Chinese drum magazine seems to offer a more practical form factor for a grenade launcher

35mm grenade 

Schnuersi, 

Math is a funny thing and I'm glad you brought it up...

What happens if you use the wrong formula to solve for a given problem?

Let's say you try to calculate the area of a rectangle while using the formula to calculate the area of a square for instance. Are you going to get the right answer once you do the math?

Of course you won't right?

But you applied the formula exactly the way the formula is supposed to work so how could you get a wrong, or maybe even misleading for instance answer, answer if you applied the formula correctly but used the wrong formula?!

I agree with you that the best guess casualty radius for 25mm, 30mm, 35mm, or even 40x46 MV doesn't look All that impressive compared to let's say a 60mm mortar or an airburst charlie G round.

Where I disagree strenuously with you is that the casualty radius is the Important number here. (Especially since even the worst case 25mm radius is actually more than sufficient IF you're actually doing the right math!)

The key here is doing the right math.

So what's the right math in this case?

The right math in this case looks something like this. 

1. In an active fire fight at medium range how many seconds can someone expose themselves to take an aimed shot before their likelihood of getting hit goes parabolic?

2. What is the average windage and ranging error for a soldier under stress with standard issue optics and weapons when given the answer from number 1 minus 1 seconds of time to line up a shot?

3. What is the ranging and windage error with something like SSW or xm29 with the same number of seconds from 2, and does that put a shot within a close enough distance to a national target to be within your system's casualty radius?

4. If you can use offboard cuing can you speed 3 up to a point where it's possible to get off 2 shots in the time from #2?

I could add several more variables and calculation factors to my version of "the right equation" but I think I have at least somewhat illustrated my point here.

Yes the casualty radii aren't super impressive on paper in and of themselves but I believe if you factor in the other relevant factors and variables you do actually have a fairly solid mathematical case for employment of things of this nature.

Are there going to be situations where a squad with one guy carrying something like this will perform objectively worse than a pure KE direct fire squad?

Absolutely

Can you adjust your squad's tactics and TTP's to make those instances rare enough that they're actually better off with things like SSW/XM29 than a pure KE direct fire squad?

I believe that the answer as of today is a resounding yes.

More importantly with the direction infantry combat and equipment is going, I believe that this will actually make an approach like this more and more potent.

I could be wrong though, I am entirely open to the idea that it's me doing the math wrong. I think I have brought up things that are definitely worth thinking about and discussing further though.

Mr. T (MrT4) said:

Chinese drum magazine seems to offer a more practical form factor for a grenade launcher

The ARDEC OICW concept displayed at the 1994 NDIA meeting had a drum magazine.

IIRC, the drum was supposed to hold eight 25mm rounds.

roguetechie said:

Where I disagree strenuously with you is that the casualty radius is the Important number here

Yes I do agree as well as Emeric did. The casulty radius is overly optimistic because it assumes unprotected targets.

roguetechie said:

1. In an active fire fight at medium range how many seconds can someone expose themselves to take an aimed shot before their likelihood of getting hit goes parabolic?

What is medium range?
The likelihood of getting hit is primary related to getting spotted. Which at ranges above 100 m can allready take time if it happens at all without the exposed person opening fire. At ranges behond 300 m even after opening fire its not a given that the shooter is spotted at all.
In the first video posted the guys esposed themself for minutes. Peeking and aiming over their cover.
 

roguetechie said:

2. What is the average windage and ranging error for a soldier under stress with standard issue optics and weapons when given the answer from number 1 minus 1 seconds of time to line up a shot?

This is where a machine gun with ROF and density of fire comes in. Of course a rifle is ineffective more than 99 % of the time. Again this is nothing new.

roguetechie said:

3. What is the ranging and windage error with something like SSW or xm29 with the same number of seconds from 2, and does that put a shot within a close enough distance to a national target to be within your system's casualty radius?

A 40 mm will most likely do better than a 20 mm. But both won't do great. Especially against small targets and targets in cover.

roguetechie said:

4. If you can use offboard cuing can you speed 3 up to a point where it's possible to get off 2 shots in the time from #2?

If you can do that why limit yourself to small grenades which are used in direct fire? Why not use something bigger and indirect. Like a rifle grenade or light mortar?

roguetechie said:

Are there going to be situations where a squad with one guy carrying something like this will perform objectively worse than a pure KE direct fire squad?

But that is another extreme. Of course issuing a GL to a squad is sensible. But its nothing new or game changing. Especially with the proliferation of protective gear the effective radius of the smaller grenades is very reduced. This means it gets very difficult to get them to land close enough.

roguetechie said:

More importantly with the direction infantry combat and equipment is going,

and what would this direction be? To me it currently seems like we are going back to "normal" or better the way it has been befor the focus on LIC and COIN. Most of the footage I have seen from UA are pretty much exactly how and what I was trained for allmost three decades ago. Attacking strongpoints, trench sweeping, fighting in woodland, anti vehicle ambushes and MOUT. All with close cooperation of AFV and liberal use of heavy weapons. Fighting is dominated by heavy weapons. Infantry engagements are rather short ranged. If not the MGs decide. All troops are pretty well equiped with at least flak jackets and helmets. I think under these conditions the smaller GLs make less sense than they did in Afghanistan and Iraq.

roguetechie said:

I could be wrong though, I am entirely open to the idea that it's me doing the math wrong.

To me it seems like a try to improve the hit propability of the rifleman at range by using an area effect weapon. The XM29 definetly went into this direction. I think the idea is flawed. Because the base assumption: the rifleman contributes in a significant way to the firepower for firefights above 100 m, is false. The idea to focus the effort on a support weapon is much more sensible. But just increasing the number of shots of 40 mm seems questionable.

