Crashing ships as weapons

[gchuck]

Why not use 'KEW's'? ( Kinetic Energy Weapons)
If a 'terrorist' can steal/appropriate a ship, why waste it on a planet?
If they can get a ship, what would be the difficulty in stealing ten or fifteen steel girders, attaching a simple guidance package, and launching them at a planet?
Seems to me a little bit far fetched for a sentient. Barring insanity/emotional distress.

 

[Ex_Pendable]

Why not use 'KEW's'? ( Kinetic Energy Weapons)
If a 'terrorist' can steal/appropriate a ship, why waste it on a planet?
If they can get a ship, what would be the difficulty in stealing ten or fifteen steel girders, attaching a simple guidance package, and launching them at a planet?
Seems to me a little bit far fetched for a sentient. Barring insanity/emotional distress.

It really depends on your available resources - if you're throwing rocks, any rock will do. Ships already have full guidance and control systems installed, so all you need is a pilot and fuel.

EDIT - Planetary batteries would have no issue destroying an unmanned missile, but what if the ship thrusting in is a passenger liner full of innocent hostages? Sadly, history is full of such choices.

 

[BwapTED]

Assuming one is using CT 1977 Book 2 rules on M drives, J drives, fuel use, power-plants, charted space lanes, ship sizes, 6G limit-- all that, how feasible is a planet-busting suicide run?

 

[aramis]

Assuming one is using CT 1977 Book 2 rules on M drives, J drives, fuel use, power-plants, charted space lanes, ship sizes, 6G limit-- all that, how feasible is a planet-busting suicide run?

3 weeks of acceleration, and a week in jump...

3 * 7 * 24 * 3600 = 1814400 seconds.
108,864 km/s at impact. That's gonna make a hell of a boom.

 

[AnotherDilbert]

A fully fuelled power plant will enable a starship an effectively unlimited number of accelerations (at least 288) if necessary to use the maneuver drive during the trip...

Under 1977 rules we can only accelerate about 50 hours with default fuel, but that must also include the fuel used to take us to the start position. Let's call it 40 hours of effective acceleration towards the target, e.g. a Free Trader:

40 × 3600 s × 10 m/s² ≈ 1440 km/s.

That is a total energy of about E = mv²/2 = 2000000 × 1400000² / 2 ≈ 2 × 10¹⁸ J ≈ 500 megaton TNT equivalent.

Much of that will be expended high in the atmosphere (I guess) so a small starship would hit with the yield of a powerful nuke, but not much more than that.


A 1000 Dton 6 g ship (which is the biggest 6 g ship we can build in LBB2'77?) with double the normal fuel would achive a speed of about:

80 × 3600 s × 60 m/s² ≈ 17000 km/s.

for a kinetic energy of about 10 000 000 × 17 000 000² / 2 ≈ 1.4 × 10²¹ J ≈ 360 gigaton.

I have no idea if that is enough to damage a planet, but at perhaps 10000 times the Tunguska event I assume damage would be extensive, speculatively like a magnitude 9 - 10 earthquake.

 

[BwapTED]

3 weeks of acceleration, and a week in jump...

3 * 7 * 24 * 3600 = 1814400 seconds.
108,864 km/s at impact. That's gonna make a hell of a boom.

But why does jump matter?

 

[McPerth]

But why does jump matter?

I guess to avoid being detected while the acceleration. You accelerate in another system and then jump to crash.

Of course, the main problema on this is the uncertainly of jump time and point of appearence, that may make you to miss hte target...

 

[BwapTED]

I guess to avoid being detected while the acceleration. You accelerate in another system and then jump to crash.

Of course, the main problema on this is the uncertainly of jump time and point of appearence, that may make you to miss hte target...

That's what I'm thinking.

Although I'm not sure an incoming jump cannot be spotted.

The 1977 rules do not make any explicit mention of jump space, but do note that ships ''exit combat into interstellar space' and travel ''through interstellar space'' when jump drive is activated.

To me, ''interstellar space'' means normal space, between star systems.
So jump could be interpreted as a kind of space fold drive or some other sort of 'real-space' FTL.

If that's the case, maybe you can spot starships coming if you are looking in the right direction?

This won't apply to Traveller using jump space as developed later (in JTAS first? In the 1980 rules? I'd better take another look...)

 

[aramis]

But why does jump matter?

Because by careful use of it, you can change your vector from orbital to impact-assisting, plus most of your acceleration becomes gravity-assisted.

 

[BwapTED]

Because by careful use of it, you can change your vector from orbital to impact-assisting, plus most of your acceleration becomes gravity-assisted.

Right.

But we are only talking about acceleration after arriving at the destination jump point, yes?

