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Best Point Defense Versus Space Battles.... Scifi and Real Life


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On 1/25/2022 at 1:24 AM, Spacescifi said:

Plasma:  Can be fired at high speeds but damage is light unless the target is at relatively close range... which is bad if ut us a swarm of missiles.

Plasma weapons as depicted in scifi don't and cannot exist. Plasma won't hold itself together and will just puff out like hot gas. The closest real world equivalent is particle beams. They act like lasers in most cases.

On 1/25/2022 at 3:48 PM, JoeSchmuckatelli said:

Your best bet is to think like a weapons designer.  And then escalate and counter.  Escalate and counter. 

The best advice so far!

On 1/25/2022 at 4:19 PM, Rakaydos said:

Sand doesnt accelerate, and so is useless for  counter-countermeasures for missiles.

The missiles are coming towards you. They have a very high closing velocity, and necessarily come from a narrow range of angles. The sand just has to be between you and the missiles in the last moments before impact. If the missiles dodge the sand, they won't be able to hit without spending many more hours turning back around. If they go through the sand, they'll have sensors, mirrors, antennae and anything else exposed scraped off, turning them into blind sticks that you can dodge with a short RCS burn. 

On 1/25/2022 at 5:19 PM, DeadJohn said:

If the missiles have 15g thrust for 2 hours, I think their final velocity is 3.8 BILLION meters/h, or greater than 10 times light speed.

15g x 9.81 m/s^2 x 3600s x 2 = 1,059,480 m/s
Which is 0.35% of the speed of light.

On 1/25/2022 at 6:50 PM, kerbiloid said:

And that's why the old Soviet projects are tougher than the Expanse battle ships.

The Expanse spacecraft are designed with 'no armor is best armor' in mind. They know that they can never withstand a direct hit from a railgun or a torpedo, so they sacrifice that dead weight for extra maneuverability and point defences.

On 1/25/2022 at 7:11 PM, kerbiloid said:

And the machine railguns like in Expanse would overheat in seconds, and start missing.

The PDCs in the Expanse have never overheated in the 9 books or 6 seasons of the TV show. They have jammed though.

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

Regarding the main question: the best way to defeat these hyper-missiles with 15g accelerate is to use an interceptor drone. This is a small and cheap drone with a ring of small RCS thrusters around a section of steel plate. It just drops off your spaceship's hull and maneuvers itself between the incoming missile and yourself.  The incoming missiles have such a high closing velocity that just scraping the tip of this steel plate is enough to obliterate them. One drone per missile.

It doesn't need a big gun to shoot the drone off. You don't need to supply any energy. Their 'firing rate' is just how many you choose to drop at once. They continuously guide themselves into a collision course, so accuracy is perfect. Each drone is massively cheaper and lighter than the missile it destroys, so you can easily carry several interceptor drones for each missile that could be launched at you. 

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On 1/25/2022 at 5:00 PM, Spacescifi said:

There is a saying that battles are won before they are fought.

At times people are just are too stubborn to accept defeat until they are forced to accept it even when they know the battle is lost

As someone who has lived with these things... I caution you away from the 'Armchair General / After-Action-Report' "That was obvious, everyone should have known it before they began" line of thinking.  Fog of war is a real thing.  You only know what you know, don't know what they know and your best guess as to their plan and how your plan will work does not survive first contact.

The OODA loop is a real thing; and those who master it are better than those who don't.

-  -  - 

Let's think about a scenario: Future Chinese Privateer craft attacks and seizes the cargo of a British Commercial Mining Vessel in the Asteroid Belt.  Britain and China do not have an openly hostile relationship, and there is a sincere question whether this was a rogue pirate captain acting on his own in the Chinese vessel, or a commissioned ship of war - and the Chinese are claiming the British violated international law and jumped an unregistered Chinese claim.  An American Space Guard Cutter is the only ship on station and it tries to interdict the Chinese Privateer.  The Privateer preemptively attacks and damages the American Cutter, but it manages to destroy the Chinese craft.  Then it discovers that a Chinese Battle Cruiser out of Mars Station is inbound and firing missiles at the American Cutter in a counter to it's destruction of the Chinese Privateer; so the American runs for cover, and the rest of the fleet at the L5 of Jupiter.

There is no way the American can outrun the Cutter's missiles.

Does it really need 'torchship missiles' to defeat the Chinese missiles?

