Shoot! But Not Up in the Air

 

Question: What is the terminal velocity of a returning .223 bullet once shot into the air and coming back to the ground, and will it perforate a standard corrugated steel roof?  And what is the attitude of a bullet falling to earth?  Point first?  Point up as it was when it was fired?  Flat?

I’ve lived in this house for probably eight years, and it’s pretty standard to hear relatively distant gunfire on midnight entering the new year.  In years past living at a different house, this has been done from a high public park perched over the ocean, firing (one would think) out to sea in the direction the old Spanish cannons are pointed, and incidentally setting the steep grassy slope to the ocean on fire – never knew how – but pretty and without fireworks, and lasting a good hour or so.  Not much danger, except to the local cemetery.  Cemeteries, it seems, always get the choice locations and best views.

But for the past several years I’ve lived inland, and rapid gunfire on New Year’s was always in the distance.  This year new neighbors (there are a lot of them, including on the adjoining hill facing my house) have been getting less neighborly with their loud noises, setting off what I assume were M80s either singly or seemingly tied together and lit with a single fuse, pretty much testing them (or enjoying them) any time of the day or night.  They sound like gunfire and I figure this was why several police cars rolled up with sirens on a few days ago.

It’s hard for me to tell wrapped fireworks from semi-automatic gunfire, though tonight at half past twelve I did hear full-auto fire a quarter of a mile away, oddly, coming from the direction that I hear “The Star Spangled Banner” played every morning on the naval base.

As an aside, when I was in my teens, I wanted to live in a faraway land, in an exotic location, and in my imaginings, Truk (now called Chuuk) was pretty much as far as anyone could get, thousands of miles from anywhere.  And very interestingly, I recently realized that that’s just where circumstances have led me to live, in Oceania, near enough to Truk (or Chuuk) where Chuukese can find it in their interests to fly in on weekends and deliver reasonably fresh reef fish and rock lobsters to the local Sunday morning market.  And even today I’ve had a couple of Chuukese men and a boy cutting ten-foot-tall grass and jungle on my side lot.  Nice guys, Christian, and they speak English, though they are hard for me to understand and tend to do other things than what I employ them for, performing a different job than I wanted, but it seems to be turning out alright anyway.

Getting back to New Year’s, I was awakened a little before midnight by music blaring, engines revving, and explosions, and alerted with the sound of what seemed like a bullet or two hitting and clanging either along or through my roof.  And it got me thinking.

Spitzer-shaped bullets, in all the charts I’ve seen, travel in an arc, but never have I seen – but only was left to suppose – the attitude of the bullet in flight.  If a bullet is fired into the air at, say, a 30-degree angle, and the spin of the bullet continues throughout its flight, does the bullet keep its upward-pointing attitude?  Or does the spin reduce and allow the bullet to tumble?  And if tumbling, does free-fall cause the bullet to nose down at the end of its trajectory, perhaps as the result of aerodynamic drag?

In other words, am I more, or less, likely to have a hole in my roof?  Any answers would be welcome – other than that I just have to get up there and look for scratches or holes – which, deep down, I already know.

Thanks in advance,
Flicker

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  1. BDB Inactive
    BDB
    @BDB

    Flicker (View Comment):

    Manny (View Comment):

    Flicker (View Comment):

    Manny (View Comment):

    I think most bullets are designed to keep spinning for well over their projected range. It should still be spinning when it hits the ground from gravity drop if was fired around a degree or two angle. Most small bullets are direct fire, far below 30 deg elevation. I would guess it would tumble at some point if fired at 30 degrees but you would have to know it’s muzzle velocity and when spin is designed to slow down. If you knew that, it could be calculated. It would definitely tumble if fired vertically on the way down but I think it would be stable and spinning until it reached its height. I could be wrong on that last thought.

    Yes. Actually I was intending that the bullet was fired into the air, meaning no more than 30 degrees from vertical. The bullet comes to near a stop at apogee and reaccelerates on it’s way down. It is a good question, whether the rotational inertia on a bullet is less than the forward inertia. And I don’t know if it’s rotational drag coefficient near apogee is more or less than its forward drag.

    Either way, two sources, BDB I think, and one on Quora, said that when fired upwards, rotation stops near apogee and after that the bullet tumbles on its return or else turns to fall butt-first. These two orientations give different drag coefficients.

    You know, you made me realize that while I understand the principles of spinning bullets, I know very little about how they despin. Normally they have plenty of spin for their range. I should look up artillery rounds. They spin, fired at high elevations, and have long ranges.

    And do arching artillery rounds hit point first?

