The warships are dead...

A thread of 3 messages, 2 June 1993 to 3 June 1993, in the order they were sent.

#5532 The warships are dead...

  ...Long live the Missileboats?

> It may be.  If so, we should chuck the HE and HEAP missiles in favor of
> a KEAP missile (cheaper, and lighter too!).  Could you work out this and
> the nuclear missiles we discussed earlier

  I think there are things to discuss wrgt the KEAP missiles still. Regarding
nukes I am 25% of the way through 'The Effects of Nuclear Weapons' and I'll
have to do som wild guesses in any case (mostly with regards to how damage in
TNE relates to damage in Real Life) so it might take a little time too.

  (A NPC have 50% chance of dying after 10D of concussion damage. Since this
very aproximately equals 65 PSI (but it is different with conventional
weapons) so each die can be assumed to be 6.5 PSI)

> (I *still* haven't gotten back
> to that section in T:TNE --- I've been reading through it carefully, and
> spending far too much time posting on the net:).  Then I'll pull it all
> together so that we have everything in one place.

  I've looked on the kinetic energies of 200kg (100kg electronics etc and 100kg
structural members of the burned out engine. I assume a solid fuel engine
here but I have a few ideas on how to make a solid fuel rocket maneuverable)
moving at from 1 to 30 range bands(1). But remember that this is less than
half the normal payload, so this type of missile should get aprox 20 Gturns.

 (1) It would be really nice to know the 'typical closing velocity', but we
     don't have that data yet. If someone runs a space combat with missiles,
     please please note their closing velocity and post it to the TML.

  The kinetic energy varies between 2.8e10 J and 2.5e13J which is the same
as 0.006 to 6 kilotons. Redone into kg of TNT and via the demolition rules
into penetration means 705 to 21,000 or 30 to 900 major hits worth. This is
well above the damage of either the HE or HEAP, even at velocity 1. Definite
shipkiller size, since you only need 200 in remaining penetration after armour
to inflict a critical hit on a ship of any size.


  Based on the classic studies of optimum ship design done for TCS, I suspect
that missiles this effective will totally transform the game. Any price of
warship can be matched by an equal tonnage of cheaper missile craft (100T 6G
J1, 1 missile turret) that has a good chanse of getting in a few hits and the
warship is history.

  This would be a retcon even more major than those jumpbarges we discussed
just before the pocket mailing list started.


  Do we want this? And if we don't, how do we explain it away? One big grey
area is how a heavy object of low density behaves when it collides with a
very dense material. It is also debatable wether energy translates directly
into penetration.

  Using Richard Ogorkiewicz 'Technology of Tanks' as a source on how things
behave when they collide at high speeds I have two guesses: The first is that
the penetration goes up with speed, but it doesn't increase much with speeds
over 5km/s. Since velocity 1 is 16km/s, we are well into the flat part of
the curve in all cases. Since the equations for penetrators approach the
equations for shaped charge jets we can assume that the missile is a shaped
charge jet and use those simpler equations:)
  The maximum penetration is thus:

		     Density of jet
  Length of jet * ( -----------------) ^ 0.5
		    Density of target

  Using the density of the missiles engine (the electronics package is
denser but it is too short) which I assume to be 0,014, the length of the
missile (7m) and the density of the hull (7 for steel, this is a best
case penetration caculation) the maximum penetration is 318mm aka Pen 63.
It won't penetrate an SDB!! (sorry, PDB:)

  That is good news, since that is aproximately the same total penetration
as the HE missile and *less* than the HEAP missile. So they will still have
a place, and the KEAP missile will not be the ultimate shipkiller.

  (I suspect the excess energy goes into transforming the missile and those
300mm of hull into plasma. I don't have any data on the energy needed to
transform various metals into plasma so it is only a guess)

  (Yes, I know we can put a 7m depleted uranium penetrator in the center of the
missile and it will penetrate 11m of armour steel if it gets a closing velocity
of 4 or more. I think the question is if we want the missile boat to rule or
not. If we do we mention the KEAPDU missile, otherwise we ignore it.)

> True, but blocking the missile's commo link with sand *has* to be easier
> than taking out the missile with anti-missile laser fire.

  The laser fire is speed of light, the sand is slower.

> >   Ok, perhaps. But not more than -1 difficulty.
>
> You are probably right; I haven't read the complete combat rules yet.
> 25% is a high enough chance; I was afraid that it would be less than
> that.

