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.

One factor which hasn't been mentioned recently: suppression.

From what I recall of suppression effectiveness research, a 40mm grenade exploding in the general vicinity has a vastly greater suppressive effect than any small arms bullets.

stancrist said:

OICW sought to improve his effectiveness.

Yes and that was dumb. If the effectiveness is 0,01 and I double it it becomes 0,02. Which is such a marginal improvement it is hardly worth any resource invenstment.
The effectiveness of a rifleman or better infantry man goes up significantly from 100 m and closer. So doubling a significantly larger number would have yielded significant results... most likely for less resource investment.

stancrist said:

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.

Why? The rifle/small arm has a flat trajectory. Why have two weapons with the same profile?
For engaging targets behind cover or in defilade an arcing trajectory is far better. If airburst is used all the better. The fragmentation pattern of a steep falling grenade bursting 2 m above ground is far better and more efficient than that of a grenade traveling allmost parallel to  the ground.
Simple air burst fuses (proximity) for rifle grenades for example would work great. This solution would be dirt cheap in comparison and offer a significant improvement. Issue such grenades liberally to you men and an infantry squad can fire an instant light mortar barrage while the machine gunner supresses and pins the enemy.

autogun said:

From what I recall of suppression effectiveness research, a 40mm grenade exploding in the general vicinity has a vastly greater suppressive effect than any small arms bullets.

Yes but it there is a time aspect to supression. So to keep the effect up there needs to be repeated impacts. The question is how this effect scales. Since 40 mm grenades are rather large and heavy.

stancrist said:

Concur on the need for a large grenade, but I see no need for an arcing trajectory with airburst rounds.

Keeping recoil to a safe level?

A large grenade launched at high MV (to have a flat trajectory) will have too much recoil for being shoulder-launched.

The 40x53 mm is already producing too much recoil for a shoulder-fire system, and it's not really a "large" grenade (but the MV is OK).

Additionnally, with a high-velocity grenade you need to setup the fuze after firing, because you need to take into account the round-to-round velocity dispersion, or the grenade will detonate either too short or too long.

EmericD said:

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

STK used 330x 0.25g Tungsten balls in its LVER grenade concept:

https://ndiastorage.blob.core.usgovcloudapi.net/ndia/2005/smallarms/thursday/fong.pdf

Performance as described - even against IIIA type protection - looks pretty solid.

It's basically like a micro claymore mine.