No - all it has to do is mine the missiles path with low-speed, highly maneuverable bomblets as it runs.  A pair of drone radar C&C satellites can coordinate the bomblet cloud, triangulating on the bogies, which should interdict 70% of the incoming missiles with the remaining 30% covered by point defense with a 90% success rate.  The American ship is crippled, and now its a race between the faster craft of the L5 fleet and the challenge faced by the Chinese Cruiser Captain; does he close in for the kill and risk his craft, or does he veer off?

Edited by JoeSchmuckatelli
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14 minutes ago, JoeSchmuckatelli said:

As someone who has lived with these things... I caution you away from the 'Armchair General / After-Action-Report' "That was obvious, everyone should have known it before they began" line of thinking.  Fog of war is a real thing.  You only know what you know, don't know what they know and your best guess as to their plan and how your plan will work does not survive first contact.

The OODA loop is a real thing; and those who master it are better than those who don't.

-  -  - 

Let's think about a scenario: Future Chinese Privateer craft attacks and seizes the cargo of a British Commercial Mining Vessel in the Asteroid Belt.  Britain and China do not have an openly hostile relationship, and there is a sincere question whether this was a rogue pirate captain acting on his own in the Chinese vessel, or a commissioned ship of war - and the Chinese are claiming the British violated international law and jumped an unregistered Chinese claim.  An American Space Guard Cutter is the only ship on station and it tries to interdict the Chinese Privateer.  The Privateer preemptively attacks and damages the American Cutter, but it manages to destroy the Chinese craft.  Then it discovers that a Chinese Cruiser is inbound and firing missiles at the American Cutter in a counter to it's destruction of the Chinese Privateer; so the American runs for cover, and the rest of the fleet at the L5 of Jupiter.

There is no way the American can outrun the Cutter's missiles.

Does it really need 'torchship missiles' to defeat the Chinese missiles?

No - all it has to do is mine the missiles path with low-speed, highly maneuverable bomblets as it runs.  A pair of drone radar C&C satellites can coordinate the bomblet cloud, triangulating on the bogies, which should interdict 70% of the incoming missiles with the remaining 30% covered by point defense with a 90% success rate.  The American ship is crippled, and now its a race between the faster craft of the L5 fleet and the challenge faced by the Chinese Cruiser Captain; does he close in for the kill and risk his craft, or does he veer off?

 

Wow Joe... you should write a short story! That was entertaining!

The safest thing for the chinese cruiser to do is bail out of the situation.

Since even if it takes out the American I reckon the fleet has missiles that could take it out as well.

I reckon Chinese are not known for kamikazi tactics anyway..... that's the Japanese.

If anything the Chinese in war are cautious, and prefer fights they KNOW they will win.

 

So 9 times out if ten I expect the Chinese commander to bail.

 

In the unlikely chance that he decides to give chase I doubt his crew will oppose him, but I do think it ends with his ship disabled and captured by the L5 fleet.... leading to a diplomatic solution or a full-on China/America war... in SPAAACE!

 

It's simple newtonian mechanics. He would have to either fly through American controlled space or retroburn toward it to escape the fleet.... either of which give ample opportunities for the fleet to spam more missiles tgan the cruiser can ward off.

Edited by Spacescifi
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37 minutes ago, MatterBeam said:

The Expanse spacecraft are designed with 'no armor is best armor' in mind.

Doesn't matter. The main idea is "shoot on fly-by".

37 minutes ago, MatterBeam said:

The PDCs in the Expanse have never overheated in the 9 books or 6 seasons of the TV show.

Because it's sci-fi. Their ships also lack radiator panels.

38 minutes ago, MatterBeam said:

Plasma weapons as depicted in scifi don't and cannot exist. Plasma won't hold itself together and will just puff out like hot gas.

The projects of magnetically self-containing "plasmoids".

Edited by kerbiloid
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33 minutes ago, MatterBeam said:
On 1/25/2022 at 12:19 PM, DeadJohn said:

If the missiles have 15g thrust for 2 hours, I think their final velocity is 3.8 BILLION meters/h, or greater than 10 times light speed.

15g x 9.81 m/s^2 x 3600s x 2 = 1,059,480 m/s
Which is 0.35% of the speed of light.

You're absolutely correct.

Your 1,059,480 m/s and my 3.8 billion m/h velocities are equivalent, but I then stupidly compared m/h to lightspeed in m/s without any conversion.

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19 minutes ago, Spacescifi said:

you should write a short story!

I have; I'm a heck of a writer, but absolute crap as an editor!  (of my own work)

I'm really, really bad at figuring out what makes my 'fantastic' novel, read like some aspirational twit's word-barf.

