Relativity

tlb wrote:

kzt wrote:The NATO standard for air defense statuses is:
Weapons Hold, where you don’t engage a target even if hostile without further orders
Weapons Tight, where you can engage targets positively ID as hostile without further orders
Weapons Free, where anything not identified as friendly may be engaged without further orders
So at weapons free anything inbound that isn’t ID as friendly will get shot at as soon as the system prioritizes it in the queue and it’s reaches the right range.

That is how you can get the incident in 3 July 1988. Under orders issued after the USS Stark was hit by missiles a year earlier, essentially designed to err on the side of protecting US lives -- and with just minutes to decide if his vessel was within range of missiles carried by an Iranian warplane -- the captain of the guided-missile cruiser USS Vincennes gave the order to fire.

Seven minutes after takeoff, the Iran Air Airbus A300 was struck by surface-to-air missiles fired from the US cruiser. The US military later called it "a tragic and regrettable accident after "US Navy investigations of the incident showed the Iranian airliner was in an approved commercial airway and was identifying itself on air traffic control frequencies as a civilian flight.

Without fighters in the sky to intercept and identify the plane as a passenger jet, there was no alternative.

ThinksMarkedly wrote:

Jonathan_S wrote:These ships are designed to bring up their defenses really quickly and the defenses are initially mostly under computer control - so you really just need a couple crew to hit the "defenses activate" buttons and the tac computers will get busy firing them. It may take several minutes to get everything to full effectiveness (hard to pick the optimal ECM or counter-ECM if you aren't sure who's shooting at you or given several salvos to analyze their response. But the basic sidewalls up, PDLCs and CM active and firing, can be done by normal watch crew in seconds.
This isn't WWII where people have to run to physically man the AA guns before they can begin firing back.

When I briefly worked on Safety Critical software development, I was told that the US Navy warships' point defence reaction time is 15 milliseconds. I understood that to be the time between radar confirming incoming bogey to commanding the PD weapons to move to aim. I don't know if the actual firing needs a human to press a button and don't know how long the guns take to physically move.

Identifying isn't difficult. What else could there be moving at high speed (or high accel) on an intercept course except a hostile missile or projectile? The problem is mis-identifying due to faulty sensors or data processing. A false positive means you identify something innocent as a hostile and shoot some poor people or property down. A false negative means you fail to identify a threat -- this is usually the province of ECM.

Here's another possible HH weapon: a gravitic rail gun that fires a massive projectile (1 tonne of depleted uranium, for example) at 0.5c. At light-seconds away, that's just 6 seconds from launch to impact. The projectile itself radiates no energy; depending on its shape it can also have a very small radar/lidar profile. Because of those two factors, it might confuse the crews and computers long enough to make the impact inevitable. By that I mean that there's not enough time to fire a CM which rotates to present its wedge to the projectile; and the sidewalls may not rise up fully in time to make it go "fzzt."

Of course, the physics of such a rail gun would require quite a bit of handwavium. If it is a spinal mount on a 10-km long ship, the projectile would need to accelerate for 266.85 ms, at a whopping 57.2 billion gravities. If you think that's a big number, consider this: ignoring relativity, a projectile of 1 tonne would have a kinetic energy of 11.2 billion gigajoules. And since this was all discharged over 266.85 ms, that's a power generation of at least 84 billion gigawatts. Or 0.02% of the power output of the Sun.

With this amount of energy dumped into it, the projectile might come out of the rail gun as a blob of plasma. Which would make it an energy torpedo.

kzt wrote:The NATO standard for air defense statuses is:
Weapons Hold, where you don’t engage a target even if hostile without further orders
Weapons Tight, where you can engage targets positively ID as hostile without further orders
Weapons Free, where anything not identified as friendly may be engaged without further orders
So at weapons free anything inbound that isn’t ID as friendly will get shot at as soon as the system prioritizes it in the queue and it’s reaches the right range.

tlb wrote:That is how you can get the incident in 3 July 1988. Under orders issued after the USS Stark was hit by missiles a year earlier, essentially designed to err on the side of protecting US lives -- and with just minutes to decide if his vessel was within range of missiles carried by an Iranian warplane -- the captain of the guided-missile cruiser USS Vincennes gave the order to fire.

Seven minutes after takeoff, the Iran Air Airbus A300 was struck by surface-to-air missiles fired from the US cruiser. The US military later called it "a tragic and regrettable accident after "US Navy investigations of the incident showed the Iranian airliner was in an approved commercial airway and was identifying itself on air traffic control frequencies as a civilian flight.

Without fighters in the sky to intercept and identify the plane as a passenger jet, there was no alternative.

Jonathan_S wrote:Well, given the systems of the day and what the crew thought they were seeing. There were apparently some issues with how the data was presented that caused the crew to misunderstand what the computers were telling them the plane was doing; leading them to think it was on a much more aggressive flight profile. Improved presentation of data would likely have avoided the incident.