  Evasion will make it smaller (to 12% or smaller, assuming skill 5 and stat 5
of the firing character). And it is possible that having a MFD might increase
it to up to 95%.

> >   Cluster warheads are also a possibility but the anti-ship effect of those
> > would be inferior to cannister IMHO.
>
> On the other hand, they could be very useful for a planetary attack
> missile.  How about a series of missiles with re-entry heat-shields and
> HE, HEAP, CBM, and nuclear (and probably thermonuclear) warheads?

  Why missiles? It would be cheaper to use the 'LGB preudomissile' model
and fill the empty shell with guided bombs of different kinds. 7000kg of
TL-13 'Rockeyes' will impress almost anyone.

  (Correction: I started to think about the weights and densities of bombs,
and a 1000kg bomb will probably only displace around 0.3m3, so both the
heatshield and non-heatshield LGB pseudomissile should contain 6 1000kg
bombs: That the weight has to conform to the normal missile is the limiting
factor, not space).

> Other possibilities: a cheap, light-weight missile with (say) about 7
> G-turns of fuel and warhead, shorter endurance, etc.

  Remember that a 6G ships has a 12 Gturns per turn capability. To reach it
you need a missile that has more.

> Designed
> to be launched from fighters at close range (in the same range band).
> These can probably get by with a much simpler guidance system
> (laser-designated target?).  Although the lower cost is nice, the real
> goal is a smaller, lighter missile, so that a fighter could have 2 or 4
> on launch rails.

  Or make them short but of the same diameter as normal missiles so that
several can be stacked in a normal launch tube and launched one at the time.

> Other ideas:
> 	The T:TNE equivalent of a phalanx gun: installed in a turret
> hardpoint, this is a small, rapid-fire laser (or gatling laser).  It has
> it's own sensor, and fires at anything that comes near.  It can operate
> in FIM (Fully-Independent Mode) or SIM, just like a missile.  Intended
> to be a defense against proximity and impact missiles, its damage and
> penetration aren't much, but effective against missiles out to about
> 100km.
> 	Sensor drone: the same general size and shape as a standard
> missile, but the "warhead" is the best sensor system that can be crammed
> into the available space (probably with a folding array).  Communicates
> sensor data back to the mother ship.  Recoverable/reusable.

  I'll look on this later. We'd probably need the Techbook and Shipdesign
book to do them correctly, though.

> [email removed]

- -bertil-
- --
"It can be shown that for any nutty theory, beyond-the-fringe political view or
 strange religion there exists a proponent on the Net. The proof is left as an
 exercise for your kill-file."

#5541 T:TNE Space Combat Fix and more on missiles

Bertil Jonell [email removed] writes:
> The kinetic energy varies between 2.8e10 J and 2.5e13J which is the same
> as 0.006 to 6 kilotons. Redone into kg of TNT and via the demolition rules
> into penetration means 705 to 21,000 or 30 to 900 major hits worth. This is

 ... way too much.  Probably the kinetic energy of impact doesn't convert
readily into explosion damage, and so the demolition rules are producing
funny numbers.

>   Do we want this? And if we don't, how do we explain it away?

I don't think we want this, and it seems that you've managed to explain
it away pretty effectively below ...

> this is a best
> case penetration caculation) the maximum penetration is 318mm aka Pen 63.
> It won't penetrate an SDB!! (sorry, PDB:)

That's much better!  Lethal to unarmored ships, but a warship with
enough armor doesn't have to worry as much (and as you point out, it
leaves a place for the HEAP missile).

HEAP missiles can reasonably be restricted-purchase items (since the
only thing they are really good for is shooting at military-type ships).

> I think the question is if we want the missile boat to rule or
> not. If we do we mention the KEAPDU missile, otherwise we ignore it.

My feeling is that we keep very hush-hush about the KEAPDU missile;
after all, it may not even be practical (how much does that slug of
depleted uranium weigh, after all).

>   Evasion will make it smaller (to 12% or smaller, assuming skill 5 and stat 5
> of the firing character). And it is possible that having a MFD might increase
> it to up to 95%.

95% seems a little too high ... maybe we should work out some way that a
MFD has less (or no) effect on these new missiles.  Or maybe increase
the difficulty of impact and close-proximity so thatyou *have* to have a
MFD to have any reasonable chance of hitting with them.  What do you
think?

