For Questions That Don't Merit Their Own Thread

[magnemoe]

4 hours ago, DDE said:

That's a Saiga, a 12-gauge Kalashnikov.

Ok. thought the magazine looked weird. 

[StrandedonEarth]

Ok, here's one. After reading an article that stated that it's cheaper to develop new solar/wind power (with batteries) than to keep existing coal-fired power plants running, that made me think that coal is on it's way out, to the detriment of communities that rely on it. But commuters that deal with seemingly endless coal trains would rejoice... or would they? It's my understanding that the coal trains around here carry metallurgical coal (few undesirable impurities) to be exported for steel-making. After all, even if made in an electric-arc furnace, a key ingredient of steel is carbon.  Which begs the question: Can other sources of carbon, such as carbon dioxide, be used for steel-making?

Tangentially-related side note: Poor-quality imported steel on the outrigger legs  of a concrete-pumper was blamed for an accident that killed a construction worker here a few years ago.

E: Quora.com says not in any significant industrial quantity, except maybe with carbon electrodes in the electric furnace, which could be expensive,

Edited July 6, 2020 by StrandedonEarth

[K^2]

The first step in making steel is making pig iron. That is followed by all kinds of purification steps to make high quality steel. How you make pig iron has little effect on quality of steel you're making - any quality of pig iron will require purification and burning off excess carbon. So I wouldn't worry about quality of steel degrading due to coal becoming more expensive.

And yeah, you can substitute coal with pretty much any carbon. Charcoal has been historically used, and while there were a lot of benefits of switching from charcoal to coke, most of these can be rectified with modern industrial processes. So bio-sourced carbon is definitely on the table. Air capture would be very expensive, but if carbon tax is implemented, we might have a market for carbon captured from industrial waste. Turning CO2 into carbon you can use in metallurgy is a bit of a process, but it's definitely an option. All that said, I suspect we'll be sticking with fossil fuels for blast furnaces for quite a while still.

[kerbiloid]

By having a lot of electric power from any source, you can avoid using carbon at all, by heating the rock up to ionization temperature and sorting out the ions of the required metals.

This method requires a lot of energy and provides excessive purity for excessive cost, so currently has limited usage, just for chemically pure metals.

But when your society has developed recycling industry, and when you force them to unmaterialize their needs (virtual books and paintings, electronic walls and tables, augmented reality instead of casual single-use things, microclimate instead of excessive clothes etc.), you need less and less raw materials, mostly recycling the unused things.

So, the more developed is your society, the less raw ore you need to reduce. And the plasmatic method becomes enough productive to fulfil your limited needs in it.
Also, it allows to use any material as a source, makes no difference between ore and scrap, and  ore and random stone, so can be used for limited metal production on other celestial bodies without building industrial plants there.

Of course, this means that the modern fansy separated collection of waste is a temporary ecoish heresy, because all of them should be put on fire and ionized (together with their microbes, viruses, and toxines), then collected.
The iron-containing stones, including ore, can be thrown there, too, together with broken metal things.
Just first you heat the mess a little to remove all organics and turn it into water, nitrogen, and coke, then heat up to extract the metals.

Then you get a green civ with just several ore mines per continent, and local recycling plants instead of the metallurgical industry.

Of course, this requires energy, so it's more important to establish controlled living space and virtualise the daily needs as much as possible, than struggle against the carbon dioxide and global warming.
And this will cease the economics in the modern sense of it.
So, it will happen automatically when the industry and farming has gotten fully automated, most of people are living off the basic income rather than salary (because there is no salary when robots do the work for you), i.e. several (a couple of?) decades later.

Edited July 6, 2020 by kerbiloid

[ARS]

Does fixed forward mounted weapon makes sense for space warship?

In a lot of science fiction, there's bound to be a ship with gigantic forward mounted weapon that can only be aimed by reorienting the whole ship like WW2 era tank destroyer. These weapons tend to be very powerful (as in, fleet-melting level) or just plain necessary when dealing with slow moving capital ships in space warfare where ordinary guns and missiles has no effect on them

The reason that I get is that, due to it's power, these weapons tend to be large, thus making turret mount impossible, so it's placed as spinal mount. If anything, the space environment also supports the placement of such weapon since it's easier to orient large structure in space by using RCS thrusters

[K^2]

I think it might, actually. With tech we either have or are reasonably certain about, combat isn't going to be an up close dog fight. It's going to be ships lobbing missiles at each other from very, very far away. In which case, building a ship around a massive railgun seems like a way to go. I just can't think of anything that trumps that. A rocket seems like it's only going to be useful on terminal run. Firing engines early on is just another way for your opponent to have early warning. Yeeting a small missile at high acceleration from a railgun gives you best chances of surprising enemy fleet, and the missile can use small rocket engine to make final course corrections with insufficient warning for enemy to do anything about it. Then you just go for a kinetic kill, and that's all she wrote. Given that time between firing the missile and it punching holes in the other guys' hulls is going to be measured in hours if not days, the fact that it might take a few minutes to aim the main gun by rotating the entire ship seems insignificant.

