Brookehurst Auxiliary : Notes on torpedo attack rules

Torpedoes - examples	In Service	Speed	Range	Warhead
18 inch. Mark XII aerial (UK)	1935	74kmh (36)	1,400m (9m)	176kg (AP-7/HE5)
21 inch Mark V seaborne (UK)	1917	74kmh (36)	12,400m (82m)	336kg (AP-11/HE9)
21inch. Mark 14 aerial (USA)	1931	85kmh (48)	4,100m (27m)	292kg (AP-8/HE6)
21 inch. Bliss-Leavitt Mk 8 seaborne (USA)	1911	65kmh (36)	14,630m (97m)	211kg (AP-7/HE6)
24 inch. Type 90 seaborne (Japan)	1933	85kmh (48)	15,000m (100m)	400kg (AP-12/HE10)
18 inch. Type 91 aerial (Japan)	1931	78kmh (36)	2000m (13m)	235kg (AP-8/HE6)

A torpedo is launched multiple rounds before it hits it’s target and so it must be registered on the table, or the table’s edge at a point of launch with a marker.

Once a torpedo has been launched and its point of launch has been established, then the distance between the launch point marker and the intended target must be calculated and divided by the torpedo’s speed.

The further from the target a torpedo is launched, the less chance it has of a successful hit. A torpedo suffers a 1 point penalty for each round it takes to reach its target. Thus, the closer to it’s target a torpedo is launched, the more chance it has of a successful hit.

Torpedoes cannot support each other, nor can they be supported by any other attack. For example, two torpedoes launched by two seperate aircraft against the same ship, count as seperate attacks, as do four seperate torpedoes launched by the same submarine. This is because each torpedo is subject to its own environmental conditions during it’s journey to the target.

The outcome of a torpedo attack is only decided by a die roll once the torpedo has reached its intended target. If the die indicates that the attack has failed then the torpedo has missed.

Once a target has been hit, and the immediate damage of the explosion has been inflicted, then secondary damage must be established – or to put it another way - what has the exploding torpedo done to the ship? To determine this additional effect of the attack, use the attacking die roll, with the chart below, to establish secondary damage.,

1	Minor damage. The ship is taking on water but her pumps can accomidate the influx and she is not in danger of sinking.	Ship can move and can keep fighting.
2	Limited damage. The ship is taking on water but the ship’s crew is able to stop the leaks within a few minutes. The ship still has engine power.	Ship can move at half speed and can keep fighting.
3	Moderate damage. The ship is taking on water. The ship’s crew is trying desperately to stop the leaks, but the ship will eventually sink unless it can reach a port within 1d6 hours. ~10% crew lost.	Ship can move at quarter speed and can keep fighting.
4	Heavy damage. The ship is critically damaged and will sink within half an hour. ~20% crew lost.	Ship can no longer move nor fight.
5	Critical damage. The ship’s structural integrity has been compromised and she will sink within minutes. ~50% crew lost.	Ship can no longer move nor fight.
6	Catastrophic damage. Secondary explosions rip the ship apart and she sinks at once. ~90% crew lost.	Ship can no longer move nor fight.

Test games.

Game 1: Bristol Type 156 Beaufighter Vs German Minesweeper The ship is defending itself with a single Bofors 40mm firing (AP-2). The plane is on a torpedo attack run with a single Mk XII torpedo. It is rolling for Shot At +2 to the front and Flak +2.
Round	Distance	Minesweeper	Beaufighter
1	400cm	1 +1 = 2	1 +2 +2 (-2) = 3	No effect.
2	300cm	1 +3 = 4	6 +2 +2 (-1) = 8	No effect.
3	200cm	3 +5 = 8	6 +2 +2 (-1) = 8	No effect.
4	100cm	4 +7 = 11	3 +2 +2 (-1) = 5	Plane defeated.

Note - I forgot to take altitude into account for this first game!

Game 2: Two Il-2 Shturmoviks Vs German Minesweeper The ship is defending itself with a Bofors 40mm firing (AP-2) and an Oerlikon 20mm, also firing (AP-2). The planes are on a torpedo attack run with Mk XII style torpedoes. They are rolling for Shot At +2 from the front and have +3 against Flak. The ship is firing at the foremost plane first.
Round	Distance	Minesweeper		Shturmoviks
1	400cm	6 +1 = 7		2 +2 +3 +4 (-1 -2) = 8		Planes at 240m altitude (+4). No effect.
2	300cm	3 +3 = 6		1 +2 +3 +3 (-1 -2) = 6		Planes at 120m altitude (+3). No effect.
3	200cm	4 +5 = 9		1 +2 +3 +2 (-1 -2) = 5		Planes at 60m altitude (+2). No effect.
4	Both torpedoes dropped at 110cm
	100cm	5 +7 =12		2 +2 +3 +1 (-1 -2) = 5		Planes at 20m altitude (+1). First plane defeated.
5	Second plane attacks with minesweeper with cannons and MGs. The aim point is the Oerlikon.
	100cm	2nd Shturmovik		Oerlikon AA gun – has +1 for gun mantel, and +2 for cover.
		5 +7 +3 =15		4 +3 (-2) = 5		Oerlikon battery is defeated.
6	First plane crashes into sea. Second plane banks left and begins to climb away. Torpedoes running (73cm).
	100cm	Minesweeper		2nd Shturmovik – now roll for Shot At +5
		1 +7 = 8		1 +5 +3 (-2) = 7		Plane at 60m altitude. No effect.
7	-	-		-		Torpedoes running (38cm).
8	-	-		-		Torpedoes running (2cm).
9	Both torpedoes reach the minesweeper. Each torpedo is rolled as a seperate attack. (AP-7/HE5)
		1st Torpedo	2nd Torpedo		Minesweeper – hull integrity is estimated to be +6
		2 +8* = 10	3 +8* = 11		5 +6 (-7) = 4		5 +6 (-7) = 4

* Since the torpedoes have yet to be worked out, I’m using the Combat Bonus for a 600kg bomb as a rough estimate.

