Re: Just how low IS low recoil?

Mark F. Cook [email removed]
> In TML note 1856, Adrian Hurt [email removed] writes:
> >
> > Time for some number crunching.  First, a correction to the above.  It's
> > momentum, not energy, that Newton's 3rd law deals with.
>
> You're picking nits, Adrian.  Assume the following symbols:
>         m = mass of the gauss needle
>         a = acceleration of the needle at the barrel mouth
>         M = mass of the gauss rifle
>         A = acceleration of the rifle in the opposite direction
	v = velocity of the gauss needle
	V = velocity of the rifle
> If ma=F->, then MA=<-F, right?  By definition, "Momentum" is the magnitude
> of F, without the vector component (staight out of Halliday & Resnick's
> "Fundanemtals of Physics").

Either you've misread "Fundamentals of Physics", or Halliday & Resnick are
wrong, or the universe has changed since I learnt physics.  Momentum is a
vector.  That's how momentum is conserved.  Before firing, momentum of rifle
= momentum of needle = 0.  After firing, momentum of rifle = MV, momentum of
needle = mv, MV = -mv, so MV + mv = 0.

Force is also a vector.  It's rate of change of momentum.  If MV = -mv at any
time up to when the needle leaves the barrel, and MV and mv have had the same
amount of time in which to change, then F = -f.

> >                                                          Figures for
> > Traveller assault rifle and gauss rifle come from Book 4; figures for M-16
> > assault rifle come from "The Armory" by Kevin Dockery, in brackets in the
> > assault rifle part for comparison.

(Lots of figures deleted; you've seen them twice before, and they've served
their purpose.)

> These values are slightly off (you've listed the UNLOADED wt. of the M-16
> and the slug velocity is a little low for a std. DoD issue M193 ball round),
> but I accept your point.

Those values were taken straight from the book, and the weight I quoted was
for a M-16 with a 30-round magazine.  Don't blame me if Kevin Dockery got
them wrong; give us the right figures!

> > =>    A gauss rifle is no more a low recoil weapon than an assault rifle.
>
> Let's qualify that: it's no more low recoil that a 5.56mm assault rifle.
> I don't argue this, ever.  The flaw in your argument is assuming that the
> 5.56mm assault rifle IS NOT ALSO A LOW RECOIL WEAPON.

So in TDR, put gauss rifles and 5mm assault rifles in the same recoil class.

> If compare the M-16 to a "real" assault rifle (my definition of "real";
> you're mileage may vary), like the 7.62mm ARM/AR Galil, there's a noticable
> difference.
> ...
>         Velocity of rifle = 2.04 m/s
> This is about 130% that of the gauss rifle and the MT Player's Manual refers
> to this type of weapon as "Med. Recoil" (see the entry "Assault Rifle (7mm)
> on pg. 76).
>
> Let's compare the momentum of the 5.56mm slug to a different, but popular,
> American round: the std. .22 Long Rifle round.
> ...
>         Velocity of rifle = 0.5 m/s.
> Now, that's only about 37% of the M-16, and about 33% of the gauss rifle.
> (I guess that makes it a "No Recoil" weapon.) :-)
> ...
>		      The 5.56mm M-16 is about in the middle, as is the
> gauss rifle (although tending slightly towards the higher end).  This
> pretty definitely puts both of them in the "Low Recoil" catagory, at
> least by MT combat standards.

So, 5mm assault rifles and gauss rifles are low recoil; 7mm assault rifles
are medium recoil; 5mm pistols are very low recoil.  If anyone is really
interested, I'll do similar sums for 9mm pistols, 7mm bolt-action rifles,
and SMG's.

> One last point, the MT Imperial Encyclopedia (pg. 71) states that standard
> equipment for the gauss rifle includes gyrostabilization.  If that addition
> doesn't make it "Low Recoil", then I don't know what does.

Doesn't the ACR also have that?  Is the ACR also low recoil?

- - --
 "Keyboard?  How quaint!" - M. Scott

 Adrian Hurt			     |	JANET:  [email removed]
 UUCP: ..!ukc!cs.hw.ac.uk!adrian     |  ARPA:   [email removed]