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What happens to all that debris?

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Re: What happens to all that debris?
Post by cthia   » Sun Aug 30, 2020 10:44 am

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Jonathan_S wrote:
cthia wrote:Forgive me for such a simple analogy. But if five bullets are shot out of a nine millimeter and the sixth shot causes the gun to explode, the five bullets should be found far away from the fragments of the explosion which are bringing up the rear, certainly if the event happened in the vacuum of space. Regardless of whether the gun is accelerating or decelerating. What am I missing?
Well there isn't enough space on the fore and aft hammerheads for lifepod tubes - so the ship isn't going to be firing the pod ahead of itself.
Also your analogy is missing the "gun" is accelerating so fast it'll quickly overtake the "bullet". Kind of like the F-11 Tiger which was the jet that was the first plane to shoot itself down (turns out it's dangerous to be about to fly fast enough to overtake your own bullets)

I'm assuming that the hammerheads and broadsides have little space for pod launchers (and the launch tubes would be massive weak spots in the armor for any ship heavy enough to carry it. So my default assumption is that they mostly fire out of the less armored and less exposed dorsal and ventral area. But that means that their launch velocity can't be all that high unless the ship has already dropped it wedge - because they need to cover less than 30 km up or down from the ship before falling out the kilt of the wedge.

So even though grav plates in the pods could theoreticlly let them safely launch at 100+ gees you can't risk clipping the ship's wedge.


As for heading to the planet, as I recall from HAE they'll head for a habitable planet if they can. But it's not just whether they're in the same system as one; it's whether they have the fuel to reach the planet and then safely land. If you eject while the ships are heading away from the planet at 0.1c or more the chemical thrusters on a pod are very unlikely to have the fuel to reverse that vector and then slow down again to safely approach the planet.

Got it. Except, the ship will cease to accelerate very shortly. Perhaps has already before the last pod escapes. I suppose its momentum can still carry it past the pods. Certainly not in the case of the fighter jet, though other factors apply. But still.

The gun stopped accelerating after it exploded.

Son, your mother says I have to hang you. Personally I don't think this is a capital offense. But if I don't hang you, she's gonna hang me and frankly, I'm not the one in trouble. —cthia's father. Incident in ? Axiom of Common Sense
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Re: What happens to all that debris?
Post by Brigade XO   » Sun Aug 30, 2020 11:23 am

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tlb wrote:
Brigade XO wrote:It isn't likely that a pod can dodge a missile which has been fired or- if it's beacon is damaged and for some reason a missile which has missed it's target manages pick up a pod as a target.

Would a missile even bother with a pod? It seems to me that a pod is in much more danger from the wedge of the missile than the laserhead, although blast created shrapnel from a missile explosion is another possible pod killer.

Also wasn't Michelle Henke's ship shooting at the enemy Haven ships at the same time her ship was being abandoned? That might not be be counter to the rules, but certainly seems counter to the spirit.


One of the bits of plot in Uncompromsing Honor was the intent by the next to last commander of the SLN commander at Hypatia System to specificaly target the life pods of the RMN ships after he had his command fire on the crippled remnants of the RMN squadron. That was by missile, not energy mounts.
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Re: What happens to all that debris?
Post by tlb   » Sun Aug 30, 2020 11:29 am

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cthia wrote:Got it. Except, the ship will cease to accelerate very shortly. Perhaps has already before the last pod escapes. I suppose its momentum can still carry it past the pods. Certainly not in the case of the fighter jet, though other factors apply. But still.

The gun stopped accelerating after it exploded.

The bullets from a gun are expected to be fast; but it is not clear how much velocity is imparted to a pod, given that its limited fuel supply might have to work to overcome a velocity that is too high. It might be better to give the pods a lower velocity and program the ship to accelerate away, putting most of the pods behind the ship (particularly if most of the force of any explosion is expected to be perpendicular to the long axis, since that is the shortest way out).
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Re: What happens to all that debris?
Post by tlb   » Sun Aug 30, 2020 11:32 am

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Brigade XO wrote:One of the bits of plot in Uncompromsing Honor was the intent by the next to last commander of the SLN commander at Hypatia System to specificaly target the life pods of the RMN ships after he had his command fire on the crippled remnants of the RMN squadron. That was by missile, not energy mounts.

