JFK Assassination Forum
JFK Assassination Discussion & Debate => JFK Assassination Discussion & Debate => Topic started by: Brian Roselle on February 14, 2022, 10:47:15 PM
-
This summarizes the results of an extended study taking a closer look at JFK’s motions in the Zapruder film from z312 to z324 in an effort to further understand the possible causes and subsequent effects resulting in his motion. A math model of key body part positions (head and upper torso) over this time appears to be effective in explaining the dynamics observed. JFK’s reactions seen starting shortly after z222 are also considered as being related to determining the subsequent motion seen after z312.
Conclusions:
With an observed initial ~2" forward head deflection and just over ~1" forward upper torso deflection it appears JFK’s motion from z312 to z324 could be caused by one bullet strike to the head in this timeframe, striking from the rear, with no frontal shot necessary or indicated in this timeframe.
- Overall, the model's solution for back of head and back of upper torso horizontal positions provided good agreement with the measured horizontal position data points seen on the Z-film.
- It appeared JFK’s motion observed over the time z312-z324 (forward->backward->forward) could be accounted for by a significant rear strike impulse with rearward motion influenced by a jet effect and the physical properties of JFK (which included his back brace and changing neck stiffness) over that timeframe.
- Furthermore, in this case a jet effect did appear to manifest itself during the strike to help facilitate the observed rearward motion, but in principle a type of general motion (forward->backward->forward) after a rear strike wouldn’t always require additional forces (like a jet effect, or a neuromuscular reaction or its removal, or someone tugging backwards or a second bullet impulse coming from the front) as long as there was some mechanism to store potential energy derived from the initial strike’s kinetic energy, and that it is reversible to facilitate oscillation.
- This modeling and Zapruder film analysis suggested a scenario where JFK’s extended motions on the Z-film (from z313 thru z324), after a rear head strike that occurred at inter-frame z312/z313, were oscillatory in nature and could be associated with a macro interaction involving two semi-independent principal mass centers, his head and upper torso, at a point in time when both of the structures supporting those components, the (neck) and (lower-back) respectively, happened to be under the influence of extraneous stiffening effects (with the neck stiffness changing shortly after the z312/z313 head strike).
- There was no indication of a frontal shot striking the President in this timeframe based on this analysis.
If further interested, the overall summary and the complete details of this study’s methodology can be found as a PowerPoint presentation at the link below. A video version of the ppt presentation is provided along with just the ppt file (Be Aware: these are quite long due to the decision to include, in detail, every step taken along the way in the study). The video has additional discussion and background via audio commentary accompanying the slide presentation.
https://sites.google.com/view/perspectiveonbackandtotheleft/home
-
This summarizes the results of an extended study taking a closer look at JFK’s motions in the Zapruder film from z312 to z324 in an effort to further understand the possible causes and subsequent effects resulting in his motion. A math model of key body part positions (head and upper torso) over this time appears to be effective in explaining the dynamics observed. JFK’s reactions seen starting shortly after z222 are also considered as being related to determining the subsequent motion seen after z312.
Conclusions:
With an observed initial ~2" forward head deflection and just over ~1" forward upper torso deflection it appears JFK’s motion from z312 to z324 could be caused by one bullet strike to the head in this timeframe, striking from the rear, with no frontal shot necessary or indicated in this timeframe.
- Overall, the model's solution for back of head and back of upper torso horizontal positions provided good agreement with the measured horizontal position data points seen on the Z-film.
- It appeared JFK’s motion observed over the time z312-z324 (forward->backward->forward) could be accounted for by a significant rear strike impulse with rearward motion influenced by a jet effect and the physical properties of JFK (which included his back brace and changing neck stiffness) over that timeframe.
- Furthermore, in this case a jet effect did appear to manifest itself during the strike to help facilitate the observed rearward motion, but in principle a type of general motion (forward->backward->forward) after a rear strike wouldn’t always require additional forces (like a jet effect, or a neuromuscular reaction or its removal, or someone tugging backwards or a second bullet impulse coming from the front) as long as there was some mechanism to store potential energy derived from the initial strike’s kinetic energy, and that it is reversible to facilitate oscillation.
- This modeling and Zapruder film analysis suggested a scenario where JFK’s extended motions on the Z-film (from z313 thru z324), after a rear head strike that occurred at inter-frame z312/z313, were oscillatory in nature and could be associated with a macro interaction involving two semi-independent principal mass centers, his head and upper torso, at a point in time when both of the structures supporting those components, the (neck) and (lower-back) respectively, happened to be under the influence of extraneous stiffening effects (with the neck stiffness changing shortly after the z312/z313 head strike).
- There was no indication of a frontal shot striking the President in this timeframe based on this analysis.
If further interested, the overall summary and the complete details of this study’s methodology can be found as a PowerPoint presentation at the link below. A video version of the ppt presentation is provided along with just the ppt file (Be Aware: these are quite long due to the decision to include, in detail, every step taken along the way in the study). The video has additional discussion and background via audio commentary accompanying the slide presentation.
https://sites.google.com/view/perspectiveonbackandtotheleft/home
I think you've really over-complicated things.
JFK is shot high in the back of his head.
The way his head explodes indicates the magnitude of the force acting on his head.
This large force being applied to the back of his head drives his head forward and down.
The key to understanding why his head then moves back and to the left is that, at the moment of impact, his chin is resting on his chest.
This large force drives his head into his chest.
Some force is transferred into his body but there is a large component of "equal and opposite reaction" applied to his head from his chest.
It is this "equal and opposite reaction" that then drives his head backwards and to the left.
-
Yes, I had heard someone else speculate on the head bouncing off the chest/sternum in the past.
For this study I couldn’t exclude the possibility of some interaction between the chin and upper sternum, but I had a hard time making my chin make hard contact the upper part of my sternum, and my sternum doesn’t seem overly elastic to return a lot of energy.
The other thing I wondered about when thinking about this was that if there was a very hard impact, would there be any abrasion or bruising evident on the chin or sternum. I don’t recall any mention of abrasion or bruising observed in autopsy or at Parkland. Of course, at Parkland even though they were looking right at that area, I’m sure the main focus was the tracheostomy insertion.
Lacking additional evidence that this occurred, I didn't include it in this modeling, but rather relied primarily on the neck composition with paralysis, i.e. a stiffened neck reaction, with a some jet effect at the very beginning. The neck stiffness value/change was also a key variable used throughout the rest of the motion after ~z316. If at a later date I find evidence that a major head/sternum collision augmented these other variables, this would be a good build to try and measure and incorporate in the model as well.
-
Yes, I had heard someone else speculate on the head bouncing off the chest/sternum in the past.
For this study I couldn’t exclude the possibility of some interaction between the chin and upper sternum, but I had a hard time making my chin make hard contact the upper part of my sternum, and my sternum doesn’t seem overly elastic to return a lot of energy.
You show some good logical thinking. Rather than simply accept the head bouncing off the chest, you ran the experiment yourself. Certainly, for my body, I can barely get the chin to contact the chest, let alone have the chin bounce off the sternum.
The other thing I wondered about when thinking about this was that if there was a very hard impact, would there be any abrasion or bruising evident on the chin or sternum. I don’t recall any mention of abrasion or bruising observed in autopsy or at Parkland. Of course, at Parkland even though they were looking right at that area, I’m sure the main focus was the tracheostomy insertion.
