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"It's never Finished - Infantry smoke Grenades" Topic

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18 Jan 2023 1:40 p.m. PST
by Editor in Chief Bill

  • Changed title from "Its never Finnished - Infantry smoke Grenades." to "It's never Finnished - Infantry smoke Grenades"

18 Jan 2023 1:41 p.m. PST
by Editor in Chief Bill

  • Changed title from "It's never Finnished - Infantry smoke Grenades" to "It's never Finished - Infantry smoke Grenades"

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UshCha18 Jan 2023 7:58 a.m. PST

Well the latest big game has highlighted, particularly for 1/144 that our smoke marker for infantry smoke grenades may be a bit on the large size. The 1/144 ground scale is a bit less than twice of the 1/172 scale (1/1400 (approx) vs 1/1000) respectively so the scaled down current maker is already bigger, that and 1/72 models are unrealistically big vs our real scale 1/144 modes) makes us a bit weary of our current assumptions.
So does any body have experience or can suggest a source for how big a screen an infantry smoke grenade makes makes. Anecdotal/personal experience is fine (as wide as a 2/4/6 lane road is fine: as that will be how we represent it, our roads are by definition out of scale with the ground so we will scale the screen relative to actual features anyway. I would appreciate an estimate of the height but that is probably harder to judge and anticipate it be a function of the wind velocity anyway. Even size (length) of the screen vs wind speed would be of interest but for simplicity we never have much wind in our games (lots of hot air but no game scale wind).

79thPA Supporting Member of TMP In the TMP Dawghouse18 Jan 2023 8:16 a.m. PST

For purposes of your game, is smoke considered to be a single grenade, or multiple grenades?

Frederick Supporting Member of TMP18 Jan 2023 8:26 a.m. PST

Also duration can be an issue – as I recall the venerable M-18 smoke grenade has smoke that lasts maybe a couple of minutes

Martin Rapier18 Jan 2023 8:38 a.m. PST

I would reckon on 50m with a duration of a couple of minutes. Partly depends on type of smoke, some take up to 30 seconds to build up, others are instantaneous.

35thOVI Supporting Member of TMP18 Jan 2023 8:48 a.m. PST

Interesting. I wonder if the smoke is like gunpowder smoke during re-enactments? Most of the time is dissipates fairly quickly. But if atmospheric conditions are right, it hangs and never seems to disappear. I've been within 25 yards of the other side and could just see muzzle flashes. Of course these are large battles with anywhere from 8000 and to around 15000 involved.

Personal logo Sgt Slag Supporting Member of TMP18 Jan 2023 9:30 a.m. PST

Have you tried looking it up on the Internet? The American Willy-Peters (White Phosphorus) Grenade is well known and well documented. Wikipedia has some stats for the M34 WP Grenade: 30 Meter throwing range, 34 Meter blast radius! I remember seeing them listed in a Jane's book, circa 1980, in my local library. Can't remember what Jane's listed, but I know it listed three radii: kill distance, wound distance, and smoke distance (the largest, like 2-3 times the wound radius). Happy hunting! Cheers!

79thPA Supporting Member of TMP In the TMP Dawghouse18 Jan 2023 12:30 p.m. PST

It's been many decades since I've been around a smoke grenade, but here's my recollection.

For a US M18 smoke grenade expect about a minute of smoke. Also, the smoke blows out of a hole in the bottom of the canister, so you do not get a radius -- you get a stream that blows in whatever direction the bottom of the cannister is facing. The smoke moves laterally, then quickly rises and then dissipates. Maybe 25 feet of concealment or partial concealment if memory serves. You can have smoke 30 or 40 feet in the air, but it is pretty wispy by then. If operating in dry areas, roll to see if you start a field fire.

UshCha18 Jan 2023 1:04 p.m. PST

Martin, Sgt Slag most helpful you both have a similar approximation of a 50 to 60m screen. This is very interesting and illustrates issues with the approximations required even where simulation is a high priority in a table top game.