22 minutes ago, Spacescifi said:

reckon Chinese are not known for kamikazi tactics

Neither were / are the Japanese.  That was absolute desperation on their part, fearing wholesale annihilation.  I doubt modern Japanese would repeat that tragedy.

Again - when thinking forward, don't overly rely upon the past.  The Chinese may be thought of having 100 year plans, but on a point-to-point spectrum the decision maker has a lot of pressure: the need to succeed, avoid the impression of failure, his own aggressiveness or lack thereof, helmet fires, fog of war and etc.  Don't forget the Chinese experience of Korea; they did not act cautiously.  When writing a story, you can have an absolutely reckless and brilliant Chinese Commander and a cautious and tradition-bound American face off with predictable outcomes; especially if the brilliant guy has a blind-spot and the cautious guy gets his friends killed.

That's the fun of fiction!

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1 hour ago, MatterBeam said:

Regarding the main question: the best way to defeat these hyper-missiles with 15g accelerate is to use an interceptor drone. This is a small and cheap drone with a ring of small RCS thrusters around a section of steel plate. It just drops off your spaceship's hull and maneuvers itself between the incoming missile and yourself.  The incoming missiles have such a high closing velocity that just scraping the tip of this steel plate is enough to obliterate them. One drone per missile.

The wave of decoys takes out most of the drones.
The wave of EMP missiles burns most of the rest.

The main wave missiles (behind the "sand" cloud) perform a strafe on approaching, and the drones need over-acceleration to catch them, if even can "see" behinf the cloud.

The main wave missiles rotate to the ship (not the velocity vector, but the rocket body by RCS), aim, engage the nuke, hit the ship from 1 000 km distance by an Xray laser.

1 hour ago, MatterBeam said:

The missiles are coming towards you. They have a very high closing velocity, and necessarily come from a narrow range of angles.

They don't.
The shooting (not impacting) missiles need to pass in a 1 000 km radius sphere.
And they don't need to fly directly into the ship. Their trajectories are fly-by.

So, the attacking missile needs to "hit" a ~1 000 000 m large aim, while the interceptors need to hit a 1 m rocket.

If make the interceptors Xray, too, then anyway on approaching the missile should aim a ~100 m large ship, while the interceptor needs to shoot at ~1 m rocket.


At  the 1 000 km distance (of the laser shot) the missiles are coming in ~90° angle, while all interceptors have to be launched from one point, the ship.

1 hour ago, MatterBeam said:

It doesn't need a big gun to shoot the drone off. You don't need to supply any energy. Their 'firing rate' is just how many you choose to drop at once.

The firing rate is limited by the heat capacity of the shooting device and the projectiles, and can't be much higher than the modern ones, because the cannon will overheat.

The projectiles (who are basically conducting carriages) start overheating and melting even earlier, so at high rate or speed they will turn into expanding plasma clouds.
This makes any high-rate or high-speed railgun the worst form of particle accelerator.

So, the railguns are just an equivalent of the modern anti-aircraft naval guns for short distances and non-existing fighters.
At 1 000 km they will miss just because any missile performs a counter-anti-aircraft maneuver (in this case - the strafe).

Edited by kerbiloid
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1 hour ago, JoeSchmuckatelli said:

I have; I'm a heck of a writer, but absolute crap as an editor!  (of my own work)

I'm really, really bad at figuring out what makes my 'fantastic' novel, read like some aspirational twit's word-barf.

Neither were / are the Japanese.  That was absolute desperation on their part, fearing wholesale annihilation.  I doubt modern Japanese would repeat that tragedy.

Again - when thinking forward, don't overly rely upon the past.  The Chinese may be thought of having 100 year plans, but on a point-to-point spectrum the decision maker has a lot of pressure: the need to succeed, avoid the impression of failure, his own aggressiveness or lack thereof, helmet fires, fog of war and etc.  Don't forget the Chinese experience of Korea; they did not act cautiously.  When writing a story, you can have an absolutely reckless and brilliant Chinese Commander and a cautious and tradition-bound American face off with predictable outcomes; especially if the brilliant guy has a blind-spot and the cautious guy gets his friends killed.

That's the fun of fiction!

 

Hmmm.... true.

 

As regards writing though, it is an art in of itself.

 

Some books are better at teaching this than others, but finding a good book on writing would be a good start.

Avoid any of the For Dummies series of books on writing like the plague they are (just read the one star reviews, which are far more honest than the glowing 5 star ones).

But given that you have family and other responsibilities and hobbies, I can totalky understand if you do not want to commit to that.