Lacking additional evidence that this occurred, I didn't include it in this modeling, but rather relied primarily on the neck composition with paralysis, i.e. a stiffened neck reaction, with a some jet effect at the very beginning. The neck stiffness value/change was also a key variable used throughout the rest of the motion after ~z316. If at a later date I find evidence that a major head/sternum collision augmented these other variables, this would be a good build to try and measure and incorporate in the model as well.
There was no strong “Jet Effect” at the beginning. The very first movement, from z312 to z313, was forward, by two inches. This was the fastest the head ever moved, about two MPH, during z300 through z330. A strong “Jet Effect”, right from the beginning, would occur within 5 to 10 milliseconds, as soon as the head explodes are pieces of the head start flying forward, and the rest of the head would start moving backwards immediately, not 55 milliseconds later.
Instead, the head didn’t start to move backwards until the next frame interval, between z313 and z314. This approximately 55 millisecond delay is well aligned with the Neurological Spasm reaction, which matches closely the observed 40 millisecond delay in goats. Of course, this experiment cannot be carried out in humans for ethical reasons.
Also, the momentum backwards gradually builds up during z313 through z317. This is to be expected of a biological explanation, not a physical explanation, like from the Jet Effect or from the push of a bullet from the front.
Certainly, the conclusion we come to, must be based on evidence. If the head started moving backwards immediately, then it would be more logical to go with the “Jet Effect” or a “Bullet from the Front” theory, and not with “Neurological Spasm” theory, which wouldn’t kick in until 40 to 55 milliseconds later (possibly a little more than 40 milliseconds because a human is a little larger than a goat).
But this is not the case. The delay in the onset of the backwards movement and the gradual buildup of backwards momentum only supports the “Neurological Spasm” theory.
By the way, an earlier thread where this topic was discussed a good deal is at:
Where “Six Seconds in Dallas” by Josiah Thompson may be found.
https://www.jfkassassinationforum.com/index.php/topic,2552.msg87055.html#msg87055 (https://www.jfkassassinationforum.com/index.php/topic,2552.msg87055.html#msg87055)
-
Joe, you make some good points, and one thing that was unknown to me when doing this was what the dynamics were between the strike at say z312.7 (where 312.5 is the close of shutter for that frame) and just after the opening of the shutter at z313. This dynamic was outside the scope of what I was doing which was basically taking the observed frame by frame position data and modeling that, but I wondered about what happened at the very start after strike and before what I finally see recorded on film at the end of exposure of z313. The dynamics before z313 are very fast and violent and there may be happenings that I haven’t considered like the head actually initially going forward a little more than seen at end frame z313, but it was “braked” or slowed and reversed some before where you see it end up at the end of exposure in frame z313, after which point it seems to have transitioned to moving slowly forward towards position seen at z314. Net, maybe it did not instantly go backwards with the jet onset, it slowed down and then reversed a little, before and possibly some during early z313.
In this model a very stiff neck would also have had some cantilever like effect aiding the retardation and helping reverse the head’s forward motion in conjunction with the jet, and slowly causing it to apparently accelerate slowly more in reverse after the jet was complete. The recoil velocity of a cantilever after it is maximally deflected from neutral starts out slow at maximum deflection (minimum velocity) and picks up speed from there to a maximum velocity (and zero acceleration) when it gets back to the neutral point which in this analogy is just after z315. Although mechanical in nature without delay it can build up velocity (sinusoidally), but it’s not a biological delay build up.
Related to that, I have heard that some neuromuscular reactions can kick in very fast, and I’m wondering if some of that could well have happened and contribute to the early part of the motion. But in this scenario, all the muscular reactions would end at around z316, as flaccid paralysis set in.
-
Yes, I had heard someone else speculate on the head bouncing off the chest/sternum in the past.
For this study I couldn’t exclude the possibility of some interaction between the chin and upper sternum, but I had a hard time making my chin make hard contact the upper part of my sternum, and my sternum doesn’t seem overly elastic to return a lot of energy.
The other thing I wondered about when thinking about this was that if there was a very hard impact, would there be any abrasion or bruising evident on the chin or sternum. I don’t recall any mention of abrasion or bruising observed in autopsy or at Parkland. Of course, at Parkland even though they were looking right at that area, I’m sure the main focus was the tracheostomy insertion.
Lacking additional evidence that this occurred, I didn't include it in this modeling, but rather relied primarily on the neck composition with paralysis, i.e. a stiffened neck reaction, with a some jet effect at the very beginning. The neck stiffness value/change was also a key variable used throughout the rest of the motion after ~z316. If at a later date I find evidence that a major head/sternum collision augmented these other variables, this would be a good build to try and measure and incorporate in the model as well.
"Lacking additional evidence that this occurred, I didn't include it in this modeling, but rather relied primarily on the neck composition with paralysis, i.e. a stiffened neck reaction, with a some jet effect at the very beginning."
There is, in fact, the best evidence you can have - film footage of it actually happening, whereas there is zero evidence neck paralysis occurred and, as we shall see, very strong evidence against any kind of jet effect.
There are a number of things to note in the clip below:
1) At the moment of impact JFK's chin is resting on his chest (the sternum is a non-issue)
2) The initial movement at impact is forward
3) That this movement is JFK's head being driven into his chest
4) The massive crater in the top of JFK's head after impact
(https://i.postimg.cc/RFV4RpQQ/Head-Shot-close.gif) (https://postimages.org/)
The majority of the top of JFK's head is blown off by the impact. This is evidenced by the crater clearly visible in the top of his head. The jet effect might work through a small exit hole out of which matter is ejected but it is totally negated by such a massive head wound.
JFK's head can be clearly seen being driven into his chest, there is nowhere for it to go so it rebounds.
-
I’m glad you discussed this, as it will be something for me keep my eye on for possible future use. But at this time I don’t agree enough with your statements to make large changes in the modeling. Here are some of the "statements" I disagree with and reasons why I disagree:
“there is zero evidence neck paralysis occurred”
All I can do is to mention the basis I used for the assessment that there was significant neck stiffness (in addition to shoulder, arms, hands and fingers).
1) It is called spasticity or spastic paralysis due to damage to the lower cervical part of the spine and the brachial plexus. In this case via a bullet transit that occurred circa z222.
https://sites.google.com/view/spastic-paralysis/home
2) Some Neurological opinions. From the Study Slide 54 or video time 2:07:00
Comments from Dr. Robert Artwohl explaining why we saw the arms stiffening upward.
“JFK’s reaction to the neck wound was, for all intents and purposes, instantaneous to the hit at Z-223/224. As the bullet passed through his neck, the pressure cavity caused an immediate and wide spread stimulation of all the nerves in the immediate vicinity, that is of the brachial plexus, the large group of nerves that emerge from C5-T1. These are the nerves that supply motor function to the arms.”
Comments from neurologist Dr. Strully in a letter sent by Dr. Strully to Dr. Robert Artwohl, dated April 9, 1994 as to an even greater possible extent of the muscle contractions.
"Before all else, it is necessary to remember that this assassination reveals a sequence of neural responses initiated in the neck by the shock wave and cavitation induced by the bullet in its traverse of the neck. This traumatized all structures in a 6 inch radius in all directions from the path of passage through the neck. This spread of forces occurred in a fraction of a second, traumatizing all neural structures in the immediate vicinity within a fraction of a second as determined by the speed of the missile according to ballistic studies.