A quick google check gives a 2 carriage way road, expected to carry trucks, as 7.3m minimum (in the UK). Plus the pavement (sidewalk I think its called in the US). In the UK it varies but most new roads have about 1.5m as a typical minimum, wider if they include a cycle path. Now just to make sure, I have just measured our 2 carriage way road that is the main GLOC to the small village under dispute in the big game. It measures 50mm width. Now we recognize, to get a representative level of fire restriction 1.e. no wide fire arc available at range in an urban area, we ignore gardens in urban areas as the buildings are way too big for the ground scale. So as an approximation we can take our 50mm road to be 10m to 15 wide if you include pavements and hedges/grass strips beside the carriage, way which we do not model. On that basis the identified smoke could be argued to be approximately 4 roads wide in the real world. That is 200 mm long model scale and 200m in ground scale, way too big on the ground as its almost full RPG range. So compromise is needed!

So the starting point was the Issue 1 and 2 rules that set the marker at 100mm long for infantry. Thrown 40m to the front, too far in ground scale, but not really across one of our roads at model scale! The width is 100mm so 100m on the ground scale, too big but not a lot too big and it covers 2 road widths. Not perhaps a wildly unreasonable approximation, it does function some what correctly, it shields infantry crossing a typical 2 lane road ( we don't model wider roads as the ground to model scale discrepancy gets worse as the size of the model increases).

Now interestingly we just cut out a smaller smoke marker, it measures 55mm long. That's only just 1 road wide so at model scale its a long way out, in those terms our un-referenced judgement was way off.

So this thread is very helpful, It shows us that the original approximation is not wildly out, given the compromises needed. We could change but to be honest it would be a different compromise, but probably no better overall. Further more, changing our current approach would mean an additional markers, never a good thing unless there is an overwhelmingly good reason which there is not. So sticking to our current 2 markers standards is the way to go. At 1/72 ground scale the situation is marginally better so even less intensive to change.

Thank you all for the reply's and I hope explaining our logic was of some interest. I would appreciate your opinions on the issue.

For interest the screen could be deployed 300mm away (300m ground scale at 1/144) if a hand held grenade launcher was available.

Andy ONeill18 Jan 2023 1:49 p.m. PST

Isn't one of the downsides of wp that hot air rises?

Wolfhag Supporting Member of TMP18 Jan 2023 1:58 p.m. PST

79thPA seems correct: YouTube link

It works better in a jungle.

Compare it to WWII WP grenade: YouTube link


Personal logo Sgt Slag Supporting Member of TMP18 Jan 2023 2:04 p.m. PST

Smoke in real-life battles, is not as "ideal" as presented within war games. There are sooo many variables involved. The reality is that a game is a simulation, which fudges all but a few major influences -- it is a poor approximation.

My advice is simple: make a rule, play with it for a while, see if it makes for a playable game. Even if you go with the stat's listed in Jane's, or some other authoritative source, it is still a game, not reality. My go-to position is this: is it playable/is it fun?

I am not a military war game simulationist. I play for fun, not as a job working with military personnel. Therefore I have plenty of leeway in how I play my games. LOL! Cheers!

Personal logo Dal Gavan Supporting Member of TMP18 Jan 2023 3:22 p.m. PST

+1 SGT Slag.

Hand grenade smoke is just meant to block a narrow line of sight (eg a fire lane, doorway, window, bunker aperture, track and similar) for a minute or so, it's not meant to be used to form a persistent smoke screen, nor is it capable of doing so with the small number carried at section/squad level. Up until 2000 the front line load of a section was four WP and two coloured smoke, split up between between section commander, 2IC and No 1 RFLMN. If you want a lot of smoke or persistent screens then it means mortars or artillery, not grenades.

Most smoke grenades release for a minute or less. Some of the larger coloured smoke grenades would release a bit longer, but could only be thrown about 10m to 15m. The variables- wind, ambient temperature, vegetation, humidity, where the grenade lands (plonking a coloured smoke into a creek did not work well at all…), and many more- will all effect how long the smoke hangs around, how dense it is and how far it spreads.

