AFV Coax Thread

[Xlucine]

6 hours ago, Vicious_CB said:

 

I see. So a M230LF coax is probably out the question since its eating up too much space inside the turret. In terms of ammo volume 7.62 vs .50 cal, I know the M1 Abrams particularly carries an absurd amount to coax ammo comparably to other tanks, something like 10,000 rounds. Im not quite sure what ratio would be if you swapped 7.62 to .50 cal(2:1?3:1?) you would probably still have as much coax ammo as other MBTs. Also logistically .50 cal is very common in both light infantry and with the stryker guys so there would be no shortage there. 

 

Per hunnicutt it's 11,400 rounds, which is high but not a world away from other contemporaries. M60 and chieftain are both meant to carry 6,000. Just by comparing volume for the rounds, the ratio looks like 1:2.7:5.3 (for .50:.338 NM:7.62, modelling each as a cylinder with L = OAL, D = rim diameter + 1mm to represent the belt links)

 

7 hours ago, Vicious_CB said:

 

As far as gunners lighting everything up with main gun, isnt that a training issue? Like we say in the shooting community,  sounds like a software issue not a hardware issue. Something like a technical probably doesnt warrant a main gun round. .50 cal API also makes swiss cheese out of double reinforced concrete walls that can easily stop 7.62 SLAP. Also Ive heard more than few times in Helmand where USMC tanks on overwatch were unable to support their infantry clearing a compound due to the fears of some devil dog catching a sabot petal in the back of the head. I have no idea what the danger space is when firing a saboted round is but Ive heard its a real issue when supporting infantry.  

 

Sabots are dangerous, but non-saboted rounds are available - IIRC Nick Moran said he carried a full load of M830 on patrol (not M830A1), and the USMC have a proper HE round in service now for the 120mm

[Ramlaen]

I think the proper way to address what coax to use is to first decide what your coax is for instead of going straight to how big of a gun can you fit.

[Serge]

Yes. 

 

12,7 HMG integration is not so cumbersome 

[Belesarius]

4 minutes ago, Serge said:

Yes. 

 

12,7 HMG integration is not so cumbersome 

Not so much the gun, as the ammo, is the point that was being raised earlier. 12.7mm takes up a hell of a lot more volume than 7.62mm does.

 

[Serge]

And you have to take into account the terminal effect of calibres.

If it takes you a 3 12,7mm rounds burst to knock out a vehicle, how many 7,62mm will you use ? And once you have the number, you have the volume consumed. 

[FORMATOSE]

Early Chrysler XM-1 validation phase model with a coaxial Bushmaster weapon system :

 

[Collimatrix]

16 hours ago, Vicious_CB said:

 

As far as gunners lighting everything up with main gun, isnt that a training issue? Like we say in the shooting community,  sounds like a software issue not a hardware issue. Something like a technical probably doesnt warrant a main gun round. .50 cal API also makes swiss cheese out of double reinforced concrete walls that can easily stop 7.62 SLAP. Also Ive heard more than few times in Helmand where USMC tanks on overwatch were unable to support their infantry clearing a compound due to the fears of some devil dog catching a sabot petal in the back of the head. I have no idea what the danger space is when firing a saboted round is but Ive heard its a real issue when supporting infantry. 

 

Maybe the answer is stick a M230LF on the commanders CROWS? if you used the CROWS-LP it probably wouldnt be much larger than the CROWS /w M2HB(height wise) than we have now. The question is where to store all the ammo. Now at least you have some HE throwing capability when infantry are within the danger space of the main gun. 

 

 

Tank combat involves a lot of hiding the vehicle partially or entirely behind terrain features, vehicles wear camouflage and the resolution through a thermal imager isn't the best.  IDing a target and determining the most appropriate weapon to dispatch the target is time consuming.  Or, at least, it is with current sensor technology.  Tankers put a lot of emphasis on engaging first too, so they won't be too happy about anything that slows that down too much.

 

The danger zone from firing off the main armament of a modern tank is considerable.  The sabots are a bother, and the blast overpressure from the muzzle is enough to be dangerous at a surprising distance:

 

The conflicts in Yemen and Syria are reinforcing that decades-old lesson that tanks unsupported by infantry die.  But how are the infantry supposed to support the tanks if they have to stand at least fifty meters away from them at all times?

 

I think there is a case to be made for a less devastating weapon on MBTs, but exactly how to do it is tricky.

[Xoon]

1 hour ago, Collimatrix said:

 

Tank combat involves a lot of hiding the vehicle partially or entirely behind terrain features, vehicles wear camouflage and the resolution through a thermal imager isn't the best.  IDing a target and determining the most appropriate weapon to dispatch the target is time consuming.  Or, at least, it is with current sensor technology.  Tankers put a lot of emphasis on engaging first too, so they won't be too happy about anything that slows that down too much.

 

The danger zone from firing off the main armament of a modern tank is considerable.  The sabots are a bother, and the blast overpressure from the muzzle is enough to be dangerous at a surprising distance:

 

The conflicts in Yemen and Syria are reinforcing that decades-old lesson that tanks unsupported by infantry die.  But how are the infantry supposed to support the tanks if they have to stand at least fifty meters away from them at all times?

 

I think there is a case to be made for a less devastating weapon on MBTs, but exactly how to do it is tricky.

Has any AFV ever been designed with a suppressor or alike to reduce the effects?

[Mighty_Zuk]

16 minutes ago, Xoon said:

Has any AFV ever been designed with a suppressor or alike to reduce the effects?

Suppressed guns get the effect of reduced sound mostly from subsonic munitions. That's the last thing you'd want in a tank. 

 

But if you would take such a project seriously, you'll find out you need some serious size to actually put a suppressor there.