[Spacescifi]

14 minutes ago, ARS said:

Does fixed forward mounted weapon makes sense for space warship?

In a lot of science fiction, there's bound to be a ship with gigantic forward mounted weapon that can only be aimed by reorienting the whole ship like WW2 era tank destroyer. These weapons tend to be very powerful (as in, fleet-melting level) or just plain necessary when dealing with slow moving capital ships in space warfare where ordinary guns and missiles has no effect on them

The reason that I get is that, due to it's power, these weapons tend to be large, thus making turret mount impossible, so it's placed as spinal mount. If anything, the space environment also supports the placement of such weapon since it's easier to orient large structure in space by using RCS thrusters

 

I cannot speak for fictional weaponry, but regarding real weapons it depends on the type of weapon.

Railgun: You could mount a spinal rail down the core of your ship for extra firepower. Longer rail equals longer acceleration/thrust for projectiles fired.

Coilguns: Same idea, but better since you are not damaging the coils as you fire, which I read does happen with railguns if what I read is true.

Lasers: You don't need a spinal mount, they turret just fine. So completely optional.

Edited July 6, 2020 by Spacescifi

[DDE]

8 minutes ago, ARS said:

Does fixed forward mounted weapon makes sense for space warship?

Well, let's start by saying that the only gun ever mounted on a spacecraft, a modified Richter R-23 revolver autocannon, was a fixed mount.

9 minutes ago, ARS said:

that can only be aimed by reorienting the whole ship like WW2 era tank destroyer

Stop it right there. The gun on those was not fixed, it merely had limited traverse. This is an important distinction relative to the Swedish S-tank, which does have to make fine aiming adjustments using the suspension.

Bow to me, Swede!

Good boy.

They did, however, eschew a rotating turret, which was a major weight-saver. E.g. the StuG III mounted the same gun as the much heavier and more expensive Pz IV.

The same probably applies to spacecraft whenever you're dealing with an elongated weapon: you could theoretically have one part of the ship (the gun) swivel around the entire other half, but it would be difficult.

Then there's recoil. From what little I understand about structural engineering, it's easier to design against loads with a uniform direction - and it's definitely easier if that direction is down the longitudinal axis already reinforced against thrust loads. A powerful enough gun could snap a spaceship in half.

[magnemoe]

19 minutes ago, ARS said:

Does fixed forward mounted weapon makes sense for space warship?

In a lot of science fiction, there's bound to be a ship with gigantic forward mounted weapon that can only be aimed by reorienting the whole ship like WW2 era tank destroyer. These weapons tend to be very powerful (as in, fleet-melting level) or just plain necessary when dealing with slow moving capital ships in space warfare where ordinary guns and missiles has no effect on them

The reason that I get is that, due to it's power, these weapons tend to be large, thus making turret mount impossible, so it's placed as spinal mount. If anything, the space environment also supports the placement of such weapon since it's easier to orient large structure in space by using RCS thrusters

For some weapons it might like, an gun who is very long or have strong recoil works best this way, think an coil gun, rail gun or an particle accelerator gun. Remember you can rotate you ship freely. Downside is that your will not be able to dodge unless you have very engine class side trusters and even this will mess up aiming a bit. This would be for long range or bombardment only, at closer range this gun will become more and more useless. 

Most lasers has no issue with turrets as you can use mirrors, missiles don't need turrets smaller guns you want in turrets as they will mostly be close in weapons. One idea might be to launch missiles with the coilgun as an free first stage. 

Fun fact the US navy ones thought about having an cannon pointing straight up An study of shooting very long range smart shells found that best was shooting pretty much straight up and turn over high in the atmosphere so just point it straight up. Benefit was that recoil was much easier to handle, ammo handling was also easy, as most of the mass was deep down in ship you could even start thinking about larger guns, downside was that it could only fire smart shells at long range while naval guns are very nice at closer range so you must have both.  

[kerbiloid]

A bullpup cruiser, with main gun from the rear end with reactors to the nose.
Gimballed and +/- 5° adjustable.

