Ramming

[Carlobrand]

...Even if the missile/ramming ship has a speed advantage, I don't think that alone isn't enough to guarantee that you can make hi-speed contact. (If speed at impact in not a concern, then yes, I think [2] is probably true.)

It is obviously easier to chase a slower target down from behind, (though your energy on impact will be substantially less) than trying to intercept head on. (If you have enough time, you can turn around and try again if you miss.)

I think we need to remember that even a relatively low speed contact can carry a heck of a lot of energy when talking about ships instead of missiles. Even if we're talking about a little 10 dTon fighter, if we assume the average 10:1 figure then we have around a hundred metric tons of mass impacting the target hull. If you did nothing but coast beside him and then give a 1 second 1 G burst, that'd still be a 5 million joule impact. Now think about catching up from behind with only that 1G difference and and only one standard thousand second or 20 minute turn of thrust behind it: that hundred tons of mass is colliding at speeds measured in kilometers per second, and impact energy is measured in kilotons.

 

[mike wightman]

Why do 10 ton Dragon cargo capsules not smash the ISS to pieces even though they are moving at 7.7km/s?

 

[esampson]

. . .It is obviously easier to chase a slower target down from behind, (though your energy on impact will be substantially less) than trying to intercept head on. (If you have enough time, you can turn around and try again if you miss.)

That depends on some interpretations of how engines work. Yes, technically it is easier in a mathematical sense to chase the ship from behind but then you have to expose yourself to the exhaust of the ship and in a lot of interpretations (especially TNE with its HEPlaR drives) that's a very bad thing.

 

[aramis]

Why do 10 ton Dragon cargo capsules not smash the ISS to pieces even though they are moving at 7.7km/s?

Because the station is moving 7.7km/s, too.

 

[mike wightman]

Exactly - energy transfer in a collision is a function of relative velocity not total kinetic energy as seen from a different frame of reference.

 

[aramis]

Keep in mind why people are likely to turn to ramming:

1) they're staring down a planet killing ship impact
2) They're already facing a death sentence
3) they have a rabid hatred of the opponent

In case 1, you're never going to match velocities. If your missiles missed, the launching fighter is the next best thing. Keep in mind that the ct 1 hit per 300mm scaled vector is for a 100 kg missile; a 10 ton fighter should get 1 hundreds of hits through. More than enough to run everything on the table for anything under 5000 tons if the bad-guy is inbound on a planet cracking mission.

Also, in such cases, the planet cracker has a very limited ∆V budget to dodge with. And they can only dodge into a limited range, lest they lose a potential intercept.

In case 2, it's likely to be low relative speed.

Case 3, it depends upon when they ID you...

 

[Carlobrand]

Exactly - energy transfer in a collision is a function of relative velocity not total kinetic energy as seen from a different frame of reference.

And since the thread is about ramming, instead of docking ...