24hourcampfire.com
24hourcampfire.com
-->
Previous Thread
Next Thread
Print Thread
Hop To
Joined: Mar 2003
Posts: 463
Bug Offline OP
Campfire Member
OP Offline
Campfire Member
Joined: Mar 2003
Posts: 463
I wish to do so, as well.
In a recent article in Handloader magazine, one of our more popular scribes refers to hydrostatic shock. To wit:

Quote
We've been told for decades that extra speed always results in extra "killing power," whether through more foot-pounds of kinetic energyor high velocity's Holy Grail, hydrostatic shock.


Isn't the use of the term "hydrostatic" technically incorrect? The term would seem to imply liquid under pressure, but at rest; ie.,not moving. What is referred to, in this instance might me more correctly phrased as "hydrodynamic shock." This implies liquid, under pressure, GOING somewhere, and DOING something. This is what is happening. Shouldn't we all strive to be more technically, if not politically, correct?

P.S. John,
You see just how ridiculous this can get???????
Ya just can't make everyone happy! Even when you do, someone will get PO'ed about that! <img src="/ubbthreads/images/graemlins/confused.gif" alt="" />..................Bug.

GB1

Joined: Jul 2001
Posts: 60,241
Likes: 31
M
Campfire Kahuna
Online Content
Campfire Kahuna
M
Joined: Jul 2001
Posts: 60,241
Likes: 31
Bug--

I just used the common term.

If I talked about hydrodynamic shock, or liquid-pressure instant capillary expansion, or any other term not generally known to the average rifle loony, some people would still be scratching their heads, and many more would be writing in to HANDLOADER asking why the heck JB doesn't know the proper term is "hydrostatic shock."

So you see, I DO know how ridiculous this can get!

Thanks,
JB

Joined: Aug 2003
Posts: 13,550
JOG Offline
Campfire Outfitter
Offline
Campfire Outfitter
Joined: Aug 2003
Posts: 13,550
Bug,

Dusting off my physics, I believe "hydrostatic" is correct. A hydrostatic shockwave is not created by moving water, but rather by the elasticity of water.

I hate to get into all the stuff about permanent and temporary stretch/crush cavities and all that, and I'm sure you're right that hydrodynamic shock occurs at and near the bullet impact. Hydrostatic shock is often credited for doing damage at a considerable distance from the impact.


Forgive me my nonsense, as I also forgive the nonsense of those that think they talk sense.
Robert Frost
Joined: Feb 2004
Posts: 1,128
R
Campfire Regular
Offline
Campfire Regular
R
Joined: Feb 2004
Posts: 1,128
I think it's both, I'll try to keep it simple:

"hydrostatic" effect --> from pulsating shock miniwaves in "non-moving" liquid (no particles moved) very close to impact and wound channel

"hydrodynamic" effect --> result from and reaction to pulsatory cavern (moving liquid - particles moved) second close to wound channel and even transferred to outer edges of the medium

Roe Deer

Joined: Feb 2001
Posts: 8,549
Likes: 2
Campfire Outfitter
Offline
Campfire Outfitter
Joined: Feb 2001
Posts: 8,549
Likes: 2
Read an article by P.O. Ackley in his reloading vol. 1 about rotational spin causing hydrostatic shock. He stated that the faster a bullet went, the greater the rotational spin, thus causing greater "killing" ability.
He stated that a 220 swift, with proper bullets, compared to a 30-06, shooting the same number of deer, that the 220 swift would have killed MORE DEER! because of the faster rotational spin which created more hydrostatic shock.
Food for thought....
Virgil B.

IC B2

Joined: Dec 2000
Posts: 29,348
Campfire Ranger
Offline
Campfire Ranger
Joined: Dec 2000
Posts: 29,348
"-static" has always seemed out of place in this expression to me, too. Also, it has always seemed to me that knowing what's going-on is far more important (more useful) than just knowing which term to use. This process in down-range ballistics has been an item of study for me since the early 1950s, but I didn't gain on it until sheer luck had me studying physics (1956) with a professor who happened to be a ballistician and took a special interest in a student who was curious about ballistics.

The process that we're talking about here is a dynamic application of simple hydraulic pressure -- an incompressible fluid subjected to a given pressure transmits that pressure, essentially undiminished, to all surfaces of the fluid -- just as in a hydraulic jack or lift, except dynamically rather than statically when a fast bullet applies the pressure.

This is the principle that makes hydraulic systems work -- a relatively small force applied to a body of fluid by a very small ram becomes a very large force by the exertion of the same pressure over the larger area of the work ram. In a hydraulic system, the trade-off is in the movement of the two rams -- the small ram applying the pressure must move farther to move the larger ram slightly. (The fluid, being incompressible, remains the same in volume throughout.)

The pressure also remains the same throughout. A small ram applies a small pressure with its small area of application, and this same small pressure exerted over the much larger area of the work ram exerts a correspondingly larger force.

A pressure of ten pounds per square inch, for example, takes an effort of only ten pounds to apply it to a container of fluid with a small ram with an application area of only one square inch -- but it becomes a force of a thousand pounds when the fluid transmits it to a larger ram with an area of a hundred square inches (1 sq in. � 10 lb/sq in. = 10 lb for the small ram; 100 sq in. � 10 lb/sq in. = 1,000 lb for the large ram). A bullet smaller in diameter is a smaller application ram than a bullet of a larger caliber. Spin has nothing to do with how the bullet applies its force to the body of fluid.

The hydraulic system relies on containment -- the fluid must not move except to apply force to the work ram. A can of Pepsi or the body of a deer does not contain its fluid with the strength of a cast-iron hydraulic jack -- and the small ram (bullet) applies its pressure and movement virtually instantaneously -- so the fluid goes in all directions more or less equally, tearing its way free as it goes.

... no matter what you choose to call it.


"Good enough" isn't.

Always take your responsibilities seriously but never yourself.




















Moderated by  RickBin 

Link Copied to Clipboard
AX24

538 members (25aught6, 222Sako, 10gaugemag, 1badf350, 222ND, 163bc, 63 invisible), 2,474 guests, and 1,077 robots.
Key: Admin, Global Mod, Mod
Forum Statistics
Forums81
Topics1,194,489
Posts18,529,776
Members74,033
Most Online11,491
Jul 7th, 2023


 


Fish & Game Departments | Solunar Tables | Mission Statement | Privacy Policy | Contact Us | DMCA
Hunting | Fishing | Camping | Backpacking | Reloading | Campfire Forums | Gear Shop
Copyright © 2000-2024 24hourcampfire.com, Inc. All Rights Reserved.



Powered by UBB.threads™ PHP Forum Software 7.7.5
(Release build 20201027)
Responsive Width:

PHP: 7.3.33 Page Time: 0.122s Queries: 25 (0.009s) Memory: 0.8180 MB (Peak: 0.8576 MB) Data Comp: Zlib Server Time: 2024-05-22 18:04:51 UTC
Valid HTML 5 and Valid CSS