Freefalling Bullets

[turtlespeed 212]

You mean like in the head doooowwwnnn Pooseeeetion?

I'm not usually into the whole 3-way thing, but you got me a little excited with that. - Skymama
BTR #1 / OTB^5 Official #2 / Hellfish #408 / VSCR #108/Tortuga/Orfun

[Pi-314 0]

Quote

The only thing that makes a bullet stable is the spin that is put on it by the barrel of a gun. Allowing the bullet to go up, stop and fall back down will also completly reduce the spoin, this making the bullet fall back down in an unpredictable radical tumble.

True about the spin - Especially when the center of gravity of most all bullets is toward the base of the bullets. This center of gravity establishes a preference that the base would face the ground in freefall. If the bullet could avoid an end to end spin at the outset - The based will continue to fall facing the Earth, where the bullet tip wobbles back and forth by air resistence on the sides.

[pop 0]

Followed but a seet fli poseeetion

7 ounce wonders, music and dogs that are not into beer

[turtlespeed 212]

I'm not usually into the whole 3-way thing, but you got me a little excited with that. - Skymama
BTR #1 / OTB^5 Official #2 / Hellfish #408 / VSCR #108/Tortuga/Orfun

[pop 0]

Why is your post empty?

7 ounce wonders, music and dogs that are not into beer

[mfrese 0]

Pop...you been hittin' the tequila already, buddy?

Doctor I ain't gonna die,
Just write me an alibi! ---- Lemmy/Slash

[pop 0]

Nahh, I've been waiting on you

7 ounce wonders, music and dogs that are not into beer

[turtlespeed 212]

It wasn't supposed to be.

It was supposed to say that there are three Four questions now:
1) Does the spin decrease as the apex is reached?
2) Does the bullet seek the flight path of least resistance?
3) If the flight path of least resistance is sought, and the spin does not decrease, could it reach the same velocity that it achieved on the way up?
4) Do we really care?

I'm not usually into the whole 3-way thing, but you got me a little excited with that. - Skymama
BTR #1 / OTB^5 Official #2 / Hellfish #408 / VSCR #108/Tortuga/Orfun

[kallend 1,623]

Quote

I was checking into this idea that freefalling bullets kill, when I ran into this thread and noticed your experiment.

There are a few things you didn't take into account. One of them is in regards to the (spin end over end) when releasing the bullet. It is important to note that you released the bullets when they were already falling at 120 MPH, as opposed to a bullet that reaches it's highest point and begins to drop from zero velocity. A bullet drop from zero velocity will have a much greater chance of becoming stable and drop with the base of the bullet facing the earth, than one released from a standpoint of air passing it at 120 MPH.

Quote

Why would that be? I don't understand your reasoning.

If you let go of the bullet at 120 MPH, and if it isn't in what would be a stable position to begin with - It will spin end over end from the start with perhaps no chance of stability before it hits the ground. In effect you lose perhaps 50% of it's potential velocity from the get go.

A more important point to be made is your body dropping next to the bullet is contaminating the experiment. When you are in freefall - There is a greater air pressure created below you as you drop, while you in effect created a sort of vaccum above your body. This creates a sort of wind tunnel around you. I.E. The air below you rushes past you to fill the vaccum above you. Although you may be dropping at 120 MPH - The air around could be passing at say 180 MPH in relation to you. So the bullet could be dropping at 180 MPH in relation to the air thats moving at 60 MPH to fill the vaccum above you.

Quote

The effect of interference drag (this is what you are talking about) decreases rapidly with separation. You only have to be two or three body widths apart for the effect to be negligible. You argument would apply equally well to another skydiver next to you. When you do a 2-way does the guy next to you experience 180mph winds from your presence (and vice versa)?

Hence - You will see the bullet as if it is falling slower than you, when in reality it's moving 180 MPH in relation to the air. When the bullet gets to an area of calmer air ( away from you). It will accelerate in relation to the calmer air. It could concievably catch up to you if it could fall away from the disturbance you created during your fall.

If you put the bullet on your back side - It should stay there. considering there is a bit of a vaccum there.

I'm guessing bullets will drop anywhere from 150 to 300 MPH, and anything above 200 MPH has a fairly good chance of taking you out, should it hit you in the noggin.

...

The only sure way to survive a canopy collision is not to have one.

[JohnRich 4]

Quote

There are a few things you didn't take into account. One of them is in regards to the (spin end over end) when releasing the bullet. It is important to note that you released the bullets when they were already falling at 120 MPH, as opposed to a bullet that reaches it's highest point and begins to drop from zero velocity. A bullet drop from zero velocity will have a much greater chance of becoming stable and drop with the base of the bullet facing the earth...