As a result, contraction of the muscles innervated by nerves closest to the bullet's path took place first; -- right deltoid, left deltoid, right biceps followed by the left biceps and sequential contraction of all muscles in the forearms, hands, chest, abdominal walls and paraspinal muscle groups, with muscles in the lower extremities, farthest from the shock wave, responding last. All neural structures in the neck were stimulated at the same moment…”
3) Some assessments of the Presidents condition from extended film inspections. From the Study Slide 5 video time 0:08:19
My assessment of the film from z226-z254 and z262-z312 was simply that “JFK looked like a statue locked in place”.
ITEK Corporation’s assessment in their report was that “He appeared to remain in a frozen position”.
4) From voluntary neck stiffening seen in sports at stressful times. From the Study Slide 40 or video time 1:35:50
Besides involuntary stiffening that are likely related to a stretch reflex, there can be in some stressful situations some voluntarily stiffening of necks taken like in the sports of soccer and boxing.
There is "very strong evidence against any kind of jet effect"
All I can do is to mention the basis I used for the assessment that there was some jet effect.
1) The modeling overall did a good job of predicting position of the head and upper torso, but there was one place it didn’t respond well and that was between z312 and z313. The model wanted to say that the head position at z313 should have gone even further ahead and taken longer to come back than it did. I struggled with why the heck this was happening, and finally realized that the model did not include any slowing of the head by another force at that time, i.e. some jet effect. Accounting for this corrected that issue.
2) Simply put, typically when you see a noticeable jet, you get some jet effect. There was noticeable jet fan going forward at z313 that I saw, while its net direction may have been a little forward and to the right. A good experiment would be going out in the yard and take a garden hose with a sprayer on the end. With the hose full of water, open the sprayer to provide a noticeable fan and see if you feel zero force pushing back or is there some detectable force pushing back against your hand.
3) Nick Nalli made the most in-depth calculations I have seen on the head shot and concluded there was some jet effect and further estimated some ranges for its effect on the head. I checked and within those ranges there would be enough to correct my model as described in 1) just above.
4) We see a jet in the Z-film but experiments to show head reversal by jet effect are tricky to set up exactly right, and don’t always work, but typically the ones that fail are ones that don’t show much of a jet. This is described some in the examples of the Study on Slide 7 or video time 0:13:39.
"At the moment of impact JFK's chin is resting on his chest (the sternum is a non-issue) JFK's head can be clearly seen being driven into his chest, there is nowhere for it to go so it rebounds.
That this movement is JFK's head being driven into his chest"
When I hold my head at like a 45 degree angle, it is not resting on my chest, but I cannot see his chest directly relative to his chin extent, so can’t comment on this.
"The initial movement at impact is forward"
I agree and both his head and upper torso have initial forward movement.
"The massive crater in the top of JFK's head after impact"
Yes, It looks like the jet exited the top opening going forward.
"The jet effect might work through a small exit hole out of which matter is ejected but it is totally negated by such a massive head wound."
In experiments small exit holes are good for directionally which is important, but they suffer in that they present a much larger pressure drop to overcome to discharge the mass or fast volumetric mass flow out that orifice which is important to the momentum exchange. In fact I think small holes are overall more limiting in this regard as I think it is easier to get directionality out of generous sized hole than large mass flow rates out of a small hole. You commonly see a melon shot with a small exit hole and with a focused but a limited discharge jet and not much movement at all. This is also discussed briefly in the Study on Slide 7 in the video at time 0:13:39.
Like I said originally, I would expect there would have been some observation of a mark on chin or chest if such a violent collision happened. Because no one saw a mark does not mean it didn’t happen, but it boils down to just a lack of confirmatory evidence at this point that would prevent me in trying to redefine the whole model base on something I can’t really see, or confirm at this point.
-
I’m glad you discussed this, as it will be something for me keep my eye on for possible future use. But at this time I don’t agree enough with your statements to make large changes in the modeling. Here are some of the "statements" I disagree with and reasons why I disagree:
Clearly you've put a lot of time into this aspect of the case but there are key issues I have to disagree with, in particular the notion of neck paralysis at the moment of impact and the so-called jet effect.
Understanding the mechanics of the headshot is of immense importance as, in my opinion, the "back and to the left" motion is the cornerstone of the majority of "multiple shooters" conspiracy thinking. Watching the Z-film in real time it is very difficult to get away from the intuitive perception that the "back and to the left" motion can be caused by anything other than a shot from the right front but a close analysis of the headshot reveals this motion was caused by a shot hitting JFK's head from behind.
“there is zero evidence neck paralysis occurred”
All I can do is to mention the basis I used for the assessment that there was significant neck stiffness (in addition to shoulder, arms, hands and fingers).
1) It is called spasticity or spastic paralysis due to damage to the lower cervical part of the spine and the brachial plexus. In this case via a bullet transit that occurred circa z222.
https://sites.google.com/view/spastic-paralysis/home
2) Some Neurological opinions. From the Study Slide 54 or video time 2:07:00
Comments from Dr. Robert Artwohl explaining why we saw the arms stiffening upward.
“JFK’s reaction to the neck wound was, for all intents and purposes, instantaneous to the hit at Z-223/224. As the bullet passed through his neck, the pressure cavity caused an immediate and wide spread stimulation of all the nerves in the immediate vicinity, that is of the brachial plexus, the large group of nerves that emerge from C5-T1. These are the nerves that supply motor function to the arms.”
Comments from neurologist Dr. Strully in a letter sent by Dr. Strully to Dr. Robert Artwohl, dated April 9, 1994 as to an even greater possible extent of the muscle contractions.
"Before all else, it is necessary to remember that this assassination reveals a sequence of neural responses initiated in the neck by the shock wave and cavitation induced by the bullet in its traverse of the neck. This traumatized all structures in a 6 inch radius in all directions from the path of passage through the neck. This spread of forces occurred in a fraction of a second, traumatizing all neural structures in the immediate vicinity within a fraction of a second as determined by the speed of the missile according to ballistic studies.
As a result, contraction of the muscles innervated by nerves closest to the bullet's path took place first; -- right deltoid, left deltoid, right biceps followed by the left biceps and sequential contraction of all muscles in the forearms, hands, chest, abdominal walls and paraspinal muscle groups, with muscles in the lower extremities, farthest from the shock wave, responding last. All neural structures in the neck were stimulated at the same moment…”
3) Some assessments of the Presidents condition from extended film inspections. From the Study Slide 5 video time 0:08:19
My assessment of the film from z226-z254 and z262-z312 was simply that “JFK looked like a statue locked in place”.
ITEK Corporation’s assessment in their report was that “He appeared to remain in a frozen position”.
4) From voluntary neck stiffening seen in sports at stressful times. From the Study Slide 40 or video time 1:35:50
Besides involuntary stiffening that are likely related to a stretch reflex, there can be in some stressful situations some voluntarily stiffening of necks taken like in the sports of soccer and boxing.
I am in total agreement that the shot through JFK's neck causes an almost instantaneous reflex reaction due to the bullet damaging the nerves of the Brachial Plexus. Elsewhere I have posted the following:
The bullet passed between the C7 and T1 vertebrae, close to the spinal column.
