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by MojoTexas
Fri Sep 10, 2010 4:21 pm
Forum: General Gun, Shooting & Equipment Discussion
Topic: Mystery Bullet In Rowlett
Replies: 44
Views: 8720

Re: Mystery Bullet In Rowlett

glock27 wrote:would terminal velocity come into play at that far? it would seem that one mile away you would be able to catch it in your hand.

i watch mythbusters they did a terminal velocity test on dropping a penny from "empire state building" all in scale of course. but a pennies maximum speed is something like 62 miles per hour. a .22 would weigh less than a penny and have less terminal velocity

which leaves me to think that if the bullet where already started to come downward when shot at a 45degree angle all or most of its energy/velocity from the gunpowder would be exemt????
I think if the bullet were fired in an arc, it would still be spinning from the rifling, and would probably be pretty aerodynamic so that there wouldn't be a lot of drag. It would lose some velocity to drag but not enough to make harmless.

Firing straight up (which the Mythbusters found was very difficult to do exactly), the bullet eventually stops, then starts falling again, which I would guess is when the tumbling starts in. If it's tumbling and stuff, it's going to have more drag and a lower terminal velocity.

I remember the penny episode also...it'd be interesting to replicate that with a .22 LR bullet under the different scenarios.
by MojoTexas
Fri Sep 10, 2010 11:16 am
Forum: General Gun, Shooting & Equipment Discussion
Topic: Mystery Bullet In Rowlett
Replies: 44
Views: 8720

Re: Mystery Bullet In Rowlett

jimlongley wrote:
Mike1951 wrote:I sent this to the alleged reporter.
We checked; a .22-caliber projectile can travel approximately one mile in a straight line.

Uh, no! A .22 can reach one mile if fired at a 45 degree upward angle, resulting in a high arc trajectory.

Once it is fired, it begins to fall to the ground at 32 feet per second. A six foot person firing the rifle level means the bullet would hit the ground in 1/5 second.

The velocity of .22 rimfire rounds is from 1000-1300 feet per second. So in that 1/5 second, the farthest the bullet could go when fired level would be from 200-260 feet.

Therefore, rifles are not fired level. Sights are adjusted so that the barrel is angled upward to the degree necessary to extend its range as needed by the shooter.

Sights do not allow sufficient elevation to reach a mile. Someone had to aim the rifle upwards at a 45 angle, which means it could not have crossed adjoining properties level. It would have been dropping from its high arc.

Mike Earls
I think my numbers are close.
Gravitational acceleration is 32 feet per second, per second. After one second the gravitational velocity is 32fps, after two 64fps, and after three 96fps and so on. After one second the drop would be about 16 feet, after two, 64 feet, and after three 144 feet. Leaving out air resistance and calculating from a maximum muzzle velocity of 1300fps, that's three seconds for a mile, so the projectile would have to have been shot at an angle of 144/5280, or 144 feet above the "target" a mile away, not really a very high angle. Now if you add in the change of velocity due to air resistance, then the angle increases but even then it will be well below 45 degrees.

You are right about it needing to be fired at a high arc, despite the slightly flawed ballistics.
The television show Mythbusters (on Discovery Channel) did an episode about bullets fired into the air.

http://mythbustersresults.com/episode50
http://en.wikipedia.org/wiki/MythBuster ... s_Fired_Up

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