Attacking Darius:

kzt wrote:Not really. Typical velocity will be under 30,000 KM/sec, so you can open fire at 90,000 KM and fire for three seconds, then two clouds of plasma pass through each other. Range at which you can burn-through a sidewall is highly unclear due to lack of data.

If you can arrange to engage against the front or rear that would be best. You can also engage against the rear where the range is continually opening as opposed to closing.

The geometry doesn't work. Mind the triangle of proportions 245 base by 150 height. If the missile is moving at 0.1c (30,000 km/s), in the three seconds it's firing it will have moved 90,000 km longitudinally. For the first and last photons to clear the wedge and strike a ship in the exact centre, the missile at the closest point will be at 90000 * 150 / 245 = 55102 km. If it passes any closer or any faster, some photons from the graser will be spent on the wedge. That's 0.18 light-seconds at the closest approach and 71142 km (.23 ls) at the beam's start and end, so the torpedo will have difficulty keeping the beam on-target if it has to keep a 4 rpm average rotation of the entire body and has 0.2 light-second lag. Not impossible, but difficult.

Those numbers are for the ship turned exactly perpendicular to the torpedo's vector of motion. That's a reasonable assumption only if the torpedoes have been detected and are all coming in one axis. Detecting them is not impossible, because there will be a shell of LACs and escorts around the big guys, and intercepting a weapon at a mere 0.1 c (less than an SDM) is doable. Single axis is more of a stretch because the attack could attempt a time-on-target, which is not easy against an enemy that is changing their velocity, but not impossible either. Then there's the question of whether the ships can turn quickly enough.

Anyway, this was an average calculation. Some torpedoes will be luckier and some will be less lucky if they pass towards the throat of the wedge instead of towards the kilt.

What makes you think the torpedo will be moving at 30,000 km/sec? If it could do that it would just directly attack. Say it is moving at 5000 km sec perpendicular to the trajectory of the ship. It crosses behind it a 10,000km and starts firing. This would put it about 10,000 km to the flank, so when it gets done it’s about 10,000 km on the other side and 100,000 km behind. Well inside the kilt.

kzt wrote:What makes you think the torpedo will be moving at 30,000 km/sec? If it could do that it would just directly attack. Say it is moving at 5000 km sec perpendicular to the trajectory of the ship. It crosses behind it a 10,000km and starts firing. This would put it about 10,000 km to the flank, so when it gets done it’s about 10,000 km on the other side and 100,000 km behind. Well inside the kilt.

I don't think it can get to 0.1c. That was just a low speed that is the minimum reasonable. The torpedo still requires 5.66 hours to get to that speed and 306 million km (17 light-minutes). And this is if it makes a straight-line trajectory. To make a multi-axis time-on-target attack, you need multiple curves which means a longer time but possibly they can do it in a shorter direct distance. Can't think right now of how the formula for that would be, but it sounds about right.

So, yes, let's say it's moving at 5000 km/s relative to the ship's own motion. In terms of the orientation of the ship, I don't agree it could approach from an aspect of its choosing, unless it's a time-on-target attack from multiple axes. If it's from a single one, the threat may have been detected, even if just a shadow of a detection, which means the ship will orient its wedge towards the direction the threat is coming from. Moreover, there are multiple ships and multiple torpedoes that can't all reach their targets at the same time. Some of them have to open fire first, lest they be detected when they get close enough to the ships they are not firing upon on the way to the one they want to fire upon.

But even if the ship can't complete the manoeuvre to interpose the wedge, the torpedo can't wait for the closest approach to fire. No torpedo or missile does that, because that would mean it's spending an eternity within sensor range and point-defence basket. Let's calculate: if it's only moving at 5000 km/s relative to the ship, the firing pass will span 15,000 km relative; if it will make the closest approach at 10,000 km, that means the closest firing pass starts when it's 12,500 km from the ship and lasts until it's again at 12,500 km from the ship. Unfortunately, to get there, it's been within 30,000 km for 4.15 s.

So, no, it won't wait for the best shot to fire. It may not start firing when the wedge is clear, but it will start firing before it reaches 30,000 km, probably even 50,000 km, to avoid being intercepted. That's way too close even for MAN stealth. More importantly, the MAN has no way of knowing how far the GA sensors can burn through their stealth until they launch their first attack, which means this first attack must err on the side of caution and fire early.

But we go back to the problem of wedge interposition, the fact that the torpedoes will arrive with very low relative velocity, and the fact that they have to cross a shell of Ghost Riders and LACs before getting to the capital ships. At 5000 km/s relative, that means 41.6 seconds within 1 light-second of the ships it means to target, which also means it must have passed close to GRs a minute earlier than that or worse.

And at 30,000 km/s relative, that means the torpedo salvo must have been launched 5.6 hours before. And they still spend 10 seconds within 1 light-second.

Honorverse large ships, like SDs, maneuver like garbage scows. They take minutes to turn. And given that the ship in this situation is moving at 0.1C, at a minute ago it was 1.8m km away. So it's not going to doing much maneuvering if it detects something five seconds early. That would certainly be undesirable, but it's not alone going to save them.