Conclusion; the ship was penetrated twice and is taking on water. The ship’s crew is trying desperately to stop the leaks, but the ship will eventually sink unless it can reach a port within 1d6 hours. ~10% crew lost.

Notes
Flak requires its own ammunition type - based on grenades perhaps?

Game three: Two Milicia Rojo Polikarpov R5 bombers with one Polikarpov I-16 fighter Vs a VNA minesweeper guarded by two P16 fighters. The ship is defending itself with two Bofors 40mm firing (Flak 2), two Oerlikon 20mm firing (Flak 1) and two 4 inch guns firing (Flak 3). The R5s are on a torpedo attack run, each with a Mk XII sized nominal torpedo +6 (AP-7/HE5). They are Shot At +2 from the front and have +1 against Flak.
Rd	Polikarpov R5_1	Polikarpov R5_2	Polikarpov I-16	Minesweeper		Boeing P-16_1	Boeing P-16_2
1	The R5s approach from the south at 120m altitude (+2) with the I-16 above them at 480m altitude (+5). The P-16s at 480m altitude are intercepting them from the NNE. The ship opens fire with its port side batteries. The 4 inch guns target the foremost R5 and the AA guns target the second R5.
1	4 +2 (-1) = 5	2 +2 (-1) = 3	-	5 +3 = 9	3 +2 = 5	-	-	No effect.
1	The P-16s both open fire on the I-16 at maximum range.
1	-	-	2 +2 (-1) = 3	-	-	1 -1 = 0	-	No effect.
2	The I-16 attacks the ships Bofors 40mm batteries with rockets (area effect). He then accelerates and climbs, passing between and above the P-16s and banking to the NW behind them. The R5s have dropped to 20m altitude (+0) and both launch their torpedoes before breaking away, each in the opposite direction at full speed (west and eastwards)
2	-	-	1 +8 +3 = 12	-	1 +2 +2 = 5 4 +2 +2 = 8 3 +2 +2 = 7	-	-	The I-16’s rocket attack destroys the port side Bofors 40mm battery, and the aft 4-inch gun. Torpedoes running.
2	Both P-16s use Opportunity Fire to engage the I-16 as it approaches them. The port side Oerlikon 20mm uses Opportunity Fire to engage the first R5 as it banks across his arc of fire.
2	6 +3 (-1) = 8	-	2 +2 (-1) = 3	4 +7 (-1) = 10	-	4 +7+1 (-1) = 11	-	Polikarpov I-16 is defeated. Post defeat roll: 1 (complete destruction, pilot killed) No effect against the R5
3	Both torpedoes running at 36cm per round. Both R5s running off table at full speed.
3	-	-	-	-	-	-	-	No effect.
3	The P-16s break formation with each plane chasing after an R5.
3	-	-	-	-	-	-	-	No effect.
4	Both torpedoes running at 36cm per round.
4	-	-	-	-	-	-	-	No effect.
4	The P-16s attack the R5s in Off Table Combat. Seperate fights are marked A & B.
4	B_3 +2 = 5	A_4 +2 = 6	-	-	-	A_5 +3 = 8	B_4 +3 = 7	A_No effect. B_No effect.
5	Both torpedoes reach the ship. Seperate attacks are marked C & D. The minesweeper’s hull integrity is estimated to be +6.
5	B_4 +2 = 6 C_1 +6 = 7	A_6 +2 = 8 D_6 +6 = 12	-	C_6+6 (-7) = 5	D_2 +6 (-7) = 1	A_1 +3 = 4	B_1 +3 = 4	A_No effect. B_P-16 is defeated. Pilot is killed. C_Torpedo misses target. D_Torpedo hits target. Catastrophic damage. Secondary explosions rip the ship apart and she sinks at once. ~90% crew lost.
5	The minesweeper sinks. The remaining p-16 continues the dogfight.
5	-	A_4 +2 = 6	-	-	-	A_3 +3 = 6	-	No effect.
Conclusion: Game ends with victory for the Milicia Rojo. The minesweeper has been sunk. The last two aircraft break off their dogfight, presumably as they run out of ammunition. Notes. The rockets seem to be too powerful and so I decided to reduce their nominal range from 288 to 144. They were still horribly effective, even with a die roll of 1. I think perhaps a further reduction to 72 is in order. I reduced the combat factor for the torpedoes from the previous game, from +8 to +6. On table dogfights are over with much faster than off table fights. I'm not sure if this is a good or a bad thing?

I played all these games out on my kitchen floor (please excuse the grubbiness, I have three children and a dog). The squares are usefully, 25x25cm.

R: Polikarpov I-16. M: Polikarpov R5. L: Boeing P-16.

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22 July, 2019. Edited to add: