Re: Orion Drive space battle

Random browser glitch occured, so fingers crossed this won't be a
double-post.

I wasn't thinking of it in terms of realism, but in terms of
distracting the viewer with instantly noticeable "oddness".
It's not like the viewer is going to have any difficulty
understanding the notion of a hypothetical camera in
the middle of nowhere. It's just that it's something he
can't help notice on a conscious level. It's a distraction
that I don't think offers a useful benefit.

In Moore's Battlestar Galactica, Moore initially went
overboard with the "gritty realistic shake-cam" look.
Some time between the making of the pilot miniseries
and the start of season one production, he decided
to scale it back. IMHO, the production was improved
for it.

I'd say this is more of a personal preference for how things are
displayed. What I plan to do is have most of the shots as "Gods-eye"
views (for want of a better term) where the camera shows the overview
of the scene - it may move and rotate but doesn't really interact with
the scene - and some over-the-shoulder and missile chase-cam views,
where the camera appears to be in some way associated with the ship or
missiles, and will shake due to nearby explosions.
(haven't seen much of B.G. - all I have seen I'm afraid I've found to
be very dull)

If you want to design a ship to limit damage to a "narrow
cone", then what you really want is a very flat/thin widespread
hull design. For example, you might make a ship which is
looks like a huge flat net of radiator panels. The "thicker"
components are distributed around this flat plane. A hit
on a radiator panel will mostly "blow through" causing minimal
damage. A hit on a more substantial component will cause
a big explosion and a gaping hole in the ship as the nearby
radiator panels are blown away...but the rest of the ship
will survive.

Of course, regardless of whether this sort of ship makes
sense, it's far too much of a departure from your existing
work to consider incorporating.

OK, forget that idea then. Interesting stuff though.

It doesn't necessarily need to take up space, nor does it need to
be internal. For example, if the pusher plate is supported by a
single central shaft, then it could be rotated to roll the ship. Or
if the fuel supply is stored in a large drum magazine, the drum
can be rotated to roll the ship. Or you could even roll the ship
with the turret itself pinwheeling its long heavy barrel (this is how
cats dropped from 2+ feet right themselves).

Of course, whether or not any of these concepts are good ideas
depends upon the particular designs and goals involved. With
your behemoths, it's almost certainly NOT worth the trouble of
rolling the ship. They're simply too big and massive to rotate
quickly without excessively powerful motors or thrusters.

As above. :)

There's no chance of it handling larger hypervelocity projectiles,
but it would more or less completely block background radiation
(which is a good thing). It would also handle the explosion of
a nearby nuke, making the pusher plates superfluous.

Wouldn't you still need a way to reduce the accleration from the nuke
to a survivable level ? If I recall correctly the bomb plasma impacts
the ship over about a millisecond. If it has sufficient effect to
increase the ship speed by 1m/s, that would cause a 1 million tonne
ship an acceleration of 100g.

Anyway... here is a more or less completely revamped plan, together
with many crude and highly suspect numerical estimates, incorporating
(or at least trying to) the many ideas and facts suggested here. I'd be
grateful if people would like to give the maths a quick check. If it's
accurate to an order of mangitude that will probaby suffice. Where
possible I've noted any assumptions (and design flaws !) and there are
also a few other questions not related to previous discussion that
would also be of help. If anything thinks it's actually WORSE than the
previous plan, I'll be rather depressed.



Armour

Total ship mass envisaged as up to 1,000,000 tonnes. Pusher plates
likely to be too small, but ah well.
Soviet ship
Approximate as 80m diameter 300m length cylinder
Circumference = pi d = 251m
Surface area = pi d l = 75,398 sq m
Steel density = 7700 kg m^-3
At 1 m thickness, armour mass = 75,398 * 1 *7700 = 580 million kg =
580,564 tonnes (will actually be slightly less due to conical

nose)

US Ship :
Approximate main hull as sphere 200m diameter
Surface area = 4 pi r^2 = 125,664 sq m
At 1m thickness, armour mass = 125,664 * 1 * 7700 = 967 million kg =
967,610 tonnes