This is confirmed by a fracture found in JFK's spine:
“There is an undisplaced fracture of the proximal portion of the right transverse process of T1 (or the region of the costovertebral junction)”
Quote from the report of the HSCA consulting radiologist, G.M. McDonnel, MD, in: HSCA vol.7: 219.
[see https://www.history-matters.com/archive/jfk/hsca/reportvols/vol7/html/HSCA_Vol7_0115a.htm]
An "undisplaced" fracture is one in which the bones remain aligned indicating a glancing blow by the bullet. This may have affected the trajectory of the bullet through JFK but that is not being considered at this moment. The fracture is of the right transverse process, in accordance with the entry of the bullet slightly to the right of the spine. Looking at this diagram again (obviously the diagram is of the left side of the body but the arguments apply due to the symmetry of the body):
(https://i.postimg.cc/90ZSyXyD/brachial-plexus.jpg) (https://postimages.org/)
A bullet passing between the C7 and T1 vertebrae, glancing off the transverse process of T1, would almost inevitably sever, or at least severely damage, the nerve marked T1 in the diagram, affecting in particular the Ulnar nerve which has its roots in the "T1" (and C8) nerve. The Ulnar nerve runs the length of the arm, entering the hand where it "flexes the ring and little fingers at the distal interphalangeal joint".
A bullet severing the Ulnar nerve may cause the hand to rapidly contract, however the Ulnar nerve only controls the flexion of the ring and little fingers.
I wish I could find a clearer image than the one below but there is a very strange aspect of JFK's hands in reaction to being shot. One might expect someone to 'clutch' at their throat if they were shot there but JFK doesn't do this. Instead he appears to clench his hands into fists and thrusts them under the area of his chin.
But even this is not quite correct. A clear image (I've seen one but can't find it at the moment) reveals that JFK appears to be 'pointing' at his throat:
(https://i.postimg.cc/wvGv6CYW/Screenshot-27.png) (https://postimages.org/)
I believe this indicates the bullet has severed his Ulnar nerve, causing some of his fingers (ring and little) to instantly clench shut but leaving his index finger unaffected and in a 'pointing' position.
What I did not take into account was the profound effect of "cavitation" as pointed out by Dr Strully:
"This traumatized all structures in a 6 inch radius in all directions from the path of passage through the neck."
The full effect of cavitation is demonstrated in this short video:
It is important to note a secondary explosion, referred to as "dieseling", that occurs within the cavitation. I believe this plays an important role in the headshot itself.
So, while I agree that momentary "neck paralysis" appears to have occurred as a result of the shot through the neck, I completely disagree that this paralysis was present at the moment of the headshot. In the clip below we can clearly see that after the initial reaction, during which JFK's elbows extend fully and his body appears to stiffen, his body then relaxes as he slumps to one side and his head drops forward:
(https://i.postimg.cc/T3tyBYnw/z221-286-close.gif) (https://postimages.org/)
By the moment of the headshot JFK's arms have come down and his head has slumped forward, if anything this is indicative that his neck has totally relaxed by the time of the headshot. A frame from just before the headshot shows this relaxed posture more clearly:
(https://i.postimg.cc/qMDc7bNq/z280mpi.jpg) (https://postimages.org/)
There is "very strong evidence against any kind of jet effect"
All I can do is to mention the basis I used for the assessment that there was some jet effect.
1) The modeling overall did a good job of predicting position of the head and upper torso, but there was one place it didn’t respond well and that was between z312 and z313. The model wanted to say that the head position at z313 should have gone even further ahead and taken longer to come back than it did. I struggled with why the heck this was happening, and finally realized that the model did not include any slowing of the head by another force at that time, i.e. some jet effect. Accounting for this corrected that issue.
2) Simply put, typically when you see a noticeable jet, you get some jet effect. There was noticeable jet fan going forward at z313 that I saw, while its net direction may have been a little forward and to the right. A good experiment would be going out in the yard and take a garden hose with a sprayer on the end. With the hose full of water, open the sprayer to provide a noticeable fan and see if you feel zero force pushing back or is there some detectable force pushing back against your hand.
3) Nick Nalli made the most in-depth calculations I have seen on the head shot and concluded there was some jet effect and further estimated some ranges for its effect on the head. I checked and within those ranges there would be enough to correct my model as described in 1) just above.
4) We see a jet in the Z-film but experiments to show head reversal by jet effect are tricky to set up exactly right, and don’t always work, but typically the ones that fail are ones that don’t show much of a jet. This is described some in the examples of the Study on Slide 7 or video time 0:13:39.
"At the moment of impact JFK's chin is resting on his chest (the sternum is a non-issue) JFK's head can be clearly seen being driven into his chest, there is nowhere for it to go so it rebounds.
That this movement is JFK's head being driven into his chest"
When I hold my head at like a 45 degree angle, it is not resting on my chest, but I cannot see his chest directly relative to his chin extent, so can’t comment on this.
"The initial movement at impact is forward"
I agree and both his head and upper torso have initial forward movement.
"The massive crater in the top of JFK's head after impact"
Yes, It looks like the jet exited the top opening going forward.
"The jet effect might work through a small exit hole out of which matter is ejected but it is totally negated by such a massive head wound."
In experiments small exit holes are good for directionally which is important, but they suffer in that they present a much larger pressure drop to overcome to discharge the mass or fast volumetric mass flow out that orifice which is important to the momentum exchange. In fact I think small holes are overall more limiting in this regard as I think it is easier to get directionality out of generous sized hole than large mass flow rates out of a small hole. You commonly see a melon shot with a small exit hole and with a focused but a limited discharge jet and not much movement at all. This is also discussed briefly in the Study on Slide 7 in the video at time 0:13:39.
Like I said originally, I would expect there would have been some observation of a mark on chin or chest if such a violent collision happened. Because no one saw a mark does not mean it didn’t happen, but it boils down to just a lack of confirmatory evidence at this point that would prevent me in trying to redefine the whole model base on something I can’t really see, or confirm at this point.
There is an even more counter-intuitive aspect to the headshot than the "back and to the left" movement caused by a shot from behind and that is the nature of the injury to JFK's head. In chapter 16 on his website, Pat Speer explains in detail the nature of this injury, concluding it is what is referred to as a "gutter" or "trench" wound. The bullet enters the head quite high up on the skull and exits just above the hairline. At some point the bullet fragments, either entering or exiting the skull, and some of these fragments pepper the inside of the front of the limo. This would seem to indicate the main injury would be sustained towards the front of the skull (other than a small entrance wound at the rear).
In fact, what happens is that almost the entire top portion of the right side of JFK's head is blown directly upwards, perpendicular to the direction of the bullet transit.
That the top of JFK's head is blown off is evidenced in a number of ways. In the clip below pay particular attention to the shape of JFK's head before the headshot and then to the massive crater that appears in the top of his head immediately after:
(https://i.postimg.cc/RFV4RpQQ/Head-Shot-close.gif) (https://postimages.org/)
The injury is clearly to the top of his head:
(https://i.postimg.cc/jSxdS6qD/z328-3.jpg) (https://postimages.org/)
The gif below was created by John Mytton and clearly shows the massive injury to the top of JFK's head:
(https://i.postimg.cc/SxK2VSdv/JFKAutopsy-Morph.gif) (https://postimages.org/)
And finally, z313 shows two "jets" exiting the top of JFK's head. The more pronounced "jet" is picked out by the red arrow, the lesser one by the yellow arrow.
