M255 A1 Flechette warheads for rockets

[shagrat]

The addition of the M255A1 Flechette warheads to the Hydra/FFAR system against infantry and vehicles would be cool.

In addition the damage modeling of HE warheads against infantry in the open would benefit from an overhaul.

For a purpose built area effect weapon against infantry and light/unarmored vehicles the current performance leaves some room for improvement. As one of the AH-64D standard weapons, it would be a shame, if we still need to use gun or Hellfire to engage infantry with any noticeable effect.

Flechette especially is designed to slice through cover and light revetments with their tungsten darts.

In combination with the rocket pods launch zones for "mixed" rocket loadouts, this would give us the real life versatility to choose different warheads on the battlefield, by zone.

[DaemonPhobos]

M255 rockets are pretty much confirmed by the manual, along with MPSM, M229, illumination, smoke, etc.

The only ones that were not available by that era were the M247 heat and the M282 multipurpose ones apparently.

Now, the damage model requires an overhaul in order to make them effective, both flechette an HE. (And the 30mm gun rounds, they have a very interesting butterfly shaped frag pattern.)

Something very cool about the Apache is that, while having only 3 weapons in theory, it's still versatile because you can mix a lot of different rockets and missiles.

Radar aided L hellfires, SAL double tandem warhead K hellfire, blast frag M hellfire, thermobaric MAC N hellfire, Multipurpose submunition rockets, flechette rockets, WP, illumination, smoke, M229 rockets with 2.2kg of explosive instead of 1 kg of the M151, and a gun with 2 minutes worth of ammunition (not counting cool down time between firing bursts).

 

 

Edited April 28, 2021 by DaemonPhobos

[shagrat]

2 hours ago, DaemonPhobos said:

M255 rockets are pretty much confirmed by the manual, along with MPSM, M229, illumination, smoke, etc.

The only ones that were not available by that era were the M247 heat and the M282 multipurpose ones apparently.

Now, the damage model requires an overhaul in order to make them effective, both flechette an HE. (And the 30mm gun rounds, they have a very interesting butterfly shaped frag pattern.)

Something very cool about the Apache is that, while having only 3 weapons in theory, it's still versatile because you can mix a lot of different rockets and missiles.

Radar aided L hellfires, SAL double tandem warhead K hellfire, blast frag M hellfire, thermobaric MAC N hellfire, Multipurpose submunition rockets, flechette rockets, WP, illumination, smoke, M229 rockets with 2.2kg of explosive instead of 1 kg of the M151, and a gun with 2 minutes worth of ammunition (not counting cool down time between firing bursts).

 

 

 

By that logic we should have Flechette since the Huey, already. It was widely used in the 1960ies, as well. Maybe different fuses...

[MRTX]

I see the flechett rockets being more of a problem when it comes to implementing them into DCS.

 

You could either simulate each dart of the rocket, which would obviously kill performance. Or you could make the rocket go invisible at the point when it should release the flechettes, and let it be a simple HE rocket with a modified blast radius that mimmics the spread of the darts + a special impact effect, that looks like the flechettes hitting the ground.

 

In the end, none of these solutions are perfect.

Edited May 2, 2021 by MRTX

[Northstar98]

I don't see why I can't be set-up similar to how current CBUs are set up - we just need an appropriate damage model for units.

[Baaz]

Very interesting video on the subject matter:

 

https://www.military.com/video/operations-and-strategy/vietnam-war/cobra-firing-flechette-rockets-in-vietnam/983606175001

[Dr.SquirrelBoy12]

I think this would be awesome to have in DCS, but frankly I don't really know if it is practical for them to implement given how pointless it is to use anti-infantry weapons in DCS.
It's not like ARMA where the infantry AI is at least decent...

[Baaz]

On 5/3/2021 at 11:22 AM, Dr.SquirrelBoy12 said:

I think this would be awesome to have in DCS, but frankly I don't really know if it is practical for them to implement given how pointless it is to use anti-infantry weapons in DCS.
It's not like ARMA where the infantry AI is at least decent...

Not only that, but how to simulate 10,000 nails flying through the air without causing a HUGE lag spike. 

 

The only way I see it even remotely possible is if, for example, they simulate 10 nails flying through the air.  On impact those 10 nails create, instead of a massive explosion, a small dust cloud (similar to what we see from low flying helicopters now) that would show the impact area of what the 10,000 nails would cover.  Then some kind of blast area for those 10 nails would have to be developed to simulate the destruction of what 10,000 would cause. 

 

Unfortunately, all this would be moot if ED doesn't correct the issue with blast damage.

