Could easily test this Scott. Find a load cell, attach it to the paddle of the target, and get to testing! 
Upvote 0
How Much ENERGY is actually delivered to a target struck ? ... A Conversation
- Thread starter Motorhead
- Start date
Load cell - electric gadget that uses increasing resistance to measure force. i.e. a doodad that will show how much force (weight) is present. These are the heart of every electronic bathroom and industrial scale.
Upvote 0
Figured something like that .... being such impact is of such short duration, wonder if the "Weighting" measurement can be done in this manor ?
If having the miens, a devise such as a newtons cradle of some relative size could be fabricated to quantify input in equates to output we can measure via ball HEIGHT swing or something linear in scale ???
Great conversation guys ... thanks !!
If having the miens, a devise such as a newtons cradle of some relative size could be fabricated to quantify input in equates to output we can measure via ball HEIGHT swing or something linear in scale ???
Great conversation guys ... thanks !!
Upvote 0
Seems like the energy absorbed by the target is the difference between the energy the projectile arrived with and the energy the projectile (in pieces or whole) left the collision with. I agree that deformation of the pellet - and also the target - takes some of the projectile energy but it's hard to say how much without tests. Is the energy to distort the projectile into small pieces greater than the energy to distort the projectile into a very different shape but still one piece? Maybe. But the distortion to the target also probably increases if the projectile stays in one piece too so that "loss" may offset at least part of the difference. My gut feel is the energy to distort the projectile and target is smaller than the projectile leaving energy - unless the impact is exactly perpendicular to the target. For a perfectly perpendicular impact the projectile should fall to the ground if it is intact and leave with minimal energy if it splatters. Impacts at an angle should result in much larger departing energy for the projectile - the impact changes their direction but doesn't totally stop their progress.
I'm not into cameras but it seems like a camera that produces results that could be slowed down to frame by frame focused on a "know your limits" target and shot by a couple different projectiles would get us a lot closer to understanding the answer. Camera should probably be in a protective case because it is likely to get hit with fragments. The target pendulum will move the furthest for the higher energy transfer to the target. The nice thing about a no limits target is you could pick a target that moves significantly without spinning to make the difference easier to see.
I'm not into cameras but it seems like a camera that produces results that could be slowed down to frame by frame focused on a "know your limits" target and shot by a couple different projectiles would get us a lot closer to understanding the answer. Camera should probably be in a protective case because it is likely to get hit with fragments. The target pendulum will move the furthest for the higher energy transfer to the target. The nice thing about a no limits target is you could pick a target that moves significantly without spinning to make the difference easier to see.
Upvote 0
Material, yield strength, brinell hardness
lead, 145psi, 5(pure) to 11-30 (hard cast)
A36, 36,000psi, 119-159
AR500, 180,000psi, 477-550
Approx 0.01fpe ends up as kinetic energy in the paddle. For a 100% elastic collision, all the rest would be kinetic energy in the pellet as it ricochets.
For an inelastic collision, the amount of damage "absorbed" by the paddle is highly dependent on the relative strength/hardness of the colliding materials.
A36 is about 30x harder and 250x stronger than pure lead. It will hold up for awhile for a field target.
AR500 is about 4x harder and 4x stronger than A36. After testing, this is my choice. About 1/8" thick minimum for 20fpe lead for long term damage control.
Most field targets use materials somewhere between A36 and AR500.
For damage concerns, the material used in the FT is much more of a factor than the shape of the soft lead projectile. Also, the hardness of the lead used is more of a factor than the projectile shape.
If target damage were the real concern, for the banning of slugs, than the AAFTA rules should specify a minimum material specification for the targets. Regulating the shape of the pellet is a round about (and ineffective) way of trying to address that problem.
I think the actual reason given for the banning of slugs was because the potentially higher BC could allow them to carry too far for some of the existing small FT courses at a few clubs. We need a backstop or sufficient down range real estate to allow a safe down range impact when a target is completely missed. I'm assuming that some of those clubs have neither. So AAFTA put in a round about restriction to hopefully limit the BC of the projectile, and applied it to all ranges hosting an AAFTA match.
lead, 145psi, 5(pure) to 11-30 (hard cast)
A36, 36,000psi, 119-159
AR500, 180,000psi, 477-550
Approx 0.01fpe ends up as kinetic energy in the paddle. For a 100% elastic collision, all the rest would be kinetic energy in the pellet as it ricochets.
For an inelastic collision, the amount of damage "absorbed" by the paddle is highly dependent on the relative strength/hardness of the colliding materials.
A36 is about 30x harder and 250x stronger than pure lead. It will hold up for awhile for a field target.
AR500 is about 4x harder and 4x stronger than A36. After testing, this is my choice. About 1/8" thick minimum for 20fpe lead for long term damage control.
Most field targets use materials somewhere between A36 and AR500.