(https://i.postimg.cc/CMJmBSSm/z313-4.jpg) (https://postimages.org/)
If there was any jet effect it would be related to these lines of ejected material being blown from the top of JFK's head. The direction of any jet effect can be seen to have no component that would drive JFK's head backwards:
(https://i.postimg.cc/FRr0Nkdm/z313-3.jpg) (https://postimages.org/)
Referring back to this clip. At the moment of the headshot there appears to be a fan or spray of material moving forwards:
(https://i.postimg.cc/RFV4RpQQ/Head-Shot-close.gif) (https://postimages.org/)
The cause of this requires a deeper understanding of the mechanics of the head injury.
As the bullet enters and exits the head it tears through the scalp at the back and the front creating weak spots in the integrity of the scalp. It also shatters the skull into numerous small pieces, completely destroying the structural integrity of the skull. As the pieces of skull explode upwards they lacerate the scalp between the two weak spots creating a tear along the top of the head. In the Mytton gif we can see some scalp folded over to the left (as we look at it) but there is no scalp covering the right side of the exposed brain.
This part of the scalp is blown to the right side of the head and is the large, pendulous mass of flesh seen hanging down the side of JFK's head. As this large mass of scalp/skull is blown away it creates the fan of material seen moving forward.
But what is the cause of the upwards explosion of skull and brain matter that lacerates the scalp?
The answer is "cavitation". Take one more look at this video posted above demonstrating cavitation caused by a bullet. It is this force acting on the compromised skull that, quite literally, blows the top of the head off.
After the neck shot JFK has a almost instantaneous reflex reaction causing his body to stiffen as his elbows shoot up to their full extent.
His body then relaxes and his head slumps forward. When the shot hits the back of his head it drives it forward and downward. Having nowhere else to go, his head rebounds upwards and backwards in the characteristic "back and to the left" motion.
-
A new perspective on “Back and to the Left” in the Z-film...This summarizes the results of an extended study taking a closer look at JFK’s motions....- There was no indication of a frontal shot striking the President
There's nothing 'new' about all that. It appears to be the same old Belin/Ford/Spector blurb.
-
A few comments and questions only on the parts in question.
A bullet passing between the C7 and T1 vertebrae, glancing off the transverse process of T1, would almost inevitably sever, or at least severely damage, the nerve marked T1 in the diagram, affecting in particular the Ulnar nerve which has its roots in the "T1" (and C8) nerve. The Ulnar nerve runs the length of the arm, entering the hand where it "flexes the ring and little fingers at the distal interphalangeal joint".
A bullet severing the Ulnar nerve may cause the hand to rapidly contract, however the Ulnar nerve only controls the flexion of the ring and little fingers.
I wish I could find a clearer image than the one below but there is a very strange aspect of JFK's hands in reaction to being shot. One might expect someone to 'clutch' at their throat if they were shot there but JFK doesn't do this. Instead he appears to clench his hands into fists and thrusts them under the area of his chin.
But even this is not quite correct. A clear image (I've seen one but can't find it at the moment) reveals that JFK appears to be 'pointing' at his throat:
I believe this indicates the bullet has severed his Ulnar nerve, causing some of his fingers (ring and little) to instantly clench shut but leaving his index finger unaffected and in a 'pointing' position.
I’m not sure about damage to the ulnar nerve, which looks to branch from the medial cord just before the armpit. Not sure how the bullet would go down there to sever the ulnar nerve, did you mean damage to the nerve root further back up near the transverse process that only effected the ulnar nerve?
It is important to note a secondary explosion, referred to as "dieseling", that occurs within the cavitation. I believe this plays an important role in the headshot itself.
I have heard of dieseling effect, but not heard of any theory of an internal explosion in the head by dieseling. That’s an interesting new one to me.
By the moment of the headshot JFK's arms have come down and his head has slumped forward, if anything this is indicative that his neck has totally relaxed by the time of the headshot. A frame from just before the headshot shows this relaxed posture more clearly:
Based on the neurological references I found, I think that spastic paralysis is what you are seeing happen in the upper torso area around the z222 strike location, and it was dynamic here, not instantaneous, and progresses from ~z226-z254 and then it was effectively in place for the near term (did not just instantly go away in a few seconds) and was complete with the stiffness set in and basically in place, where he looked the same from ~z262-312 and where his position did not change much at all. I thought he effectively looked “locked in place” and ITEK called him “frozen” up to z312. There were small changes in posture witch I attribute to the forces on him over this time frame like Jackie trying to pull down on his extended arm and of course gravity doing some work on the body.
Bottom line, I don’t believe upper body spastic paralysis would set in so dramatically and then passively totally disappear in less than 5 seconds. I don’t believe the people that I showed in photographs with similar spastic paralysis symptoms had those symptoms photographed only within 5 seconds of their occurrence before their symptoms disappeared.
But as you saw in my earlier discussion, an active intervention like the z313 head strike could facilitate flaccid paralysis setting in, much more extensively and quicker, in as soon at 0.2 seconds.
What you may be thinking about is his bending forward in this z262-312 timeframe, and I could see where you could see it as a relaxation or slump. If the spasticity did not effect his lower torso/abdominals, then that part of him might have leaned forward and slumped forward. Perhaps the blow to the back would nudge him forward a little. If however, spasticity was able to extend that far down then it might cause some forward bending, if so then that is what is observed.
In either case, his bending forward would continue to where the forward pressure on the back brace became equalized by the back brace restoring force pushing backwards which would keep his body at an equilibrium or neutral tilted position until z313 when it was displaced some more forward beyond that neutral position, loading up the back brace with a cantilever like force that quickly began to push the torso backwards as indicated by the upper torso’s position motion measured over time.
Net, there is plenty of reason to believe there was stiffness, at least in the upper torso, through z312.
The gif below was created by John Mytton and clearly shows the massive injury to the top of JFK's head:
I haven’t studied the dynamics of the head rupture and relative to the x-rays etc., but doesn’t all this agree with what Larry Sturdivan said in that it can be difficult to determine the direction of a bullet just by looking at the blowout? I believe this would be because the internal cranium pressure rises high in all directions and would blow out the weakest area which could be set up by a bullet exit, or just a weak skull bone area. I’m thinking one of weakest areas of the skull is the temple area, so if a bullet or fragment exited that area, it would be pretty ripe for a blowout starting.
If there was any jet effect it would be related to these lines of ejected material being blown from the top of JFK's head. The direction of any jet effect can be seen to have no component that would drive JFK's head backwards:
I thought the white dots were supposed to be skull fragments tumbling in the air during the camera exposure, with the bright side showing up after each rotation. If so, this would represent only two pieces of mass. Wouldn’t you want to consider all the mass ejected to do a mass and momentum balance when making a judgement on if there was any jet effect in play? It is fair to ignore all that red fan gunk ahead of his forehead and face? Should brain, scalp, blood, connective tissue, and perhaps other fragments be excluded? Even if one did ignore all this other stuff, wouldn’t two vectors representing the recoil of these two displayed vectors have some down and to the back components?
