Re: Plasma Trails, Missiles, and Relativity

Date: Fri, 25 Aug 1995 13:48:02 -0500 (CDT)
From: jlockett@hanszen.rice.edu (Joseph L Lockett)
Subject: Re: Plasma Trails, Missiles, and Relativity

>   8) Re: Plasma Trails, Missiles, and Relativity
> 	by merrick@Rt66.com (Merrick Burkhardt)
>
> > I suspect this, along with thermal radiation from those huge fusion
> > plants, is exactly what is used in the "lock-on" from Brilliant Lances
> > et alia.  This doesn't help for contact missiles (which it sounds like
> > some people are re-proposing), since Traveller lasers are such awesome
> > point-defense weapons in interplanetary space. 
> 
> Huh?  This would *help* KE missiles.  They can use passive homing, and since
> they're small, you might not ever know you're locked on.  Remember that 
> missiles (for the most part) don't use fusion drives of any sort, they're
> chemical rockets.  And lasers aren't very good since using the sensor rules 
> you'd never even see them :) (in BL, anyway)

There is _no_way_, at canonical Traveller distances and speeds, that missiles
will be able to use normal, impact-capable chemical rockets, unless they're
the size of Saturn V's.  The speeds and vectors involved, the precise
targeting adjustments needed to reach and strike a ship, are horrendous.
Try the math involved: you'll find the same result GDW did.  When they made
space combat ranges as long as they "ought" to be, they simultaneously forced
themselves into invoking "gravitic focussing" to make lasers practical, and
sounded the death-knell for conventional impact missiles.  Instead, missiles
should be more like 2300 AD's unmanned drones, built and equipped exactly like
small craft except for the lack of crew.

Note that I've never designed a Traveller missile.  Looking up the relevant 
info, I find that FFS, on p. 146, confirms that "most space missiles use
EAPlaC solid-fuel thrusters", defined on FFS p. 70 defined as "Electrothermal 
Augmented Plasma Combustion" (as opposed to HEPlaR's "High-Efficiency Plasma
Recombustion", which we know does not "combust" using oxygen -- a misnomer?)
I'd warrant that EAPlaC's are closer to fusion rockets (which share their tech
level) or HEPlaR's than the earlier, pure chemical rockets: they'd use a high-
energy power source (fission or fusion) to heat and expel reaction mass,
something like the Nerva rockets the US experimented with briefly.

Whatever the propulsion method, if it involves "plasma" then your exhaust
is going to have the same problems as those we've discussed for larger craft.
Given the grotesque ranges and efficiencies given to lasers, the target has
plenty of time to shoot a contact missile full of holes before it reaches
him.  The far more practical solution is to use the same advantage against
him, and design a missile to sneak up to within a BL hex or more (a far
simpler task than nosing right up to the hull!) and destroy itself to pump
a detonation laser: as the canonical TNE material describes.

Impact missiles are dead, dead, dead.  :-) 

----------------------------*-------------------------*-----------------------
Joseph L. "Chepe" Lockett   | "Nullum magnum ingenium | GURPS fan, Amiga user,
jlockett@hanszen.rice.edu   |  sine mixtura dementiae | Shakespearean scholar,
http://www.io.com/~jlockett |  fuit." -- Seneca       | actor and director.
----------------------------*-------------------------*-----------------------

Date: Sat, 26 Aug 1995 13:30:29 GMT
From: "Brendan O'Donovan" <Brendan@odonovan.demon.co.uk>
Subject: Re: Missiles

:From the message dated Friday 25, August 1995 :

> Impact missiles are dead, dead, dead.  :-) 

Impact missiles are sick and bedridden in standard combat, but you could make a 
useable one for some situations -

