Quote:
Originally Posted by MikeG
Sigh. I would appreciate it if you read everything I wrote as I have been with your posts.
Ed = Cv * V
Ed is 'Deposited Energy'. V is the volume of the PERMANENT hole caused by the projectile. If there is no permanent hole, this equation does. not. apply.
My source is this paper: https://oa.doria.fi/bitstream/handle...pdf?sequence=1 (Wound ballistic simulation:
Assessment of the legitimacy of law enforcement firearms
ammunition by means of wound ballistic simulation
Jorma Jussila - 2005)
Anyway, I hope that the others monitoring this discussion will understand what I'm trying to get at, since you are being absolutely unreasonable. Good night. |
Mike i hope i did not cause any offence. None was intended.
I know exactly what you mean and i agree that the paper relates to wounds for real firearms. And that the values that one should use relate to penetration (volume of the wound). That paper is the only study i could find that actually makes reference to other studies on the matter.
All i am saying (i admit that i have not come across very clearly) is that the formula correlates wounds with energy dissipation (which seems like a no brainer).
If we combine that knowledge with the laws of physics (that energy transfer from one object to another depends on how much time the objects actually are able to remain in contact) then it makes a lot of sense to conclude that a plastic bb that is able to deform (vs a hard bb that is less able to) will remain on target for a longer period of time vs a hard bb (at equal velocities) and will be able to transfer more energy to the target.
Penetration I guess would be the ideal situation and low velocity non penetration the most difficult to guage.
FLATLANDER - I agree with you too. I personally do not have any specific qualifications in the field of terminal balistics. And yes this thread is all over the place.
The article also points to another interesting formula that can be used by us?:
"A bullet
[bb?] impacting the target has an impact mass of mi (g) and velocity vi (m/s). Its kinetic energy Ei (J) is defined as:
[4] Ei = 0.5 * mi * vi2 / 1000
Impact energy Ei is partially dissipated into
[onto?] the target and performs work upon it. From Eq. 4 we can see that both the bullet
[bb?] mass but more significantly its velocity determines the amount of kinetic energy. If the energy is not dissipated into the target, it is used somewhere else
[!]. The wound ballistic energy equation can be expressed as:
[5] Er = Ei – Edef – Ed
where Er is the residual kinetic energy, Ei the impact energy, Edef the energy used by bullet
[bb?] deformation and Ed the energy dissipated into
[onto?] the target tissue. Since Ei has to be significant, Edef and Ed must be maximised in order to minimise Er. The residual energy is a significant factor describing the danger to bystanders
[players ?] when the bullet completely penetrates
[bb ricochets?] and exits
[bb bounces off, rebounds off a wall ?] the primary target continuing its flight. The factor of Edef has often been overlooked in the literature [Tikka 1989, Pirlot et al. 2001]. Pirlot also uses the term deformation energy in conjunction with deformation of tissue simulant. Kinetic energy dissipation (Ed) can be increased by bullet instability, deformation and fragmentation. When a rigid tail-heavy bullet hits the target it tends to start tumbling because the rate of spin is insufficient to maintain stability in dense medium like tissue. This increases the cross-sectional area in the direction of penetration
[impact?] which increases the dissipation of kinetic energy. The process is, however, somewhat out of control. The precise depth at which
tumbling occurs is difficult to predict as it depends on the yaw angle on impact, properties of the tissue encountered and internal instabilities of the bullet [Peters et al. 1996]."
Yes this thread is all over the place ...