I have no idea what is planned, but if I were in charge I'm be producing a whole lot of cheap semi-stealthy objects to keep the RMN busy. Probably not using the spider drive, as that is sensitive, but doing something that is calculated to produce barely detectable targets. Which also hopefully makes the RMN refine their system AI to detect these and not the real threats.

kzt wrote:Honorverse large ships, like SDs, maneuver like garbage scows. They take minutes to turn. And given that the ship in this situation is moving at 0.1C, at a minute ago it was 1.8m km away. So it's not going to doing much maneuvering if it detects something five seconds early. That would certainly be undesirable, but it's not alone going to save them.

It doesn't start turning when the torpedo crosses the 30,000 km range. It starts turning when the Ghost Riders a million km out (or more) do. That means they've had most of a minute to turn. The manoeuvre won't be complete, but the starting angle won't be the worst either. Something is better than nothing.

This is assuming the GRs didn't detect something incoming even further out. TEiF spoilers required to discuss this.

I have no idea what is planned, but if I were in charge I'm be producing a whole lot of cheap semi-stealthy objects to keep the RMN busy. Probably not using the spider drive, as that is sensitive, but doing something that is calculated to produce barely detectable targets. Which also hopefully makes the RMN refine their system AI to detect these and not the real threats.

Indeed. Just throw more of them. Earlier this thread we speculated just how many there could be, to a couple thousand.

I think TEiF throws those numbers out the window.

tlb wrote:At Darius, the graser torpedoes will be on spider drives and so will not be visible in the same way.
Careful, this might be a leak of something as yet unread by many.

No. The first wave wasn't detected because of it's drive, but because it was disturbing the interplanetary medium. A spider torp would be detected the same way at the same distance.

tlb wrote:Thinking about it for a bit, consider that it is impossible to make a quick right angle turn in space (** see below); so zigzagging a single ship might not be as effective as you think. Sure you can change the orientation of the ship ninety degrees and begin accelerating in a new direction; but you still have the original velocity that you built up and your ship will continue on that merry way until your new acceleration kills the old velocity. It's not like a car which uses friction with the ground to facilitate maneuvers, nor a ship on the sea. In fact a big ship at sea can have a very large turning radius, even with the resistance of the water.

** Actually you can make a space ship do a perfect slow right turn, but only by reversing the ship and coming to a complete stop; then rotating ninety and accelerating off.

AFIAK nobody's suggesting making a right angle turn.

Honorverse drives are very powerful. Anything in the fleet can easily produce 5000 m/s^2. Lets say your attacker is 1 light second away and is trying to aim at your ship. 1 second for the image of where you are to reach the warhead, 1 second for the warhead's beam to come back. In that time the ship can move 1/2 * 5000 m/s (a) * 2^2s (t) = 10,000 m. That's a circle with an area of 79 km^2 while even a waller has a profile of no more than .3 km^2. In other words, a 1 in 250 chance that attacking a point actually hits. A graser torp with a clean attack fares better, by spraying the beam around it can get it on target for about 10 milliseconds.

However, as has been noted wedges will be rolled, it won't have a clean attack and will in practice have to settle for a flyby. The chances of a hit are maximized if it sweeps it's beam across the inside of the wedge as it bears but this still around 1% if the ship has a free choice of orientation against the graser.

Even if you limit the amount the ship can zig to less than this the lightspeed lag is an incredible handicap for long range energy engagements.

Reality: The graser torp is a devastating ambush weapon but little better than an ordinary missile (by giving up the range advantage it has) against a knowledgeable foe. To End in Fire got it very, very wrong.

ThinksMarkedly wrote:I agree for baseline changes. For routine evasions, we haven't heard anything but we know they're doing it. We know the ship does move inside the wedge, but we haven't ever heard anyone calling for it. We also haven't heard the useless call from the CO to implement evasion manoeuvres, like we hear on Star Trek a lot. Evasion shouldn't be opt-in, a second thought. It should be SOP.

Note, though, that if you're evading hard you're giving up drive power. Occasionally that would be important.

ThinksMarkedly wrote:I was not talking about a right-angle complete change of direction, whether that's a right-angle step change or a slow turn. That's not the point. The point is that you can impart a perpendicular change to your base vector that is sufficient to make an aimed weapon miss you, if it can't compensate as fast.

The real issue is that energy weapons aren't seeking at all, they can't compensate at all. They have to lead their targets by twice the time light takes to cover the distance. Thus long range energy shots will have abysmal hit rates.

ThinksMarkedly wrote:Or maybe not. Maybe the regular missiles themselves aren't reorienting, only the warheads are. We know that during attack, the missile ejects the grav lensing before the body detonates to produce the energy that will be channelled into the X-Ray laser. We know the GA has independently-focusing lenses, multiple ones in each missile. So maybe the missile itself isn't reorienting, only those lenses do.

That's how I see it, also. The rods and associated equipment are ejected before detonation, the missile is ballistic at that point and there's no reason the rods can't turn to point at whatever they want. The missile never points.

In which case a 3-second graser may not be able to do it.

I don't think this will be relevant in the story, even if so.

If it can't point it's useless.