Ships reach the jump point at 'zero velocity' right?

So they are presumably at 'zero velocity' when they arrive at the far end of the jump.

 

[McPerth]

Right.

But we are only talking about acceleration after arriving at the destination jump point, yes?

Ships reach the jump point at 'zero velocity' right?

So they are presumably at 'zero velocity' when they arrive at the far end of the jump.

There's controversial on this...

In MT there's an adventure (on a Challenge, IIRC) where the ships must accelerate before jumping because they target a quick moving brown dwarf,,,

 

[BwapTED]

There's controversial on this...

In MT there's an adventure (on a Challenge, IIRC) where the ships must accelerate before jumping because they target a quick moving brown dwarf,,,

Ah, yes...
I finished reading the article in JTAS 24.
Miller describes the 'zero velocity' thing--but it's a safety measure done by commercial ships. It isn't a physical requirement of the drive or the phenomenon of jump at all.
Military ships and couriers jump in going fast.

Was that article the first time ships were described as retaining speed and direction through jump?

 

[mike wightman]

Right.

But we are only talking about acceleration after arriving at the destination jump point, yes?

Ships reach the jump point at 'zero velocity' right?

So they are presumably at 'zero velocity' when they arrive at the far end of the jump.

Nope.

Ships maintain their real world velocity when they jump.

 

[mike wightman]

Ah, yes...
I finished reading the article in JTAS 24.
Miller describes the 'zero velocity' thing--but it's a safety measure done by commercial ships. It isn't a physical requirement of the drive or the phenomenon of jump at all.
Military ships and couriers jump in going fast.

Was that article the first time ships were described as retaining speed and direction through jump?

Nope, it mentioned in LBB:5 High Guard.

 

[aramis]

Right.

But we are only talking about acceleration after arriving at the destination jump point, yes?

Ships reach the jump point at 'zero velocity' right?

So they are presumably at 'zero velocity' when they arrive at the far end of the jump.

Nothing requires zero velocity (and relativity says there's no such thing). Jump preserves your vector. You leave solar-anti-spin and a bit out, then jump so that you are 2 weeks 7 days (or whatevery your fuel load allows) ahead of intercept, and burn in as it comes to meet you. You are ensuring that the maximum fuel is used for acceleration planetward by changing your outbound vector pre jump to an inbound vector post-jump, without actually changing the vector, just your location. Basically, you turn the slowing effects of local gravity into acceleration effects.

 

[AnotherDilbert]

In MT there's an adventure (on a Challenge, IIRC) where the ships must accelerate before jumping because they target a quick moving brown dwarf,,,

In general, stars are not at rest to each other, they have perhaps similar but not identical velocity vectors of their own.

So even if you jump with a zero vector relative to the local star, you will arrive with a different vector than the destination star, i.e. you will have a speed relative the destination system.

In addition planets have an orbital velocity relative the star (Earth: ~30 km/s).


This is of course known in advance so you can time your vector and jump to arrive almost at rest relative the destination planet.

 

[AnotherDilbert]

To me, ''interstellar space'' means normal space, between star systems.
So jump could be interpreted as a kind of space fold drive or some other sort of 'real-space' FTL.

If that's the case, maybe you can spot starships coming if you are looking in the right direction?

I don't think "interstellar space" should be interpreted all that literally.

Even if the jump is performed in normal space you move at many times the speed of light, hence the ship will arrive faster than the sight of it so the ship will arrive before you can see it approach.

 

[BwapTED]

I don't think "interstellar space" should be interpreted all that literally.

Even if the jump is performed in normal space you move at many times the speed of light, hence the ship will arrive faster than the sight of it so the ship will arrive before you can see it approach.

True.
:toast:

 

[BwapTED]

Nope, it mentioned in LBB:5 High Guard.

Ah, yes!

I rarely look in HG, so I forgot about the source of that rule.

I see why the designers included it.

They wanted to cut down on busting certain laws of nature.

In conjuction with some of the other game rules, this aspect of jump does seem to enable the whole ''near-C rocks of doom/suicide ship'' problem, though.
Thus we have this thread.

I don't know that small starships being able to toast planets makes much sense with the default assumptions about trade or the private ownership of small starships.

 

[BwapTED]

Nothing requires zero velocity (and relativity says there's no such thing). Jump preserves your vector. You leave solar-anti-spin and a bit out, then jump so that you are 2 weeks 7 days (or whatever your fuel load allows) ahead of intercept, and burn in as it comes to meet you. You are ensuring that the maximum fuel is used for acceleration planetward by changing your outbound vector pre jump to an inbound vector post-jump, without actually changing the vector, just your location. Basically, you turn the slowing effects of local gravity into acceleration effects.

That makes sense. Thanks.