Physics of the Ballistic Pressure Wave

[Michael Courtney]

I would think discussing these findings on open internet forums would also be in violation of the non-disclosure agreement, especially before they are published. I know someone who works in the intellectual property field and she says participation on a hobbyists forum would be enough to get someone fired and possiblly sued.

It is not uncommon for non-disclosure agreements to specify that certain information can be approved for release prior to publication, certain information can be released at the time of publication, and certain information may never be released.

When the scientists in our group were negotiating the non-disclosure agreement, we clearly stated the need to release certain information after the initial three projects were complete but prior to publication in order to get valuable feedback from the broader ballistics community as well as to retain the possibility of submitting grant proposals prior to publication. The scientists also wanted to ensure complete disclosure (at publication) of our experimental methods in order to allow our work to be repeated by other groups.

These two aspects were granted, but we had to compromise on a on a few other points by agreeing not to ever release photographs without prior approval, not to reveal the source of the funding, and not to identify collaborators without their written consent. We were only able to release photograps that were posted at glocktalk because these were not an official part of our research efforts. The deer was shot by a youth hunter (not a member of the research group), the necropsy was done in the field rather than the laboratory, and the pictures were taken with a personally owned camera, etc.

The bottom line is that our non-disclosure agreement was carefully negotiated and we have full permission to release the information we have released, but there are certain facts that must wait for publication, and other aspects that will remain private.

Michael Courtney

 

[Shear_stress]

Give it up, man! Based on previous posts, you are nothing but a deer hunter/farmer/trapper out of Ohio with grand ideas about himself.

More disturbing, though, is your rather famous reputation on internet news groups. I invite anyone to research your rich history via Google groups.

 

[Michael Courtney]

How much of the hemorrhaging to the lungs do you think might be caused by the resulting deflating of the lung? I seem to recall the protocall for treating a wound like that is to seal it airtight to prevent further damage as the victim breathes. I would expect to see hemorrhaging to the lungs far beyond the wound.

Deer shot in the lungs with a broadhead experience deflation of the lungs with nowhere near the hemorrhaging we see with high pressure wave bullets. Therefore, we think it is reasonable to conclude that deflation of the lung is not the cause of hemorrhaging.

And you don't think you'll receive hassles from the animal rights fanatics when you publish your work?

We expect that the live animal aspects of our work might be curtailed by animal rights fanatics for a considerable time after publication. This is why we have delayed releasing much information until at least our first three projects were completed. We will be well-positioned for an animal-rights backlash after publication, and we have a plan to counter act the backlash and get back to work, but there will probably be some inconveneince and delay after publication. This is why we decided to publish all three of our first projects simultaneously, so we would have one backlash rather than three.

Or are you just going to post on the internet? Who is peer reviewing it?

We fully intend to publish by conventional means. We have already distributed our first draft to some other scientists and engineers, and we hope to give some invited talks this winter and spring. Selection of peer-reviewers of the final manuscript prior to publication is up to the editors of the periodical to which the paper is submitted. Of course, after publication, any researcher in the field my submit their peer reviews for publication.

Preparing three projects for publication and going through the peer review and publication process takes time. From my previous experience in the process, it will probably be between 1 and 2 years before the work appears in print. Scientist almost always make use of informal communication to disseminate results and findings prior to publication. This allows valuable feedback from other parties, and it allows other researchers in the field to be aware of a paper before publication. Researchers in a field often feel slighted by the authors if a work appears in print before they heard about it in an informal setting.

I'm going to refer this thread to Dr. Gary Roberts for his input. If anyone can tell us if there is any truth to this, he can. You don't mind a little peer review from someone who is known in the field do you?

I appreciate input from the established researchers in the field. However, I always have a keen mind for distinguishing long-held beliefs from assertions that can be verified by repeatable experiments.

We are seeing tissue damage that far exceeds the extent of the permanent crush cavity. We are seeing bullets with a larger pressure wave incapacitate more rapidly than bullets with a relatively small pressure wave, even though their permanent crush cavities are nearly the same. This may go against long held beliefs, but it would be much more convincing if someone could refer to a carefully controlled experiment that shows differently.

