Thursday, March 7, 2019

OSR In Country: Vietnam. Heavy Vehicles


A post on running Armored Vehicle combat and stats for such during the Vietnam war.
Not an expert so a few things are probably off to Veteran eye's. I did my best.

Here are the original vehicle rules these are modified from. The original rules should be used with unarmored normal vehicles such as jeeps, cars, trucks, etc.

Armored Vehicle Movement
Driving Checks
The Drive Check is simply a normal Dex roll modified by road conditions, damage, and perhaps even a Class Ability.  All penalties and bonuses are cumulative.

Most situations won't call for a check.
Taking damage, encountering and obstacle, a damaged Driver, etc will require a check to maintain control if the tank was moving.

Failure
IF the Drive Check is failed by 1-5 on the roll of d20: Slip
IF the Drive Check is failed by 6-10 on the roll of d20: Skid
IF the Drive Check is failed by 11+ on the roll of d20: Spin

Slip
The vehicle slips to the right or left (random) a number of feet equal to half of the speed it is travelling while continuing to move forward. This can bring it into a collision with another vehicle or objects.
On the Driver's initiative the next round he can roll with no penalty to the Drive check to recover. Otherwise the vehicle must be braked or it plows ahead off course.

Skid
The nose of the vehicle skews to the right or left but the vehicle continue to travels in the direction it was heading side-ways for a distance of feet equal to 1/2 of the speed it was travelling in mph. The Driver must make a Drive Check at the end of the skid or the vehicle comes to an abrupt halt. While skidding out of control it may collide with another vehicles or objects.

Spin
The vehicle spins wildly for the round and ends up facing a random (1d8) direction. If the Driver makes a successful Drive Check with a -4 penalty the vehicle can continue at normal speed if. If failed it skids to a stop after a distance in feet equal to 1/2 of the speed it was travelling in mph, now facing the new direction. If the vehicle hits an object both take damage as per normal collision rules. 

Bog Down/Hung Up
Wet environments can suck a tire or tread down fast, bogging the vehicle into an immobile state.
Mud, swampy ground, rice paddies, etc can stop a vehicle fast if care is not taken.

Trying to cross over rubble, tree piles, wide trenches, etc can have the same effect, hanging up the tank and stalling movement.

Whenever failing a Driving check by 5+ while crossing the above conditions or obstacles the Driver must immediately make another check with no penalty. If he fails this one he has become bogged down and unable to continue. He can make one more Drive check with a -8 penalty to free himself otherwise he cannot move without help from another vehicle or a major digging project.

Armored Vehicle Combat
Armor and Weapon Ratings
All armored vehicles have an armor rating of Light, Medium, or Heavy.
All armor vehicles are immune to small arms fire, machineguns, and grenades.

Heavy weaponry have the same ratings and affect how they damage vehicle armor based on these ratings.
If the weapon is the same rating as armor the vehicle will take full damage.
If the weapon is one rating lower than the armor the vehicle will take half damage.
If the weapon is two ratings lower than the armor the vehicle will take no damage.

Hard and Soft Targets
Sometimes in tank combat it's important to know how hard or soft a target is that you're shooting or ramming into. If it comes up here are guidelines:
Hard Target: Armored vehicles, metal and concrete buildings and bunkers.
Soft Target: Open trenches, unarmored vehicles, wooden buildings, etc.

Vehicle Damage
At half hit points the vehicle is at a -2 penalty to drive due to damage.
At 0 hit points the vehicle is immobile.
At -10 hit points the vehicle is either on fire as per the Fire critical result
At -20 or lover the vehicle explodes as per the Boom critical result.

Critical Hits
A roll of a natural 20 on the 1d20 attack roll is considered a critical hit and, if it does damage to an armored vehicle, causes a roll on the critical hit chart in addition to damage to the vehicle hit points. Because of the armor rules a Light vehicle weapon might hit a Heavy armor vehicle doing no damage and negating the critical hit.

Every damaging hit to the vehicle when it is at half of it's current hit points or greater is cause for a roll on the critical chart.

Find where the gunner was aiming and roll in the appropriate area (Turret, Hull, Treads) to see what happened.

APC Crits
1. Driver compartment hit. Driver takes full damage, Save for 1/2 damage. See Crew
2. Gunner MG:Destroyed.
3. Gunner hit. Gunner takes full damage, Save for 1/2.
4. Radio: Destroyed
5. Passengers: Random roll for full passengers ( 8 passengers = 1d8, etc.) hit for full damage, Save for 1/2 damage.
6. Engine Hit: The vehicle is now at half speed. If hit again the engine is destroyed. If the first hit is by five or more over the AC the engine is immediately taken out.
7. Fire: The vehicle is burning. The vehicle and all crew take 2d6 damage per round. It increases by 1d6 per round until the vehicle destroyed.
8. Boom: The vehicle explodes in  fire and shrapnel as fuel or ammo or both ignite. The crew takes full damage from the attack and an additional 3d6 fire damage each round inside the vehicle. Those within a 50' radius of the vehicle takes half damage from the attack damage, Save for 1/4 damage.