>   Why missiles? It would be cheaper to use the 'LGB preudomissile' model
> and fill the empty shell with guided bombs of different kinds. 7000kg of
> TL-13 'Rockeyes' will impress almost anyone.

Good point.  That's enough to ruin almost any TED's day.

> > Other possibilities: a cheap, light-weight missile with (say) about 7
> > G-turns of fuel and warhead, shorter endurance, etc.
>
>   Remember that a 6G ships has a 12 Gturns per turn capability. To reach it
> you need a missile that has more.

Ummm, I don't see that bit anywhere; but I do see on pp.313 "Each ship
may spend a number of G-turns limited by its G rating (maneuver
performance)" --- so I concluded that a 6 G ship has 6 Gturns of combat
maneuver capability.  Each Gturn of combat maneuver burns a half of a
G-Hour of maneuver fuel (because each turn is a half an hour).

I also see a potential problem with the space combat rules.  On pp.313
it says "each 2 Gturns of accelleration spent by a ship changes the
closing velocity for the current turn by one".  However, by referring to
good old Sir Isaac:

Accelleration = Constant             A = 10 m/s^2
Velocity = Acelleration * Time       V = 10 m/s^2 * 30 m
                                       = 10 m/2^2 * 1800 s = 18000 m/s
                                                           = 64800 km/hr
Distance = 0.5 * Accell * Time ^ 2   D = 0.5 * 10 m/s^2 * 1800^2 s^2
                                       = 5 m/2^2 * 3240000 s^2
                                       = 16200000 m = 16200 km

Putting this into T:TNE terms, a velocity of 1 is one range band per
combat turn (or 30000km per 30 mins; 60000 km/hr).  A distance of 1 is
one range band (or 30000km), and the unit of time is the turn (30
minutes; 1800 s).

SO, each Gturn of accelleration increases the ship's velocity *for next
turn* by slightly over 1 band/turn.  The distance travelled in the
*current turn* during this accelleration is slightly more than a half a
range band per Gturn of accelleration expended.


FIX: alter the "Speed Change" and "Compute New Range" paragraphs on
pp.313-314 to read as follows:
	SPEED CHANGE: Each ship may spend a number of Gturns limited by
its G rating (maneuver performance) in order to modify the closing
velocity.  Each Gturn of accelleration spent by a ship changes the closing
velocity *for the next turn* by one.  In addition, each 2 Gturns of
accelleration spent changes the closing velocity *for the current turn*
by one (drop fractions).  The closing velocity may be increased or
decreased.  As Gturns of accelleration are spent, players must
declare whether they are going to increase or decrease the closing
velocity.
	COMPUTE NEW RANGE: At the end of each turn, subtract the current
closing velocity (the velocity *for this turn* as computed above) from
the current range to get the new range for the next turn.  When the
closing velocity is a negative number, remember that subtracting a
negative number is the same as adding a positive number, thus actually
increasing the range.

ALTERNATE FIX: the above, while accurate, may seem too complicated for
some players.  Thus, the suggested simplified fix: alter the "Speed
Change" and "Compute New Range" paragraphs on pp.313-314 to read:
	SPEED CHANGE: Each ship may spend a number of Gturns limited by
its G rating (maneuver performance) in order th modify the closing
velocity.  Each Gturn of accelleration spent by a ship changes the
closing velocity *for the next turn* by one.  The closing velocity may
be increased or decreased.  As Gturns of accelleration are spent,
players must declare whether they are going to increase or decrease the
closing velocity.
	COMPUTE NEW RANGE: At the end of each turn, subtract the current
closing velocity (before the speed changes above) from the current range
to get the new range for the next turn.  When the closing velocity is a
negative number, remember that subtracting anegative number is the same
as adding a positive number, thus actually increasing the range.


EXAMPLES: To help clarify what's going on, the following examples
presime that a standard Scout/Courier (maneuver performance 2 G) is
closing in at velocity 4 on a patrol ship which is station-keeping 8
range bands away.  The scoutship wants to break to a stop as quickly as
possible.

NEWTON: A = 20 m/s^2.  240000 km/hr = 66667 m/s = 20 m/s^2 * T s.  Time
to decellerate to a stop is T = 3333 s = 55.6 min, or about 2 turns.
Distance travelled while stopping is D = 0.5 * A * T^2 = 111111 km, or
about 3.7 range bands.  The ship is stopped at the end of the second
turn, slightly more than 4 range bands from the patrol ship.