For damage concerns, the material used in the FT is much more of a factor than the shape of the soft lead projectile. Also, the hardness of the lead used is more of a factor than the projectile shape.
If target damage were the real concern, for the banning of slugs, than the AAFTA rules should specify a minimum material specification for the targets. Regulating the shape of the pellet is a round about (and ineffective) way of trying to address that problem.
I think the actual reason given for the banning of slugs was because the potentially higher BC could allow them to carry too far for some of the existing small FT courses at a few clubs. We need a backstop or sufficient down range real estate to allow a safe down range impact when a target is completely missed. I'm assuming that some of those clubs have neither. So AAFTA put in a round about restriction to hopefully limit the BC of the projectile, and applied it to all ranges hosting an AAFTA match.
Upvote 0
While a slug will generally carry more velocity, over a given distance, than a pellet it means a slug will in turn have a greater fpe at that distance. What isn't being considered is the projectile shape. Pellets traditionally have a rounded nose, or at least most of what is used for FT, while slugs tend to come to somewhat of a point. The slug is imparting a greater point load to the target due to its smaller nose diameter and residual energy.
Upvote 0
A tid-bit from my schooling. Energy is never created or destroyed, but it can be stored or transferred or transformed.
Look at the question as a whole unit. The energy of the projectile just before impact begins is the same energy as after the impact, just not all in Kinetic Energy (Ke). The pellet transfers some of the total energy to the target as (1) heat and some as Ke of making the target (2) move (swing) (3) vibrate (ring). The pellet absorbs the Ke of impact as heat and the pellet distorts or mushrooms until the shear force of the displacement overcomes the bonds between the molecules in the pellet (covalent bonds are quite strong but not very elastic) and the pellet material breaks down into smaller parts. The sum total of the energy parts is equal before the impact as immediately after the impact. Sound, heat and movement are tough units to work in - but they are all measurements of energy.
Pellet or slug material is important. -hardness
Target material is important - hardness
Total energy delivered it important - how much is transferred to heat, sound or movement
Projectile shape is not as important - but can be a factor if the preceding factors are combined.
My humble opinions, only. Whatever you shoot,
Shoot'em good
Look at the question as a whole unit. The energy of the projectile just before impact begins is the same energy as after the impact, just not all in Kinetic Energy (Ke). The pellet transfers some of the total energy to the target as (1) heat and some as Ke of making the target (2) move (swing) (3) vibrate (ring). The pellet absorbs the Ke of impact as heat and the pellet distorts or mushrooms until the shear force of the displacement overcomes the bonds between the molecules in the pellet (covalent bonds are quite strong but not very elastic) and the pellet material breaks down into smaller parts. The sum total of the energy parts is equal before the impact as immediately after the impact. Sound, heat and movement are tough units to work in - but they are all measurements of energy.
Pellet or slug material is important. -hardness
Target material is important - hardness
Total energy delivered it important - how much is transferred to heat, sound or movement
Projectile shape is not as important - but can be a factor if the preceding factors are combined.
My humble opinions, only. Whatever you shoot,
Shoot'em good
Upvote 0
"...used for FT, while slugs tend to come to somewhat of a point...."
Most "slugs" in the size/weight suitable for 20fpe FT tend to have hollow tips, not sharp points.
Which imparts a greater "point load"? The somewhat pointed pellet or the hollow point slug?
Upvote 0
Yup Jim got the answer for you Scott, being 6 hours ahead of you guys right now is making replying to comments hard!
Sure there would be a way to set up a target with a cell behind it. With the cell attached to a computer you would be able to see the spike in pressure when the projectile hits the plate. Could be a fun experiment to be honest
Sure there would be a way to set up a target with a cell behind it. With the cell attached to a computer you would be able to see the spike in pressure when the projectile hits the plate. Could be a fun experiment to be honest
Upvote 0
Fantastic read from those who contributed. While conclusive data or physics lead to an anwser of original question the overall information shared was / is very enlightening.
Thank you all !!
Scott S
Thank you all !!
Scott S
Upvote 0
I don't know why I am replying to this question. You have the 2nd to last sentence in my reply or you have a physics doctorate problem to use on masters degree graduates to see if they can spot all the ways the energy will be distributed on impact.The sand bag isn't in the running no heat,sound,particle disintegration, not instantaneous but a simple transfer of energy over a measurable time.Does the target move at all when struck by the projectile. Is the target "dented" when struck by the projectile. 2 more times when energy could be dissipated. Any part of the projectile depending on the angle of incidence ( strike of projectile on target, 90 to 0 = degrees) could loose almost 100% of the energy if "dead stop" occurs. Any impart imparts some energy in the form of heat to the target and retain some based on the angle of incidence and mass of the particles that leave the impact site, also sound generated upon impact is part of the energy transferred. Justs depends on how "deep" you want to carry the study. Being a casual shooter---100 lb hardened steel target, round pure lead ball projectile, all particles retained on or at the bottom of the target. force =mass x velocity at target. Heat and sound generated should be extremely small. It would in the least necesitate a slow motion camera, db meter, infrared meter and capturing all departing particles leaving the target to be weighed later. Seems to me the range is concerned about a legal situation.