Treads/Tires
There is no chart to roll. The treads are hit and damaged. Drive rolls suffer a -4 penalty. If hit again the vehicle is immobilized. If the first hit is by five or more over the AC the vehicle is immobilized.

Tank Crits
Turret
1. Main Gun: The first hit causes a -4 penalty to all shots from damage. A second hit destroys it. If the first hit is by five or more over the AC the gun is immediately destroyed.
2. Crew: 1d3 crew (commander, gunner, loader) hit for full damage, Save for 1/2 damage. See Crew Hit Chart below.
3. Turret Jam: Stuck at current position.
4. Co-Ax (turret) MG:Destroyed.
5. Hatch torn off. If Commander standing in it he takes full damage, Save for 1/2.
6. Turret Explosion: It's gone. All crew take 5d6 damage, Save for half.

Hull
1. Radio: Destroyed
2. Bow MG: Destroyed
3. Crew: 1d4 crew (see below for random crew hit chart) hit for full damage, Save for 1/2 damage.
4. Engine Hit: The vehicle is now at half speed. If hit again the engine is destroyed. If the first hit is by five or more over the AC the engine is immediately taken out.
5. Fire: The vehicle is burning. The vehicle and all crew take 2d6 damage per round. It increases by 1d6 per round until the vehicle destroyed.
6.  Boom: The vehicle explodes in  fire and shrapnel as fuel or ammo or both ignite. The crew takes full damage from the attack and an additional 3d6 fire damage each round inside the vehicle. Those within a 50' radius of the vehicle takes half damage from the attack damage, Save for 1/4 damage.

Treads/Tires
There is no chart to roll. The treads are hit and damaged. Drive rolls suffer a -4 penalty. If hit again the vehicle is immobilized. If the first hit is by five or more over the AC the vehicle is immobilized.

Crew Hit Chart
(multiple hits on the same crew member count and diminishes hits due to other crew.)
1-2 Commander
3-4 Gunner
5-6 Loader
7-8 Driver

Aiming At an Armored Vehicle
With an extra -4 penalty on the roll the attacker, if a crit is scored, can choose a critical effect.
Turret: Main Gun, Crew, or Turret Jam
Hull: Crew or Engine Hit
Treads/TIres

Ramming and Collisions
To successfully ram a vehicle or other object a Driver must make a Drive Check with a +4 bonus. If successful the vehicle plow into its target. Tanks are good at ramming things, especially smaller vehicles.

If a vehicle is hit the rammed Driver must make a Drive Check or lose control. If the attacking Driver fails and rolls a natural 1 or 2 on the d20 the attacking Driver  must make a Drive Check of  his own or lose control.

If two vehicles are attempting to ram each other, each Driver makes a normal Drive Check with a +4 bonus. Whomever makes the highest roll has the advantage; the other Driver must make a second Drive Check or wreck his vehicle. If both miss,  nobody hit. If it's a tied roll, both take damage and both make Drive Check to see if they lose control.

Damage
Crashing or ramming vehicles take 1d6 points of damage for every ten miles per hour they are travelling. Armored vehicles multiply this damage: x2 for Light armor, x4 for Medium armor, x8 for Heavy armor.

Against unarmored vehicles a Light armored vehicle takes 1/4 damage. For collisions with other armored vehicles damage is reduced the same as if the opposing AV is a weapon of the same rating as its armor. Thus a Heavy armor tank ramming a Light armor tank would take no damage; the light tank would take full damage.
If a Vehicle rams another from behind subtract the target Vehicle's mph from the ramming Vehicle's mph. The remainder is the damage to both Vehicles and Drive Checks are required as normal. .
If a Vehicle T-bones another vehicle both take the damage from the ramming vehicle's mph. Unarmored vehicles or armored of the same rating come to a dead stop. Smaller armored vehicles are knocked aside. An armored vehicle will plow over or through a smaller unarmored vehicle.
If two Vehicles hit head-on add the amount of d6 damage from BOTH Vehicles mph and add them together for damage. Unarmored vehicles or armored of the same rating come to a dead stop. An armored vehicle will plow over or through a smaller unarmored vehicle.

When ramming buildings etc use the following guidelines adjusted for fortifications, etc.
Hard targets: concrete buildings and barricades rate as Light armor, heavy steel rates as Medium armor.
Soft Targets: Normal wood and earth rate as no armor or Light armor if thick trees, etc.

