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> The use of a gun limited effective range to no more than 1500 yards Aren't sniper rifles effective at that distance (if they hit)? A weapon not constrained t

> The use of a gun limited effective range to no more than 1500 yards Aren't sniper rifles effective at that distance (if they hit)? A weapon not constrained to human limits in dynamic movement, heat, sound, pressure, size, etc, isn't effective at a much greater distance?

unwind 3y ago
I am no expert but I imagine one important tradeoff is between cartridge power (necessary for long range with sufficient energy) and cartridge size/mass, these systems have high rates of fire (because trying to hit very fast-moving targets) and that can't be easy with a giant cartridge. What happened to "Metal storm"?
- numpad0 3y ago
  It didn't go anywhere that's for sure, found an /r/NCD post speculating reasons as to why[1]. Looks like they were bought and pivoted to explosive drones somehow[2]. 1: https://old.reddit.com/r/NonCredibleDefense/comments/16xhmpv/ https://old.reddit.com/r/NonCredibleDefense/comments/16xhmpv... 2: https://en.wikipedia.org/wiki/Metal_Storm https://en.wikipedia.org/wiki/Metal_Storm
laverya 3y ago
How long does it take for a bullet to reach 1500 yards? Around 2 seconds. How confident do you have to be in the movement of your target to hit them with a 2 second lead? Very. (Or you can follow the CIWS methodology and throw quite a few bullets at once) The effective range isn't limited by the ballistics of the weapon (The 20 mm shells it fires will easily go 5+km), it's limited by actually hitting the damn thing you're aiming at.
ranger207 3y ago
Sniper rifles are firing a single shot, the bullet is smaller, and snipers can take significant time to prepare. I've heard of snipers firing a few hundred yards away from their target first to see exactly how their shot will be affected by drop and wind and only then aiming at their target. Sniper rifles have much less stress on them imposed by firing the cartridge than a Phalanx; a 12.7x99mm cartridge is nothing compared to 20x102mm. Finally, a sniper is firing a single carefully aimed shot; a Phalanx is firing 75 rounds a second from six rotating barrels.
- wolverine876 3y ago
  How does that reduce effectiveness of a Phalanx against a drone? With all that metal flying, the pinpoint accuracy problem seems solved.
  - icegreentea2 3y ago
    The M61 (the gun the Phalanx is built around) apparently has a 80% dispersion of ~5 milliradians (see this amazing reddit post complaining about DCS - note that the evidence points to a range of values - I think 5 milliradians is a fair summary https://old.reddit.com/r/hoggit/comments/eyddn3/m61_and_gau8_dispersion_values_are_wrong_what_ive/ https://old.reddit.com/r/hoggit/comments/eyddn3/m61_and_gau8... ). At 1500m that works out to a 75cm radius (I'm pretty sure its radius...) disc. Assuming your firing at a missile flying right at you, and assuming a Cold War era threat (so say a Kh-22 fired from a Tu-22M), you're talking about a 92cm diameter target (46cm radius) that you're trying to hit. In reality, things are worse because in addition to dispersion, your actual point of aim of your stream of bullets will be effected by external factors (like wind). You can see how in the scenario layed out above, you do actually have what seems to be a reasonable chance of landing a few hits when you're spewing out hundreds of rounds within seconds. But you can also see how quickly the odds go to crap as you push the range further and further. I think that gets to the reality of what the "effective range" value is. It is a rule of thumb designed to help weapons officers quickly determine how best to react in a scenario. Remember that CIWS was envisioned to be deployed in a scenario where USN ships would be subject to saturation attacks by supersonic anti-ship missiles from multiple bearings and sources. Phalanx itself only has a magazine of ~1000 rounds, which is good for maybe only 10s of firing, so you really do need to conserve ammo.
jabl 3y ago
The shell itself flies considerably longer, although 20mm shells start to slow down and drop much more quickly than even slightly bigger shells like 30mm (see e.g. the Goalkeeper CIWS for a similar concept using the same 30mm gun as the A-10 aircraft). It's a question of hitting the target with a usefully high probability. At longer ranges dispersion is higher, so even if the aim is correct there's a chance it won't hit. And think of how it works; it shoots out a stream of shells, and tracks the target and the shells with radar. But what if the target is doing some evasive maneuvers, which AFAIU many anti-ship missiles do in their final phases? The shells fly out at about 900 m/s, and a subsonic missile flies at maybe 300 m/s. So by the time the shells whizz by the missile it has moved a quite considerable distance, and while the radar tracking can apply the correct amount of lead (with a Kalman filter or similar to take into account measurement noise), if the missile is doing some unpredictable maneuvers that might not help. With the missile closing at 300 m/s, you don't have very many cycles of shoot-see-where-the-shell-goes-adjust-aim before the missile slams into the ship. And to make matters worse, there are also supersonic anti-ship missiles. Now evasive maneuvers in the high-density air at the surface isn't really a concept that works out for Mach 3 missiles, but, well, the missile compensates by flying as fast as the cannon shells. Hence stuff like this RAM thingy is seen as a better system against high-end anti-ship missiles.
- dredmorbius 3y ago
  There's a third option, though I've very little knowledge of its capabilities: "smart" munitions. These are ballistic, like bullets or shells, but have some capability for maneuver, as with a guided missile. A smart munition with longer range might make for a more effective countermeasure against high-speed (supersonic or hypersonic) missiles. Or possibly high-speed (supersonic) torpedoes, another emerging class of anti-ship weapons. See: <https://en.wikipedia.org/wiki/Smart_bullet https://en.wikipedia.org/wiki/Smart_bullet>

unwind 3y ago

I am no expert but I imagine one important tradeoff is between cartridge power (necessary for long range with sufficient energy) and cartridge size/mass, these systems have high rates of fire (because trying to hit very fast-moving targets) and that can't be easy with a giant cartridge. What happened to "Metal storm"?