Upvote 0
This series of videos does some analysis of the issue. I must really be a power nerd.
https://youtu.be/eKzMkn6Cqvg
https://youtu.be/eKzMkn6Cqvg
Upvote 0
There is a thing, called a ballistics pendulum. When shot it absorbs all the energy of the projectile because it catches it as gently as it can. It is essentially a plumb bob hanging in front of a scale with a catching device attached. You video tape it being hit and you can calculate exactly how much energy the target absorbed. They have been around for at least a couple of centuries.
Don't over think the problem.
** I believe I have repeated what you said in the first place Scott.
So I went back and scanned the thread...
Wrote this:
Scott, IF you are trying to figure out how much energy is absorbed and how much is either reflected (in the form of fragments or heat or noise, OR RF for that matter) then you are indeed working on a very hard problem. If you are trying to understand how much energy a pellet dumps in a critter when it PASSES through said critter, then again you are working on a very hard problem. If you are trying to figure out how much energy it dumps into something soft which essentially catches the pellet without deforming it much, say a critter that gets the full energy of the pellet (no pass through). That problem isn't so hard.
The best way to answer your question on a steel target for example is going to be high speed photography and a lot of calculations but you could get a pretty accurate answer given that the camera will pick up the tiniest pieces and the sound as well. You would be able to answer that question under those circumstances very accurately.
The real question is, would it be worth the cost?
Sorry to jump in here and rain on the parade. I expected you folks were talking about how much energy an animal takes upon being hit. That's a really hard problem, especially with a pass through.
Then I went back and reread it again.
Then I came up with an answer which I think is appropriate...
MOST OF IT. That's all that matters on this one. The slug is heavier (usually), flying faster and holding velocity more effectively (usually), and shaped to deliver all that energy to a smaller point (usually)... Clearly it is going to damage the targets more. If someone argues with you on that, just tell them you want them to show you the math...
Don't over think the problem.
** I believe I have repeated what you said in the first place Scott.
So I went back and scanned the thread...
Wrote this:
Scott, IF you are trying to figure out how much energy is absorbed and how much is either reflected (in the form of fragments or heat or noise, OR RF for that matter) then you are indeed working on a very hard problem. If you are trying to understand how much energy a pellet dumps in a critter when it PASSES through said critter, then again you are working on a very hard problem. If you are trying to figure out how much energy it dumps into something soft which essentially catches the pellet without deforming it much, say a critter that gets the full energy of the pellet (no pass through). That problem isn't so hard.
The best way to answer your question on a steel target for example is going to be high speed photography and a lot of calculations but you could get a pretty accurate answer given that the camera will pick up the tiniest pieces and the sound as well. You would be able to answer that question under those circumstances very accurately.
The real question is, would it be worth the cost?
Sorry to jump in here and rain on the parade. I expected you folks were talking about how much energy an animal takes upon being hit. That's a really hard problem, especially with a pass through.
Then I went back and reread it again.
Then I came up with an answer which I think is appropriate...
MOST OF IT. That's all that matters on this one. The slug is heavier (usually), flying faster and holding velocity more effectively (usually), and shaped to deliver all that energy to a smaller point (usually)... Clearly it is going to damage the targets more. If someone argues with you on that, just tell them you want them to show you the math...
Upvote 0
Provided the pellet remains in one piece, and we know V1 and V2 (entry and exit), don't we have a pretty good idea how much energy was dumped in the critter?
Upvote 0
You have substantially narrowed the problem but ok. Yes if you meet the criteria you specify it wouldn't t be that bad.
How many bones broken? What direction did it traverse? Did it tumble? How much did the projectile deform? Did bone fragments become secondary projectiles and also exit?
The problem becomes difficult because the projectile took energy away from the collision but there is no way to know how much it left behind.
But sure if you run the experiment in a box and can capture all the data you can calculate anything.
In all cases when the projectile does not exit the problem becomes trivial. I think?
Upvote 0
Well, that is a different topic altogether...tissue damage. Presumably then on to trauma and eventually lethality. Yes, much harder to quantify than the amount of energy dumped in the critter.
If we are switching back to the topic of energy, yes. If we are taking the expanded topic of tissue damage, no I don't think so.
Upvote 0
But isn't Scott talking about or trying to relate the problem to damage he's seeing on steel targets on a range?
Mind you I do agree with you if that projectile exits the animal and you can capture the exit velocity and the projectile is intact then sure you can know how much energy was deposited. As matter of fact it's pretty trivial problem as you said.
Mind you I do agree with you if that projectile exits the animal and you can capture the exit velocity and the projectile is intact then sure you can know how much energy was deposited. As matter of fact it's pretty trivial problem as you said.
Upvote 0