Traders, and battleship fleets on transit, not expecting combat, would usually 
make insystem burns in a very straight, predictable manner, so as to keep the 
transit time as low as possible, and the fuel expenditure likewise as low as 
possible. An undetected ship could launch a missile from a very long way off, 
which could accelerate to get a reasonable velocity for impact and interception 
purposes, and then shut down its engines. It could then raise a miniature black 
globe (you'd need to expand the table in defensive systems to include some much 
smaller generators), and providing it was small enough, the sensor task to 
detect it could be subject to +6 or so difficulty modifiers. This would mean 
that there would be simply no way for a ship to see this missile and avoid it at 
any range (You may want to allow some chance to see it at very close range, but 
only enough to shoot it down, not to move out of the way) . However, the missile 
wouldn't be able to maneuver, so this would only work if the position and path 
of the target was known exactly, so the tactical uses of the missile would be 
limited, but still significant. It could be used against:

Orbiting space platforms
Ships in predictable transit
Ships in a fixed air/space traffic control holding pattern
Ships linked to ships allied to the missile craft and so not thrusting
   - Adventure Idea: RCES stretch clipper docks with smallish Guild vessel for 
diplomatic talks. The clipper is destroyed, while other ships from both sides 
look on. Initially a third party should be suspected - no guild personnel had 
left their ship, so explosives could not have been planted, none of the guild 
vessels (appeared to) fire any weapons. Characters could get involved in 
detective work with the sensor logs, on the guild vessels (finding fire control 
solutions but no firing records, coded mesages and transmissions to the asteroid 
belt nearby). Clues from this lead the players to a missle silo hidden in an 
asteroid. Once the guild is found out they have a fight on their hands, but if 
they win they can at least capture the technology and return it to the RCES. 
There it will be examined, and changes to operating procedures could be made, 
introducing randomness into the RCES craft's maneuver patterns to protect 
against missile attacks.

This missile can only really be used once against an enemy (once they have 
identified what hit them, and if they survive to spread word), as it is simple 
to defend against once it is known about. For this reason I haven't actually 
designed one, just use it as a plot device.

Some merchant ships don't have any lasers at all, so you could use homing KKMs 
against them. - Anyone want to design a 5MJ socket laser to sell to the traders?

> ----------------------------*-------------------------*-----------------------
> Joseph L. "Chepe" Lockett   | "Nullum magnum ingenium | GURPS fan, Amiga user,
> jlockett@hanszen.rice.edu   |  sine mixtura dementiae | Shakespearean scholar,
> http://www.io.com/~jlockett |  fuit." -- Seneca       | actor and director.
> ----------------------------*-------------------------*-----------------------
> 

-- 
Brendan 

------------------------------

Date: Sat, 26 Aug 1995 12:07:21 -0600 (MDT)
From: merrick@Rt66.com (Merrick Burkhardt)
Subject: Re: Plasma Trails, Missiles, and Relativity

Hi,
 
> > 
> > Huh?  This would *help* KE missiles.  They can use passive homing, and since
> > they're small, you might not ever know you're locked on.  Remember that 
> > missiles (for the most part) don't use fusion drives of any sort, they're
> > chemical rockets.  And lasers aren't very good since using the sensor rules 
> > you'd never even see them :) (in BL, anyway)
> 
> There is _no_way_, at canonical Traveller distances and speeds, that missiles
> will be able to use normal, impact-capable chemical rockets, unless they're
> the size of Saturn V's.  The speeds and vectors involved, the precise
> targeting adjustments needed to reach and strike a ship, are horrendous.

True, unless you're dealing in traveller canon, not reality...  frequently 2
different things, but we're gaming in traveller, not reality :)

> Try the math involved: you'll find the same result GDW did.  When they made

The assertion that GDW did the math on anything seems far-fetched to me... 
they can't even be bothered with play-testing, much less math.

> space combat ranges as long as they "ought" to be, they simultaneously forced
> themselves into invoking "gravitic focussing" to make lasers practical, and
> sounded the death-knell for conventional impact missiles.  Instead, missiles
> should be more like 2300 AD's unmanned drones, built and equipped exactly like
> small craft except for the lack of crew.