Or use much less armour on spheres but more on habitats : outer diamter
200m, inner diameter 140m. 25m depth.
Outer surface area = pi *d *l = pi * 200 * 25 = 15,700 sq m. 1 m steel
armour = 120,000 tonnes.
Upper and lower areas combined = pi *100^2 - pi*70^2 = 16,022 *2 =
32,000 sq m. 1m steel armour = 246,000 tonnes.
Inner surface area (necessary ?) = pi*140*25 = 11,000 sq m. 1m steel
armour = 85,000 tonnes.
Maximum total per habitat = 451,000
But may cut out upper area of one and lower of the other, also inner
area of both. Total mass= 120,000*2 + 246,000 = 366,000 tonnes for
both.

Are ships viable with such massive deadweights ? Smaller, ~10,000 tonne
ships planned as having only 25% payload + about 25% deadweight, so
seems plausible, assuming don't need to scale up pusher/shock absorbers
proportionally with increasing overall
mass. Larger, >1,000,000 tonne "Super Orions" typically starships
(albeit bad ones), sacrificing payload for speed, hence comparision
invalid. In reality would probably use Medusa/Classic Orion/Mini-mag
hybrids, so probably not worth worrying about too much.

Ship visibility (22 lens) :
1km : Clear. Fins, drive mechanism, rocket shrouds, Gauss cannons
easily visible. Missile turrets just visible.
5km : Clearly a ship. Heat fins, hull clearly visible. Drive mechanism
distinguishable. Gauss cannons just visible.
10km : Clearly a ship. Can distinguish heat fins from hull.
20km : Becoming a smudge. Can see heat fins.
30km : A yellowish smudge.
50km : A smudge.

35 lens :
1km : Very clear. Only smallest details not visible.
5km : Quite clear. Heat fins, hull shape, drive mechanism clearly
visible. Guass cannons just visible.
10km : Clearly a ship. Hull shape clearly visibe. Heat fins, drive
mechanism distinguishable. Guass cannons maybe just visible.
20km : Just visible as a ship. Fins/hull distinguishable.
30km : Becoming a smudge. Fins/hull just distinguishable.
40km : A yellowish smudge.
50km : An orange smudge.
60km : A yellow dot.
100km : A dot.

So ideally, would like (at some point - not continuously) to have
enemies within 10km of each other. If can't think of good excuse, will
show victors approaching enemy wrecks (or debris) after the battle.

Allied Lasers :
Diameter Rl = 3m. Wavelength W blue (4.75e-7m). 24 turrets.
Available power determined by cooling fins :
Upper fins : 26,546 m^2
Central fins : 32,832 m^2
Lower fins : 39904 m^2
Total : 99282 m^2, call it 100,000 sq m.

L = Re * (5.67x10e-8) * Ra * Rt^4
Where L = luminosity (total waste heat), Re = emissivity, call it 0.98,
Ra = area, Rt = temperature, call it 1600K.
This gives L = 3.64e10 W or 36 GW.
Assume reactor has efficiency of 50% : 36 / (1-0.5) = 72 GW generated,
36 GW useful.
Equates to 1.5 GW power per turret turret if all firing at once. But
lasers terribly inefficient, say 20%. So actually only 300 MW per
laser. Assuming available power magically constant when fins retracted
(can't be bothered re-calculating everything).

Radius of beam at target :
Rt = 0.61 * D * W / Rl
D = ?, W = 4.75e-7, Rl = 3
Want to find Dm - the maximum distance capable of killing a missile and
Ds - the maximum distance capable of drilling a hole in ship. Firstly,
Dm.

Missile hardness is 10KJ/sq cm. Assume that the maximum practical time
a turret may dwell on the same spot of a target is 3 seconds. Over 1 sq
cm, this requires :
Power * 3 seconds = 10 KJ => Power = 3 KJ per sq cm.
Now need to find distance at which beam brightness = 3KJ per sq cm = 30
MJ, or 10 MW for 3 seconds, over 1sq m.

