Weapon systems, part 0001

[DeathByTheSword]

ok this is all great but when a missile or what ever explodes it shoots scrapnel every way....in an atmosphere and with gravity they would stop to fly every direction and fall to the ground. but with no atmosphere and gravity the cload will expanded for ever...now if you would fire 5 missiles lets and let them explode 5k before you there will be 5 shockwaves with scrapnel moving towards you. now thaking in to acount that the supply scrapnel is end less you will also be hit by the explosion....not taking in to a count that the supply of scrapnel is endless then you could only fire at target very far away and you would have to change your heading right after firing you rocket. so that is way it is unlikely that you would use explosions in space....I am not saying we shouldnt but i think it is unrealistic....atleast it is unrealistic to have dogsfight and shortrange firing...because destroying the an enemy craft will cause debri to expand outward to everything...

[Martin the Dane]

Well DeathByTheSword no matter what weaponds you are up against you would want to consider using evasive action.

But as this thread is about weaponds I'll get back to the topic.

My preffered space weapond is a misile with a couple of seriouse nukes at the tip. The misile should be fired by a canon, or railgun at great speed towards the target.

The target will probably change heading so if we send a normal projectile it would most likely miss. That's where the misile comes in, when it reaches a point believed to be close to the target it will go hot, and attempt to lock onto the target. If the target is using radar to try to track the misile, the misile has a nice beacon to fly towards.

When the misile has aquired the target it fires up it's engines and just before reaching the target it fires a number of warhrads with a little spread. The warheads goes of simultaneousley, and are mostly vaporized, hopefully along with part of the target.

For this to work, the warheads have to get close to the target, and risks being destroyed, if they go of prematurely the blast will have cooled to much to do any damage once the wave reaches the target. Space based warships will have to have some seriouse form of radiation shielding if he crews are going survive out there for any significant time so radiation would not be a problem unless you get close to the blast.

The advantage of using this aproach is that you won't run into a wave of scrapnell from your own weaponds. A dying enemy ship might however try to take the atacker with him by blowing himself to pices.

Now back to the misile, if it does not aquire a target it goes cold, for a periode of time, and then turns on a beacon so it can be picked up by it's owners. Btw. if I were a space captain I would think twice befor attempting to pick up someone else's misiles. They might not be as dead as they seem.

[Gateway103]

Let me check your computation, Martin de Dane,

Initial State
Va = 10km/s
Vb1 = 14km/s
Vb2 = 12km/s

Transform to A's frame
Va = 0km/s
Vb1 = 14-10 = 4km/s (not 1, arithmetic error)
Vb2 = 12-10 = 2km/s

Consider straight line travel
Projectile velocity:10km/s to the left I presume, since B1 and B2 are gaining. So in essence -10km/s
Distance: 1000km

Time to intercept
Tb1 = 1000 / (4-(-10)) = 71.4 s
Tb2 = 1000 / (2-(-10)) = 83.3 s

Acceleration
10gee = 98 m/s^2 or roughly = 0.1 km/s^2

Max separation distance if pulling 10gee, from stragith line intercept point:
D1 = 0.5*0.1*71.4^2 = 255 km
D2 = 0.5*0.1*83.3^2 = 347 km

Max angle if pulling 10gee, from straight line inctercept point:
A1 = Arctan (D1 / (Tb1*10)) = 19.7 degrees
A2 = Arctan (D2 / (Tb2*10)) = 22.6 degrees

Conclusion
B2 has distance and angle advantage over B1, and B2 is the slower of the 2 vessels.

Therefore, in trailing, the faster trailing ship is more likely to get hit.
-----------------------------------------------------------------------------------

Regarding stress

I'm not too keen on structrual engineering, so you may be correct on the stress aspect.

In this case, however, the faster Defender moving away from (escape course) or the slower Defender moving towards (persuit course) the Attacker would have higher chance of survival. So the movie I rendered is then erroneous. My apology.

-Gateway103

[Martin the Dane]

Well I se I did make some errors.

