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DemetriiOSC t1_j90qfbg wrote

Reply to comment by Sunspider2 in Tortoise vs Hare by toonhole

A bullets’ terminal velocity required to penetrate the skin is between 45.1 and 60.0 m/s (148 and 197 ft/s) and bullets traveling at <60.0 m/s (200 ft/s) can penetrate the skull.

In the launch angle region of 80º…90º the bullet basically lands the base first. The terminal velocity might vary between values 40…85 m/s. The result depends on possible Magnus-moment caused bullet instability or the bullet/flow resonance. The buffeting-like phenomenon described is new to the authors of the current paper at this particular context. However, the flow time-dependent phenomena detected were found out to have negligible effect on flight without matching of the natural frequencies (flow/bullet).

Experimental result found for an upwards fired 7.62 mm bullet terminal velocity is about 90 m/s, which is near to the base first landing case simulated result. The typical terminal velocities given in literature for spent bullets are from 300 fps to 600 fps (90...180 m/s).

In many simulated cases through the launch angle region the bullet possessed the estimated minimum lethal energy 40 J at the end of trajectory. The skull penetrating speed 60 m/s was mostly clearly exceeded. A preliminary value for shooter-centered danger zone diameter obtained was found out to be approximately 8 km.

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Sunspider2 t1_j91ozh2 wrote

A bullet fired straight up on Earth, assuming there’s no wind, might still be able to reach a maximum height of around three kilometers (about 10,000 feet), and will then fall back down to Earth. However, just like a human skydiver only accelerates for a few seconds before reaching terminal velocity, the air resistance acting on the bullet will prevent it from reaching speeds even close to muzzle velocity ever again.

Instead, a falling bullet comes back down with a speed of only around 150 miles-per-hour (241 kilometers per hour), which is just 10% of the speed it was fired with. Because of how energy works (proportional to your speed squared), a bullet that falls from high in the air only possesses 1% of the energy of a bullet newly fired from a gun: the equivalent of a brick dropped from a height of just 50 cm (about 20 inches) off the ground.

In terms of speed and energy, this simple treatment does, in fact, correctly give us the properties of a bullet fired up into the air when it hits the ground. But in terms of location, bullets that are fired even straight up can actually come back down up to two miles (about three kilometers) away from where they were fired.

A 150 mile-per-hour bullet won’t be lethal in most instances, but there are two factors that can change the equation dramatically.

Bullets that are fired at an angle, rather than straight up, may never stop and begin tumbling; instead, they can maintain much greater speeds: many hundreds of miles-per-hour.

If a bullet has enough speed to break the skin, it can potentially be lethal; this occurs at different speeds for different bullets and different individual people.

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DemetriiOSC t1_j91vqie wrote

So guess we just cite our sources, piss on em shake hands and call it a day?

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Sunspider2 t1_j9246oe wrote

Lol...no...I admit I was partly wrong. In that while falling bullets are certainly highly unlikely to be fatal, it is possible if all the variables align correctly.

I would contend they are a bit more dangerous than I first thought, but certainly not as dangerous as the initial stats you posted implied....for bullets propelled only by gravity.

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DemetriiOSC t1_j925ni6 wrote

For sure those stats it's pretty much assured they didn't account for angles and just that the location and trajectory showed them that they were from a "celebratory shot".

All I know is if someone is shooting in the air at any angle imma head inside cause I definitely won't rely on those variables not coming together, even in the very unlikely chance that it will hit me as well.

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