Michael Courtney

 

[C-grunt]

WOW!!!!!
I dont know if this is all true or BS. Lots of numbers and equations. I got my own equation for yall. I might even publish it.

Using this bullet(X) + Shooting this bad guy/animal(Y)= Dead target(Z)

If X+Y doesnt equal Z?

Then use more X

I knew I shoulda gone to college. Theres my thesis for my doctorate

 

[Michael Courtney]

Give it up, man! Based on previous posts, you are nothing but a deer hunter/farmer/trapper out of Ohio with grand ideas about himself.

You have taken the low road and slipped downward from a discussion of the ideas on their merits to an ad hominem attack on the researchers.

You forgot to mention the PhD in Physics from the Massachusetts Institute of Technology.

You also forgot to mention that my PhD thesis was recognized by the American Physical Society as one of the top five in my field.

You also forgot to mention that I am a Physics Professor who teaches not only Physics, but beginning statistics, advanced statistics, and forensic science.

Finally, you forgot to mention that I have published many papers regarding wave motion and statistics in the most prestigious Physics journals, _Physical Review Letters_ and Physical Review A.

I am also working with another scientist with a PhD in Biomechanical Engineering from Harvard University. This scientist has worked as a research scientist for Reebok and for the Cleveland Clinic and been on the faculty of Ohio State University, as well as being internationaly recognized.

Michael Courtney

 

[Shear_stress]

Michael, I am afraid your reputation proceeds you. You have been at this game for years, apparently. I have already looked through many of your posts on alt.rec.hunting, and alt.atheism. Your MO there is exactly the same as here.

We have already dealt with your supposed qualifications. Until you can provide some actual proof of your research, or research group, please stop bringing it up!

 

[Michael Courtney]

We have already dealt with your supposed qualifications.

And exactly which aspect of my qualifications have you disproven?

Until you can provide some actual proof of your research, or research group, please stop bringing it up!

There are some photographs posted to a discussion at glocktalk. I have offered to post them here as attachments. I have also offered to post the abstract of our paper that is in preparation.

The initial post in this thread represents a significant part of the description of the physics of the pressure wave that we intend to publish. It proves we have done some theoretical work understanding the pressure wave, and all you need to do is put a PZT-based pressure sensor into ballistic gelatin to see that the predictions accurately distinguish bullets which create a large pressure wave from bullets which create a small pressure wave.

You can also test my assertion that the peak pressure magnitude predicted by our model correlates very well with the TSC volume. Alll you need to do is use the model I presented in the initial post to compute the pressure wave magnitudes for a number of loads and plot these vs. the TSC volumes that have been published by others. If the TSC volumes you use are all measured with the same method, you will find good correlation between the peak pressure magnitude and the TSC volume.

You can test my description of damage in the 180 lb buck, by going out and shooting a deer with the same bullet at the same impact velocity. If somehow the pictures I have offered don't provide sufficient proof, you can see for yourself.

The proof of scientific work is in the ability for others to repeat the work.

Michael Courtney

 

[BigMak]

Michael,

I'm curious as to your opinion of the body of
work known as "Bullet Penetration", by Duncan
MacPherson.

Could you please give us your assessment of
this endeavor, both pro and con.

Much Thanks,

BigMak

 

[Michael Courtney]

Michael relies heavilly on a blizzard of jargon, the whole "if you can't dazzle 'em with brilliance, baffle 'em with bull****" school of thought.

Please show where my post "The Physics of the Ballistic Pressure Wave" is in error. After all, if your claim is true that it is "bull****" then you must be able to back up your claim and point out the error in the physics. There are some approximations at various points, but these are clearly stated as such and reasonable.

See above for his sudden and unsolicited mention of the Bernoulli equation, where he holds forth at length on a concept taught in first-semester fluid mechanics.

A discussion on the Bernoulli equation is not out of place when discussing the physics of the ballistic pressure wave because it has been misapplied by others in the field to estimate the pressure wave magnitude.