Major Mike18 Jan 2023 4:16 p.m. PST

There are a couple types of smoke grenades. The first that many have mentioned are signal smoke grenades. These come in different colors (purple, green, yellow, red and white). They can be used to create a very temporary smoke screen of a short duration of a minute or two. Next come smoke (HC) grenades. These will quickly create a heavy smoke screen that will last more than a couple of minutes but will clear in around 5-10 minutes. Finally there are WP grenades. It will quickly create smoke, but will also throw around flaming blobs of WP that are not kind to uniforms, load bearing equipment, flesh or other things that might like to burn.

Personal logo Dal Gavan Supporting Member of TMP18 Jan 2023 4:48 p.m. PST

I only saw HICAP grenades once in 24 years, Major Mike. They were a special issue, I think for a battalion deliberate attack (exercise), but be <snip>ed if I can remember what we did with them. Our normal issue we carried was either US or UK coloured smoke (probably US- M18?) and No 80 WP.


For interest the screen could be deployed 300mm away (300m ground scale at 1/144) if a hand held grenade launcher was available.

150m is much more realistic, mate, whether it's the 40mm from a grenade launcher or a No 80 WP from a rifle grenade adaptor. You can fire them a bit further only at the cost of any accuracy.

79thPA Supporting Member of TMP In the TMP Dawghouse18 Jan 2023 4:58 p.m. PST

UshCha,if you want to effectively cover 50 meters, you are going to have to throw everything you've got at once. Have your mortars drop some smoke for that.

Martin Rapier19 Jan 2023 1:07 a.m. PST

Yes, I was thinking of ng of 2" smoke. Hand held smoke grenades are more like 50 feet of screen, tops, depending on the wind etc.

They work much better in some sort of defile (between buildings, wood lined road etc) as the smoke gets trapped.

You can certainly screen a two lane road, anything bigger will need multiple noted by other posters, they are a somewhat erratic point Solution. If you want a serious screen, it needs mortars, artillery or engineer smoke generators.

UshCha19 Jan 2023 8:24 a.m. PST

Gents yet again great info. I read lots more (I am a Sad Man) and while there are lots of manuals, and UTube demos, real data or even not so good data is not around.

A few things came up.

1)It's SOP for the Brits to use smoke grenades to break off contact for small groups so It must work a bit.
2) The manufactures claim a 40mm grenade launcher like the M203 can be used to throw a smoke grenade 700m (the medium velocity grenades), but it does seem a lot. The US pass for a M203 in the manual is close enough to a group target to suppress it at 300m. Windows were a pass at about 100m.
3) The only plausible actual sorce of data was from this link.

This is probably a bit optimistic but gives 12 to 18m that's about 40 to 60 ft. Now that looks close enough to Martins Figure of 50ft to look sensible.

The Mill-X is supposed to burn for 90 seconds. As a young man I could walk all day with a light pack at 5mph a tad over 7 ft a second. So a man with kit can probably do that for say 60 sec when the smoke is up. That's about 100m a tad more in yds. That is enough to get across a road with some margin. So 2 grenades which is you are expecting to use them is not too much to carry makes, our 2 road gap coverage not insane (i.e real world 30m gap).

Our infantry smoke only lasts one bound so as you rightly state it will not provide any long term coverage neither were we expecting it to. What it does do if you are sensible about where you go, is give you chance to break contact if cover is only 100m or so away or possibly get across a road/gap between houses.

I felt Guilty so I went back and checked my figures were not far out for the M203

see PDF link

Table 4-5 what you have to hit to pass with an M203.

Many thanks for the participation in the thread . To me this is what war game design threads should be about, not esoteric discussions but plain very basic data on the whys and wherefores.

Personal logo Dal Gavan Supporting Member of TMP19 Jan 2023 5:26 p.m. PST

UshChar, to answer your points in order:

1. It's SOP for the Poms, Aussies, Canucks, Kiwis and possibly even the US to consider it, and use it if it can be effective. I don't remember Poms using smoke to break contact on EX (but then again all ammo was in short supply in the 70's and 80's). However it's no use wasting time or ammo if the smoke won't be effective or isn't necessary. Remember, too, that popping smoke can draw fire into the area, so another reason only to do it if it's going to be really useful.