[Xoon]

49 minutes ago, Mighty_Zuk said:

Suppressed guns get the effect of reduced sound mostly from subsonic munitions. That's the last thing you'd want in a tank. 

 

But if you would take such a project seriously, you'll find out you need some serious size to actually put a suppressor there.

You missed the point. The point was to reduce the danger zone. 

 

A suppressor works by using sound baffles to expand the gas, slowing it down and cooling it.  It decreases both sound and muzzle blast.
Not sure how subsonic ammunition is relevant here, considering we are talking about tanks, were the engine roar can be heard from miles away.

 

No need for a huge suppressor to reduce everything to comfortable levels, just a small enough reduction that the infantry can actually stand close to the tank. I am no physics engineer or doctor though, so I can't really calculate the required size of the 120mm suppressor to reduce the danger to manageable levels.

 

 

If there is not practical way of doing this, then I guess the other option is to either go the STRV 2000 route and limit the use of the main gun while supported by infantry, or have mechanized/robotic support instead.

[Mighty_Zuk]

On my phone so I cant link any photos, but just google M109 suppressor and you'll see what size it should be. Of course 155mm =/= 120mm but it's not going to be too far off.

 

The concept of a coaxial medium cannon is nice, but it is probably not so relevant in the presence of a critical mass of HIFVs.

 

This could really be fixed by improving protection of the infantry, although far from all are wearing any form of hearing protection from what I've seen. In the US alone, the annual compensation for hearing loss stood at $1 billion a couple years ago.

 

There are so many sources of very damaging sounds on the battlefield that trying to reduce every single one of them will prove to be so expensive and so impractical compared with very simple and relatively cheap selective hearing protection gear that has been available for a while now.

 

So dont worry about tanks being loud.

[ZloyKrolik]

>The danger zone from firing off the main armament of a modern tank is considerable.  The sabots are a bother, and the blast overpressure from the muzzle is enough to be dangerous at a surprising distance:

 

I've seen in person what happens when a freindly crunchy gets in front of the muzzle when firing a amin gun round. During a CALFEX in Germany a soldier took up a prone position in front of my tank. I was the driver on an M60A3 at the time and could see him out the left driver's periscope. After the 1st round we fired he had his hands over his ears, the 2nd he was curled up in a fetal position, the 3rd had him being dragged off by his buddies. This was with a 105, not a 120. Anything you can take out with an autocannon will brew up quite nicely with a HEAT round. Coax is for troops, a 70 ton tripod with 10x thermal sights firing 25 round bursts works quite well on troops.

[Collimatrix]

1 hour ago, ZloyKrolik said:

 

I've seen in person what happens when a freindly crunchy gets in front of the muzzle when firing a amin gun round. During a CALFEX in Germany a soldier took up a prone position in front of my tank. I was the driver on an M60A3 at the time and could see him out the left driver's periscope. After the 1st round we fired he had his hands over his ears, the 2nd he was curled up in a fetal position, the 3rd had him being dragged off by his buddies. This was with a 105, not a 120. Anything you can take out with an autocannon will brew up quite nicely with a HEAT round. Coax is for troops, a 70 ton tripod with 10x thermal sights firing 25 round bursts works quite well on troops.

 

Yikes!

[ZloyKrolik]

I also saw a 2LT lose his helmet and get knocked on his ass when he was standing next to the muzzle of a 105 when it went off. Our unit was boresighting the tanks and he was looking for the boresight device, M26 Boresight device, and went up the end of the gun tube just as the crew fired off a round for calibration. I spoke with him about it a couple of weeks later, he said that his ears were ringing so loud that he couldn't hear the CO chewing him out, just saw his lips moving.

[Collimatrix]

On 4/22/2018 at 3:11 PM, Mighty_Zuk said:

Suppressed guns get the effect of reduced sound mostly from subsonic munitions. That's the last thing you'd want in a tank. 

 

Not true.  7.62x51mm rifles with a suppressor are borderline hearing safe and can be fired comfortably, if not necessarily perfectly safely, without hearing protection.  I've done it.  The bullet makes enough noise to make its presence known, but the sound from the bullet isn't anywhere near loud enough to cause hearing damage.

 

Same deal with tank guns.  The problem is the blast overpressure from the muzzle, not the supersonic shockwave from the projectile.  I would imagine that the sound of a 105mm projectile going overhead might cause a few soiled pants, but pants can be replaced, hearing damage from blasts cannot.

 

Simply making the main gun have a longer barrel would improve things somewhat, but there are obvious limitations here.

[Mighty_Zuk]

1 hour ago, Collimatrix said:

 

Not true.  7.62x51mm rifles with a suppressor are borderline hearing safe and can be fired comfortably, if not necessarily perfectly safely, without hearing protection.  I've done it.  The bullet makes enough noise to make its presence known, but the sound from the bullet isn't anywhere near loud enough to cause hearing damage.

 

Same deal with tank guns.  The problem is the blast overpressure from the muzzle, not the supersonic shockwave from the projectile.  I would imagine that the sound of a 105mm projectile going overhead might cause a few soiled pants, but pants can be replaced, hearing damage from blasts cannot.

 

Simply making the main gun have a longer barrel would improve things somewhat, but there are obvious limitations here.

Wouldn't it require very frequent replacement of the suppressor?

 

Anyway, I still think personal protection for the infantry is the one and only solution that should be developed for this issue.

[Collimatrix]

12 minutes ago, Mighty_Zuk said:

Wouldn't it require very frequent replacement of the suppressor?

 

No.  Modern rifle suppressors can last at least as long as the barrels they are attached to.

[Xlucine]

A tank silence would need an absurd volume for the gas to expand into.

 

Interestingly, 7.62 NATO in a 16" barrel and the L44 120mm (per hunnicutt) have almost identical expansion ratios (~5.5, ignoring the substantial pressure difference involved)