When challenged, though, he tends to change his story to reflect the nature of the challenge. See how he responded to my inquiry about him doing ballistics research on fetuses that suddenly became unborn deer fetuses in his reply.

My initial statement made it clear that I was talking about deer fetuses. You must have mis-comprehended what I thought was a clear statement:

Quote:
We've also seen major hemorrhaging in unborn fetuses of does shot broadside through the center of the chest

I wrote "unborn fetuses of does."

doe = female deer

How did you miss the fact that I wrote "fetuses of does"?

How could you interpret this to mean anything other than an unborn deer fetus?

Or maybe look at the backflips he had to do after I asked how exactly he was going to tell if a submerged mammal was incapacitated.

You asked. I provided a detailed answer.

First you claim that science means disclosure, then when I offer a more detailed explanation of the experiment, you complain.

The biggest threat to his credibility is that he offers nothing in the way of published, verifiable data to back up his claims

Every research project has a period of time after the project is completed but before the work appears in print. This is the current status, as I have clearly stated before.

I am happy to discuss the aspects of our work on the scientific merits (or lack thereof). I am hoping to engage in legitimate discourse of the scientific issues on their merits and avoid the "low road" and ad hominem attacks.

Is this too much to expect on a forum called "The High Road."

Michael Courtney

 

[Shear_stress]

Nope. Not good enough. When I ask for disclosure, I don't want you to keep throwing stuff at us on an internet forum. Please give us the website for the Ballistic Testing Group. Please post references to the Group's papers, and I don't mean photographs posted on Glocktalk. I want bibliographies of your group's work. In the absence of published papers or even evidence of a research group, we have nothing to talk about.

 

[Michael Courtney]

Michael,

I'm curious as to your opinion of the body of
work known as "Bullet Penetration", by Duncan
MacPherson.

Could you please give us your assessment of
this endeavor, both pro and con.

There's some aspects I agree with, others I think will ultimately be shown to be incorrect as more research is done in the field. If you can summarize a particular idea or assertion, I can comment more specifically on it.

Michael Courtney

 

[Gewehr98]

It does sound, unfortunately...

Like Shear_Stress is on a witch hunt. The signal to noise ratio in here is getting awfully garbled. Moderators ain't helpin' a whole lot with their tone of voice, either.

This Dr. Gary Roberts, will he bring his qualifications for examination under the withering scrutiny of faceless names hiding behind Internet aliases? Likewise, where did Shear_Stress get his degree from, we should request - no, demand - he provide credentials on this Internet forum! I mean, he's coming out swinging with both fists, telling people to shut up on what's otherwise an open discussion forum, so there's an axe to bury somewhere, right?

In other words, Michael, trying to forward a body of research on an internet discussion forum is more akin to teaching a pig to sing, if you get my drift. If you haven't noticed, Taylor vs. Fackler gets rehashed on a regular basis.

Not that I buy your theory myself, (my degree's in physics) but I'm well aware that hecklers from the peanut gallery drop in from seemingly everywhere, and even track you down across forums, sometimes stalking you. Witness the nasty tone in the Gabe Suarez discussions, and the more recent Charlie Wenzel lynch mob, we even have folks here at THR supporting that stuff in their Sig lines.

 

[Michael Courtney]

Nope. Not good enough. When I ask for disclosure, I don't want you to keep throwing stuff at us on an internet forum. Please give us the website for the Ballistic Testing Group. Please post references to the Group's papers, and I don't mean photographs posted on Glocktalk. I want bibliographies of your group's work. In the absence of published papers or even evidence of a research group, we have nothing to talk about.

Can you read?

I have clearly stated that our first three projects are in preparation for publication. Yet you keep asking for references to completed publications, as if a research group does not exist until after it has published.

I have also clearly stated that we have kept a low key due to a non-disclosure agreement and a desire to minimize trouble from the animal-rights fanatics. Yet you seem to think that not having a web site is proof that we do not exist. If we had a web site, it wouldn't contain any more information than we can release under the non-disclosure, so you still wouldn't be happy, because it would not contain the name of an institution, funding source, or address beyond a PO Box, because listing any of these gives provides a much more accessible target for a restraining order.