2. and 3. Gun runners- sorry, I mean Original Equipment Manufacturers' (OEM) representatives- aren't known for accuracy in their claims. I'll believe the ranges we were taught (which were developed from weapon and ammo testing at the Proof and Experimental Ranges). The short 40mm as used in the M79 and M203 (and derivatives) has an effective point target range of 150m, and an area target effective range of 300m. Yes, it can reach out to 400m+ but, even if you had a line of sight to a target that far away, the rounds will be all over the shop and probably wasted.

A section 2IC only carried three to six 40mm WP as standard first line. If I had to fire WP to screen an enemy possie 300m away then I'd fire at a point 150m away, so I knew the round would be close to where I wanted it, rather than spraying rounds 300m away in the hope that one may do the job.

UshCha20 Jan 2023 2:51 a.m. PST

Dal Gavan I agree The US fornal document actually puts the pass rate for suppressing infantry at 350m. We dropped it to 300m. I suspect our rules are somewaht diffrent to most so fleeing (1 min) opertunities are more common. The only other set that has that level of ebb and flow is Barkers 1925 to 1950 set and that was a bit limited (proably as I tried to use it at high level, it was in hind sight a very small game if you look at the terrain chosing system so did not scale up well despite its claims.

Personal logo Dal Gavan Supporting Member of TMP20 Jan 2023 3:36 a.m. PST

I remember those rules reasonably fondly, mate. My first wargames group used them and we also found out that too big a battle (BN +) just ground to a halt well before the game was finished, usually because we ran out of time.

Back on topic, smoke can be very useful pre-thermal imaging on the battlefield. ("Hot smoke" is used to reduce the usefulness of those, but I don't know whether they've managed to get it into grenades.) But smoke only ever provided concealment and, at the level of game you seem to be looking at, luck is as big a factor as timing and placement. So I'd be looking at smoke reducing the possibility of hits/suppression from firing, not negating fire altogether. As I said, smoke attracts fire and, even if the firer can't see the target, a burst or two through the smoke presents the possibility of suppression or casualties.

Andy ONeill20 Jan 2023 12:06 p.m. PST

Smoke was way too effective in the original 1925-55. You added one puff a turn for so many turns then removed one per turn.

I played a tournament where the one guy who chose Japanese revealed why. He covered the entire table with smoke. Had a lot of cheap short 75mm armed tanks.
Oh, the joys of my youth.

We did a bulge game with 5 massive tables in a school one summer holiday using those rules. Slightly modified.
One day I ran some American support unit of "cooks and bottle washers" fighting with -1 dice modifier.

Up until we discovered those rules we designed our own.

Martin Rapier20 Jan 2023 11:42 p.m. PST

Yes, WRG games invariably vanished under piles of cotton wool balls, unless you restricted it a bit.

UshCha21 Jan 2023 2:55 a.m. PST

We use arillery/mortar laid smoke a fair bit as was in the case of WW2, but we have been careful. However with our effective ranges being less "toy soldiers standard", like is says in some texts, smoke can be a rwo edged weapon splitting your distant support for the troops without carefull planning.

Personal logo Dal Gavan Supporting Member of TMP21 Jan 2023 4:22 a.m. PST

We tried a few six player games, Andy, but coordinating six wargamers is harder than herding sixty cats. Invariably the game stuttered to a close without a result.

Yes, WRG games invariably vanished under piles of cotton wool balls, unless you restricted it a bit.

I can't remember that being a problem, Martin, but it's possible the game organisers restricted smoke.

smoke can be a two edged weapon splitting your distant support for the troops without carefull planning.

It's hard to adjust indirect fire when you can't see the round splash because there's more smoke around than in a 70's disco. That's why a lot of mortar and artillery adjust firing uses WP- so you can more easily see where the round splashed- and saves the HE for fire for effect.

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