Beam divergence θ = 1.22 L/Rl = 1.932e-7 radians
Bpt = Bp/(π * (D * tan(θ/2))2)
Bpt = Beam power intensity at target, MW/sq m
Bp = Beam power at aperture, MW
Re-arrange to get D :
D = (1/tan(θ/2)) * sqrt(Bp / (pi * Bpt)) = 32,528 km

But, maximum angular resolution of 3m telescope is 1.932e-7 radians.
Smallest missiles are 5m long by 0.6m wide. Angular size of missiles :
s = r*θ Where s = length of arc = 0.6m, r = distance, θ = angle
subtended = 1.932e-7
r = s/θ = 0.6/1.932e-7 = 3105 km - Maximum distance can target
missiles (assuming no interferometers).

[uncertain if angular resoultion would really mean objects smaller than
a.res aren't at all visible, but it should definately make them very
hard to target]

At 3000 km, Bpt = 1100 MW/sq m
1100 MW/sq m = 1100 MW/10,000 sq cm = 0.11 MW/sq cm = 110 KJ/s/sq cm

Beam radius = 0.61 * D * W / Rl = 0.3m = same as missile apparent
radius.

Given missile hardness, turrets easily capable of destroying missiles
at 3000km, IF can target it at that range. If no interferometers, may
need smaller range for accurate targetting. Negligible time to
destruction once targeted - delivers 10 KJ over whole missile in
fraction of second. If missiles approaching at 5km/s (say relative ship
speed of 4 km/s, plus 1km/s extra for missiles), time available = 600s.
If takes 2 seconds to target and destroy each missile, 1 turret can
destroy 300 missiles. 24 turrets can destroy 7200 missiles. But if
takes 10 seconds to target and destroy, 24 turrets can only destroy
1440 missiles. Soviets may release when only 300s away, then 2 volleys
from turrets alone capable of saturating lasers (assuming 1 ship
against 1 ship). Or, with rapid-fire unguided projectiles plus
silo-launched missiles, easily capable of defeating laser defences at
3000km. Gauss cannons may rapid-fire missiles with high speed plus
enough delta-v rocket capability to act as guided missiles without
expending much propellant cannon-launched rockets - plausible ?). So
from 3000km, Soviets should have capability to substantially
oversaturate lasers. Does not guarantee kill :
1) So many missiles, some are simply bound to miss.
2) Not all may be lethal-yield nuclear, some may be cheap chemical
explosives - tie up lasers for minimal cost (Allies can't see which
ones are nukes), launched first to 'shield' higher-yield weapons - may
damage Allied cooling fins and laser turrets.
2) Allies have other defensive systems - guns as directly targeting
missiles or launching mass volleys of nukes (together with their own
missiles).
ABL takes 3-5 seconds to destroy a target but is experimental and does
not have a great honkin' fusion reactor powering it. Targeting time I
can't find, so maybe giving lasers an unfair disadvantage for those who
love numbers. Still, the essence of the
power of a laser defense system - able to handle thousands of missiles
in minutes - is there.

Problem : lasers may easily target ship directly at 3000km range.
Maximum range at which Soviet ship resolved by 3m telescopes :
r = s/θ = 80/1.932e-7 = 414,000 km
But probability of hit due to lightspeed lag = 0.01, assuming 1g
acceleration available to Soviets. Equivalent to about 1%. Hence, need
closer range.

At 3000km range, beam radius = 0.3m, equivalent to about 0.3 sq m with
beam power 1100MW/sq m. Assume 1m thickness of armour. Volume to steel
to be cut = 0.3*1 = 0.3 cubic meters = 300,000 cubic cm. Heat of
vapourization = 60KJ/cm^3. Heat needed = 18,000 MJ. Delivering 300MJ
per second. 300 * ? = 18,000 => Burn time = 60 seconds. In reality will
be less with pulsed lasers. On the other hand have only calculated by
heat of vapourization - need to heat up metal AND melt first, requiring
more heat than calculated. Estimate additional heat :

Let all metal be at room-temperature 293K. Iron melting temperature =
1809K, deltaT = 1516K. E = mc.deltaT. Mass m = 0.3*7700 = 2310 kg.
Approximate c = constant = 440 J/kgK. Heat to raise temperatue = 1540
MJ. Heat of fusion = 530 KJ/kg (I think). Heat to melt = 2310*530,000 =
1224 MJ. Heat to raise temp. to boiling point (assuming same c, very
dodgy - can't find value for liquid iron) = 2310 * 440 * 1326 = 1350
MJ. Total heat = 22,000 MJ. So heating+melting+more heating is
insignificant compared to vapourizing. Does not account for conduction
of heat within metal.