The first is a type, my calculations are based on the VB1=11 km/s but lets include both. We now have the following

Initial state (all traveling the same direction)
VA =10 km/s
VB1=11 km/s
VB2=12 km/s
VB3=14 km/s
VM =20 km/s
D0 =1000 km

Transformed to A's frame
Va =VA -VA= 0 km/s
Vb1=VB1-VA= 1 km/s
Vb2=VB2-VA= 2 km/s
Vm =VM -VA= 10 km/s
D0 =1000 km

Time to Intercept
Tb#=D0/Vb#-Vm
Tb1=1000/9 = 111s
Tb2=1000/8 = 125s
Tb3=1000/8 = 167s

Acceleration
10gee~98m/s^2=.1km/s^2
I don't know how I got 10m/s my notes say 100m/s sorry about that.

Distance to intercept (distance traveled by misile)
MD#=1000+Vb#*Tb#
MD1=1000+1*111=1111km
MD2=1000+2*125=1250km
MD3=1000+4*167=1668km

Seperation at intercept at 10gee
D#=.5*10gee*T#^2=.5*.1*T#
D1=.5*.1*111^2= 616km
D2=.5*.1*125^2= 781km
D3=.5*.1*167^2=1394km
Here i forgot the .5

Angle of seperation at intercept
A# = Arctan (D# / MD#)
A2 = Arctan ( 616 / 1111) = 29.0 degrees
A1 = Arctan ( 781 / 1250) = 32.0 degrees
A2 = Arctan (1394 / 1668) = 39.9 degrees


As you can se the faster ship still gets the best seperation both in terms of distance, to the attacker and the misile, and the best angular seperation.

Note that B3 can outrun the misile, since it's initial speed allows it to accelerate beond 10 km/s within the given timeframe.

If the atacker was gaining on the targets, the slower target would be the one with the highest speed relative to the attacker.

If we however considered a heasds-on case the faster ship would not have the advantage of seperation, but this might not be as important since the attacker has a much shorter time to fire, and will be reluctant to fire on anything that might hit himself if killed

----

As for structural stress caused by speed, i do know about that, so either take my word for it or read some mekanical engeneering texts, I can't give you any titles right now, my textbooks are packed away as I don't use them at the moment. But Amazon.com has some execlent titles.

Martin the Dane

[Gateway103]

Hmm... I think we are have some misunderstanding here, in fact, we are both correct

First, VBn>VA for n=1,2,3, this means either
1) the VBn's are chasing VA and gaining, or
2) the VA are chasing the VBn's and trailing behind.

When I did the computation above, I calculated for CASE 1, so my Vm is -10 km/s. However, you seemed to calculated for CASE 2, as your Vm is 10 km/s. This is also evident in the time to intecept (e.g. I divide distance by 10+VBn(relative), whereas you use 10-VBn(relative) )

To skip a bit further, you'll notice in my conclusion I said that: "Therefore, in trailing, the faster trailing ship is more likely to get hit." What I meant by "trailing" is that that Bn's are chasing A from behind (I suppose "persuit" might be more clearer, in retrospect), that is CASE 1, which I think you'll agree is correct.

Lastly I said, "... the faster Defender moving away from (escape course) or the slower Defender moving towards (persuit course) the Attacker would have higher chance of survival..."
In fact, this last statement is consistent with both our results. In other words, we are both correct, just we were describing the different CASES ^_^

-Gateway103

[targon]

Modern interceptors may withstand something like 12g during short time period. The main concern is that human simply can't withstand higher g's. Trainded proffecional persons may survive several dozens seconds of 10g or several minutes of 5g, but I think that any human-piloted ship will be eventualy outmanoeuvred by smart enough cyberpilot. Modern AA missiles, in fact, survive dozens of G's and there are confirmed rumors of gun projectiles with auto-targeting (Russian "Krasnopol" artillery and "Smelchak" howtizer rounds to be sure, NATO rumors please?) that means _thousands_ of G's.
About nuking your "freinds": nukes are't as spectacular in space, as there is't any medium to transfer momentum of shock wave. So nukes may harm enemies via radiation (most notably, soft X-ray) or EMP wave. And you surely can't hit unwilling ship via any missile. Even modern AAM or SAM can't hit their prey, they explode on proximity and shred aircraft in pieces using shrapnel. Aircrafts, filled with fuel tanks, really hot engines, loads of munitions and various devices are in fact very fragile, as you can't plate every vulnerable spot and still fly. Projectile weapons are suffer from really low hit ratios, and this will be surely even worse in space. Can't imagine how spaceship may be armored, but for any thickness armor exists some projectile that pierces it... and reactive engine exhausts can't be armored, and it's really fragile thing as it's very heat-strained.