    Yes, as they are designed to maintain spin throughout their effective range.  So is any rifled projectile.  The effective range of a rifle round is far less than its potential range, as indirect fire is not in its required capabilities.

    Larger rounds typically use a “rotating band”.  I don’t know where that dividing line is.

    • #91
  2. Manny Coolidge
    Manny
    @Manny

    Percival (View Comment):

    BDB (View Comment):

    Randy Weivoda (View Comment):

    Flicker (View Comment):
    Actually I was intending that the bullet was fired into the air, meaning no more than 30 degrees from vertical.

    And 30 degrees off vertical in which direction? If we want to get stupendously technical, we have to factor in if you have fired in the direction of the Earth’s spin or opposite it.

    Why? Over the range and time involved, the Earth might as well be flat. Also, the atmosphere moves with the Earth.

    You’ve got to shoot a lot farther than a .22 can before you have to start worrying about all that.

    Yeah, that’s right.  Small caliber bullets don’t go that far to think about de-spin.

     

    • #92
  3. Manny Coolidge
    Manny
    @Manny

    Flicker (View Comment):

    Randy Weivoda (View Comment):

    Flicker (View Comment):
    Actually I was intending that the bullet was fired into the air, meaning no more than 30 degrees from vertical.

    And 30 degrees off vertical in which direction? If we want to get stupendously technical, we have to factor in if you have fired in the direction of the Earth’s spin or opposite it.

    Into the wind.

    But, yes, I thought of that, and Coriolis effect and wind speed. My guess is that tumbling would change point of impact more than earth’s rotation.

    The point of this article is that the point of impact of these bullets is presupposed, and land on my house. :)

    Oh definitely.  Tumbling is completely unpredictable.

    • #93
  4. Manny Coolidge
    Manny
    @Manny

    Flicker (View Comment):

    Manny (View Comment):

    Flicker (View Comment):

    Manny (View Comment):

    I think most bullets are designed to keep spinning for well over their projected range. It should still be spinning when it hits the ground from gravity drop if was fired around a degree or two angle. Most small bullets are direct fire, far below 30 deg elevation. I would guess it would tumble at some point if fired at 30 degrees but you would have to know it’s muzzle velocity and when spin is designed to slow down. If you knew that, it could be calculated. It would definitely tumble if fired vertically on the way down but I think it would be stable and spinning until it reached its height. I could be wrong on that last thought.

    Yes. Actually I was intending that the bullet was fired into the air, meaning no more than 30 degrees from vertical. The bullet comes to near a stop at apogee and reaccelerates on it’s way down. It is a good question, whether the rotational inertia on a bullet is less than the forward inertia. And I don’t know if it’s rotational drag coefficient near apogee is more or less than its forward drag.

    Either way, two sources, BDB I think, and one on Quora, said that when fired upwards, rotation stops near apogee and after that the bullet tumbles on its return or else turns to fall butt-first. These two orientations give different drag coefficients.

    You know, you made me realize that while I understand the principles of spinning bullets, I know very little about how they despin. Normally they have plenty of spin for their range. I should look up artillery rounds. They spin, fired at high elevations, and have long ranges.

    And do arching artillery rounds hit point first?

    Yes.  They do not tumble, so they must spin for their entire range.  They are amazingly accurate.  

    • #94
  5. Flicker Coolidge
    Flicker
    @Flicker

    BDB (View Comment):

    Flicker (View Comment):

    Manny (View Comment):

    Flicker (View Comment):

    Manny (View Comment):

    I think most bullets are designed to keep spinning for well over their projected range. It should still be spinning when it hits the ground from gravity drop if was fired around a degree or two angle. Most small bullets are direct fire, far below 30 deg elevation. I would guess it would tumble at some point if fired at 30 degrees but you would have to know it’s muzzle velocity and when spin is designed to slow down. If you knew that, it could be calculated. It would definitely tumble if fired vertically on the way down but I think it would be stable and spinning until it reached its height. I could be wrong on that last thought.

    Yes. Actually I was intending that the bullet was fired into the air, meaning no more than 30 degrees from vertical. The bullet comes to near a stop at apogee and reaccelerates on it’s way down. It is a good question, whether the rotational inertia on a bullet is less than the forward inertia. And I don’t know if it’s rotational drag coefficient near apogee is more or less than its forward drag.

    Either way, two sources, BDB I think, and one on Quora, said that when fired upwards, rotation stops near apogee and after that the bullet tumbles on its return or else turns to fall butt-first. These two orientations give different drag coefficients.

    You know, you made me realize that while I understand the principles of spinning bullets, I know very little about how they despin. Normally they have plenty of spin for their range. I should look up artillery rounds. They spin, fired at high elevations, and have long ranges.