True, but that just changes how they get to the target, not what they do when
they get there.
 
> Note that I've never designed a Traveller missile.  Looking up the relevant 
> info, I find that FFS, on p. 146, confirms that "most space missiles use
> EAPlaC solid-fuel thrusters", defined on FFS p. 70 defined as "Electrothermal 
> Augmented Plasma Combustion" (as opposed to HEPlaR's "High-Efficiency Plasma
> Recombustion", which we know does not "combust" using oxygen -- a misnomer?)
> I'd warrant that EAPlaC's are closer to fusion rockets (which share their tech
> level) or HEPlaR's than the earlier, pure chemical rockets: they'd use a high-
> energy power source (fission or fusion) to heat and expel reaction mass,
> something like the Nerva rockets the US experimented with briefly.

Agreed, they're all crazy propulsion systems.  HEPlaR is a fusion Nerva far as
I can tell.  If you do the math on HEPlaR, it has to be what FFS calls a
"fusion rocket" regardless (just to give the exhaust the KE it has) :-)
 
> Whatever the propulsion method, if it involves "plasma" then your exhaust
> is going to have the same problems as those we've discussed for larger craft.

OK, so missiles sigs are higher regardless of type.  If you fix that, then you
might even be able to get a lock on most of them (assuming they don't coast 
into your hex, *then* light up at 12gs when it's too late for you to do much.

> Given the grotesque ranges and efficiencies given to lasers, the target has
> plenty of time to shoot a contact missile full of holes before it reaches
> him. 

But you have an absolute limit on the number of shots you can fire in the
canon of TNE (800).  And 5% of tasks *always* fail.  The TNE (and the real, what
a surprise they match :) universe is an uncertain place.

> The far more practical solution is to use the same advantage against
> him, and design a missile to sneak up to within a BL hex or more (a far
> simpler task than nosing right up to the hull!) and destroy itself to pump
> a detonation laser: as the canonical TNE material describes.

Try to kill the 15,000 missiles a Tigress could launch using BL.  Hell try
locking on a single missle in BL.  Canon TNE on this is garbage.  If you can't
have contact missiles because it's impossible to miss them, then why is it that
you can't even *lock* them a reasonable fraction of the time.  At what point
does the "sneak up within a BL hex" end, and the "it's impossible not to 
detect, lock, and shoot down an infinite number of missiles with one, or even
*no* directed energy weapons" begin?

> 
> Impact missiles are dead, dead, dead.  :-) 
 
Nope.  I'll grant that missiles might have bigger signatures due to high-
energy exhaust, but as it stands you can't hit 'em in the rules too well (and
the rules *are* canon).  Also, det laser missiles go off in the same hex for
the most part.  The less than 3 minutes it takes your 12g missile to get to the
middle of the hex is 10 shots at a ROF of 100.  How does your laser shoot 100 
missiles down when 5% will always miss (task=easy)?  What about my free trader
that just had its laser shot off by that pirate?  What about that dead maneuver
drive on the Patrol Cruiser?  Dead powerplant, too.  How does it shoot down the
easy to kill contact missile?  Oh yeah, my sensors got toasted 15 minutes ago,
how do I see the missile?

Besides, what if the target isn't eavading?  At the point when a det laser would
fire, the contact missile spreads a big cloud of nasty pellets that will cross
the certain path of the target with X pellets per kiloliter (this would be
fractional, for sure) such that more or less for every 100tons of target 
displacement there would be 1 pellet.  You'd have the same chance to shoot it
down that you do for a det-laser.  Now you have 10E6 targets smaller than your
beam cross section (laser).  Hell, how do you *see* them?  If you do how do you 
kill them?

Given that contact missiles would, and should work (under the conditions that
*no* defense is perfect, especially one that doesn't exist), I agree that the
plasma coming out the back-end would make lock-on easier (or at the least
a bogey detection).  

-Merrick