I covered this in my original post, admitted it as a weakness in my experiment, and offered it as an explanation for the differences between my personal observations and the calculations done by Hatcher.

Quote

A more important point to be made is your body dropping next to the bullet is contaminating the experiment...

I think releasing the bullets at arms length pretty much puts them into "clean" air, just like throwing out your pilot chute. I don't believe the effect you describe would be significant. Especially since the .45 caliber bullet fell relative to me, immediately from release, and I continued to fly with it after backing off a bit. If there was 180 mph air around our bodies in freefall, we would have a lot harder time than we do docking on our friends in freefall formations.

Quote

I'm guessing bullets will drop anywhere from 150 to 300 MPH

I disagree. My guess, based upon my own experiment, as well as other reading, puts the range between about 100 mph and 180 mph, depending upon weight and stability.

[JohnRich 4]

Quote

The only thing that makes a bullet stable is the spin that is put on it by the barrel of a gun. Allowing the bullet to go up, stop and fall back down will also completly reduce the spin, this making the bullet fall back down in an unpredictable radical tumble.

Negative. The spin is independent of the velocity. It does not automatically stop spinning just because it reaches apogee. If you spin-up a gyroscope and then throw it onto the desk, it doesn't quit spinning after it falls onto the desk. It continues to spin as it falls back to earth. Hatcher's experiments confirmed this, with dents in the sheet metal roof showing that the bullets struck hind-end first - spin stabilized.

[JohnRich 4]

Quote

1) Does the spin decrease as the apex is reached?

The spin rate may degrade over time, but it is independent of the bullet's position in its trajectory.

Quote

2) Does the bullet seek the flight path of least resistance?

It's not so much "least reisistance" I think, as it is center of gravity, and wind resistance, just like a shuttlecock. Since bullets have tapered tips, the center of mass is towards the rear, so that without a spin to stabilize it, it wants to fall base-first.

Quote

3) If the flight path of least resistance is sought, and the spin does not decrease, could it reach the same velocity that it achieved on the way up?

No. Wind resistance prevents it from achieving the same velocity it reached from being fired out of a gun barrel, which is in the vicinity of 800 to 3,500 feet per second, depending upon caliber.

The .45 bullet in my test has a muzzle velocity out of a handgun of 850 fps, while in freefall I observed it at 175 fps, or only 20% of it's original velocity. A .223 bullet is fired at 3,200 fps, and freefalls at about 140 fps, or only 4% of its original velocity.

[LouDiamond 1]

Just got this in an E-mail:


Falling Bullets an Issue in Iraqi Town

By ERIC TALMADGE
.c The Associated Press

SAMAWAH, Iraq (AP) - Eight-year-old Zehra Kadhum was outside near her family's garage playing, when she saw her parents kneel to pray. As she bent down to join them, she felt a sharp pain.

``I thought my sister had kicked me,'' she said from her hospital bed Sunday. ``But I was bleeding and I heard my family shouting and my mother was crying.''

Zehra had been hit in the back by a bullet dropping out of the sky.

Like many places throughout Iraq, there is a gun in virtually every household in this desert city, some 230 miles southeast of Baghdad. The sound of weapons - from AK-47 rifles to small-caliber pistols - is as much a part of the evening din as is the chanting of the daily prayers.

Along with offering protection in an unstable country, the guns are a means of self-expression. Men fire off shots to celebrate, to mark funerals or just to beat the monotony of life in the country.

But so many shots are fired that the returning rain of bullets - not stray rounds, but bullets simply falling back to earth - sends an average of one or more people to the hospital each month.

``It's terrible, the governing council in Baghdad has to do something about this situation,'' said Dr. Ali al Azawi, who removed the bullet from Zehra at Samawah General Hospital last week.

The girl is in stable condition.

``We suffer from this especially here in the south, because everybody has weapons in their house,'' he said. ``It is especially unforgivable at this time, when we lack medicine and health care.''

It's easy to get a gun in Samawah.

Ghazi Fahid Wali, who runs one of the many small gun shops here, said he sells from two to four weapons a month, mostly machine guns, but also pistols and old hunting rifles. A Kalishnikov automatic rifle goes for about US$110, he said.

``Among Arabs, we believe that if a person owns a gun nobody will harm him,'' he said. ``Looters will stay away, troublemakers will stay away.''

Wali said he had heard of several incidents in which people in town had been injured by falling bullets, most often around especially festive times.

But he wasn't particularly concerned.

