Re: "Conventional" missiles for T:TNE

Bertil Jonell [email removed] writes:
> [assumptions about missiles]

These seem reasonable.

>   I think we should divide it into four types instead of three.

That sounds good, too.  But I'm going to argue that Cannister missiles
should be in category three (short-range shrapnel missiles).  The levels
of difficulty seem about right, too.  One more thing: in category four,
we should probably add "smart rocks": an "impact only" missile with no
warhead; damage by kinetic energy of impact.

>   I assume that types 3 and 4 include some kind of end phase autonomous
> guidance (and a proximity fuse for type 3). Apart from this I agree with your
> rules on final burn fuel.

I was assuming that the exact type and capability of the terminal
guidance would make a big difference in the effectiveness of the
missile.  But you have a good point; the basics are covered under the
FIM/SIM rules.  The sensor/guidance system types should be optional
rules.

>   BTW: Having some professional experience with missiles, IMHO the best
> guidance model is the Track Via Missile guidance. It is basically a
> combination of the best features of FIM and SIM.

I'm partial to inertial with terminal active radar homing (and of
course, the bearing only launch option).  The USN Harpoon is a good
example of what I mean.

>   In traveller terms, I'd describe it as a FIM that uses the best of gunners
> skill and onboard skill as long as it is in communication with the firing
> ship during the final round. Normal restrictions on number of simultaneously
> controlled missiles apply during this round.

That sounds reasonable; and the same rules can apply to any type of FIM
missile that has a command reciever as well.  One more thing I can think
of, though.  T:TNE assumes a tightbeam command link (laser); if the
missile ever goes fully independent (the command limk is cut off for
whatever reason), you can't re-acquire the missile --- it stays in FIM
mode because you no longer have accurate pointing data your laser.

> But the shock could travel on through the hull and affect all areas
> to a lesser degree.

That's what I was thinking.  1H for those areas that absorbed X-ray
energy directly, and 1h for those areas that were subject to the
concussion transmitted through the ship.

>   To achieve 3.5 hits against a 100m3 target, there has to be one sphere per
> 30m3. The radius of the cloud at impact will thus be 400m. To achieve a spread
> of 400m at a closing velocity of 1 to 30 (60,000km/h to 1,800,000km/h) and
> a range of 30,000 km (one range band) requires a radial velocity of 0.2m/s to
> 6m/s.
>   So I persist that the 'detonation' range of the cannister round can be the
> same as for the xray missile:)

I persist in insisting that it's practically impossible.  You are
putting the detination at 30,000km from the target; anywhere from anout
a minute to nearly thirty minutes between detonation and impact.  But
you can no longer guide that cloud of pellets after detonation.
Assuming the worst case, the target has only to move 400m in that minute
in order to be 100% safe; this works out to slightly under 0.25g --- for
slower approach velocities, the neccessicary accelleration is even less.
So even minor "jinking" by the target can throw off the aim of the
cannister shot; the maneuver expenditure is relatively minor, so ships
could afford to jump around this way even if they didn't detect a
missile closing on them.

On the other hand, detonating one of these at a kilometer or so away
gives the target less than 0.005 second to respond; getting an assumed
50m diameter ship out of the path of the fragments would require
thousands of Gs of accelleration.

> (Although I think a variable rate gas generator
> might be more appropriate than a charge, since the rate of dispersion has to
> vary with the closing velocity).

No; fire the bursting charge based on estimated time to impact, so that
the fragments always have the same amount of time to disperse.

> > From an "Impact" hit, all of these fragments
> > would go into one or two hit locations, with pretty severe results.
>
>   Perhaps too severe for game balance. The effect of one 10mm tungsten sphere
> at 16km/second (closure velocity of 1) is 2-30 if I write it in the same
> form as the laser damage. Imagine a 7 ton missile...

But hitting the target is pretty hard, as we have both pointed out.
Cannister rounds detonated at tens of thousands of km provide the target
with far too much time to get out of the way.

A couple of other points which have occurred to me: the missiles use a
laser link for communications to the firing ship.  A cannister of
anti-laser "sand" placed at just the right spot should do wonders to
break this link; and once lost, it should be nearly impossible to
re-establish.  I'd treat it as firing the sandcaster at the missile; a
hit breaks the link, the results of which depend on the type of guidance
the missile has.

Managing to intercept the target and go for a proximity or impact hit
should be considerably easier if you are quite close to the target.
Like in the same range band with it.  Does T:TNE already have a modifier
for this? (if not, there probably should be one for <1 range band and >5
range bands for proximity and impact missiles).

>   I'll post a message with tenative designs for HE, HEAT, Cannister, SFF and
> LGB missiles as soon as I've typed them in.

Aside from the gotcha with cannister, I've seen these and like them.


[email removed]
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