numpad0 3y ago
It didn't go anywhere that's for sure, found an /r/NCD post speculating reasons as to why[1]. Looks like they were bought and pivoted to explosive drones somehow[2]. 1: https://old.reddit.com/r/NonCredibleDefense/comments/16xhmpv/ https://old.reddit.com/r/NonCredibleDefense/comments/16xhmpv... 2: https://en.wikipedia.org/wiki/Metal_Storm https://en.wikipedia.org/wiki/Metal_Storm

laverya 3y ago

How long does it take for a bullet to reach 1500 yards? Around 2 seconds. How confident do you have to be in the movement of your target to hit them with a 2 second lead? Very. (Or you can follow the CIWS methodology and throw quite a few bullets at once) The effective range isn't limited by the ballistics of the weapon (The 20 mm shells it fires will easily go 5+km), it's limited by actually hitting the damn thing you're aiming at.

ranger207 3y ago

Sniper rifles are firing a single shot, the bullet is smaller, and snipers can take significant time to prepare. I've heard of snipers firing a few hundred yards away from their target first to see exactly how their shot will be affected by drop and wind and only then aiming at their target. Sniper rifles have much less stress on them imposed by firing the cartridge than a Phalanx; a 12.7x99mm cartridge is nothing compared to 20x102mm. Finally, a sniper is firing a single carefully aimed shot; a Phalanx is firing 75 rounds a second from six rotating barrels.

wolverine876 3y ago
How does that reduce effectiveness of a Phalanx against a drone? With all that metal flying, the pinpoint accuracy problem seems solved.
- icegreentea2 3y ago
  The M61 (the gun the Phalanx is built around) apparently has a 80% dispersion of ~5 milliradians (see this amazing reddit post complaining about DCS - note that the evidence points to a range of values - I think 5 milliradians is a fair summary https://old.reddit.com/r/hoggit/comments/eyddn3/m61_and_gau8_dispersion_values_are_wrong_what_ive/ https://old.reddit.com/r/hoggit/comments/eyddn3/m61_and_gau8... ). At 1500m that works out to a 75cm radius (I'm pretty sure its radius...) disc. Assuming your firing at a missile flying right at you, and assuming a Cold War era threat (so say a Kh-22 fired from a Tu-22M), you're talking about a 92cm diameter target (46cm radius) that you're trying to hit. In reality, things are worse because in addition to dispersion, your actual point of aim of your stream of bullets will be effected by external factors (like wind). You can see how in the scenario layed out above, you do actually have what seems to be a reasonable chance of landing a few hits when you're spewing out hundreds of rounds within seconds. But you can also see how quickly the odds go to crap as you push the range further and further. I think that gets to the reality of what the "effective range" value is. It is a rule of thumb designed to help weapons officers quickly determine how best to react in a scenario. Remember that CIWS was envisioned to be deployed in a scenario where USN ships would be subject to saturation attacks by supersonic anti-ship missiles from multiple bearings and sources. Phalanx itself only has a magazine of ~1000 rounds, which is good for maybe only 10s of firing, so you really do need to conserve ammo.

jabl 3y ago

The shell itself flies considerably longer, although 20mm shells start to slow down and drop much more quickly than even slightly bigger shells like 30mm (see e.g. the Goalkeeper CIWS for a similar concept using the same 30mm gun as the A-10 aircraft). It's a question of hitting the target with a usefully high probability. At longer ranges dispersion is higher, so even if the aim is correct there's a chance it won't hit. And think of how it works; it shoots out a stream of shells, and tracks the target and the shells with radar. But what if the target is doing some evasive maneuvers, which AFAIU many anti-ship missiles do in their final phases? The shells fly out at about 900 m/s, and a subsonic missile flies at maybe 300 m/s. So by the time the shells whizz by the missile it has moved a quite considerable distance, and while the radar tracking can apply the correct amount of lead (with a Kalman filter or similar to take into account measurement noise), if the missile is doing some unpredictable maneuvers that might not help. With the missile closing at 300 m/s, you don't have very many cycles of shoot-see-where-the-shell-goes-adjust-aim before the missile slams into the ship. And to make matters worse, there are also supersonic anti-ship missiles. Now evasive maneuvers in the high-density air at the surface isn't really a concept that works out for Mach 3 missiles, but, well, the missile compensates by flying as fast as the cannon shells. Hence stuff like this RAM thingy is seen as a better system against high-end anti-ship missiles.

dredmorbius 3y ago
There's a third option, though I've very little knowledge of its capabilities: "smart" munitions. These are ballistic, like bullets or shells, but have some capability for maneuver, as with a guided missile. A smart munition with longer range might make for a more effective countermeasure against high-speed (supersonic or hypersonic) missiles. Or possibly high-speed (supersonic) torpedoes, another emerging class of anti-ship weapons. See: <https://en.wikipedia.org/wiki/Smart_bullet https://en.wikipedia.org/wiki/Smart_bullet>