The evidence of a research group is research results that can be repeated and verified.

Michael Courtney

 

[Shear_stress]

I started out applauding Michael for posting empirical data. I have no opinion about the content of the work. However, he has made claims that he refuses to back up.

This Dr. Gary Roberts, will he bring his qualifications for examination under the withering scrutiny of faceless names hiding behind Internet aliases?

Dr. Gary Roberts can be cited without any effort at all. His work is found instantly with a Google search. Michael's work seems to have the curious property of not existing.

The evidence of a research group is research results that can be repeated and verified.

Right, and this evidence could be gleaned from peer-reviewed journals.

I have also clearly stated that we have kept a low key due to a non-disclosure agreement and a desire to minimize trouble from the animal-rights fanatics. Yet you seem to think that not having a web site is proof that we do not exist. If we had a web site, it wouldn't contain any more information than we can release under the non-disclosure, so you still wouldn't be happy, because it would not contain the name of an institution, funding source, or address beyond a PO Box, because listing any of these gives provides a much more accessible target for a restraining order.

I'm sorry, but this is hard to swallow when the Primate Research Center, of all places, offers *tours* of their facility. http://onprc.ohsu.edu/tours/index.cfm

 

[Michael Courtney]

Michael's work seems to have the curious property of not existing.

Your logic is flawed.

How much sense does it make to conclude that a research group doesn't exist before it has published?

Every legitimate research group exists before it publishes.

How much sense does it make to conclude that a research result does not exist before it has been published.

Every legitimate research result must exist before it is published.

Your propensity for not believing something is real because you can't verify it without leaving your computer screen is revealing.

Michael Courtney

 

[Gewehr98]

That's a barometer of credibility?

Dr. Gary Roberts can be cited without any effort at all. His work is found instantly with a Google search. Michael's work seems to have the curious property of not existing.

I'm not even allowed to discuss or print my work for Uncle Sam until 75 years after I retire, based on the non-disclosure agreement I signed. They chose that 75 year timeline, knowing I'll be several years into a dirt nap by the time it expires. It's too bad, really, I'm sure the American public would love to know what my organization and I did for the intelligence community for the last 20 years. But I'll guarantee my published work ain't gonna show up on Google anytime soon. (Unless some Senate staffer trying to get ahead in his miserable little life leaks it to the media)

 

[Shear_stress]

I'm not even allowed to discuss or print my work for Uncle Sam until 75 years after I retire, based on the non-disclosure agreement I signed.

And you probably couldn't cite it at length on an internet forum, either.

 

[Gewehr98]

Yes and no.

The unclassified portion, already released to the public in printed form, can be discussed. But that's no fun.

 

[BigMak]

Michael,

I'm specifically interested in your assessment
of MacPherson's statements about temporary
wound cavity (p.58-63), and particularly your
input as to why his explanation of kinetic energy
not being a main factor in wound trauma
incapacitation is invalid.

Pages 13-16 give further thoughts on kinetic
energy and the reasons that their effects from
a handgun are (generally) insignificant.

I guess what I'd like to hear from you is where
specifically do you find that his tests/viewpoints
are invalid, both in the areas of kinetic energy
effect and, also, temporary cavity elasticity.

Much thanks,

BigMak

 

[jc2]

I'm curious as to your opinion of the body of work known as "Bullet Penetration", by Duncan MacPherson.

As an aside, I would strongly recommend everybody interested in the subject buy McPherson's book (Bullet Penetration). It is in print again and readily available over the internet. If nothing else, it will show you a good example of properly conducted, documented and peer-reviewed research in the subject versus the tripe and sophistry being peddled in this thread.

 

[P95Carry]

There appears to be some useful data within the thread but - attacks are becoming more and more personal. There is a fine balance between questioning data and actual integrity - not always easy to separate. Attack arguments as best you can without attacking the proponent.

If the attacking persons type trend does not cease the thread will have to close.