Especially usable when the enemy is far, so occupies a narrow angle close to the cruiser direction, to attack it on oppoiste course, or chase it when it runs.

Also to support assault troops.

Edited July 6, 2020 by kerbiloid

[DDE]

5 hours ago, magnemoe said:

Fun fact the US navy ones thought about having an cannon pointing straight up

Not just them. Once the Soviets decided that Pr 956 Sarych ('Sovremenny') would be a gun-focused destroyer, they floated everything from navalized versions of these

Spoiler

to a vertical 406 mm gun/missile launcher (for a military with 125 mm missile-compatible guns on their tanks this wasn't far-fetched)

Spoiler

 

Spoiler

 

[sevenperforce]

Funny...

https://xkcd.com/2328/

By this I assume that the odds of a meteor passing through that hoop from space are 0.3^30?

A standard hoop is 280 square inches.

That is 1/2.824e15 the surface area of Earth.

500 meteorites reach the surface of Earth per year.

Thus, on average, it will take 5.648 trillion years for a meteor to fall through any particular 280-square-inch region on Earth's surface.

1/0.3^30 = 4.86e15 , so on average Randall will take that many shots before he gets 30 in a row. So he needs to make 860 attempts per year or about 2.4 attempts per day to break even.

 

 

[Spacescifi]

How would the plume of an antimatter or nuclear thermal water propelled rocket look?

My guess is a bluish whitish plume with a lot of white vapor in atmophere, but in space you will just see plume, and not as much plume as in atmospheres.

 

What is the most correct answer? Thanks.

Edited July 6, 2020 by Spacescifi

[JoeSchmuckatelli]

18 hours ago, DDE said:

Well, let's start by saying that the only gun ever mounted on a spacecraft, a modified Richter R-23 revolver autocannon, was a fixed mount.

Stop it right there. The gun on those was not fixed, it merely had limited traverse. This is an important distinction relative to the Swedish S-tank, which does have to make fine aiming adjustments using the suspension.

Bow to me, Swede!

Good boy.

They did, however, eschew a rotating turret, which was a major weight-saver. E.g. the StuG III mounted the same gun as the much heavier and more expensive Pz IV.

The same probably applies to spacecraft whenever you're dealing with an elongated weapon: you could theoretically have one part of the ship (the gun) swivel around the entire other half, but it would be difficult.

Then there's recoil. From what little I understand about structural engineering, it's easier to design against loads with a uniform direction - and it's definitely easier if that direction is down the longitudinal axis already reinforced against thrust loads. A powerful enough gun could snap a spaceship in half.

Well - the STRV is a fun example to bring up, but a closer analog from aerospace would be the A-10.  They basically took a tank killing gun and built a plane around it. It's a fantastic airframe and purpose built weapon system. 

 

Too bad the AirFarce doesn't care about ground attack aircraft = not sexy enough... If they did perhaps they might spend a bit of time teaching their pilots what USMC ground combat vehicles look like. 

[kerbiloid]

An antimatter water propelled rocket would look like a bright bluish flash before the retina had gone from UV.

[ARS]

Does attempting to fire a supercapacitor-equipped portable railgun while underwater counts as high tech scientific equivalent of "suicide by toaster in the bathtub"? Joke aside, is it even possible to fire a railgun underwater?

[K^2]

3 minutes ago, ARS said:

Does attempting to fire a supercapacitor-equipped portable railgun while underwater counts as high tech scientific equivalent of "suicide by toaster in the bathtub"? Joke aside, is it even possible to fire a railgun underwater?

Yes, railgun will still fire. Water isn't THAT conductive, even sea water, and path of least resistance will still be through the projectile. Efficiency might drop both due to resistance and to some of the current flowing via other paths. It might also fry control systems or the capacitor itself, as it's likely to draw more current than normal shot.

And just like toaster in the bathtub, it's not inherently deadly. There still needs to be a reason for current to travel through your body. It doesn't take a lot of current through human heart to stop it, and there is going to be quite a bit flowing through water, but the electromotive forces are going to rapidly decay away from the rail, and you still need to create a potential across the heart, which would take some unfortunate positioning of things. I wouldn't feel confident firing a railgun under water just for the hell of it, but if it's a life-or-death situation, I'd probably take the risk.

[DDE]

10 hours ago, JoeSchmuckatelli said:

Well - the STRV is a fun example to bring up, but a closer analog from aerospace would be the A-10.  They basically took a tank killing gun and built a plane around it. It's a fantastic airframe and purpose built weapon system. 

They weren't exactly the first. One of the three options for gun mounting in the WWII era was firing through the propeller shaft.