 

I I could recommend any book it would be the all everything writing book (I have vol 2).

I have had too much going on lately to read it much, but I enjoyed it when I did.

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His writing  isn't everyone's cup of tea but I found Stephen King's 'On Writing' to be a useful and readable primer on... well writing. :) From personal experience, I can also highly recommend finding a patient and generous beta reader to help turn your word salad into something readable. Or something you could submit for publication without blushing too hard, if that's the way you wanted to go.

And yeah, as Han Solo didn't say, editing is the real trick. I just sold a short story and the most satisfying thing about writing it was going solo (hah) on most of the editing. Not just spotting that the beginning was weak and didn't really fit but figuring out a better one which got you into the story a lot faster and then made the ending land a lot harder.  

 

 

 

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Thanks guys

My experience with writing is akin to carpentry.  Just because you have the tools and can bang a nail into a piece of wood it does not mean that you are a carpenter.  That takes practice. 

Even once you become a carpenter and are good at it - you may still not be able to build a house... Again, that takes practice! 

 

So with me - I have written most of my life and finally sat down to write a novel length story.  It was fantastic fun.  Once ready to share it - I found four friends willing to read the first chapter and I sent it out, expecting to hear from them asking for more. 

 

 

... 

 

 

 

Silence 

 

 

... 

 

 

 

What a fabulous gift!  (it took a while to get over my wounded pride to realize how valuable that non - response was) 

 

---   ---   ---

 

Edit: (wink)

Moving this here: 

  If you want to continue.  I don't want to derail Science talk or Spacescifi's thread.

Edited by JoeSchmuckatelli
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10 hours ago, JoeSchmuckatelli said:

Neither were / are the Japanese.  That was absolute desperation on their part, fearing wholesale annihilation.  I doubt modern Japanese would repeat that tragedy.

I've heard it claimed that the Japanese did the math and determined that bombing capital ships was so incredibly dangerous that they would lose less pilots/planes per ship sunk/seriously damaged than using conventional tactics.  Of course, the Japanese military was even more rigidly bureaucratic than most militaries, so that once such a decision was made it was etched in stone and attacking capital ships would be done kamikaze style.  The US lost  35 torpedo bombers alone at Midway (although shooting them all down meant that the sky was clear for the dive bombers).  The kamikaze program might have been tragic, but it wasn't "Charge of the Light Brigade" crazy.

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23 minutes ago, wumpus said:

I've heard it claimed that the Japanese did the math and determined that bombing capital ships was so incredibly dangerous that they would lose less pilots/planes per ship sunk/seriously damaged than using conventional tactics.

I think it was an emotional decision rather than calculated.  The 'calculation' part being how they justified the decision, but the decision isn't something that you can usually put a positive spin on.  The wiki puts it this way:

Quote

 

The attacks began in October 1944, at a time when the war was looking increasingly bleak for the Japanese. They had lost several important battles, many of their best pilots had been killed, their aircraft were becoming outdated, and they had lost command of the air. Japan was losing pilots faster than it could train their replacements, and the nation's industrial capacity was diminishing relative to that of the Allies. These factors, along with Japan's unwillingness to surrender, led to the use of kamikaze tactics as Allied forces advanced towards the Japanese home islands.

The tradition of death instead of defeat, capture, and shame was deeply entrenched in Japanese military culture; one of the primary values in the samurai life and the Bushido code was loyalty and honor until death

 

There was a traditional underpining in the culture (of death before failure), desperation and existential fear that led them to try this.  Again, as I wrote above, I don't think we see that again - until/unless some nation feels like its very existence is at risk.  It's like the suicide bombers in the Middle East - acts of emotional desperation that rational people don't normally do... and the victims (kamikaze/bombers) are the young and impressionable, not the leaders.

Edited by JoeSchmuckatelli
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9 minutes ago, JoeSchmuckatelli said:

 

There was a traditional underpining in the culture (of death before failure), desperation and existential fear that led them to try this.  Again, as I wrote above, I don't think we see that again - until/unless some nation feels like its very existence is at risk.  It's like the suicide bombers in the Middle East - acts of emotional desperation that rational people don't normally do... and the victims (kamikaze/bombers) are the young and impressionable, not the leaders.

Ironically, that's actually not true anymore even for suicide bombers. Someone who believes in the cause strongly enough to walk around wearing a bomb, is more valuable now as a leader inspiring others to fight than as a 1-shot guided munition. So they wear their suicide vests as a badge of their dedication to the cause, but are rarely authorized to actually attack.

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