I agree; but would that require non-standard programming, since an object without a wedge should not be high on any automatic target list?
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Re: What happens to all that debris?
Post by Loren Pechtel   » Sun Aug 30, 2020 5:08 pm

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tlb wrote:
Brigade XO wrote:One of the bits of plot in Uncompromsing Honor was the intent by the next to last commander of the SLN commander at Hypatia System to specificaly target the life pods of the RMN ships after he had his command fire on the crippled remnants of the RMN squadron. That was by missile, not energy mounts.

I agree; but would that require non-standard programming, since an object without a wedge should not be high on any automatic target list?


I would figure they were targeting the beacons.
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Re: What happens to all that debris?
Post by ThinksMarkedly   » Sun Aug 30, 2020 6:02 pm

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cthia wrote:I'm not really certain where the two navies were located in reference to each other and the planet. The Admiral's ships were hiding somewhere away from the planet I think. And the SLN's ships were headed towards the planet.


The SLN task force was in orbit of the planet and had been for a week. The RMN detachment was sunwards, between the orbits of the second and third planets, accelerating outwards towards Hypatia (though I guess not exactly towards). This detachment was destroyed still short of the planet, so their debris continued into interstellar space.

BTW, I also think we might not be on the same page about what constitutes the front and rear of the debris field . . .


Front = leading edge in the direction of movement. Also happens to be the same direction as the "front" of the ships and throat of their wedges as they're accelerating.

Rear = trailing edge.

In this configuration, after they've passed the planet, the trailing edge is the closest to the planet.

ThinksMarkedly wrote:For pods launched while the ships were inertial but still intact, I'd expect the pods to quickly accelerate away to exactly be far enough from debris and the debris field if that gets created. But not too far, you don't want to be a very dark needle in a huge haystack of space, in case you're not rescued before your beacons go dark.

Aren't you describing pods which have a headstart, hence, are way ahead of the pack. . .of junk? The front of the pack?


Headstart in time, but not position. Since the ships are still accelerating, those pods launched earlier have lower velocity and thus are behind the ships and most of the debris field. And as a consequence of the geometry, they're also closer to the planet.

If the ships had been decelerating, the pods launched earlier would have higher velocity and would thus have moved more than the debris.

I wouldn't think it mattered whether the ship was accelerating or decelerating. The velocity imparted upon the launched pods should always be greater than the velocity of the ships. I always imagined that a pod is shot out of the pod bay like a bat out of hell to escape the incoming missile storm and resulting debris. Which is why, I assume, that Relax feels they should have a compensator to protect the occupants from such a high imparted velocity.


That would be ideal but it's physically impossible. The ships' wedges are far more powerful than any acceleration that a non-wedge system could produce. Even the MAlign's vaunted spider drive could only reach 250 gravities; a pod being pushed by thrusters could maybe do 5 gravities for a minute or two. The ship formation was moving at its slowest ship's maximum acceleration: HMS Phantom, at nearly 674 gravities.

I agree that a pod is shot outwards of a ship with sufficient delta-v compared to the ship to quickly clear the ship's wedge. But the ship's own acceleration or deceleration will make most of the difference. It depends therefore on whether the ship's acceleration is adding velocity to the direction the missiles are coming from or in the opposite direction. That is, if the ship is accelerating towards the missiles (like they were in this case), any pod launched will be quickly left behind the ships, so the missiles will not threaten it. On the other hand, if the ship is decelerating towards the missiles, as a traditional pre-MDM missile exchange was, any pods launched would be between the ships and the missiles. The other two cases, of ships moving away from their attackers, are dual.

So the velocity imparted by the launchers and the pods' thrusters is irrelevant for ships under power. They are needed only to get away from the wedge quickly enough and when the ship is not under power. If the ship has lost its impellers, the damage may be sufficient to warrant getting out of Dodge as quickly as possible.