But what is the cause of the upwards explosion of skull and brain matter that lacerates the scalp?
The answer is "cavitation". Take one more look at this video posted above demonstrating cavitation caused by a bullet. It is this force acting on the compromised skull that, quite literally, blows the top of the head off.
I agree with you here, the high internal cranial pressure would create havoc. Everyone uses the term but I wish there was another word besides "cavitation" to describe a high internal pressure.
After the neck shot JFK has a almost instantaneous reflex reaction causing his body to stiffen as his elbows shoot up to their full extent.
His body then relaxes and his head slumps forward. When the shot hits the back of his head it drives it forward and downward. Having nowhere else to go, his head rebounds upwards and backwards in the characteristic "back and to the left" motion.
It looks like the main differences here to explain all JFK’s motion are just related to the models we have in place. You have a head bounce off the chest with no jet effect involved as the process, whereas my assumptions are different. Beyond that many of the observations are similar.
-
There's nothing 'new' about all that. It appears to be the same old Belin/Ford/Spector blurb.
That's good news if they did the modeling before. I'm curious to know what they had for an omega value for the head/neck from z316 to z324. Do you recall?
Thx
-
The Nicholas Nalli study----
https://www.sciencedirect.com/science/article/pii/S2405844017331882#bbr0060
This statement....the depiction of a fatal wound to the head caused by a high-powered military rifle bullet, something that ordinary citizens would not have had an inkling about in that era.
....strikes me as rather verbose. What was different about 'that era'? The Dark Ages?
Mr Nalli makes a statement that is not universally accepted but with which I agree---
a careful comparison between [the] two frames also reveals that President Kennedy's head snaps forward from Z312 to Z313
I have postulated that this just might be because there were two separate strikes to the head. One from behind and one from the right front where many in attendance claim.
Harold Weisberg also thought this...
- The head shot (or shots) remain a puzzzle, but
probably represent two nearly simultaneous impacts, first
from the rear, then from the front.
http://jfk.hood.edu/Collection/Weisberg%20Subject%20Index%20Files/D%20Disk/DeSalles%20Doug%20Jr/Item%2001.pdf
This would agree with earwitness accounts that at that moment the sound was a babam report. Localizing origins would have been astronomical.
Dan Rather viewed a private showing of the Zapruder film shortly after the event. He described it...After the final shot, the presidents head slumped forward.
A deliberate lie.
I also read thru... https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5934694/
Mr Nalli may know about physics/arithmetic but I don't think he really knows very much about the assassination.
-
A few comments and questions only on the parts in question.
I’m not sure about damage to the ulnar nerve, which looks to branch from the medial cord just before the armpit. Not sure how the bullet would go down there to sever the ulnar nerve, did you mean damage to the nerve root further back up near the transverse process that only effected the ulnar nerve?
I posted:
"A bullet passing between the C7 and T1 vertebrae, glancing off the transverse process of T1, would almost inevitably sever, or at least severely damage, the nerve marked T1 in the diagram, affecting in particular the Ulnar nerve which has its roots in the "T1" (and C8) nerve."
I make no mention of "damage" to the Ulnar nerve, only that it is affected by damage to it's root. The reason I postulate this is the unusual "pointing finger" aspect of JFK's, otherwise clenched, hand. I believe this hand position is a signifier of severe nerve damage caused by the bullet's transit through the neck.
Based on the neurological references I found, I think that spastic paralysis is what you are seeing happen in the upper torso area around the z222 strike location, and it was dynamic here, not instantaneous, and progresses from ~z226-z254 and then it was effectively in place for the near term (did not just instantly go away in a few seconds) and was complete with the stiffness set in and basically in place, where he looked the same from ~z262-312 and where his position did not change much at all. I thought he effectively looked “locked in place” and ITEK called him “frozen” up to z312. There were small changes in posture witch I attribute to the forces on him over this time frame like Jackie trying to pull down on his extended arm and of course gravity doing some work on the body.
Bottom line, I don’t believe upper body spastic paralysis would set in so dramatically and then passively totally disappear in less than 5 seconds. I don’t believe the people that I showed in photographs with similar spastic paralysis symptoms had those symptoms photographed only within 5 seconds of their occurrence before their symptoms disappeared.
But as you saw in my earlier discussion, an active intervention like the z313 head strike could facilitate flaccid paralysis setting in, much more extensively and quicker, in as soon at 0.2 seconds.
What you may be thinking about is his bending forward in this z262-312 timeframe, and I could see where you could see it as a relaxation or slump. If the spasticity did not effect his lower torso/abdominals, then that part of him might have leaned forward and slumped forward. Perhaps the blow to the back would nudge him forward a little. If however, spasticity was able to extend that far down then it might cause some forward bending, if so then that is what is observed.
In either case, his bending forward would continue to where the forward pressure on the back brace became equalized by the back brace restoring force pushing backwards which would keep his body at an equilibrium or neutral tilted position until z313 when it was displaced some more forward beyond that neutral position, loading up the back brace with a cantilever like force that quickly began to push the torso backwards as indicated by the upper torso’s position motion measured over time.
Net, there is plenty of reason to believe there was stiffness, at least in the upper torso, through z312.
Again. I just have to totally disagree with this analysis.
The very extreme initial reaction of JFK's body to the neck shot is obvious.
He straightens up, his elbows fly up to their fullest extent and his body momentarily stiffens. There can be little doubt about that.
But none of this is present by the time of the headshot.
If the paralysis was still present JFK would still be in this extreme position - elbows up, sat rigidly straight. Gravity would have no effect on this. In the clip below we see JFK's fists shoot to his neck area, his elbows fly up and he sits rigidly upright and is "frozen" for an instant. His arms then begin to relax, he looks towards Jackie as his whole body relaxes, he slumps slightly to his left, his arms come fully down and his head slumps forward as his neck relaxes:
(https://i.postimg.cc/T3tyBYnw/z221-286-close.gif) (https://postimages.org/)
To imagine he is in any way still displaying the paralysis of the initial reaction is baffling. There is no component of his initial paralysis present at the moment of the headshot so I find it very difficult to understand how this can be assumed. His body stays in the same position leading up the headshot but this is clearly due to his body being in a relaxed state, not a rigid one.
I guess we'll have to agree to disagree on that.
I haven’t studied the dynamics of the head rupture and relative to the x-rays etc., but doesn’t all this agree with what Larry Sturdivan said in that it can be difficult to determine the direction of a bullet just by looking at the blowout? I believe this would be because the internal cranium pressure rises high in all directions and would blow out the weakest area which could be set up by a bullet exit, or just a weak skull bone area. I’m thinking one of weakest areas of the skull is the temple area, so if a bullet or fragment exited that area, it would be pretty ripe for a blowout starting.
The bullet entering and exiting the skull creates massive weak spots. The scalp is punctured at both places and the skull itself is shattered into smaller pieces. The cavitation explodes through these weakened areas lacerating the scalp between the two puncture points as it blows the shattered pieces of skull upwards. All structural integrity of the skull is compromised at the moment of cavitation (as is the integrity of the scalp)
We don't need to determine the direction of the bullet from the blowout so I'm not sure how Sturdivan fits into it, to be honest.
