade ballistic gel with ample amounts of gelatin and water, but transparencies like the ones you see here are oil-based, visually clear, and more stable (they don't shrink from evaporation).
We have seen the diesel effect occur in ballistic gelatin, which is most likely the result of bullet impact vaporizing small amounts of (oil-based) gel as the channel forms, and this vaporized material ignites due to a sudden increase in pressure as it contracts.
In the video linked above (and embedded below), there's probably a little more to the mix. The rifles tested are high caliber rifles, firing large rounds with a large amount of gunpowder igniting behind each bullet. The hot powder causes the hot gases under pressure to rapidly expand, pushing the bullet through the barrel at breakneck speed. When the ball comes out, so does a jet of hot gases. Sometimes the last bits of hot powder are visible as a brief muzzle flash that accompanies the bullet leaving the barrel.
A large projectile traveling at supersonic speeds causes a large channel and expansion when it hits the ballistic gel, but when it fires...
[The Slo Mo Guys] captured something fascinating while filming firearms at 82,000 frames per second: a visible emission of light immediately preceding the impact of a bullet. The moment this happens is shown above, but if you want to skip to the point in the video where it happens, it all starts at [8:18].
The ability to capture ultra-slow motion allows us to see things that would otherwise happen far too quickly to notice, and there are quite a few visual spectacles throughout the video. We'll talk a bit about what's involved and what could happen.
Spotting anything unusual on the video replay is the essence of extreme slow motion filming.First of all, the clear blocks filmed are ballistic gel. These dense blocks are tough, resilient, and common in firearms testing because they reliably and consistently measure things like deformation, fragmentation, and bullet impact. It's possible to make homemade ballistic gel with ample amounts of gelatin and water, but transparencies like the ones you see here are oil-based, visually clear, and more stable (they don't shrink from evaporation).
We have seen the diesel effect occur in ballistic gelatin, which is most likely the result of bullet impact vaporizing small amounts of (oil-based) gel as the channel forms, and this vaporized material ignites due to a sudden increase in pressure as it contracts.
In the video linked above (and embedded below), there's probably a little more to the mix. The rifles tested are high caliber rifles, firing large rounds with a large amount of gunpowder igniting behind each bullet. The hot powder causes the hot gases under pressure to rapidly expand, pushing the bullet through the barrel at breakneck speed. When the ball comes out, so does a jet of hot gases. Sometimes the last bits of hot powder are visible as a brief muzzle flash that accompanies the bullet leaving the barrel.
A large projectile traveling at supersonic speeds causes a large channel and expansion when it hits the ballistic gel, but when it fires...
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