Sideswipe/Grazing//Pushing
Grazing a vehicle as a sideswipe does 2d6 damage to each vehicle and none to the Passengers. For armored vehicles follow the same damage guidelines as above. A sideswiped Driver must make a Driving check or lose control.

Pushing another Vehicle off the road or into obstacles is a Ramming Maneuver as above.

Passenger Damage
Passengers take half damage from all wrecks and collisions (except for grazing/sideswiping.)
Damage is whatever is left over from a vehicle after being reduced by armor, etc.
Passenger damage can be reduced by the following:
A seat belt reduces the damage by 25 percent.
A Saving Throw (Death) allows the Passenger to reduce the remaining damage by 50 percent.

Damage reduction is cumulative and follows the order of seat belt then Save.

If a Passenger in the Vehicle is brought below 0 hp but has more than -10hp he can make a Saving Throw (Death). IF successful the Passenger is stabilized but unconscious and in critical condition. For each hour they are without medical help they must roll another Saving Throw or die.

If they are at -10 hp or lower or the after wreck Saving Throw is failed the Passenger is dead at the wreck.

Injured Driver
A Driver at half hit points or lower have a Drive check penalty of -4.

Armored Vehicle Profiles
A quick explanation of a few vehicle game stats.

Armor Class (Ac)
Normal armor class to be hit. (Light, Medium, or Heavy armor.)

Hit Points (HP)
How many hit points the vehicle normally has.

Move
Maximum mph for the vehicle. To find combat movement in relation to characters us the following quick and easy way:  Every 1 mph the vehicle is moving multiply by 10'.
(ex: 25 mph equals 250 feet per round.)

Range
The miles the tank can travel on a full tank of fuel.

Armament
Where the weapon is mounted:
Turret: the main weapon of the vehicle, usually a cannon or launcher.
Pintle: a machine gun on a swivel mount, placed near a gunner hatch on an APC and a Commander's hatch on a tank.
Coaxial: a machine gun mounted in the turret aligned next to the cannon. It moves with the turret.
Bow: a machine gun mounted on a swivel in the front hull of the tank.

USA/ARVN
M113 Personnel Carrier
Ac: 13 (Light Armor)
Hp: 70
Move: 37 mph/ 3.6 mph amphibious
Weight: 12.1 tons
Range: 300 miles
Crew: 2
Passengers: 11 troopers
Armament:
Pintle: .50 MG: 2d12, 200', 100 belt, 2K rounds.

M-125 81mm Mortar Carrier 
Ac: 13 (Light Armor)
Hp: 70
Move: 40 mph/ 3.6 mph amphibious
Weight: 12.3 tons
Range: 300 miles
Crew: 6
Armament:
Rear: 81mm Mortar: 6d8, 20' radius, 1000' range inc, 114 rounds
Pintle: .50 MG: 2d12, 200', 100 belt, 2K rounds.

On a critical hit result of 'Passengers' the mortar and all crew are all hit as the rear of the APC is open top to accommodate the mortar.

M-577Al Carrier Command Post 
Ac: 13 (Light Armor)
Hp: 70
Move: 40 mph
Weight: 12.7 tons
Range: 300 miles
Crew: 8
Armament:
None

On a critical hit result ignore 'Gunner MG' and 'Gunner' results.

M551 Sheridan Tank
Ac: 14 (Light Armor)
Hp: 120
Move: 40 mph/ 3.6 mph amphibious
Weight: 17 tons
Range: 470 miles
Crew: 4
Armament:
Turret: 152mm Heavy Cannon: 5d6x6 HE/HEAT,30'/15' radius, 600' range inc., 20 rounds (AP, HE, HEAT)
Pintle: .50 MG: 2d12, 200', 100 belt, 1K rounds
Bow: 7.62 MG:  2d8, 200', 100 belt, 3k rounds

Caseless Ammo: When hit with a turret or hull critical there is a 70% that the rocket or mine sets off the ammo outright destroying the tank and killing everyone inside in an inferno.

M41 A3 Walker Bulldog Tank
Ac: 14 (Light Armor)
Hp: 170
Move: 46 mph
Weight: 23.5 tons
Range: 100 miles
Crew: 4
Armament:
Turret: 76 mm Medium Cannon, 5d6x2 HE, 20' radius, 600' range inc., 57 rounds (AP, HE, HEAT, WP)
Pintle: .50 MG: 2d12, 200', 100 belt, 600 rounds
Coaxial: .30 MG: 2d6, 200',100 belt, 5.225K rounds

M48 A3 Patton II
Ac: 15 (Medium Armor)
Hp: 200
Move: 40 mph
Weight: 52 tons
Range: 287 miles
Crew: 4
Armament:
Turret: 90 mm Medium Cannon: 5d6x3 HE/HEAT, 25'/15' radius, 600' range inc., 64 rounds (AP, HE, HEAT, WP, Beehive
Pintle: .50 MG: 2d12, 200', 100 belt, 3K rounds
Coaxial: .7.62mm:  2d8, 200', 100 belt, 10K rounds