    And do arching artillery rounds hit point first?

    Yes, as they are designed to maintain spin throughout their effective range. So is any rifled projectile. The effective range of a rifle round is far less than its potential range, as indirect fire is not in its required capabilities.

    Larger rounds typically use a “rotating band”. I don’t know where that dividing line is.

    And howitzer shells as well?

    • #95
  6. Manny Coolidge
    Manny
    @Manny

    BDB (View Comment):

    Flicker (View Comment):

    Manny (View Comment):

    Flicker (View Comment):

    Manny (View Comment):

    I think most bullets are designed to keep spinning for well over their projected range. It should still be spinning when it hits the ground from gravity drop if was fired around a degree or two angle. Most small bullets are direct fire, far below 30 deg elevation. I would guess it would tumble at some point if fired at 30 degrees but you would have to know it’s muzzle velocity and when spin is designed to slow down. If you knew that, it could be calculated. It would definitely tumble if fired vertically on the way down but I think it would be stable and spinning until it reached its height. I could be wrong on that last thought.

    Yes. Actually I was intending that the bullet was fired into the air, meaning no more than 30 degrees from vertical. The bullet comes to near a stop at apogee and reaccelerates on it’s way down. It is a good question, whether the rotational inertia on a bullet is less than the forward inertia. And I don’t know if it’s rotational drag coefficient near apogee is more or less than its forward drag.

    Either way, two sources, BDB I think, and one on Quora, said that when fired upwards, rotation stops near apogee and after that the bullet tumbles on its return or else turns to fall butt-first. These two orientations give different drag coefficients.

    You know, you made me realize that while I understand the principles of spinning bullets, I know very little about how they despin. Normally they have plenty of spin for their range. I should look up artillery rounds. They spin, fired at high elevations, and have long ranges.

    And do arching artillery rounds hit point first?

    Yes, as they are designed to maintain spin throughout their effective range. So is any rifled projectile. The effective range of a rifle round is far less than its potential range, as indirect fire is not in its required capabilities.

    Larger rounds typically use a “rotating band”. I don’t know where that dividing line is.

    I think all rounds fired from a rifled tubes have a surface for engaging the rifling.  Smooth bore guns use nylon obturators.  Small bullets may not have a specific rotating band but have a surfaced diameter that engages the rifling.  See how the rifling engaged the rear surface that was at a larger diameter than the tip.  

    • #96
  7. Flicker Coolidge
    Flicker
    @Flicker

    Manny (View Comment):

    BDB (View Comment):

    Flicker (View Comment):

    Manny (View Comment):

    Flicker (View Comment):

    Yes. Actually I was intending that the bullet was fired into the air, meaning no more than 30 degrees from vertical. The bullet comes to near a stop at apogee and reaccelerates on it’s way down. It is a good question, whether the rotational inertia on a bullet is less than the forward inertia. And I don’t know if it’s rotational drag coefficient near apogee is more or less than its forward drag.

    Either way, two sources, BDB I think, and one on Quora, said that when fired upwards, rotation stops near apogee and after that the bullet tumbles on its return or else turns to fall butt-first. These two orientations give different drag coefficients.

    You know, you made me realize that while I understand the principles of spinning bullets, I know very little about how they despin. Normally they have plenty of spin for their range. I should look up artillery rounds. They spin, fired at high elevations, and have long ranges.

    And do arching artillery rounds hit point first?

    Yes, as they are designed to maintain spin throughout their effective range. So is any rifled projectile. The effective range of a rifle round is far less than its potential range, as indirect fire is not in its required capabilities.

    Larger rounds typically use a “rotating band”. I don’t know where that dividing line is.

    I think all rounds fired from a rifled tubes have a surface for engaging the rifling. Smooth bore guns use nylon obturators. Small bullets may not have a specific rotating band but have a surfaced diameter that engages the rifling. See how the rifling engaged the rear surface that was at a larger diameter than the tip.

    What round is this?

    Added: What I’m getting at is that a gyroscope will keep it’s orientation no matter how it’s moving in any given arc.  With a highly gyroscopic round, it should stay pointing slightly up all the while that it is falling, which it begins to do upon leaving the barrel.  If you fire a howitzer into the air at say 45 to 60-degrees from horizontal, how does a shell without fins change its orientation to point back at the target on the ground?