 

[Michael Courtney]

I'm sorry, but this is hard to swallow when the Primate Research Center, of all places, offers *tours* of their facility. http://onprc.ohsu.edu/tours/index.cfm

Their security and legal budget is much larger than ours. Only a very small percentage of research groups involved in live animal research choose this level of public exposure.

I also wonder if there is a history of restraining orders in their area regarding their work. In our locality, there have been several restraining orders issued against the otherwise legal shooting of deer. There have also been numerous instances of harassment of hunters and destruction of their property.

If one contacts various agencies involved in shooting deer in our region, and they will tell you that they can't comment on when or where or whether they are shooting deer. This is because they are concerned with both harassment and with legal challenges. I've got a good working relationship with the wildlife biologist for the local park authority, but he is not allowed to discuss their deer shooting activities while they are in progress.

When local deer shooting activities attract attention, there is a circus in the press, and the fanatics have a field day. Right now, I've got an "investigative reporter" who has published animal rights stories on the front page of a major metropolitan newspaper calling us up and wanting to schedule a visit. Fortunately, we've completed the project where the deer need to be shot in a carefully controlled setting with precise shot placement, and we've moved to a new project where the deer can be shot by anyone at any location as long as we are able to determine the impact velocity of the bullet and examine the deer after it is dead.

Most people involved in live animal research keep substantial information out of public view so as not to provide ammunition to the animal rights fanatics. Only the facts needed to communicate the relevant scientific findings are communicated.

Michael Courtney

 

[Michael Courtney]

Michael,

I'm specifically interested in your assessment
of MacPherson's statements about temporary
wound cavity (p.58-63), and particularly your
input as to why his explanation of kinetic energy
not being a main factor in wound trauma
incapacitation is invalid.

MacPherson's unstated presuppostion that incapacation can only result from wound trauma that is easily detected by a medical examiner or trauma surgeon is unproven. The assertion that kinetic energy is not a main factor in incapacitation rests on this unproven presupposition.

Kinetic energy dump (dE/dx) is a main factor in both the magnitude of the ballistic pressure wave and in the temporary stretch cavity. Much of the work we have in preparation for publication is greared toward correlating the ballistic pressure wave to incapacitation without much concern for the physiological mechanisms involved. We have only recently begun a new research project to associate wounding with the pressure wave.

Because of the high correlation between the temporary cavity and the pressure wave magnitude, we cannot conclusively rule out the temporary cavity as an important contributor to incapacitation. The pressure wave correlates a bit better to incapacitation than the temporary stretch cavity, but it is not conclusive.

However, we can say that we need to consider more than the permanent crush cavity alone to get a good correlation with incapacitation. A model which includes both PCC and TSC gives good correlation, and a model using PCC and the pressure wave magnitude is slightly better. Combined with our experiments showing incapacitation of 10-20 lb mammals with only a pressure wave (no PCC or TSC), we believe we have significant supporting evidence for the pressure wave.

I don't wish to be overly critical of other researchers or their contributions. In fairness to other researchers, we are concentrating on handgun loads that produce pressure waves considerably larger than commonly showing up in the morgue or operating table. The majority of handgun loads may well fail to produce pressure wave/TSC wounding that is easily detectable, and even the most careful study that concentrates on wounding rather than a quantifiable metric of incapacitation might miss the effects we are seeing.

I guess what I'd like to hear from you is where
specifically do you find that his tests/viewpoints
are invalid, both in the areas of kinetic energy
effect and, also, temporary cavity elasticity.

In addition to the unproven presupposition that all the contributions to incapacitation are easily detectable wounding, another problem is over generalization of conclusions based on wounds from bullets with relatively low pressure waves (energy dump, dE/dx) to bullets with considerably higher pressure waves. This is an overgeneralization that readers tend to add to the idea, rather than something written explicitly.

The case regarding temporary cavity elasticity has some weak areas. It is true that some tissues have a higher tolerance than others for stretch, so the effect of the TSC depends on the internal organs within reach of the TSC. But there is another factor in play: tissue failure depends not only on the degree of stretch, but also on the rate of stretch. A tissue that can tolerate being stretched a given amount at a relatively slow rate will often tear if stretched the same amount at 50-100% faster rate. Elasticity is no guarantee against wounding as the rate of energy transfer is increased. In other words, tissue that can tolerate a stretch of 3" delivered by a load that transfers 350 ft-lbs of energy in 12" of penetration might fail if delivered the same 3" of stretch by a load that transfers 550 ft-lbs of energy in 12" of penetration.

