OSR In Country: Vietnam. Artillery

Rules suggestions for Artillery and big explosions.

Blast Radius
Artillery, tank cannon, and other big guns have a large blast radius. There are three extending blast radius'  measured in feet. The further from the center of the explosion the less damage personnel and vehicles will take.

There are three incremental radii to such explosions, each measured in feet.

• The first radius extends a set amount of feet. (For example let's say 20')
• Multiply x2 feet for the second. (21' to 40')
• Multiply x3 for the third increment. (41' to 60')

Damage done by Radius:
First: Full damage dice.  Personnel (your men and the enemy combatants) Save for 1/2 damage.
Second: half damage dice (round up.) Personnel Save for 1/2 damage.
Third:  half again damage dice (round up.)  Personnel Save for 0 damage

Cover bonus applies to saving throw.
Full cover may completely protect a character if the DM decides it is strong enough (use the light, medium, heavy armor/weapon rating for Vehicles below for guidelines.)

Basic Artillery Rules
There are several options available. A few are:
WWII Operation White Box by James Spahn

Recon from Palladium

Weird War II: Blood on the Rhine and other games from Pinnacle

All work very well and all pretty much work the same in each system:
⦁ You use your own mortar or you call in to see if Heavy Artillery is available.
⦁ Some roll is made to see if it is available/ what is available/ how much is available.
⦁ Rolls are made to see how long before the barrage will begin.
⦁ Rolls are made to see if/how close artillery hit.
⦁ Rules to do various things such as re-adjusting hits on the target, firing for effect, etc.

Heavy Arty Availability
Some missions will not have Heavy Artillery available due to it being diverted for other operations, stealth concerns, etc. It will vary.

When available on missions Heavy Artillery should be used sparingly. Over calling will result in it not being available as some REMF decides you do not need it. As a DM more than once a day for non-dedicated non-search-and-destroy target missions will be about it. Dedicated fire support will most likely be readily available as specific targets are located, not to get the PC's out of every fire fight.

If the team's mission has been given dedicated fire support it is vastly more likely it will be available. If not the chances of having support are greatly reduced. It's a crap shoot. At one point in time there were over 200 batteries of artillery were scattered over the country and often fire could overlap.

When in the field and the PC's think they need it they must roll to see if fire support is available
Roll a 1d6. A roll of 5 or 6 indicates it is available.
⦁ Dedicated: +3
⦁ Non-Dedicated: +0

What's available?
Roll a 1d6:
1 Heavy Mortar
2-3 Heavy Artillery
4-5 Gunship
6 Air Strike

How Long?
Average response time is 60 to 90 seconds.
Find how many points under his Int/Radio check the FO succeeded on his roll.
Subtract this from 15 to find how many rounds it takes for the first shell to impact (minimum 6 rounds.)

How to Hit? (Forward Observer)
Heavy Mortar and Artillery
To target the enemy and to make adjustments to the roll requires an Intelligence/Radio check. Those unskilled have a -4 penalty to the check. After the response time has elapsed a single spotting round will impact the ground on the FO who called it in's initiative. This will be the initiative for any following shells.

If the FO roll is passed the strike is on target. If it is failed the shell deviates from its intended target and lands in a random direction (use the 1d8 or 1d12 clock method) landing 2d10 x50 feet off target.

Re-Adjusting Fire
The next round the FO can call in another spotting round and try to hit the intended target with a +4 bonus to the FO roll (and a +8 if he takes another round after this but +8 is the maximum.)  If successful the re-adjusted fire hits and he can call in a Fire or Effect barrage. If failed the shell deviates but lands only 2d10x20 feet off target. This will be the deviation the next round, etc.

The FO can 'walk' the rounds over to a new target this way.

Fire for Effect (FfE)
When the target has been hit the FO can call for Fire for Effect. The battery fires with all of its guns and loaders.
⦁ Multiple shells impact on each combat round equal to it's rate of fire (RoF.)
⦁ The duration shows how many rounds the barrage lasts before the battery is exhausted, redirected, etc. A new strike, if called immediately after, gains a +8 to the FO's roll.
⦁ The shells are not as accurate as a spotter round . Roll the deviation for each shell that round.

USA/ARVN
Artillery               Dmg Inc RoF   Duration FfE Deviation
Hvy 4.2"  Mortar 10d6 35' 1d3        1d6+1       2d12x5 feet
105mm Howitzer 5d6x4 35' 1d3+1   1d6+1 2d12x5 feet
155mm Howitzer 5d6x5 50' 1d2+1   1d6 2d20x5 feet
203mm Howitzer   5d6x6 70' 1d2+1 1d4 2d20x5 feet

NVA/VC
130mm         5d6x5 50' 1d2+1   1d6 2d20x5 feet  

Required an 8 man crew.

