[MUD-Dev] Source data on Crossbow

[werda555 at yahoo.com]

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Original message: http://www.kanga.nu/archives/MUD-Dev-L/2002Q1/msg00440.php

On Wed, 13 Feb 2002 00:51:24 -0800 (PST)
"Dave Rickey" <daver at mythicentertainment.com> wrote:
> From: Christopher Kohnert <chris at achaea.com>

>> My degree is not in physics, so I'm likely not too qualified to
>> answer *G*, but I was envisioning something like a gelatinous
>> blob with lots of internal friction as the internal parts move
>> against one another. The vector sum may very well be preserved at
>> the spot of impact and for a very brief moment thereafter
>> (ie. instantaneous) but the non-rigidity, I think, would cause
>> the 'parts' to behave in a somewhat more complex manner than
>> simple conservation of momentum. I'm recalling seeing many
>> simulations of fluid dynamics, turbulence and flames, etc. Very
>> hard problems, those...

> In the end, there are only two ways for the kinetic energy to
> express its self in this context: As motion, or as heat.  However,
> if a significant portion was expressed as heat, we could pretty
> much count on all bullet wounds being self-cauterizing.  Even if
> the energy created turbulence, only the portion that became heat
> would not express itself as motion of the target.

> As it happens, one of the measures for firearms is good
> old-fashioned newtonian foot-pounds.  The hardest hitting
> commercially available modern rifle in the world (the .458
> Remington) generates just short of two thousand foot-pounds at the
> muzzle.  This would be enough to knock a human off their feet if
> they weren't braced for it, but it wouldn't knock you back in your
> tracks.  No handgun generates more than 400 foot-pounds (the .454
> Kasull Magnum, which has been known to break wrists).

> Basicly, energy at the gun must be at *least* equal to energy at
> the target (plus any losses for air drag), any weapon that could
> genuinely knock over a person through sheer force would require a
> tripod mount.  The closest to "man portable" in this category is
> the .50 BMG sniper rifle (based on the same round as a WW2
> anti-air heavy machine gun).  It can only be fired from a prone
> bipod position, or a tripod rest.

> You *could* build a crossbow with that kind of force, and
> historically it was done.  But you couldn't carry it with anything
> short of a large wagon and a 4 horse team.

I have just found this site and topic. It contains some grave
errors.

a) 458 Remington is a rifle, not a cartridge. It does not matter
from which rifle a certain cartrige is fired. You probably referr to
the 458 Winchester cartridge. However, the 458 Win.Mag is rather
mild in comparison to the 460 Weatherby or others.

b) the energy of the bullet and the rifle differ greatly. However,
the momentum of the bullet and the recoiling rifle are almost
identical. The rifle recoil momentum is higher, because the rocket
effect of the gasses exiting the muzzle with up to 6000m/s

Ballistics is very precise science which is not understood by
amateurs.

Author of the book SMALL ARMS SHOOTING AND BALLISTICS W.A.Hundt
(that is me)
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