On 5/2/2021 at 11:51 AM, MRTX said:

I see the flechett rockets being more of a problem when it comes to implementing them into DCS.

 

You could either simulate each dart of the rocket, which would obviously kill performance. Or you could make the rocket go invisible at the point when it should release the flechettes, and let it be a simple HE rocket with a modified blast radius that mimmics the spread of the darts + a special impact effect, that looks like the flechettes hitting the ground.

 

In the end, none of these solutions are perfect.

 

Sorry mate, after making my last posting I went back and re-read all the previous postings within this thread.  I then realized you basically stated the same thing.  Sorry for stepping on your toes.

[shagrat]

On 5/2/2021 at 6:51 PM, MRTX said:

I see the flechett rockets being more of a problem when it comes to implementing them into DCS.

 

You could either simulate each dart of the rocket, which would obviously kill performance. Or you could make the rocket go invisible at the point when it should release the flechettes, and let it be a simple HE rocket with a modified blast radius that mimmics the spread of the darts + a special impact effect, that looks like the flechettes hitting the ground.

 

In the end, none of these solutions are perfect.

 

I don't see any problem, knowing that a 100 bullet gun burst, also tracks each bullets trajectory in DCS. Not much difference between a Flechette cluster and a 200 rounds gun burst.

 

 

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On 5/3/2021 at 6:22 PM, Dr.SquirrelBoy12 said:

I think this would be awesome to have in DCS, but frankly I don't really know if it is practical for them to implement given how pointless it is to use anti-infantry weapons in DCS.
It's not like ARMA where the infantry AI is at least decent...

Try flying helicopters in DCS, then you will understand quickly, why Infantry, Manpads and BMPs are very relevant if half your armament is FFAR rockets, instead of guided stuff. 

Edited May 6, 2021 by shagrat
I don't like "auto merge"

[Meathawk]

Flechette ammunition seems to perform really poorly in shotguns (YouTube) and in the only video I found about Vietnam, the Testshot didnt look exactly devestating to me. Is there any convincing evidence that this kind of ammunition is effective at all?

[DaemonPhobos]

Each M255 carry like almost 1200 flechettes inside, and you may be firing pairs or ripples (or a 76 rocket salvo if you want to crash your PC), that's definitely going to cause a lag spike.

Modelling the damage effect to soft targets is quite complex.

However, the flechette rocket is basically an obligatory weapon to add, the weapon is listed as an authorized armament, the 64D has the 6FL fuze setting for firing them with the M439 airburst fuze.

 

[barundus]

9 hours ago, Meathawk said:

Flechette ammunition seems to perform really poorly in shotguns (YouTube) and in the only video I found about Vietnam, the Testshot didnt look exactly devestating to me. Is there any convincing evidence that this kind of ammunition is effective at all?

Ballistically, each nail in the M255A1 is roughly equivalent to a 5.56mm round at its effective range (this is reliant on correct firing procedures, proper ranging and fuzing, and the fuze function at the proper distance).  
As designed, the beaten-zone of a M255A1 deployment is roughly a 30m square, with roughly one nail per square meter.

[Meathawk]

@DaemonPhobos @barundus tnx guys - interesting insights. But ... is it really effective? From the Shotgun-Videos I saw the "feathers" dont work at all and the darts just tumble completely uncontrolled which makes them slow, ballistically poor and with inceased distance super unprecise. The Darts tumble towards the target and in most cases will not penetrate due to unfavourable impact angles.
Is that different in Flechette Rockets?

[AlphaOneSix]

Nope, you've hit the nail on the head, pardon the pun.

[shagrat]

22 hours ago, Meathawk said:

Flechette ammunition seems to perform really poorly in shotguns (YouTube) and in the only video I found about Vietnam, the Testshot didnt look exactly devestating to me. Is there any convincing evidence that this kind of ammunition is effective at all?

British Apaches in Afghanistan. From Ed Macy "Hellfire". Page 107, "Most commonly carried warheads were HEISAP and Flechette". Flechette description on pages 108/109.

Page 386 "Billy and I needed Flechette clearance, and soon. The HEISAP rockets were magic against buildings but rubbish in the open."

From Ed Macy "Apache". Page 76 "Nothing beats a Flechette for multiple personnel out in the open." Followed by a description of a two rocket shot against enemy position.

There are more references in that book.

[barundus]

5 hours ago, Meathawk said:

@DaemonPhobos @barundus tnx guys - interesting insights. But ... is it really effective? From the Shotgun-Videos I saw the "feathers" dont work at all and the darts just tumble completely uncontrolled which makes them slow, ballistically poor and with inceased distance super unprecise. The Darts tumble towards the target and in most cases will not penetrate due to unfavourable impact angles.
Is that different in Flechette Rockets?