EmericD said:

Concepts are always good and shiny, things start to be less interesting when you add the numbers...

The effective casualty radius of a 25 mm grenade, using a pre fragmented tungsten warhead (around 150 g), was less than 3 m.

Against protected soldiers in a trench, the effective radius of a 25 mm airburst grenade was computed to be less than 1 m.

Which is why I think it necessary to go significantly bigger than 25mm.  

https://forums.delphiforums.com/autogun/messages?msg=7519.2884

EmericD said:

       stancrist said: Bursting munition @ 3:58 eliminates the opponent.

It seems that ~9 grenades were needed...

Not true.  While 9 grenades were thrown, 8 were thrown with insufficient accuracy, and exploded harmlessly. 

And some of the grenades exploded so far from the side trench that it may not have been the intended target.

EmericD said:

An airbursting grenade would have hit soldiers helmets, shoulders and upper torso, all covered now with at least lvl IIIA body armor.  Some fragments could have hit the arms, but the effectiveness was very limited.

That might be true for airbursts above soldiers in a trench, but airbursts above soldiers who are standing, kneeling, or lying prone could be hit in the arms, lower torso, legs, or feet.

BTW, in what army is it SOP for infantry to have shoulder armor?

schnuersi said:

To me it seems like a try to improve the hit propability of the rifleman at range by using an area effect weapon. The XM29 definetly went into this direction. I think the idea is flawed. Because the base assumption: the rifleman contributes in a significant way to the firepower for firefights above 100 m, is false.

I think you are mistaken about that being the base assumption of the OICW.  The Army recognized the poor hit probability with rifles at longer distances.

My understanding of the base assumption is that airburst munitions were seen as a way to substantially increase a rifleman's effectiveness at all ranges.

stancrist said:

My understanding of the base assumption is that airburst munitions were seen as a way to substantially increase a rifleman's effectiveness at all ranges.

Yes and that includes over 100 m.
It resulted in a compromise that ultimately made the system ineffective. They made the HE component flat shooting with a small grenade. But what you actually want is an arcing trajectory and a large grenade. Basically what the 40 mm LV, rifle grenades or hand grenades do.

roguetechie said:

1. In an active fire fight at medium range how many seconds can someone expose themselves to take an aimed shot before their likelihood of getting hit goes parabolic?

Expose yourself for more than 2 seconds and you're probably a casualty.

roguetechie said:

2. What is the average windage and ranging error for a soldier under stress with standard issue optics and weapons when given the answer from number 1 minus 1 seconds of time to line up a shot?

Around 3 mils.

roguetechie said:

3. What is the ranging and windage error with something like SSW or xm29 with the same number of seconds from 2, and does that put a shot within a close enough distance to a national target to be within your system's casualty radius?

That's the failure point of the OICW (and other similar programs).

You can't aim, lase, check the relevance of the firing solution, aim again, and launch a grenade at medium range, in just 2 seconds.

You need to expose yourself and stay perfectly motionless for much more than that.

Well, if you're accurate enough to properly "lase" your target in order to have a good shooting solution, then you can also hit your target with a rifle bullet.

And even if you can speed up the acquisition sequence to stay under 2 seconds, you will have to deal with a grenade ToF that could be around 6 seconds in order to reach medium to long range.

6 seconds of flight and a dispersion of several meters, when the effective radius of your grenade is measured in 1-2 meters, is not a recipe for success.

schnuersi said:

Yes and that includes over 100 m.

Of course.  My point is there was no base assumption that "the rifleman contributes in a significant way to the firepower for firefights above 100 m".

Just the opposite.  They knew the rifleman's contribution to fights above 100 meters was not significant.  OICW sought to improve his effectiveness.

schnuersi said:

It resulted in a compromise that ultimately made the system ineffective. They made the HE component flat shooting with a small grenade.

Yes.  They tried to do too much with too little.

schnuersi said:

But what you actually want is an arcing trajectory and a large grenade.

Concur on the need for a large grenade, but I see no need for an arcing trajectory with airburst rounds.  Indeed, I think that in most infantry vs infantry combat scenarios, a flat trajectory would be preferable with airburst munitions.

stancrist said:

Which is why I think it necessary to go significantly bigger than 25mm.

What was the grenade caliber selected for OICW? Significantly bigger than 25 mm?

stancrist said:

Not true. While 9 grenades were thrown, 8 were thrown with insufficient accuracy, and exploded harmlessly.

I see, so when you are missing your target, ammo consumption does not count and the grenades are automatically respawning in your grenade pouches?

That would be a nice mod for call of duty.

stancrist said:

That might be true for airbursts above soldiers in a trench, but airbursts above soldiers who are standing, kneeling, or lying prone could be hit in the arms, lower torso, legs, or feet. BTW, in what army is it SOP for infantry to have shoulder armor?

The area of a sphere is 4.Pi.r², or 12.6 m² at a 1 m distance from the grenade, 50.3 m² at a distance of 2 m, and 113 m² at a distance of 3 m.

The standard crouching soldier target is ~0.38 m², so you need a fragment density of 2.63 frags/m² to expect scoring a hit on this target.

That means that you need at least 33 effective fragments to score a hit at 1 m, 132 effective fragments to score a hit a 2 m, and 297 effective fragments to score a hit at 3 m, on any random part of this target.

How many fragments of 1 gram could be loaded in a 40 mm / 180 g HE grenade?

And if shoulder armor is not currently standard practice, most armies have already this kind of protection in their inventories.