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Black Angus McPherson

Pondering - Bullet Flight - Need Math

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The annual warnings against shooting guns up into the air to celebrate the new year, and the evidence last night that so many people were ignoring those warnings, got me to wondering.  If I hear a shot, how long until I might hear it hit my roof?

 

IF a person were to fire a rifle, say a .30-06 150gr. bullet at 2700fps, straight up into the air, how long would it take to return to earth?  How long on its way up and how long on the way down?

 

How about a 115gr. 9mm at 1100 fps?  200 gr. .45 at 800fps?  Pick a bullet and a muzzle velocity and tell me about its flight time.

 

Somebody with a whole lot more math skill than I will have to figure that out.

 

Angus

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My mouse poof loads might reach somewhere between 50 and 100 feet up when fired from a 30 foot rifle barrel. i never tried.

 

Imis And I dont have the math skills to prove 2+2 =4

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Bullets fired straight up into the air are not dangerous to life or limb. 

The bullet rises to it maximum height and stops DEAD! It is then under the control of gravity and air resistance.

Bullets will generally tumble when falling or fall base first at a maximum speed of about 200'/sec or about 130/180 mph. This all depends on the shape and weight of the bullet but in general this will put you in the ballpark. It will also depend on the altitude at which it was launched. Air id much thicker at sea level.

A 22 caliber 55 grain round will not cause severe  injury, although you probably won't like the feeling. A 50 cal slug is going to hurt. Shotgun pellets can barely be felt through thin clothing.

Injuries occur when the round is not fired straight up. You are essentially firing a very small artillery round and the horizontal speed of the projectile will far exceed the vertical speed in most cases. And the projectile will generally impact nose first.

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1 hour ago, Ace_of_Hearts said:

Injuries occur when the round is not fired straight up.

 

Which is the case with most celebratory gunfire.   Projectiles are launched mostly between 45° and 70° and so, as Ace points out,  impact noise first and with considerable velocity. 

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Why does this remind me of TET?  Every Vietnamese with a bullet and a gun fired it in some direction.  The metal roof on our operations center sounded like a hail storm.  That was the first one for me. The second TET the bullets were definitely flying horizontal.  Going both ways, in and out.

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22 hours ago, J-BAR #18287 said:

Google:

 

 

https://science.howstuffworks.com/question281.htm

 

 

 

 

 

 

 

OK, per Hatcher, a ".30 caliber" (probably .30-06) bullet will reach ~9000' in ~18 seconds.  In about another 31 seconds it will return to the Earth at a speed of ~300fps.  That puts a total flight time at about 49 seconds.  That answers my original question.

 

I would disagree that the average .30 cal. rifle projectile is harmless at 300 fps.  I have seen car roofs dented and windshields broken by 9mm/.38 cal. bullets on New Years day.   But I have been struck by too many shotgun pellets on dove fields and would agree that the average birdshot at extreme range is barely noticeable.  Although I'm not about to volunteer to be a test subject.

 

Noz, I'd bet that "hail" during TET was a bit, um, unnerving.  I imagine it would be similar to sitting in a tank and hearing incoming rounds bounce off the armor.

Glad you made it home.

 

I gotta admit, I am a little disappointed.  In reply I thought I'd get two pages of math that looked like the dry erase boards on "The Big Bang Theory" I could not even begin to understand.  :lol:  It could even have been total BS and I'd have never known.

 

Angus

 

 

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However, even if shot exactly straight up the earth will have moved under it.  If nothing else effects it's flight it will land somewhere east of your location depending on your Latitude.  

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I aim toward Mars with my .50-140 Sharps to hit BPCR targets. The bullet almost invariably eventually drops down onto the buffalo, pig or turkey. :P

 

I usually get a chance to relax while I wait for it to drop of the sky. I don't think that I'd enjoy having that 650 grain slug hit me.  :rolleyes:

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13 hours ago, twelve mile REB said:

However, even if shot exactly straight up the earth will have moved under it.  If nothing else effects it's flight it will land somewhere east of your location depending on your Latitude.  

That would apply ONLY if there were no atmosphere, which would move the bullet with the Earth. OTOH, a projectile fired into the stratosphere will be subject to Coriollis effect.  I can tell you approximately how long it would take a "bullet" fired upwards (NOT straight up) to an altitude of about 800 miles to land somewhere...about 30 minutes!  If fired westward from California to Kwajalein it would take less time as the range is shorter!  OTOH, if fired upward to, say 200 miles and aimed parallel to the Earth's surface...it would not land for quite awhile, until air resistance caused it to deorbit! :P

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14 hours ago, twelve mile REB said:

However, even if shot exactly straight up the earth will have moved under it.  If nothing else effects it's flight it will land somewhere east of your location depending on your Latitude.  

 

I'm thinking that a bullet shot straight up would land to the west of us.  The earth is rotating from west to east, which gives astronomical bodies the appearance of moving east to west.  So after taking the vertical shot, the earth would have moved a tad towards the east, and the bullet, if not affected by wind, would come down a little bit west of the shooter.  And no it would not make any difference whether the shot was taken in the northern or southern hemisphere, it would still come down west of the shooter.  The only place where it would come down on the shooter would be at the poles,  and it would be too cold to celebrate anything there!!

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I know that a 9mm coming back down can go through the hood of a Nissan Sentra and damage the throttle body controls rendering the vehicle undrivable. It happened to a friend of mine. 
 

I know that a FMJ 9mm bullet landing 10’ behind you on a paved roadway will make a noticeable “crack” and the bullet will be noticeably deformed. It happened to me at work at night at our rail yard as I was changing out graffitied windows on NYE in 1991 in Los Angeles. I still have that bullet somewhere. 

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I know a slug from a 45acp (FMJ, guessing probably the standard 230gr) makes a helluva loud thump on your roof, and buries itself not quite flush thru two layers of asphalt tile roofing.  Happened many years ago... I remember getting sent up the ladder with tar to find and patch the hole while my dad watched from the back yard.  I always was my dad's favorite "remote controlled" tool.  Learned a lot that way.

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