The future of Light Arty (105 mm) (From: Mortars)

[jeffb]

E Battery on TF 3-06 used a 120mm mortar that was loaned to them by the US SF. It would be interesting to find out what they thought of it. The CO of 2 RCHA and two of the BCs ( D Battery and the OP Battery) were on that TF, so perhaps JeffB or someone else from the regiment could ask them.

I will do just that!

 

[FJAG]

1. From what I understand 120mm HE mortar has a greater lethal radius than a 105mm HE (its like 60-65m, I will dig up my source for that, give me a bit)

When I was researching the comparable effects of different rounds I came up with that 60-65m lethal radius figure for the 120 mm as well but I think that was a misstatement that has been repeated a number of times. I saw several US mortar manuals and effects manuals where the figure is stated as a 60m diameter which is in my mind the more logical figure. The 105 mm has a 70 m diameter which is also logical seeing that the projectile has a higher Composition B/ TNT quantity than the 120.

I also want to note GnyHwy's comment re the more circular pattern of the 120mm. This pattern is as a result of the angle of descent and the material that makes up the ground at the impact site. In general the steeper the angle of descent the more circular and even the fragment distribution. As the angle of descent becomes flatter the pattern becomes more of a butterfly wing pattern that spreads further out. In other words fragments going back towards the weapon are blown downward into the ground and therefore don't fly back as far and ones flying forward and outward are flying higher and therefore further. Assuming the gun or mortar is shooting over our friendlies heads, a shallow flying round can be brought in closer. BUT in environments where there are no fixed lines guns and mortars may fire from flanks or even head on. The effect there may in fact necessitate a greater danger close distance.

What must also be kept in mind is that the development of the lethality of rounds is an ongoing process and from time-to-time there may very well be cross-overs as new types of ammunition are introduced for a given weapon system. Similarly ranges may vary with developments but in general guns will have the edge because of the stronger barrels, longer barrel length and mass. As mortars are made heavier to increase range etc they take on the disadvantages of the gun.

Gunners, if you were forced to choose between an 81mm or 120mm mortar and lets say 105 was not even an option, which would you go for?

That all depends on the environment. Usually infantry do not have to worry about distant targets and artillery covers that. In that situation I would prefer the 81 mm because of its low weight, easy transportability, high rate of fire and the closeness that the round can be brought to our own troops.

On the other hand, If there is an absence of artillery, a need for range (such as with multiple distributed patrol bases or a wider patrol area) and less need for portability then the 120 mm would be the choice.

Afghanistan has taught us (and by us I mean coalition forces, not just Canadians) several false lessons as to indirect fire support. Some of these are the results of what we were permitted to deploy with. My natural tendency to stay conservative and flexible is to ensure both capabilities are available (perhaps even within the same platoon)  so that we can adapt to the circumstances presented rather than being left without something we need. (I understand - but can't swear to it - that when we bought automated grenade launchers Treasury Board insisted that we divest ourselves of the 60 mm mortars. To me that's not too bright. There are things to 40 mm can do that the 60 mm can't and vice versa. The option should be available to the guy on the ground even if it stresses the supply chain a bit)

 

[ArmyRick]

Another note and I am talking from years ago. I remember talking to a US Army stryker mortar grunt (in the US army, mortar man are almost a sub trade in the infantry) and do seem to remember him saying that 120mm mortar bombs were around 30-35 lbs. I do not know how much of that is RDX/Comp B/etc, but if I remember correctly an 81mm HE bomb was 10 lbs (4.5 KG) and had a 30m lethal radius, so 60-65m for a 120mm mortar is not likely exaggerated.

I still wish it was a case of both guns and mortars. You know like our American and British friends (we must know something they don't). I think it should be
-arty manning 155mm and after listening to discussions maybe maintaining a minimal reg force/heavy P Res 105mm capability (Never know what comes up)
-Infantry should have 81mm (for light/dismounted) and 120mm in strykers for LAV equipped battalions

Another point, WHY must it be a case of one or the other? Can we not have our reg f gunners keep both 155mm and 105mm guns going? It would be like a tool box, mission demands and restrictions would dictate what gun gets used. I imagine it would be easier for a chinook to fly a 105 into high mountainous terrain than say the M777?

BUT you can wish in one hand and crap in the other and see which one fills first....

 

[McG]

Gunners, if you were forced to choose between an 81mm or 120mm mortar and lets say 105 was not even an option, which would you go for?

:stop:
There is a whole other thread dedicated to discussing this very question.  If you want to take mortars out of the equation, then take your discussion back to the mortars thread.
:shooter2: :highjack:

I now return you to the light artillery discussion.

Cheers,
the staff

 

[Petard]

A lot of the comparisons in this thread are using dated, non-IM, ammunition specs

This is a link to a presentation on Rheinmetal-Denel's 105, with some useful info on a more modern ammunition system
www.dtic.mil/ndia/2004armaments/04_Vickory_105mm_Indirect_Fire.pdf
Even so, the presentation is somewhat dated (circa 2004 I think), but the important thing to note is the range the gun can achieve with all types of ammunition, and that it can fire the older M1 family of projectiles as well.

Before this flies off onto another tangent, I'm well aware of new 120mm mortar ammunition with improved lethality, the point is 105mm is still a useful calibre and could have a future if the need were more clearly defined, and options should not be limited to older ammunition limits

Post edit: Besides higher fragment hit probability than some legacy HE ammunition (including 120mm), note that the LEO can fire a LAHAT missile, for much better antitank capability (both direct and indirect) than HESH or standard 155 HE