Hard to know whether the darts tumble initially on fuze-function.  My "educated speculation" is no; they don't tumble drastically, but probably a bit.  From a pilot's perspective, I don't care.  When the expulsion charge actuates, the packed darts are forced out the front of the cargo tube, much like a shotgun.  When ranged properly, the fuze is supposed to function at a certain distance from the target, with the standoff calculated to produce the desired "beaten zone" I mentioned above, enough time to stabilize, and arrive with the velocity to retain kinetic energy equal to a 5.56 round. 

The M255 is intended for soft targets, and light skin penetration.  No reason to assume they're not effective, based on a YT video shooting darts from a shotgun.

 

[Raptor9]

Exactly what Barundus said. Comparing the ballistic characteristics of one set of ammunition to another, despite them both being in the same category of function, isn't really an accurate determination of effectiveness or performance.

 

It's like comparing the A-10's 30mm rounds to that of the Apache's 30mm. Both may have similar calibers, but both have drastically different performance characteriatics and target effects, partly due to the composition and profile of each round, as well as a vastly different-sized propellant charge behind it.

 

Even if they were exactly the same, the method of delivery and firing platform differences would alter their terminal effects.

[DaemonPhobos]

Well, we know that the fuze detonates about 150 meters before the target and that the inherent dispersion of the MK66 motors is around 10 milliradians.

I don't have figures yet for the dispersion of the flechettes themselves but from a 150 meters distance it can't be so bad.

Terminal ballistics are too complex to calculate, it has kinetic energy similar to a low caliber rifle bullet, so I don't believe it would be an instantenous kill unless you score a hit on the head or CNS.

But we have seen videos of hellfire missiles hitting trucks in the engine block, then the occupants running away from the vehicle after the explosion, a simplified damage model would be ok for this weapon.

 

 

[AlphaOneSix]

Flechette darts have much lower mass than rifle bullets, so they don't compare favorably. For example, green tip 5.56mm is 62 grains, while the darts from a flechette rocket are only about 20 grains.

[barundus]

On 5/10/2021 at 12:15 PM, AlphaOneSix said:

Flechette darts have much lower mass than rifle bullets, so they don't compare favorably. For example, green tip 5.56mm is 62 grains, while the darts from a flechette rocket are only about 20 grains.

The darts in the M255A1 (the current use type) are 60 grains.  About 1200 of them.  At 5000 meters they're still going about 225m/s. 

The old M255 used 28 grain darts.  About 2500 of them. 

 

Edited May 11, 2021 by barundus
Added some info.

[AlphaOneSix]

4 minutes ago, barundus said:

The darts in the M225A1 (the current use type) are 60 grains.  About 1200 of them.

 

[shagrat]

On 5/7/2021 at 12:59 PM, Meathawk said:

 

Another reference for actual M255 Flechette usage on AH-64 Apaches:

From Osprey Combat Aircraft Series "AH-64 Apache Units of Operations Enduring Freedom and Iraqi Freedom", Page 35 (...)"Yet, with the primary targets in Afghanistan having been personnel and a single SUV to date, the need for carrying expensive Hellfire rounds was called into question. Borrowing from Marine stocks, Army AH-64s began utilizing four M261 19-shot rocket pods, loaded with a mix of M151 10-lb and M229 17-lb HE rockets and M255 flechettes for anti-personnel use."(...)

[shagrat]

To put the effectiveness of bullets, shrapnel, flechettes against infantry into perspective we need to understand the actual effects.

Infantry hit by a bullet, shrapnel or whatever will likely not be killed immediately. Depending on the number of hits an infantryman will be more or less injured.

Now, this injury has implications beyond a simple health bar, I'd like to call that "secondary effects".

These can be split into three basic categories:

- mobility

- fighting ability

- moral/support

A simple hit to a leg will decrease mobility tremendously (can't move, at least is severely slowed down) , reduce fighting ability (pain, dizziness, blood loss over time if not treated), require support from other squad members from first aid to evacuation (depends on the fighting force but most armies don't leave there fellow soldiers to die).

Make that single hit multiple, or put into the torso, the fighter is usually out of the fight and requires immediate MEDEVAC.

So as soon as ED starts modeling these effects beyond dead or alive, any weapon/warhead that inflicts a damage point on the health bar of an infantryman the effectiveness of these weapons against infantry will drastically increase!

The effects don't need to even care about "accurate modeling of internal organs" or "hitzones for infantry". If a soldier is hit, there is 80-90% (50-60% with body armor) chance he is no longer in the fight and requires help (or is left to die later). It shouldn't be difficult to model these "effects" even with the current AI/damage model.