But one hole in hull will not be lethal if ship has airtight
compartments. Time to slice ship in 2 ? Is equivalent to slicing
through a solid *** 1m thick over a path 0.6m wide and 251m long.
Total volume 150m3 = 1.5e8 cm^3. Total energy required = 9e6 MJ.

Burn time = 9e6 / 300 = 30,120 seconds = 8 hours. With 24 turrets (or
all power through one turret) = 20 minutes. Conclusion - no point in
Allies trying to fire on Ruskis with lasers at long range. Could fire
at longer than 3000km range for longer, but : less
targeting accuracy so more difficult to keep beam on one spot, Russians
may also spin so simply cannot attack one spot for prolonged period
even if you want to. Major unkown is how much easier pulsing the lasers
makes destroying things.

Have assumed Americans facing Russians head-on, but calculated drilling
through armour as if were facing side-on. So time calculated is an even
larger underestimate, depending on how much energy is saved by using
pulsed lasers (if lots, simply ignore
this, thus avoiding any one-shot-kill-battelship lasers). It does look
like one thing the Russians aren't going to be overly concerened with
the Allies tearing up their spaceship with their laser turrets, at
least.

Russian missiles and tactics thereof
Volume of each (small) missile = pi*0.3^2 * 5 = 1.4m^3. Need at least
2000. Total volume = 2827 cubic m. Total ship volume = about 75,400
cubic m. Volume of 2000 missiles = 4% of ship space. Missile mass =
1200 tonnes (Exocet missile has v. similar size, mass is 670 kg), so
not significant with ship. Can certainly store many thousands of
missiles.

Missiles best launched as continuous barrage. If launched in
well-seperated waves, would give Allies time to shoot missile turret
and silos (can't really destroy a silo but might melt enough metal to
block tube). Will also use larger missiles with very high-yield
nukes and Excalibur lasers. Clearly no point in missiles making random
turns in order to foil lasers, they'd need absurdly powerful rockets to
have any significant affect on targeting ability of turrets. Possibly
could deliberately space themselves out widely to
increase slew time of laser turrets, but suspect this would need too
high a distance between each missile (and thus deltaV) to be plausible,
better to go for faster missiles which certainly give the laser turrets
less time to operate.

Consider 2 ships engaging. Little advantage to Soviets in launching
missiles prior to 3000km distance. Launching within this decreases time
to missile impact and with the sheer numbers of missiles involved
reduces the number the turrets are able to
destroy. Does launching time make significant difference ? Let target
and destroy time per missile per turret be x. Let the time to missile
impact be Tl, the launch distance be Dl, the number of turrets be n,
and the missile speed relative to the enemy ships be v.

Then no. missiles destroyed, assuming perfect laser accuracy :
N = no. turrets * Time available / Time to destroy one misile =
(n.Dl/v) / x = n.Tl / x
So the time (or distance) available is directly proportional to the
number of missiles that can be zapped - unless past the maximum
distance at which a missile may be targetted. Tl (or Dl) are controlled
by the targetting distance of the turrets rather than lightspeed lag
effects or diffraction. Assumes a constant rate of missile destruction.
As missile firing rate is almost unlimited, but delta V for small
missiles is at a premium, the Soviets will do well to wait as long as
possible before firing missiles (possibly, would launch just enough to
saturate lasers at 3000km, then when close launch more rapidly, making
efficient use of available missiles) But too close and their missile
turrets (and guns and heat fins for that matter) may be destroyed. Will
have to assume missile turrets can't easily be targeted at 3000km
range. They seemd like a good idea at the time but are indeed more
trouble than they're worth (which isn't much at all). Soviets could
perhaps spin ship and approach sideways up to 3000km to prevent turret
damage. Will skip this in animation for sake of time.