Let me be clear that I do not believe that MacPherson's conclusions are not supported by his observations. He might simply not have considered consider incapacitation apart from easily detectable wounding, and he might not have had ample opportunity to observe wounding and incapacitation from the handgun loads with both substantial penetration (>10") and pressure waves above 1000 PSI (on the surface of a 1" diameter circle centered at the wound tract.) It is not valid to extrapolate his observations to effects of loads with considerably larger pressure waves. I think that the readers have a greater propensity for this unwarranted extrapolation than the author.

Professionals in the wound ballistic field who consider incapacitaion apart from detectable wounding need to have other career options. It's hard to find fault with researchers who stick with the unproven presupposition that incapacitation only results from easily detactable wounding, but I think the presupposition is wrong, and investigating how it might be wrong is an important step in improving terminal performance of handgun bullets.

Michael Courtney

 

[Mr_Moore]

NOW I get an answer to my question...

Physics of the Ballistic Pressure Wave

By the chain rule of calculus,

F = dE/dx = ½ V*V dm/dx + m V dV/dx,

I have not seen that once since I taught 3rd and 4th year engineering students harmonic motion equations at Pitt. Of course the analysis basis of harmonic motion equations is the differential equation:

ad^2x/dt^2 + bdx/dt+cx=f(t)

I taught this in 2 separate courses, one on spring mass damper systems - Mechanical Engineering stuff and resistor, capacitor, inductor systems - Electrical Engineering stuff. Of course we threw in Fourier and Laplace analysis.

Looks like Mr. Courtney has a grasp of engineering. (Do you have a BS, MS or PhD? - never mind, just looking over previous posts and saw the PhD)

Anywho... I asked in another thread, why am I using Remington JHP 125 grain .357 magnum loads in my carry piece. My point was that they had been recommended to me as optimum stoppers for the .357 (vs 158 grain, 110 grain, and any other grain.) and I did not know why.

In summary, the .40 S&W Double Tap loading of the Nosler 135 grain JHP has a larger pressure wave than many other JHP bullets in that cartridge for three reasons:

1. It has greater kinetic energy.
2. It penetrates less.
3. It fragments and loses more of its mass.

One can apply this identical analysis to other JHP loads in this and other cartridges. Doing so reveals that there are a few other JHP loads which generate comparable peak pressure levels. Among them are the 125 grain Federal and Remington JHP loads in .357 Magnum that are known for their ability to incapacitate quickly.

This finally answers my question. I had heard that the 125 grain was considered a "miracle load", but of course "then a miracle happens" is considered bad science Thanks for the information.

 

[Michael Courtney]

Pressure wave is not everything

The purpose of studying the pressure wave is to study its role in wounding and incapacitation. I do not mean to imply that increasing the pressure magnitude is the primary goal. There is a trade off between penetration and pressure wave magnitude. We are not saying that the biggest pressure wave is the best bullet choice. We are saying that a bullet's ability to produce a pressure wave is one factor to be considered.

For example, the Glaser and Magsafe bullets produce very large pressure waves, yet I believe that they do not penetrate deeply enough to be a good choice of ammo for police work or self-defense in most situations.

I believe bullet performance criteria should begin with choosing a group of loads that meet the penetration requirements as determined from the likely application and risk assessments. From this group of loads I recommend narrowing the field to loads that expand reliably under a wide variety of circumstances. From this group of loads I recommend choosing the load with the largest pressure wave. (Loads should always be thoroughly tested for feeding and functional reliability in a given firearm.)

From this viewpoint, I don't believe that my load selection criteria would be considered to be dangerous by others in the field. My greater interest is in understanding the science of the pressure wave in hopes of developing new designs that offer greater performance than available today. Thanks for the opportunity to clarify.

Michael Courtney