 

In conjunction with the data @Barundus supplied, even flechettes will be very effective.

Usually you will shoot a pair of M255A1. That is 2 times 1200 darts saturating an overlapping area of about 30m*40m, if delivered correctly. The overlapping center will amount to roughly 2.5 flechettes per square meter with about 1 flechette per square meter on the left and right borders... An average human inside the center zone will take 1-2 hits, unless he has a flock of guardian angels taking special care or he is in a fortified position.

Now the "hit" itself is one thing, the damage dealt is another. The kinetic energy transferred is often neglected, but is part of effects on target and shattering bones or a shockwave rupturing internal organs is far worse, than a bullet passing through a muscle.

All facts considered I would call flechettes pretty effective against infantry and light vehicles...

[Sinclair_76]

1 hour ago, shagrat said:

To put the effectiveness of bullets, shrapnel, flechettes against infantry into perspective we need to understand the actual effects.

Infantry hit by a bullet, shrapnel or whatever will likely not be killed immediately. Depending on the number of hits an infantryman will be more or less injured.

Now, this injury has implications beyond a simple health bar, I'd like to call that "secondary effects".

These can be split into three basic categories:

- mobility

- fighting ability

- moral/support

A simple hit to a leg will decrease mobility tremendously (can't move, at least is severely slowed down) , reduce fighting ability (pain, dizziness, blood loss over time if not treated), require support from other squad members from first aid to evacuation (depends on the fighting force but most armies don't leave there fellow soldiers to die).

Make that single hit multiple, or put into the torso, the fighter is usually out of the fight and requires immediate MEDEVAC.

So as soon as ED starts modeling these effects beyond dead or alive, any weapon/warhead that inflicts a damage point on the health bar of an infantryman the effectiveness of these weapons against infantry will drastically increase!

The effects don't need to even care about "accurate modeling of internal organs" or "hitzones for infantry". If a soldier is hit, there is 80-90% (50-60% with body armor) chance he is no longer in the fight and requires help (or is left to die later). It shouldn't be difficult to model these "effects" even with the current AI/damage model.

 

In conjunction with the data @Barundus supplied, even flechettes will be very effective.

Usually you will shoot a pair of M255A1. That is 2 times 1200 darts saturating an overlapping area of about 30m*40m, if delivered correctly. The overlapping center will amount to roughly 2.5 flechettes per square meter with about 1 flechette per square meter on the left and right borders... An average human inside the center zone will take 1-2 hits, unless he has a flock of guardian angels taking special care or he is in a fortified position.

Now the "hit" itself is one thing, the damage dealt is another. The kinetic energy transferred is often neglected, but is part of effects on target and shattering bones or a shockwave rupturing internal organs is far worse, than a bullet passing through a muscle.

All facts considered I would call flechettes pretty effective against infantry and light vehicles...

The flechette is a fin stabilized projectile. Considering terminal ballistics, the stability of spin stabilized projectiles depends on the medium. Spin stabilized bullet is pretty stable moving through air but will be unstable, ie start to tumble, when moving through water. This tumbling will transfer energy from the projectile to its surroundings. A fin stabilized projectile is inherently stable in whatever medium its moving trough. Therefore it transfers a lot less energy to its surroundings compared to shrapnel (really unstable) and spin stabilized projectiles (partly unstable).

Of course this is all theory. The ejection of the flechettes'out of the rocket will damage/bend a couple of them, changing the dynamics.

[shagrat]

2 hours ago, Sinclair_76 said:

The flechette is a fin stabilized projectile. Considering terminal ballistics, the stability of spin stabilized projectiles depends on the medium. Spin stabilized bullet is pretty stable moving through air but will be unstable, ie start to tumble, when moving through water. This tumbling will transfer energy from the projectile to its surroundings. A fin stabilized projectile is inherently stable in whatever medium its moving trough. Therefore it transfers a lot less energy to its surroundings compared to shrapnel (really unstable) and spin stabilized projectiles (partly unstable).

Of course this is all theory. The ejection of the flechettes'out of the rocket will damage/bend a couple of them, changing the dynamics.

As per my sources cited above, they were obviously effective against personnel in the open, to a point, that they were the preferred solution.

As Barundus stated, they still hit with 225m/sec after 5,000m of travel. At that point it's actually more damage dealt if they are twisted, bent or travel sideways (what they don't necessarily do). An area saturation of more than 1 dart per square meter (single rocket), or usually 2,5 darts per square (pair) ensures pretty much a hit on anyone not in good Cover or extremely lucky.

After you get hit with a nail traveling at 225m/sec your usually a case for MEDEVAC or the plastic bag...