But - missile fire rate not really dependent upon no. turrets or silos.
Soviets may launch one huge volley at greater than or less than 3000km,
still only a finite amount of missiles the Allies can destroy. At
greater distances, ships may be able to out-perform missiles.

Assume that at less than 3000km, ships may be at risk of laser attack
to exterior systems. So have to launch at 3000km. Continuous barrage at
3000km inwards ensures missiles are only used as needed - if missiles
succeed in crippling/destroying ship, no need for further attack, ship
may have enough missiles left to assist comrades. Assuming missiles
don't have enough delta-v to go and attack new ships after recieving
initial targetting commands, as need to accelerate quickly to max.
speed to reduce interception time. Convieniently also makes things
easier, no need for vast, memory-hogging missile swarm.

Allies - may want to maintain distance to destroy as many lasers as
possible. Could try and "retreat" at such a speed that the missiles
can't catch them up, in which case the Russians accelerate and the
whole thing degenerates into a farcical race rather than
a battle. Will ignore this option. Whenever not saturated lasers can be
targeting enemy turrets/guns etc. Or can take risks and hope the enemy
missiles aren't filled with nukes and ignore a certain percentage of
missiles. Or can rely on lasers to handle large
numbers of missiles and use their own missiles and guns to attack the
Russians simultaneously. This forces Russians to use some missiles for
their own defence reducing the number they can use offensively. Still,
Russians should have inital advantage through sheer overwhelming
numbers.

Inital attack proceeds as follows between 2 ships : Russians bombard
Allied ship with thousands of missiles and unguided/semi-guided
projectiles. Laser defences take out the vast majority of such
missiles, however, a significant number still make it through simply on
sheer numbers. As the missiles get closer the low-yield missiles use
the last of their propellant and accelerate, reaching close enough to
detonate or even impacting. Velocity will not be enough to cause damage
(to hull) in itself but explosive power will be able to damage cooling
fins and laser turrets. This increases the chance of higher-yield
nuclear weapons of reaching a potentially lethal detonation distance.
From the Allied view we see a continuous barrage of missiles mostly
being destroyed by lasers. When any get too close for comfort they are
also bombarded by missiles and gun-fired bombs, and finally a barrage
of nuclear shells detonated as a sort of "shield". This phase lasts up
to about 10 minutes as the ships close; the Russian missiles becoming
more succesful as time progresses as the slow trickle of missiles that
make it through the formidable Allied defenses begin to have an effect.
As cooling fins damaged Allies begin to use open-cycle cooling. As
turrets damaged Allies become less and less effective at stopping the
missile attack so the risk of destruction continuously increases.

Simulatenously the Allies have been firing their own missiles at the
Russians, who rely on their own guns, cannons and nuclear shield to
protect them. Persuaded by the scientists and keen on lasers lack of
ammunition, the Allies have chosen to invest heavily in their laser
turrets but have put relatively less effort into their own missile
system, thinking they will soon make lasers obselete. They do not
possess the vast numbers of the Soviets, so their own attempts at a
missile bombardment last for less time. May hold some heavier missiles
in reserve hoping lasers give them the opportunity to use them later.

Possibilities for overall tactics :
General : Allied ships have to win. Not really giving anything away
with that - don't really like Communists much, so if Russians win,
would have to make sequel. If Allies can survive bombardment for long
enough with any laser turrets intact, possess massive
advantage - Russians have exhausted missiles, unguided projectiles only
effecitve within a few km range. 100mm gun speed 870m/s (wikipedia).
Gerlald Bull's gun up to 3.6km/s, but very large. Say max. unguided
projectiles of 2km/s (Gauss cannons higher
if can fire missiles, assume all gone by this "endgame" phase). Both
Soviets and Allies will probably have lost some guns due to
lasers/missiles by this stage. Russians have more guns to start with
but not relavent if Allies have surviving laser turrets. Allow both
ships 1g acceleration, want to find range at which unguided missiles
inevitably hit if on target :
Consider ship of 100m radius, opponent aims at dead-center, not knowing
which direction it will accelerate in (pessimistic assumption, ships
can't turn very fast and can see orientation of pusher - but can't be
certain ship will accelerate or not). Ship must
move 100m to avoid projectile. At 1g, ship will take sqrt(20) seconds
(about 5) to do this. At 2km/s for 5 seconds projectile can travel 10km
- within the desired visibility range. Ships may fire spray of
projectiles to try and force ships to turn (especially useful against
Allies as this exposes more cooling fins and habitats).