But that's a downside of taking an air defense system, Aegis, designed to deal with waves of Soviet cruise missiles in the mostly empty mid-Atlantic and stick in very close to an unfriendly nation is a very constricted and very high air traffic area. It wasn't designed to show all that nuance as that wasn't a design goal given its expected uses.

kzt wrote:The NATO standard for air defense statuses is:
Weapons Hold, where you don’t engage a target even if hostile without further orders
Weapons Tight, where you can engage targets positively ID as hostile without further orders
Weapons Free, where anything not identified as friendly may be engaged without further orders
So at weapons free anything inbound that isn’t ID as friendly will get shot at as soon as the system prioritizes it in the queue and it’s reaches the right range.

tlb wrote:That is how you can get the incident in 3 July 1988. Under orders issued after the USS Stark was hit by missiles a year earlier, essentially designed to err on the side of protecting US lives -- and with just minutes to decide if his vessel was within range of missiles carried by an Iranian warplane -- the captain of the guided-missile cruiser USS Vincennes gave the order to fire.

Seven minutes after takeoff, the Iran Air Airbus A300 was struck by surface-to-air missiles fired from the US cruiser. The US military later called it "a tragic and regrettable accident after "US Navy investigations of the incident showed the Iranian airliner was in an approved commercial airway and was identifying itself on air traffic control frequencies as a civilian flight.

Without fighters in the sky to intercept and identify the plane as a passenger jet, there was no alternative.

Jonathan_S wrote:Well, given the systems of the day and what the crew thought they were seeing. There were apparently some issues with how the data was presented that caused the crew to misunderstand what the computers were telling them the plane was doing; leading them to think it was on a much more aggressive flight profile. Improved presentation of data would likely have avoided the incident.

But that's a downside of taking an air defense system, Aegis, designed to deal with waves of Soviet cruise missiles in the mostly empty mid-Atlantic and stick in very close to an unfriendly nation is a very constricted and very high air traffic area. It wasn't designed to show all that nuance as that wasn't a design goal given its expected uses.

Theemile wrote:There is an additional component to this - the Iraqi jet which fired on the Stark was a modified Dassault Falcon passenger jet Modified, that is with Mirage 2000 firecontrol, radar, and missile hardpoints. (the 2 planes, it turns out, are closely related and share many components, allowing for an "easy" conversion of the business jet). The plane was squawking a commercial transponder when it fired the missiles. Intel indicated that the Iranians might have similar capabilities - or might modify a F-14's electronic warfare package to look like an airliner.

Jonathan_S wrote:
Now a weapon with basically the characteristics he wants does exist - a few million km range, 0.9c over its entire range, and as a bonus no FTL grav signature reducing the target's warning time still further. Too bad that weapon is the energy torpedo; and thus utterly worthless against an intact sidewall.

Theemile wrote:

Jonathan_S wrote:
Now a weapon with basically the characteristics he wants does exist - a few million km range, 0.9c over its entire range, and as a bonus no FTL grav signature reducing the target's warning time still further. Too bad that weapon is the energy torpedo; and thus utterly worthless against an intact sidewall.

Which brings me around to a question that occurred to me about a month ago.

Contact nukes in a "burn" mode set off an explosion about 5-10K km from the target ship, sending a gravity focused plasma jet into the target's sidewalls in the hope of overloading one and burning out the generator.

However, a Energy torp is essentially the same thing - a magnetically contained jet of plasma fired at a target.

The nuke MAY burn out a sidewall generator - the plasma torp will hit the sidewall and fizzle out, with no chance of doing damage to the sidewall.

Shouldn't an E-torp (or enough of them firing over a period of time) have chance of overloading a sidewall? Burn nukes are not supposed to be used against ship's hulls as they cannot do sufficient damage - where as an e-torp shreds capital ships when they are not protected by a sidewall.

What am I missing?

In Fire Forged: An Introduction to Modern Starship Armor Design wrote:The point defense laser cluster created the final layer of light speed defense that resulted in the now familiar geometrically increased chance of the missile being destroyed in the last 50,000 to 60,000 km of its run. Hits against intact defenses became rare. This relegated the impeller drive missile to a counter sidewall role in which the best that could typically be achieved was a close aboard detonation of a multiple missile salvo to burn out sidewall generators and soften the target up for an energy range attack. Sidewall burning was in fact the end to which the largest pure fusion weapons were built.

cthia wrote:In that era, it also could have been that to weaken the sidewalls you had to get enough hits on the same area of the sidewalls to affect a particular generator. The smaller salvos during that time would have been problematic. It also could have a lot to do with time. A weakened sidewall generator could recover in time, after the surge of energy is dealt with and circuits reinitiated. I think Star Trek's shields somewhat work on the same principles.

Aside:
As I posted a page or so upstream, ramming should also blow out the generators.

Theemile wrote:Shouldn't an E-torp (or enough of them firing over a period of time) have chance of overloading a sidewall? Burn nukes are not supposed to be used against ship's hulls as they cannot do sufficient damage - where as an e-torp shreds capital ships when they are not protected by a sidewall.

What am I missing?

tlb wrote:That was the sort of thing that I was considering when I said there was no alternative, without fighters in the sky to intercept and identify the plane as a passenger jet.