Canister//Beehive round.
A  105mm shell packed with thousands of flechettes (small darts like nails). It is a vicious area effect weapon used against personnel especially those hidden in dense foliage. The shell does 4d6 damage to all targets in a cone attack starting 2' wide at the firing weapon and extending in a cone 1200' in length and a 300' width at it's end.
⦁ Everyone and everything not undercover can make a Saving Throw for half damage.
⦁ Those under soft cover automatically take half damage and can make a Save to halve it again with a bonus to the Save equal to cover bonus.
⦁ Those under hard cover or in an armored vehicle take no damage if totally covered. If partially exposed they will take damage and Save as if under soft cover above.

Gunship
Gunships will come in and chew up a position. They will stick around until they start taking serious ground fire (especially RPG's) or run out of ammo. Each round they will unload with all available weapons on the ship.

Pilot(s):  Attack +2, +3 to Dex/Piloting
Gunners: Attack +3

Hog (Huey)
Two M-60's, door gunners.
⦁ Target up to six hostiles per round in a line ten feet wide and fifty feet long.
⦁ +4 to hit.
⦁ Damage: 4d8 per hit.

40mm automatic grenade launcher, nose, pilot.
⦁ Attacking Ac 10 (Area attack)
⦁ Blasts an area up to thirty feet wide and 100 feet long per round.
⦁ Damage is 6d6. Soft targets save for half.

2.75 in (70 mm) rockets -  M200 19-tube rocket launchers,  2 pods, pilot.
⦁ Attacking Ac 10 (Area attack)
⦁ Blasts an area 40' wide by 40' per pair of rockets fired. Can fire up to up to 36 pair per round.
⦁ Damage: 6d6, Light Weapon, Soft targets save for half.

Snake (Huey Cobra)
7.62 mm multi-barrel Miniguns, right front turret, pilots.
⦁ Target up to 12 hostiles per round in a line ten feet wide and 100 feet long.
 ⦁ +4 to hit.
⦁ Damage: 4d8x2 per hit.

40mm automatic grenade launcher, left front turret, pilots.
⦁ Attacking Ac 10 (Area attack)
⦁ Blasts an area up to thirty feet wide and 100 feet long per round.
⦁ Damage is 6d6. Soft targets save for half.

2.75 in (70 mm) rockets -  19-tube rocket launchers,  1 or 2 pods on each wing, pilots.
⦁ Attacking Ac 10 (Area attack)
⦁ Blasts an area 40' wide by 40' per pair of rockets fired. Can fire up to up to 36 pair per round.
⦁ Damage: 6d6, Light Weapon, Soft targets save for half.

Airstrike
Napalm, bombs, or possibly AC-47 Spooky (Puff the Magic Dragon.)
Whole sections of the jungle go away. Hills get flattened. Bunkers crack like eggs. Fire and the wrath of Uncle Sugar. The scale of this kind of devastation is almost unimaginable from the ground.

Currently beyond the mechanical scope of what I want to do. Maybe later.
For now the GM will decide the outcome of an airstrike.
If it gets too close to the PC's and allies may take a few dice of damage at the GM discretion. Good luck.

Mortars
The attack roll uses the gunner or FO's base hit bonus + Int modifier vs a stationary target Ac of 10 + range modifiers. A moving target is always Ac 20 plus range modifiers and only one shot per round can be taken.

If it is failed the shell deviates from its intended target and lands in a random direction (use the 1d8 or 1d12 clock method) landing 2d10 x25 feet off target.

Once on target no attack roll is needed for a stationary target but deviation is rolled for each shell. IF the target moves to a new location the mortar must re re-adjusted.

USA/ARVN
Mortar Dmg    Inc' RoF Range'        Deviation 
Light
M-2  60mm 5d6      15'      2      500' 1d6x5 feet
⦁ 60mm WP 2d6 (Burns for six rounds)  

Medium
M-29  81mm 8d6     25'        2   1000' 1d10x5 feet
⦁ 81mm WP 2d6 (Burns for six rounds)  
⦁ 81mm Parachute Flare (up 1800 feet and light up a 3000 ft area for 1 minute)

NVA/VC 
The communist forces used a 60mm and an 82mm, both equivalent to our 60 and 81mm.

Mortars and their shells are heavy. Most mortars break down into three pieces: tube, bipod, baseplate. The baseplate is the heaviest, half the weight of the mortar. The M-19 60mm is split among a three man crew (squad leader, a gunner, and a loader.) The M-29 81mm normally crewed by a 5 man team (squad leader, a gunner, an assistant gunner and two loaders.)

Artillery vs Vehicles
⦁ Vehicles caught in the radius of a mortar take damage normally depending on  their armor rating vs the mortar rating
⦁ A direct hit from a 150+  mm HE shell from above straight up destroys the vehicle and everyone takes full damage. Everyone in the tank then is on fire for 2d6 damage per round until they escape the vehicle. Everyone within the three radii of the shell take normal damage with Saving throws.