Enter the Aerocobra with a 37 mm gun.

It achieved a surprising popularity amongst the Soviets, who did foray into even bigger guns on Lavochkin fighters (45 mm), and bigger (MiG-8 prototype, 57 mm) and then some more (B-29 Superfotress clone, fighter variant, 100 mm). It's due to the bitter aftertaste from those that, over on this side of the barricades, we consider A-10 a try-hard built by Hans Rudel fanboys.

Spoiler

Ha-ha, rokkits go "fwoosh-fwoosh-fwoosh"

10 hours ago, JoeSchmuckatelli said:

Too bad the AirFarce doesn't care about ground attack aircraft = not sexy enough...

Yeah, SOCOM has to get involved to keep any CAS aircraft around in an era which should be seeing a CAS renaissance.

Spoiler

 

[kerbiloid]

Harry greets you

Spoiler

 

 

[Spacescifi]

 

Space Nukes:

After reading Arthur Clarke's Superiority short story, it had me wondering if there is any real life thing that could imitate the destructive capabilities of the the hundreds of kilometers of destruction radius bomb in SPACE that was in the story.

I think there is... use an antimatter bomb that has a literal ton (thousand kilograms) of antimatter.

I don't know how far the damage blast radius is, but I reckon it would be farther than 3 kilometers as with nuclear weapons in space.

Basically, if you have missiles with energy levels this high, you NEVER do close combat... because if that misdile detonates within even a few kilometers of your own your vessel will either be dead or nearly so.

 

Am I right or wrong?

For all I know the damage radius may still be similar to a nuke (3 kilometers), only the amount of damage taken by any effected vessels within the radius is far more serious and potentially deadly.

 

So which is it? Thanks.

[DDE]

19 minutes ago, Spacescifi said:

Am I right or wrong?

On a basic level, you're wrong. The design of a weapon does not necessarily provide for a premature, accidental release of its full destructive power. This is a notorious misconception with regard to nuclear and thermonuclear weapons - it's nigh-impossible for them to release a proper blast by accident or from outside damage. Low-sensitivity conventional explosives and solid fuels are also all the rage these days. And you can cook on C4, just don't try to stomp out the fires.

An antimatter warhead, however, is an example of a weapon that goes off at full power damage when shot. Or kicked. Or sneezed on. Which is why it's such a poor proposition as a weapon - never mind the financial and energy inefficiency of a pure antimatter explosion compared to some antimatter-fusion-fission combo.

Edited July 8, 2020 by DDE

[Spacescifi]

48 minutes ago, DDE said:

On a basic level, you're wrong. The design of a weapon does not necessarily provide for a premature, accidental release of its full destructive power. This is a notorious misconception with regard to nuclear and thermonuclear weapons - it's nigh-impossible for them to release a proper blast by accident or from outside damage. Low-sensitivity conventional explosives and solid fuels are also all the rage these days. And you can cook on C4, just don't try to stomp out the fires.

An antimatter warhead, however, is an example of a weapon that goes off at full power damage when shot. Or kicked. Or sneezed on. Which is why it's such a poor proposition as a weapon - never mind the financial and energy inefficiency of a pure antimatter explosion compared to some antimatter-fusion-fission combo.

 

I was not asking about nukes in space.

I used the term space nuke because AM armed missiles would be LIKE as damaging if not more so than nukes are in atmosphere... only in space.

So that was the question...  one thousand kilogram AM bomb damage range blast radius... farther than 3 kilometers I reckon?

How far?

And as I write scifi I am not deterred by modern limits on antimatter production. It is just solved as I wish.

More concerned with the bomb's effectiveness.

Edited July 8, 2020 by Spacescifi

[kerbiloid]

17 minutes ago, Spacescifi said:

So that was the question...  one thousand kilogram AM bomb damage range blast radius... farther than 3 kilometers I reckon?

43 000 Mt?
Yes, it's farther than 3 km.

18 minutes ago, Spacescifi said:

How far?

~500 km.

[Spacescifi]

11 minutes ago, kerbiloid said:

43 000 Mt?
Yes, it's farther than 3 km.

~500 km.

 

Wow... thank you.

 

So at what range would a steel space vessel be icinerated? Three or 20 kilometers?

At what range could a steel vessel survive with a charred hull? 500 kilometers? 550? 600?

Thanks.

[kerbiloid]

Without exact construction may vary from hundreds to hundreds of thousands kilometers, mostly due to the crew irradiation.

So, a ship with AM charges will be the primary target for the enemy fire, and the first destroyed AM ship will destroy all its fleet.

Edited July 9, 2020 by kerbiloid