Lethality of small projectile ? Nukes possible in small 10-20cm
diameter shells ? What yield ? Effects of such shells on 1m thick
steel, total mass 1,000,000 tonnes ? Depending on lethality, at slow
relative speeds a second pass is possible, if neccessary.

Specific tactics
1) None, really. Each ship begins by pairing off against one opponent
(worryingly Homeric...). Ship pairs at least 10km from the nearest
pair, prevents damage from nukes hitting more than 1 ship at a time,
lower distance allows ships to support each other if
necessary (ships may create nuclear shields for each other if they see
an ally is particularly hard-pressed in comparision to the themselves,
or use their own lasers to defend friendlies - maybe). Once one ship in
the pair is defeated, the other moves to assist its own side by
attacking another enemy ship. Various weak spots in fleets on both
sides will develop as ships are taken out. Will assume any ship is
capable of dealing with the attacks of 2 other ships simulatenously but
only for a very short time. Primarily, Allies through use of lasers at
faster (riskier) targetting speed + more reliance on nuclear shield,
Russians through more reliance on defensive missiles (fewer in number -
less delta-v but more destructive, reduces offensive capbility).
Pairing off prevents ships from multiple targets, each pair too
concerned with its immediate opponent to divert much attention to the
others. Assumes opponents well-matched. Allied high-yield reserve
missiles may be decisive at this point - Russians assume after initial
short Allied missile attack, have none left since they rely on lasers.
Russians have exhausted such missiles or have so few left that Allied
defence systems easily deal with them.

2) Line of battle tactics. Each ship approaches the missile-firing
range and fires its entire supply (or substantial fraction thereof) at
once, then retires from the laser range. Waits to see the effect of its
missiles on the opponent. Minimizes time Soviets are in
effective range of lasers (or could fire before even in range at all),
but perhaps not so efficient - assuming missiles go for speed rather
than maneuvering, some won't have enough delta-v left after main burn
to attack any other ships. Subsequent ships come in
and proceed with the same tactic. Once all missiles gone may resort to
close-range gunfire against survivors. But, if Allies are not in
similar deep line but are in a closer plane, lasers may easily be
capable of dealing with any number of missiles one enemy ship can
launch, as could have 192 turrets all independelty targetting and
destroying missiles (will have 8 ships per side). With this many
turrets, at 600s available time with 10 seconds targetting time per
turret, lasers can deal with 11,500 missiles - or 23,000 with 5 seconds
targetting time. So line much less effective against plane.

3) Any other ideas...?

Other questions :
What does the damage from an Excalibur-style bomb-powered laser look
like ? Powerful enough to penetrate 1m armour, or better to target
individual exterior systems i.e. weapons ? What do the "lasing rods"
actually look like ? Is it necessary to use multiple rods, or could 1
big rod give more power by intercepting more of the X-rays, or would it
be better to have multiple rods targeted on the same spot ? How are
these rods targeted, anyway ?
Checking nyrath's site, "On a target at ten megameters, it would
deposit about 300 kJ/cm2 over a spot 200 meters wide." Is this for each
rod ? 1 sq cm of 1 m thick steel needs 1cm2 * 100cm depth * 60KJ/cm3 =
6,000 KJ. So may burn through about 5% of the depth over the whole ship
- suggests if ship isn't destroyed it certainly isn't going to look
pretty afterwards. Cooling fins would be obliterated, missile turrets
and guns destroyed, silos probably clogged with melted debris. Guess
crew would be OK. But not sure if it means each rod does this or
combination of whole (hoping it means combination of all rods, would
prefer to show multiple beams on target).

.

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