M60 Main Battle Tank
Ac: 15 (Heavy Armor)
Hp: 240
Move: 30 mph
Weight: 60 tons
Range: 310 miles
Crew: 4
Armament:
Turret: 105mm Heavy Cannon, 5d6x5 HE/HEAT, 25'/15' radius, 600' range inc.,
Pintle: .50 MG: 2d12, 200', 100 belt, 3K rounds
Coaxial: .7.62mm:  2d8, 200', 100 belt, 10K rounds

NVA
Soviet PT-76  
Ac: 14 (Light Armor)
Hp: 120
Move: 27 mph / 6 mph amphibious
Weight: 14 tons
Range: 155 miles
Crew: 3
Armament:
Turret: 76mm Medium Cannon: 5d6x2 HE, 20' radius 600' range inc., 40 rounds (AP, HE)
Coaxial: .7.62mm:  2d8, 200', 100 belt, 1K rounds

Soviet T-55  
Ac: 14 (Medium Armor)
Hp: 170
Move: 30 mph
Weight: 36 tons
Range: 310 miles
Crew: 4
Armament:
Turret: 100mm Medium Cannon: 5d6x4 HE/HEAT, 25'/15' radius, 600' range inc., 43 rounds (AP, HE, HEAT)
Coaxial: .7.62mm:  2d8, 200', 100 belt, 1K rounds

Tank Cannon/Guns  
Here are some cannon stats for tanks.
The base damage is based on the High Explosive (HE) shell. There are three increments to the radius as in my Artillery rules here. This damage is used and modified for other shells.

Shell Types
High Explosive (HE, tipped with an explosive warhead.)
Standard damage round. Most effective against soft targets and infantry.

High Explosive Anti-Tank (HEAT, a shaped HE warhead designed to penetrate tank armor.)
An extra x1  to damage vs vehicle. Explosion arcs out in a 180' arc from point impact on vehicle or hard target. Automatic half damage to soft targets (personnel, animals, etc.) and may Save for another half damage.

White Phosphorus (WP, incendiary shell.)
Explodes in the normal radius for the shell. It burns for 2d6 damage for six rounds.
Damage is not reduced by radius increment but those hit do receive a bonus to their Saving throw for half damage.  The second increment gives a +2 bonus to the Save and the third increment gives a +4 bonus to the Save.

Canister//Beehive round.
Similar to the artillery version it is a 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. this shell does 3d6 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.

Because if the rarity of tank to tank combat the most popular shells were HE and canister. WP was useful but dangerous if hit in a tank. AP and HEAT were the least used.

Armor Piercing (AP, non-explosive solid rounds.) Rarely use in Vietnam.
An extra x1  to damage vs vehicle.
(Ex: a 75mm AP round would do 5d6x3, not x2.)


Light            Dmg (HE)  Radius Notes Range Inc 600'
20mm 3d6             5' Auto 3/rnd
40mm 5d6            5'

Medium       Dmg (HE)  Radius Notes Range Inc 600'
75mm 5d6x2 20'
88mm         5d6x3 20'
90mm         5d6x3 25'
95mm         5d6x4 25' HEAT Radius- 15'

Heavy          Dmg (HE)  Radius Notes Range Inc 600'
105mm       5d6x5 25' HEAT Radius- 15'
150mm       5d6x6 30' HEAT Radius- 15'

NVA/VC Anti-Tank Weapons
The communists used a popular Chinese 75mm Recoilless Rifle. It was light and had a good punch.
Functions the same as the 75mm tank cannon.
Armed with HE and HEAT rounds.

Smoke/Smoke Mortars
Smoke from explosions, fires, etc can play havoc in vehicle combat. An obscured vehicle is more difficult to hit, just as an obscured character is, and can hide movements. An obscured vehicle receives an AC bonus or +2 to +6, but it also takes a penalty equal to this amount if attacking from within the smoke. If an obscured vehicle fires from within the smoke it gives its position away and its AC bonus is halved. .

Smoke mortars on vehicles create a wall of smoke that will obscure it and its movement for 1d6+2 rounds. Smoke/WP shells could also be fired towards an enemy to cause confusion.

Cover
Vehicles can take advantage of cover such as burned out buildings, trees, and shallow depressions in the ground (going 'hull down.') Cover works the same as for a character giving a bonus based on how much of the vehicle is hidden. Camouflage netting may aid in the cover bonus.

For hard cover such as a concrete/brick walls or hiding behind a rocky hillside or burnt out tank:
+2 AC light, +4 for medium, and +6 for heavy cover.

For soft cover such as trees, an earthen hillside, etc. halve the cover bonus.



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