    • #97
  8. Sisyphus Member
    Sisyphus
    @Sisyphus

    Flicker (View Comment):

    Manny (View Comment):

    BDB (View Comment):

    Flicker (View Comment):

    Manny (View Comment):

    Flicker (View Comment):

    Manny (View Comment):

    I think most bullets are designed to keep spinning for well over their projected range. It should still be spinning when it hits the ground from gravity drop if was fired around a degree or two angle. Most small bullets are direct fire, far below 30 deg elevation. I would guess it would tumble at some point if fired at 30 degrees but you would have to know it’s muzzle velocity and when spin is designed to slow down. If you knew that, it could be calculated. It would definitely tumble if fired vertically on the way down but I think it would be stable and spinning until it reached its height. I could be wrong on that last thought.

    Yes. Actually I was intending that the bullet was fired into the air, meaning no more than 30 degrees from vertical. The bullet comes to near a stop at apogee and reaccelerates on it’s way down. It is a good question, whether the rotational inertia on a bullet is less than the forward inertia. And I don’t know if it’s rotational drag coefficient near apogee is more or less than its forward drag.

    Either way, two sources, BDB I think, and one on Quora, said that when fired upwards, rotation stops near apogee and after that the bullet tumbles on its return or else turns to fall butt-first. These two orientations give different drag coefficients.

    You know, you made me realize that while I understand the principles of spinning bullets, I know very little about how they despin. Normally they have plenty of spin for their range. I should look up artillery rounds. They spin, fired at high elevations, and have long ranges.

    And do arching artillery rounds hit point first?

    Yes, as they are designed to maintain spin throughout their effective range. So is any rifled projectile. The effective range of a rifle round is far less than its potential range, as indirect fire is not in its required capabilities.

    Larger rounds typically use a “rotating band”. I don’t know where that dividing line is.

    I think all rounds fired from a rifled tubes have a surface for engaging the rifling. Smooth bore guns use nylon obturators. Small bullets may not have a specific rotating band but have a surfaced diameter that engages the rifling. See how the rifling engaged the rear surface that was at a larger diameter than the tip.

    What round is this?

    The bullet round, naturally.

    • #98
  9. Flicker Coolidge
    Flicker
    @Flicker

    Sisyphus (View Comment):

    Flicker (View Comment):

    Manny (View Comment):

    BDB (View Comment):

    Flicker (View Comment):

    Manny (View Comment):

    Flicker (View Comment):

    Manny (View Comment):

    I think most bullets are designed to keep spinning for well over their projected range. It should still be spinning when it hits the ground from gravity drop if was fired around a degree or two angle. Most small bullets are direct fire, far below 30 deg elevation. I would guess it would tumble at some point if fired at 30 degrees but you would have to know it’s muzzle velocity and when spin is designed to slow down. If you knew that, it could be calculated. It would definitely tumble if fired vertically on the way down but I think it would be stable and spinning until it reached its height. I could be wrong on that last thought.

    Yes. Actually I was intending that the bullet was fired into the air, meaning no more than 30 degrees from vertical. The bullet comes to near a stop at apogee and reaccelerates on it’s way down. It is a good question, whether the rotational inertia on a bullet is less than the forward inertia. And I don’t know if it’s rotational drag coefficient near apogee is more or less than its forward drag.

    Either way, two sources, BDB I think, and one on Quora, said that when fired upwards, rotation stops near apogee and after that the bullet tumbles on its return or else turns to fall butt-first. These two orientations give different drag coefficients.

    You know, you made me realize that while I understand the principles of spinning bullets, I know very little about how they despin. Normally they have plenty of spin for their range. I should look up artillery rounds. They spin, fired at high elevations, and have long ranges.

    And do arching artillery rounds hit point first?

    Yes, as they are designed to maintain spin throughout their effective range. So is any rifled projectile. The effective range of a rifle round is far less than its potential range, as indirect fire is not in its required capabilities.

    Larger rounds typically use a “rotating band”. I don’t know where that dividing line is.

    I think all rounds fired from a rifled tubes have a surface for engaging the rifling. Smooth bore guns use nylon obturators. Small bullets may not have a specific rotating band but have a surfaced diameter that engages the rifling. See how the rifling engaged the rear surface that was at a larger diameter than the tip.

    What round is this?

    The bullet round, naturally.

    If I liked gummy bears, I would like a gummy bear like that.

    • #99
  10. BDB Inactive
    BDB
    @BDB

    Flicker (View Comment):

    Manny (View Comment):

    BDB (View Comment):

    Flicker (View Comment):

    Manny (View Comment):

    Flicker (View Comment):

    Yes. Actually I was intending that the bullet was fired into the air, meaning no more than 30 degrees from vertical. The bullet comes to near a stop at apogee and reaccelerates on it’s way down. It is a good question, whether the rotational inertia on a bullet is less than the forward inertia. And I don’t know if it’s rotational drag coefficient near apogee is more or less than its forward drag.