I thought the white dots were supposed to be skull fragments tumbling in the air during the camera exposure, with the bright side showing up after each rotation. If so, this would represent only two pieces of mass. Wouldn’t you want to consider all the mass ejected to do a mass and momentum balance when making a judgement on if there was any jet effect in play? It is fair to ignore all that red fan gunk ahead of his forehead and face? Should brain, scalp, blood, connective tissue, and perhaps other fragments be excluded? Even if one did ignore all this other stuff, wouldn’t two vectors representing the recoil of these two displayed vectors have some down and to the back components?
Indeed, the white dots are skull fragments being fired into the air by the immense pressures involved. They do not represent any kind of jet effect and if the did it is quite clear that they would provide no backward component to JFK's head movement. In fact, I believe the larger of the "jets" would have a forward component to it. But, as I say, it's not the jet effect, it's material being ejected from the head by the explosive cavitation.
Just to put my cards on the table - I think the Jet Effect hypothesis is one of the most embarrassingly bad pieces of "scholarship" I have ever encountered and I was not surprised to hear that Alvarez, the author of this nonsense, was found out cheating his results.
It looks like the main differences here to explain all JFK’s motion are just related to the models we have in place. You have a head bounce off the chest with no jet effect involved as the process, whereas my assumptions are different. Beyond that many of the observations are similar.
Agreed.
-
The Nicholas Nalli study----
https://www.sciencedirect.com/science/article/pii/S2405844017331882#bbr0060
This statement........strikes me as rather verbose. What was different about 'that era'? The Dark Ages?
Mr Nalli makes a statement that is not universally accepted but with which I agree---I have postulated that this just might be because there were two separate strikes to the head. One from behind and one from the right front where many in attendance claim.
Harold Weisberg also thought this...http://jfk.hood.edu/Collection/Weisberg%20Subject%20Index%20Files/D%20Disk/DeSalles%20Doug%20Jr/Item%2001.pdf
This would agree with earwitness accounts that at that moment the sound was a babam report. Localizing origins would have been astronomical.
Dan Rather viewed a private showing of the Zapruder film shortly after the event. He described it...A deliberate lie.
I also read thru... https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5934694/
Mr Nalli may know about physics/arithmetic but I don't think he really knows very much about the assassination.
"I have postulated that this just might be because there were two separate strikes to the head."
What was it that led you to postulate this?
-
Again. I just have to totally disagree with this analysis.
I understand your disagreement and concern but based on what I have found I unfortunately totally disagree with you and definitely believe there was significant residual stiffening of JFK through z312, I think he moved very little (while all others in limo moved around some) before z312. But his whole body doesn’t remain in the EXACT same position from frame z226 onward, I don’t claim that.
Also based on how the modeling reacted from z312 to z313, I believe there was some component of jet effect manifesting itself there, but the neck stiffness could still play a role up to z316, and additionally the back brace played a role continually through z324 providing the uniform upper torso sinusoidal motion. It also was primarily responsible for the torso reversal backward -> forward around z319, and not because of his upper torso slamming into the back seat reversing his motion but because of a rearward deflection of the back brace creating a restoring force at that point from its neutral position that I described it had settled into before z312. The actual upper torso horizontal displacements were not that great, just over an inch or so. To what do you attribute the reversal at z319, is it a slamming of the upper torso into the back seat and reversing its motion again in a nearly perfect sinusoidal motion that had started and continued since z312, or something else?
As to the Jet effect, I don’t know that much about Alvarez, so I don’t want to comment on his motives. I do believe he could have done a better job explaining the jet effect, the complexity of it and how it is sometimes difficult to demonstrate head reversal in tests (especially in tests where there was no additional restoring force like an stiff/elastic neck attached). If the big debate at the time was if the jet effect was real or even possible, perhaps he was focused on only showing a jet effect was theoretically possible, but I think more explanation would have been appropriate. Did the two video examples of the basics of jet effect in my presentation give you any thoughts that some level of jet can happen, or did it tend to reinforce your thoughts that jet effect can not happen? Reference on this was in slide 7, video time 0:13:39 of the video I had made.
-
The Nicholas Nalli study----
Mr Nalli makes a statement that is not universally accepted but with which I agree---I have postulated that this just might be because there were two separate strikes to the head. One from behind and one from the right front where many in attendance claim.
Harold Weisberg also thought this...http://jfk.hood.edu/Collection/Weisberg%20Subject%20Index%20Files/D%20Disk/DeSalles%20Doug%20Jr/Item%2001.pdf
I have heard of the theory of two back to back strikes to the head where the first strike drives the head forward and the next strike immediately after drives the head backwards. What concerned me about this is that the first rear shot initiated a noticeable forward movement in the upper torso as well, but if there was a following significant shot from the front at z313 it had no effect on the torso's movement trajectory as the upper torso kept smoothly moving forward until just before z315 where it reversed in a sine wave fashion.
This would agree with earwitness accounts that at that moment the sound was a babam report. Localizing origins would have been astronomical.
This sounds like the kind of thing Charles has been looking into with regards to a shock wave.
After the final shot, the presidents head slumped forward.
A deliberate lie.
I also read thru... https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5934694/
Mr Nalli may know about physics/arithmetic but I don't think he really knows very much about the assassination.
Was Dan Rather talking about what he remembered seeing at z312 or z321? In both cases the head moves forward. If he only viewed the film once, I find it hard to believe he would have picked up on the forward motion from z312 to z313, but I don't know.
I think Nick Nalli was trying to do the most comprehensive effort to date to technically describe the dynamics of the head shot. I haven't seen a more in-depth technical review yet, but maybe there is one out there somewhere.
-
I dislike viewing the images associated with all of this. They are just unsettling to me. So I have avoided this thread for the most part. But I saw something on a Smithsonian channel show called “Air Disasters” that reminded me of this subject and wanted to share the essence of it. It involves the reasons that a supersonic passenger jet (SST) crashed shortly after takeoff in France years ago. What happened was a piece of metal laying on the runway cut one of the tires as the jet was traveling around 200 mph just before it’s takeoff speed. The tire exploded and a piece of the tire struck the underside of the wing (which was also a fuel tank). The piece of tire didn’t penetrate the tank. But it set off a shockwave which did rupture the tank at its weakest point. The fuel caught fire, an engine was disabled and the plane crashed shortly thereafter due to insufficient thrust to gain altitude. Anyway, the shockwave causing the fuel tank to rupture reminded me of some of the things that have been said about JFK’s head exploding. And I thought this thread might be an appropriate place to share.
-
I dislike viewing the images associated with all of this. They are just unsettling to me. So I have avoided this thread for the most part. But I saw something on a Smithsonian channel show called “Air Disasters” that reminded me of this subject and wanted to share the essence of it. It involves the reasons that a supersonic passenger jet (SST) crashed shortly after takeoff in France years ago. What happened was a piece of metal laying on the runway cut one of the tires as the jet was traveling around 200 mph just before it’s takeoff speed. The tire exploded and a piece of the tire struck the underside of the wing (which was also a fuel tank). The piece of tire didn’t penetrate the tank. But it set off a shockwave which did rupture the tank at its weakest point. The fuel caught fire, an engine was disabled and the plane crashed shortly thereafter due to insufficient thrust to gain altitude. Anyway, the shockwave causing the fuel tank to rupture reminded me of some of the things that have been said about JFK’s head exploding. And I thought this thread might be an appropriate place to share.
