5 ms·

To add to this, the closing speeds are so fast that you would need to detonate explosives far in advance for anything to happen anywhere near the target. If yo

To add to this, the closing speeds are so fast that you would need to detonate explosives far in advance for anything to happen anywhere near the target. If you detonate at the usual anti-aircraft distances (a few meters), the time it takes for the detonator to fire and for the shock wave/chemical reaction to propagate though the explosive mass would leave the shrapnel cloud way behind the target.

grkvlt 9y ago
Wow, I hadn't actually thought of this. So, I assume that's why you go for hit-to-kill kinetic warheads, then, and just solve the accuracy issue rather than accuracy plus tricky timing issues?
- mohaine 9y ago
  I wouldn't think so. Hit to kill is going to have the same but worse timing issues as a proximity hit since the size is much smaller. I would guess the real reason is that if the target is ballistic, you need to actually "kill" it, not just wing it like you can with an airplane. If you wing it the warhead will still fall in roughly the same place with a probably intact warhead. To be safe you want to actually destroy the warhead. Worse case it goes off at point of impact, which is better than on the target.
- jasonwatkinspdx 9y ago
  That's part of it. There's also a point where the kinetic energy of impact surpasses the chemical energy of explosives for equivalent mass. This is around Mach 10 as a huge ballpark figure. So with intercepting high mach and ablatively shielded targets like ballistic missiles, it might be better to budget your projectile mass to increasing likelihood of a hit vs attempting to damage via a proximity explosion.
  - grkvlt 9y ago
    The UK Starstreak [0] missile seems to be trying for a compromise with a combination of relatively high speed (Mach 4.0) kinetic tungsten penetrator with a very small (again, relatively) 450g high explosive charge. It's an odd looking thing, because the sub-munitions aren't faired over at launch so you get this normal looking tube shaped missile with three tiny missiles stuck on the front. It seems they rely on proximity fuzing with time delay, so once the penetrator has breached the aircraft skin, causing a reasonable amount of damage, it waits until it knows its inside and then detonates for maximum effect. I guess three of the penetrators hitting your plane at M4.0 within a ~1.5m group is enough to make you have a very bad day, even if the explosive warheads turn out to be all duds! 0. https://en.wikipedia.org/wiki/Starstreak https://en.wikipedia.org/wiki/Starstreak
    - jasonwatkinspdx 9y ago
      Starstreak is a really clever design. They use a neat clutched rotation mechanism with skewed fins to get 2d attitude control via a 1d clutch signal. The US adopted a similar mechanism to build a smart fuse that can be used with existing dumb artillery shells to give them gps guidance at low cost.

grkvlt 9y ago

Wow, I hadn't actually thought of this. So, I assume that's why you go for hit-to-kill kinetic warheads, then, and just solve the accuracy issue rather than accuracy plus tricky timing issues?

mohaine 9y ago
I wouldn't think so. Hit to kill is going to have the same but worse timing issues as a proximity hit since the size is much smaller. I would guess the real reason is that if the target is ballistic, you need to actually "kill" it, not just wing it like you can with an airplane. If you wing it the warhead will still fall in roughly the same place with a probably intact warhead. To be safe you want to actually destroy the warhead. Worse case it goes off at point of impact, which is better than on the target.
jasonwatkinspdx 9y ago
That's part of it. There's also a point where the kinetic energy of impact surpasses the chemical energy of explosives for equivalent mass. This is around Mach 10 as a huge ballpark figure. So with intercepting high mach and ablatively shielded targets like ballistic missiles, it might be better to budget your projectile mass to increasing likelihood of a hit vs attempting to damage via a proximity explosion.
- grkvlt 9y ago
  The UK Starstreak [0] missile seems to be trying for a compromise with a combination of relatively high speed (Mach 4.0) kinetic tungsten penetrator with a very small (again, relatively) 450g high explosive charge. It's an odd looking thing, because the sub-munitions aren't faired over at launch so you get this normal looking tube shaped missile with three tiny missiles stuck on the front. It seems they rely on proximity fuzing with time delay, so once the penetrator has breached the aircraft skin, causing a reasonable amount of damage, it waits until it knows its inside and then detonates for maximum effect. I guess three of the penetrators hitting your plane at M4.0 within a ~1.5m group is enough to make you have a very bad day, even if the explosive warheads turn out to be all duds! 0. https://en.wikipedia.org/wiki/Starstreak https://en.wikipedia.org/wiki/Starstreak
  - jasonwatkinspdx 9y ago
    Starstreak is a really clever design. They use a neat clutched rotation mechanism with skewed fins to get 2d attitude control via a 1d clutch signal. The US adopted a similar mechanism to build a smart fuse that can be used with existing dumb artillery shells to give them gps guidance at low cost.