[Leland]

About nukes and EMP waves in space: if I am not grossly mistaken, EMP is caused by the radiation from the explosion ionizing the particles of the atmosphere around it, but in space there's nothing to ionize, hence the EM pulse will be negligible. Please correct me if I'm wrong about this.

[targon]

Nuke has something own to ionize, like compression system, missile hull an prop and charge itself. Exploding nuke will form fast expanding plasma cloud, this kind of things really _love_ to emit various radio waves. BTW, even chemical explosions form some kind of faint EMP. But you're right to some extent, as air is greatly helpful for nuke EMP's. So nukes in fact may be dangerous due to their soft X-rays ("soft" here means ~1keV), as this kind of radiantion easily forms strong shock waves in the irradiated media, unlike visible light or IR. In this aspect, vacuum may be even helpful, as it does't block X-rays.

[Martin the Dane]

just one thing about nukes, they generate quite a bit of heat, and in space this can be transmitted as heat-radiation, like we are heated from the sun.

[targon]

Sadly, vacuum is (surprise!) not a good place to be toasted with nuke.
Main heat generator for air nuke is its shock wave. Its wave moves at velocity around 10M (~3 km/s), compresses air almost to theoretical limit for shock compression and thus heats it to ~10.000K. This is _huge_ and _hot_ heat emitter, it's in fact much more bright than air and it's pretty close to earth surface.
In vacuum, expanding corona of plasma will surely emit some heat, but it is't any as good as "strong" shock wave, almost nothing compared. Most of energy will be radiated, as I said, in more hard ranged, X-rays, gamma and neutrons.
BTW, there is a way of generating something close to nuke explosion in terms of light radiation using low-tech things like chemical explosives.
Nuke wave in air is't "strong" just in terms of pressure or temperature; in fact, much more valuable thing is so-called "bulk speed", or speed of given small volume of gas just behind the shock wave. In this aspect, nuke's wave is dramaticaly good, but we can simulate this kind of perfection. All we need is some heavy gas, argon or even better xenon. Fast moving explosive gases will gain its momentum to this gas, setting initial bulk speed; but this speed is much more Mach numbers in comparison with corresponding air wave (1 Mach = speed of sound, heavy gases have much lazy sonic waves), so we can easily obtain high compression, high temperature and thus high light/heat radiation. This scheme is still too bulky to be used inside real weapons IMHO, but who knows?

[Kurilka]

Sorry for disturbing you targon, but where do you know All this stuff from?

[targon]

It seems your think I'm kinda ugly crazy Russian miliatry scientist. If so, you're wrong. I'm not ugly.
BTW, I definitely very fa..ar related to military. But problems that I'm concerned to, namely shock wave physics, has long military history, so some facts about weapons design and function, even nukes, are simply written in textbooks. All the postings I made are based on "open" sources, without any secret or non-disclosure stuff. 90% of exact design of low-tech nuke may be extracted form such sources. In fact, uranium Hugoniot curve seems to be openly published, so it's really 95% information. Some details about weapon systems are available at Janes and other books, and if your know some weapon design in depth, your can easily restore missing parts in explanation.
So it's my business to know such a things, and I hope I can help StPDT with some gameplay aspects related to physics along with graphics design. Remember, I'm not from military, so weapon systems may be my, say, hobby.

[King of Rasslin]

You forgot to mention caseless ammo. I think this would be the first and most realistic improvement to light infantry. Until we step out of the fossil fuel era, energy based weapons are impossible. There just isn't enough energy out there to make them feasible.

I do hope we get stealth tanks someday. Stealth systems on land vehicles would really improve our military. Aren't there snipers that are remote controlled, where you don't have to worry about your hands shaking? Those would be a realistic improvement, I think.

[Blake]

Hmmm, I was about to ask what exactly is so great about caseless ammo?, when I checked it on google. Lighter, no need to eject spent shells, for me, that translates to a faster firing rate, larger clips and higher reliability. Putting more lead in the air is always good

Stealth Tanks == Very cool

[Martin the Dane]

What about the American "Star Wars project" (no not the movies) they had some nuke based space laser weapos? Was that pure wishfull thinking, or did they get anywhere with it?