Terminal Velocity of Pellets

i guess all i can say is, i wouldn't want get hit in the head with one. i'm not a lucky man

i would think that a heavy rifle or pistol bullet falling would be considerably more dangerous than a pellet. you can take a steel bb and a lead bb and drop from the same height and they both hit at the same time even though the lead round weighs more, but we all know that for the same velocity, the heavier round has more energy at impact. ie forget the penny thing, drop a marble and a lead ball of the same size(equal size being for gravity reasons, they both fall at the same rate) off the empire state building. marble will shatter but the lead penetrating the pavement, but wait now i just added another factor to to equation sectional density for equal sized objects of different weights... i have to stop doing this to myself!lol. i guess what im saying is lead or any other projectile material is denser than our bodies and i dont wanna get hit with it. that being said, light projctiles(read pellets or birdshot)probably do not have enough mass to create anything more than a superficial wound when falling. however, a 308 bullet falling at 100fps or more, even if it is backwards when its coming down, i dont want to be the one getting hit with it or even a 223!

I have worked problems like this in Physics class way back when but a pellet tumbling down would be very high drag relative to its mass. As the pellets shape becomes more aerodynamic the drag coefficient would drop. As it fills with lead the mass would rise. Estimating the drag coefficient tumbling would be a bit difficult but you can do it (with calculus) or estimate it close enough. The force of gravity is always 32 ft/sec/sec. If there is no drag and you drop a bullet and shoot another sideways at the same moment and the earth is perfectly flat they will hit at the same moment (or nearly since speed influences time).

Hows that?

StubExt wrote:I have worked problems like this in Physics class way back when but a pellet tumbling down would be very high drag relative to its mass. As the pellets shape becomes more aerodynamic the drag coefficient would drop. As it fills with lead the mass would rise. Estimating the drag coefficient tumbling would be a bit difficult but you can do it (with calculus) or estimate it close enough. The force of gravity is always 32 ft/sec/sec. If there is no drag and you drop a bullet and shoot another sideways at the same moment and the earth is perfectly flat they will hit at the same moment (or nearly since speed influences time).

Hows that?

Yea, I know about the 32 per sec and the same time thing---that is if there were no air to get in the way. But exactly what you were talking about is why it (the pellet) wouldn't catch up to the more massed bullet. Same thing with those bottle rockets: They may weigh the same but when spent and they come down, it's the same thing as a feather or a leaf competing with a solid rock.

I tried to explain all this to this person I was having the conversation. I even told h'm to pick up any one of the small bore pellets I had and see if he could throw it 20 feet, as hard as he could, and see if he could break a pain of glass in a window. He wouldn't try it but wanted to give me bloody hell about the virtues of safety and how a pellet could kill someone on the way down.

Even the military doesn't think so by the article I cited.

He's a gun hater. Not specific though and not prejudice: He hates anything long and pointed that "shoots" like so many that have been programed to think that way. You can't argue with these types of people. On top of that he touts that he was an engineer for some motor company but in the same breath tells you that he didn't go to college for it. Do the math and it doesn't pass the smell test to me. But he's got the ear of a couple of people and well, I just hate that kind of thing: Talking about what they don't know about passing on the phobias about air guns, fire arms, etc. Gives us all a bad name out of what? Not just mis-education, but fear pased on as well, I think.

Ah, but I"m waxing a little philosophical about it and politics has never been my forte.

You pretty much made my point and thanks for the reply, Stub. (Long time no post here!)

Well I can tell you from real testing, my Condor with the R&L valve and cast slugs 62 grain travels about 3x farther than Kodiaks 31 grain when fired at the same angle (about 30 degrees). The obvious big advantage of diablo pellets for safer shooting are they tend to destabilize and tumble.

I use Chairgun to get maximun range at the velocity I use with any given pellet, and then plot a map with Google earth out around the vineyard to find shooting positions and angles at Starlings on the tops of Doug Firs, to see where I can and can't shoot. Usual maximum range FPE is aroujnd 5 to 6 FPE.

Now with my cast slugs in the Condor, it is all out the window, nothing gets shot out of the tops of trees with that gun.

Shooting 150 yards and watching the difference on my metal clad target with pellets and the cast LBT slugs is a real eye opener, the pellets bounce off, the bullets shoot thru, hardly any drift, light years flatter in trajectory.

When I lived out in the High Desert of Eastern Oregon where the population density is 1 person per square mile and most of the inhabinents lived in the only two cities of the county, I used to drive to the middle of a dry lake bed and shoot up in the air as straight as I could get with my 44 special. I could hear those slugs come down and have been always glad they did not come close.

Now I am not a math whiz or an engineer, but terminal velocity is 120 MPH. If you times 120 by 5280 to get feet per hour and then divide by 60 to get feet per minute and then by 60 to get feet per second, that is 176 FPS. that is 3.44 FPE with a JSB King.

So there blowhard:P

Now I got yah - thats for humans... although women are somewhat shaped like diablo pellets I guess.

"With air resistance acting upon an object that has been dropped, the object will eventually reach a terminal velocity, around 56 m/s (200 km/h or 120 mph) for a human body."

http://en.wikipedia.org/wiki/Free_fall


Assuming an object falling from rest and no change in air density with altitude, the solution is:



where the terminal speed is given by



The object's speed versus time can be integrated over time to find the vertical position as a function of time:

By gosh that is it.



We will have Myth Busters drop Kari out of a plane at the same time as a Diablo pellet!

Seriously, when I am in those situations Squirrel with jerks like your talking about, I just get in their face and back them down. I know as I get older I am risking a good a$$ kicking, but hell I have brain damage, not to mention 20 inches of wound channel in my fine body already from fighting 20 guy one night and a fine tax free lifetime pension for it from the PD so what the heck one more beating shouldn't phase me .

Regards,

Roachcreek

I would be willing to sacrifice my time and study Kari closely purely in the interest of science.

I'm on the part about the frreefallof Kari: Let Kari free fall with the pellet to see if the speed is the same and have her pull the rip coard at 1500 feet.


If you will let us know your wifes email address I can let her know it is all in the interest of science.

I dont need to bother the wife with such important efforts (or my new gun purchase last weekend). Kari has some impressive posters from her past that would go well in the gun room that the family steers clear of. I wonder if dipping in a hot tub can be extrapolated to external air gun ballistics?

If I'd of known what a riot the answers could be for this I'd of asked a loing time ago!

Got my answer though!
Thanks all!