This may be relevant and is an interesting scenario, I may have to see if I can find the story.
I wonder about their conclusion though if the tire part ejection happened just before takeoff (and not in supersonic flight), it sounds related to an old physics trick question on how fast the top of a tire goes relative to the ground/or its axel. I believe the answer is only twice the velocity. If so, that would put a broken off chunk of rubber at 400 mph (2x200mph) which is subsonic. I think the axel/airplane would have to be going close to 400 mph before takeoff to have a chunk ejected at supersonic speed. (That is if I'm thinking about it right and they didn't add on some speed from an explosion which may be what they did). But I would think a chunk of rubber at 400 mph would still be able to do some damage (heck fast foam ultimately took out a space shuttle), so I'm wondering if a physical collision could have come into play here instead of a shock wave. I may be saying this based on how I was also a little surprised how little physical disruption was done to a house of cards by the 50 cal BMG mach 3 shock wave only an inch or so away in that one video.
The other thing about the shock wave is that it stops being formed when the bullet or fragment goes subsonic. In the JFK case it might be worth checking on what the estimates were for the bullet velocity after going through the occipital bone area which might have put it subsonic, but the other thing is that the speed of sound tends to go up in liquids and solids vs gas, so I would expect the speed of sound to go up in tissues.
-
This may be relevant and is an interesting scenario, I may have to see if I can find the story.
I wonder about their conclusion though if the tire part ejection happened just before takeoff (and not in supersonic flight), it sounds related to an old physics trick question on how fast the top of a tire goes relative to the ground/or its axel. I believe the answer is only twice the velocity. If so, that would put a broken off chunk of rubber at 400 mph (2x200mph) which is subsonic. I think the axel/airplane would have to be going close to 400 mph before takeoff to have a chunk ejected at supersonic speed. (That is if I'm thinking about it right and they didn't add on some speed from an explosion which may be what they did). But I would think a chunk of rubber at 400 mph would still be able to do some damage (heck fast foam ultimately took out a space shuttle), so I'm wondering if a physical collision could have come into play here instead of a shock wave. I may be saying this based on how I was also a little surprised how little physical disruption was done to a house of cards by the 50 cal BMG mach 3 shock wave only an inch or so away in that one video.
The other thing about the shock wave is that it stops being formed when the bullet or fragment goes subsonic. In the JFK case it might be worth checking on what the estimates were for the bullet velocity after going through the occipital bone area which might have put it subsonic, but the other thing is that the speed of sound tends to go up in liquids and solids vs gas, so I would expect the speed of sound to go up in tissues.
The way I envision it, is the speed of a piece flying off of the tire circumference would depend upon the diameter of the tire (think how changing tire diameters would affect the speedometer on a car or truck), the speed of the plane relative to the runway, plus any added velocity created by the explosion of the tire. And if I remember correctly, they stressed the fact that the tire literally exploded. Also they pointed out that the fuel tanks were completely full for the long flight across the Atlantic Ocean (similar to a human head being full of semi-liquid matter). And I don’t know if supersonic speed was any part of their computer model showing that the shockwave (if that is the exact word that they used - I’m not sure because I kept being distracted while trying to watch the show). What was clear to me was that the impact of the tire piece didn’t actually penetrate the fuel tank, and that the rupture of the tank was in a different location and the metal was bent outwards. When we compare the Concorde SST situation to the JFK headshot it would be more like a blow to the head (that didn’t penetrate the skull) causing a concussion severe enough to blow the other side of the skull out. I doubt that there has ever been a documented case where that actually happened. What did happen to JFK was the bullet did penetrate the skull and it appears to me that a combination of a bullet fragment(s) and a shock wave from the impact of the bullet caused the other side of the skull to be fractured and blown out. Comparing the two very different cases, what strikes me as important is that the potential magnitude of the force of the shock wave inside a sealed container full of liquid (or semi-liquid) material can be great enough to rupture the container without the blow even penetrating it. And that the Zapruder frames 313, and a few immediately following it, showing the violent outflow of matter from JFK’s skull is visual evidence of the force of the shock wave inside his skull. Some people might have a difficult time understanding how a relatively small bullet can cause such an explosion. Just like they might have a similar time understanding how a piece of tire could do the damage that it did to the fuel tank of the Concorde plane.
-
A look at a Wikipedia article shows some more specific information:
The Concorde ran over this piece of debris during its take-off run, cutting its right-front tyre (tyre No 2) and sending a large chunk of tyre debris (4.5 kilograms or 9.9 pounds) into the underside of the left wing at an estimated speed of 140 metres per second (310 mph).[2]: 115 It did not directly puncture any of the fuel tanks, but it sent out a pressure shockwave that ruptured the number 5 fuel tank at its weakest point, just above the undercarriage.
https://en.wikipedia.org/wiki/Air_France_Flight_4590 (https://en.wikipedia.org/wiki/Air_France_Flight_4590)
Wow, a 10-pound chunk of tire at 310 mph. That was a significant amount of energy. And I think that since the shockwave was in the liquid fuel, the tire chunk didn't need to be at supersonic speed (much like a boat on a body of water doesn't need to be going the speed of sound to create a wake).
-
A look at a Wikipedia article shows some more specific information:
The Concorde ran over this piece of debris during its take-off run, cutting its right-front tyre (tyre No 2) and sending a large chunk of tyre debris (4.5 kilograms or 9.9 pounds) into the underside of the left wing at an estimated speed of 140 metres per second (310 mph).[2]: 115 It did not directly puncture any of the fuel tanks, but it sent out a pressure shockwave that ruptured the number 5 fuel tank at its weakest point, just above the undercarriage.
https://en.wikipedia.org/wiki/Air_France_Flight_4590 (https://en.wikipedia.org/wiki/Air_France_Flight_4590)
Wow, a 10-pound chunk of tire at 310 mph. That was a significant amount of energy. And I think that since the shockwave was in the liquid fuel, the tire chunk didn't need to be at supersonic speed (much like a boat on a body of water doesn't need to be going the speed of sound to create a wake).
I had totally forgot about that Flt 4590 incident, but when you mentioned it, I recalled it a little bit and how it was debated in court and was part of the demise of the Concord.
Thanks for the link, it refreshed my memory on what happened and how the Concord was different vs other jets in its take off angles and required take off (V1) speeds etc.
An interesting but sad story, it sounds like once the crew hit V1 speed while still on ground during takeoff, there was basically nothing they could do to on the ground or in the air to prevent a cataclysm of some type after their tire blew and caused that internal wing damage (fuel tank and wires) as a result of hitting a previous plane’s piece of cowling metal on the runway.
OK, here is an interesting coincidence based on what the article mentions. Get your tomatoes ready. A thrust reverser cowl door of the number 3 engine of a Continental Airlines basically lost a piece of metal. This ultimately was the cause of the Concord tire blowout and the whole incident.
Years of debate ensued over a thrust reverser. A thrust reverser directs a jet of its exhaust in the same direction the plane moves, in a forward direction, to slow down and help stop the plane’s forward motion. It typically runs continuously over a short period of time (but not just an extremely short burst or impulse) to help the plane to almost stop.
I think there has been a lot of debate over the years about the idea of some thrust reversal effect in another case. It's not exactly the same but just a coincidence I noticed. You can now throw your tomatoes at me :)