``It happens,'' he said with a shrug.



02/16/04 02:01 EST

"It's just skydiving..additional drama is not required"
Some people dream about flying, I live my dream
SKYMONKEY PUBLISHING

[JohnMitchell 14]

Some of the bullets hit the tin roof or the wood of the raft, and many of them made an impression indicating that they hit base-first. Others were point-first. None hit sideways. This would indicate that the bullets were still spin-stabilized on their return descent.

[Hooknswoop 19]

http://www.local6.com/news/4041085/detail.html

Derek

[JohnRich 4]

Quote

http://www.local6.com/news/4041085/detail.html

Since he was hit in the chest and heart, this would not have been a freefalling bullet, but rather, one that was fired at some more horizontal degree, and thus retained much more velocity.

[penniless 0]

Quote

Quote

http://www.local6.com/news/4041085/detail.html

Since he was hit in the chest and heart, this would not have been a freefalling bullet, but rather, one that was fired at some more horizontal degree, and thus retained much more velocity.

As soon as any bullet leaves the barrel it is technically freefalling. It may take a while to reach terminal velocity.

[PhreeZone 15]

We had 2 serious injuries on New Years here in Columbus from the same cause.

Yesterday is history
And tomorrow is a mystery

Parachutemanuals.com

[JohnRich 4]

Quote

As soon as any bullet leaves the barrel it is technically freefalling. It may take a while to reach terminal velocity.

That's true, but the original subject of this thread was about the freefall speed of bullets falling vertically, without any muzzle velocity remaining.

[Randy_H 0]

Interesting conclusion, but very wrong.

read this story http://www.local6.com/news/4041085/detail.html
This just happened in Orlando during New Years. Some drunken, gun toating idiot decided to fire shots into the air.

010010010110010101100001011101000111000001110101011100110111001101111001

[Hooknswoop 19]

Quote

read this story

Look up 3 posts.............

Derek

[airtwardo 6]

Quote

That's true, but the original subject of this thread was about the freefall speed of bullets falling vertically, without any muzzle velocity remaining.

Quote

Question John~

By falling 'vertically' I take it you mean
0 degrees
Top dead center?

Which would as you contend bring the projectile
back to earth, tail first, still spinning...

But~

How about if said 'idiot' fires a round at 15-20 degrees
from straight up...
When it reaches zero speed upward at the top of the arc
even though still spinning, wouldn't it 'wobble' unstable,
(long axis)
since it still has 'forward' or 'down range' speed when
the free return begins?


I ask because~

A few years ago at a small airport North of L.A.
we were discussing those thoughts in regard to
the number of 'new' holes in the hangar roofs
after New Years eve.

We found *most* of the bullets on the floor,
but some still laying in minor dents in the roof.

Some appeared to have gone through the
roof sideways....(30 cal. ball.)

But one recovered .45 ball round went through the roof
nose first, (visual damage) and had enough
speed to punch through a fabric wing.
(one side~entered, no exit hole)

We speculated that the .45 was fired nearby..
(brass outside the hangar)
and most likely straight up...while the rifle
was probably fired off the airport some
distance away and had an arched trajectory.

Your thoughts?

~ If you choke a Smurf, what color does it turn? ~

[storm1977 0]

The simple fact is, "Space" bullets do and have killed people. There are documented cases.

In physics, the laws say that an object fired into the air will come down with the SAME force as it was lanched with in perfect conditions.

FLAWS:

First off, it is almost never the case that a bullet is fired straight up into the air. It is more likely on a high arc. Therefore, the bullet never looses full motion and rifling of the bullet should continue, thus allowing greater speed than what you experienced.

I don't think this is a valid experiment.
But sounds like a shitload of fun anyway!!!!

-----------------------------------------------------
Sometimes it is more important to protect LIFE than Liberty

[Courteney 0]

Quote

The other thing is that there is probally some disfiguration due to firing, which the test bullets didn't have, which would make them more ball shaped and they wouldn't tumble as much.

Not neccesarily. If a fired bullet doesn't hit anything hard it will maintain it's original shape. Depending on the composition of the said bullet. Solids have been pulled from a wet pack, (bundle of wet magazines) that have still kept their original shape. A bullet shot straight up will spin until it stops then will tumble on the way down.

...drags me down like some sweet gravity!!!

[JohnRich 4]

Quote

Your thoughts?

The answers to your questions lie in the previous discussions in this thread.

The Hatcher experiments found the same thing with a protective tin roof under which they took shelter after firing a machinegun into the air: some bullets dinged the roof nose-down, some base-first, some while tumbling.