Forgive me for such a simple analogy. But if five bullets are shot out of a nine millimeter and the sixth shot causes the gun to explode, the five bullets should be found far away from the fragments of the explosion which are bringing up the rear, certainly if the event happened in the vacuum of space. Regardless of whether the gun is accelerating or decelerating. What am I missing?


The magnitudes of the time and the acceleration. You're focused on a gun, which usually accelerates very little and fires bullets very quickly.

Simple Kinematics says at any time t, the last bullet will be at position: x = v t where v is the relative velocity that the gun imparted on the bullet upon firing, and the gun will be at position x = ɑ/2 t² (we are adopting the inertial frame of reference of when the last bullet was fired). That gives us the equation ɑ/2 t² = vt for when the gun and bullet are at the same position at the same time. One solution is the trivial one: t = 0, which is when the bullet was fired. The other one is [t] = 2v/ɑ[/t], which is positive if v and ɑ have the same sign.

Conclusion: gun and bullet will be at the same position again at some point in the future (t > 0), if the gun hasn't exploded before the time t = 2v/ɑ.

Let's say a ship imparts a 10 km/s delta-v instantaneously to the pod. A Nike-class ship like HMS Phantom accelerates at 6.613 km/s². So if the pod was launched ahead of the ship, the ship will catch up in 3.02 seconds.

That brings up more questions. One of them I asked in the How to Abandon Ship thread. I don't recall it being answered. In a system which is inhabited, are the pods automatically launched towards the planet?


I'd say so, even if there's no hope of reaching the planet on its own. You can always help the SAR ships, even if your help is negligible.

There's a question on whether the pod should use its finite supply of resources to steer towards the planet. If the pod was launched from a position or velocity from which it cannot reach the planet on its own power, it may be best to not manoeuvre at all and instead use the batteries to keep the occupants alive for another week.
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Re: What happens to all that debris?
Post by tlb   » Sun Aug 30, 2020 9:47 pm

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Brigade XO wrote:One of the bits of plot in Uncompromsing Honor was the intent by the next to last commander of the SLN commander at Hypatia System to specificaly target the life pods of the RMN ships after he had his command fire on the crippled remnants of the RMN squadron. That was by missile, not energy mounts.

tlb wrote:I agree; but would that require non-standard programming, since an object without a wedge should not be high on any automatic target list?

Loren Pechtel wrote:I would figure they were targeting the beacons.

Which should not be on the regular target list of any civilized nation.
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Re: What happens to all that debris?
Post by ThinksMarkedly   » Sun Aug 30, 2020 9:54 pm

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Brigade XO wrote:One of the bits of plot in Uncompromsing Honor was the intent by the next to last commander of the SLN commander at Hypatia System to specificaly target the life pods of the RMN ships after he had his command fire on the crippled remnants of the RMN squadron. That was by missile, not energy mounts.


They could do that by Barricade.

tlb wrote:Which should not be on the regular target list of any civilized nation.


Right. That means the reprogramming probably would have taken a long time, while Gogunov is screaming over your shoulder...
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Re: What happens to all that debris?
Post by Brigade XO   » Mon Aug 31, 2020 6:52 pm

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Loren Pechtel wrote:
I would figure they were targeting the beacons.



That's the only way they could hit the life pods. Target the Beacons. Specificaly the commander ordered his people to target the life pods and destroy them.....and there is a record of that.

Even on thrusters, the pods are not really moving under acceleration that fast and I can't belive that they are large enough to deliberatly draw the attention of missile. I also have to wonder if, just perhaps, most navy's missils have a bit in their sensor package that would ID a lifepod beacon and NOT select it as a legit target.
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Re: What happens to all that debris?
Post by kzt   » Mon Aug 31, 2020 9:00 pm

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Brigade XO wrote:most navy's missiles have a bit in their sensor package that would ID a lifepod beacon and NOT select it as a legit target.

I'd expact that you wouldn't be able to use the beacon to target something, but the beacon doesn't provide immunity.
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