    Either way, two sources, BDB I think, and one on Quora, said that when fired upwards, rotation stops near apogee and after that the bullet tumbles on its return or else turns to fall butt-first. These two orientations give different drag coefficients.

    You know, you made me realize that while I understand the principles of spinning bullets, I know very little about how they despin. Normally they have plenty of spin for their range. I should look up artillery rounds. They spin, fired at high elevations, and have long ranges.

    And do arching artillery rounds hit point first?

    Yes, as they are designed to maintain spin throughout their effective range. So is any rifled projectile. The effective range of a rifle round is far less than its potential range, as indirect fire is not in its required capabilities.

    Larger rounds typically use a “rotating band”. I don’t know where that dividing line is.

    I think all rounds fired from a rifled tubes have a surface for engaging the rifling. Smooth bore guns use nylon obturators. Small bullets may not have a specific rotating band but have a surfaced diameter that engages the rifling. See how the rifling engaged the rear surface that was at a larger diameter than the tip.

    What round is this?

    Added: What I’m getting at is that a gyroscope will keep it’s orientation no matter how it’s moving in any given arc. With a highly gyroscopic round, it should stay pointing slightly up all the while that it is falling, which it begins to do upon leaving the barrel. If you fire a howitzer into the air at say 45 to 60-degrees from horizontal, how does a shell without fins change its orientation to point back at the target on the ground?

    I believe that a howitzer is a short-barreled non-rifled gun.  But terms change.  I presume that modern “howitzers” are called such due to purpose, rather than old definitions.  IF I’m right.

    • #100
  11. Manny Coolidge
    Manny
    @Manny

    Flicker (View Comment):

    Manny (View Comment):

    BDB (View Comment):

    Flicker (View Comment):

    Manny (View Comment):

    Flicker (View Comment):

    Yes. Actually I was intending that the bullet was fired into the air, meaning no more than 30 degrees from vertical. The bullet comes to near a stop at apogee and reaccelerates on it’s way down. It is a good question, whether the rotational inertia on a bullet is less than the forward inertia. And I don’t know if it’s rotational drag coefficient near apogee is more or less than its forward drag.

    Either way, two sources, BDB I think, and one on Quora, said that when fired upwards, rotation stops near apogee and after that the bullet tumbles on its return or else turns to fall butt-first. These two orientations give different drag coefficients.

    You know, you made me realize that while I understand the principles of spinning bullets, I know very little about how they despin. Normally they have plenty of spin for their range. I should look up artillery rounds. They spin, fired at high elevations, and have long ranges.

    And do arching artillery rounds hit point first?

    Yes, as they are designed to maintain spin throughout their effective range. So is any rifled projectile. The effective range of a rifle round is far less than its potential range, as indirect fire is not in its required capabilities.

    Larger rounds typically use a “rotating band”. I don’t know where that dividing line is.

    I think all rounds fired from a rifled tubes have a surface for engaging the rifling. Smooth bore guns use nylon obturators. Small bullets may not have a specific rotating band but have a surfaced diameter that engages the rifling. See how the rifling engaged the rear surface that was at a larger diameter than the tip.

    What round is this?

    Added: What I’m getting at is that a gyroscope will keep it’s orientation no matter how it’s moving in any given arc. With a highly gyroscopic round, it should stay pointing slightly up all the while that it is falling, which it begins to do upon leaving the barrel. If you fire a howitzer into the air at say 45 to 60-degrees from horizontal, how does a shell without fins change its orientation to point back at the target on the ground?

    No clue what round.  I just pulled off the internet searching for a picture to make my point.  I don’t know the exact answer to your last question.  From the visuals I’ve seen, I think the round tips downward once it reaches its apogee.  No gyroscope.  I think it’s a front heavy weight.

    • #101
  12. Phil Turmel Inactive
    Phil Turmel
    @PhilTurmel

    Manny (View Comment):

    No gyroscope.  I think it’s a front heavy weight.

    •  

    A spinning bullet or artillery shell is its own gyroscope.  And pretty intense ones, when you work out the RPMs they turn.  Ergo, Flicker’s question.

    • #102
  13. Manny Coolidge
    Manny
    @Manny

    Phil Turmel (View Comment):

    Manny (View Comment):

    No gyroscope. I think it’s a front heavy weight.

    •  

    A spinning bullet or artillery shell is its own gyroscope. And pretty intense ones, when you work out the RPMs they turn. Ergo, Flicker’s question.

    I had not realized. It does make sense. Thanks. 

    • #103
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