ORIGINAL: In the first turn, the scout/courier expends 2Gturns of
accelleration (at a cost of 1 Ghour of fuel).  Velocity changes by 1;
the new velocity is 3, and the new range is 5.  In the second turn, the
scout continues brakeing; new velocity 2, new range 3.  Turn 3: velocity
1, range 2.  Turn 4: the scout comes to a stop at a range of 2.

FIX: In the first turn, the scout expends 2 Gturns of accelleration (at
a cost of 1 Ghour of fuel).  Current velocity is decreases by 1 (to 3);
and the next turn's velocity decreases by 2 (to 2).  The new range is 5.
In the second turn, current velocity becomes 1, and the new velocity
decreases to 0 (the ship will stop at the end of the turn).  The new
range is 4.

ALTERNATE FIX: In the first turn, the scout expends 2 Gturns of
accelleration (at a cost of 1 Ghour of fuel).  Current velocity is
unchanged (still 4), and the next turn's velocity decreases by 2 (to 2).
The new range is 6.  In the second turn, the current velocity is 2, the
new velocity is 0, and the range is 4.


[email removed]
- --------------------------------------------------------------------------
                                                 Science-Fiction Adventure
                                                            in the New Era

#5543 Re: T:TNE Space Combat Fix and more on missiles

> > this is a best
> > case penetration caculation) the maximum penetration is 318mm aka Pen 63.
> > It won't penetrate an SDB!! (sorry, PDB:)
>
> That's much better!  Lethal to unarmored ships, but a warship with
> enough armor doesn't have to worry as much (and as you point out, it
> leaves a place for the HEAP missile).

  I should practice better dispositions, really. I forgot to note that the
'penetration is dependent on the densities' was way #2 to reduce the
penetration. And I also forgot to include the limiting effect of those 5km/s
I was talking about.

  Using both, the damage of a KEAP will be 3-200, which means that it will
be rated like this compared to HE and HEAP:

  Damage to thin armour	Damage to thick armour	Surface targets
  	HEAP			HEAP			HE
  	KEAP			KEAP			HEAP
  	HE			HE			KEAP

  So there might be a niche for the HE as a cheap multipurpose missile (while
the SFF is a better but more expensive multipurpose).

> HEAP missiles can reasonably be restricted-purchase items (since the
> only thing they are really good for is shooting at military-type ships).

  Possibly.

> > I think the question is if we want the missile boat to rule or
> > not. If we do we mention the KEAPDU missile, otherwise we ignore it.
>
> My feeling is that we keep very hush-hush about the KEAPDU missile;
> after all, it may not even be practical (how much does that slug of
> depleted uranium weigh, after all).

  Using a DU penetrator with a slenderness of 1:100 (normal today is 1:20)
around 400kg, but that slenderness might be physically impossible (too slender
and it will break instead of penetrating). With a slenderness of 1:20...
twelve tons.
  Yes, this might make a good excuse.


  BTW: I think the Cannister and SFF missiles should be modified since their
max damage is dependent on the penetration and it is limited in the same ways
as that of the KEAP missile.
  (2-50 at all speeds for the Cannister and 3-110 for the SFF since it has
larger fragments. It is probably possible to design it to reach these levels,
but the number of fragments might have to be reduced).

>>  Evasion will make it smaller (to 12% or smaller, assuming skill 5 and stat 5
>> of the firing character). And it is possible that having a MFD might increase
>> it to up to 95%.
>
> 95% seems a little too high ... maybe we should work out some way that a
> MFD has less (or no) effect on these new missiles.  Or maybe increase
> the difficulty of impact and close-proximity so thatyou *have* to have a
> MFD to have any reasonable chance of hitting with them.  What do you
> think?

  I think restricting MFD's to military ships is a better option. I'm reminded
of the old starship combat discussion where I wanted there to be a major
difference between military and civilian ships, and the MFD could be a way
of doing this.

> Ummm, I don't see that bit anywhere; but I do see on pp.313 "Each ship
> may spend a number of G-turns limited by its G rating (maneuver
> performance)"

  Argh! I misinterpreted the 'Friendly Velocity' formula on page 324.

> [email removed]

- -bertil-
- --
"It can be shown that for any nutty theory, beyond-the-fringe political view or
 strange religion there exists a proponent on the Net. The proof is left as an
 exercise for your kill-file."