I have created a prelimary design system for magazines. There are five components to each system:
1) Size
2) HTK
3) Armour Type
4) Magazine Ejection System. This is the percentage chance of successfully ejecting the magazine contents in case of damage. Starting chance is 70%. Increments are: 80, 85, 90 (4000 RP), 93, 95. 97, 98, 99
5) Magazine Feed System Efficiency. How much of the internal space of the magazine is used for actual storage rather than the mechanism. Starting efficiency is 75%. Increments are: 80, 85 (4000 RP), 90, 92, 94, 96, 98, 99
Leaving aside armour and HTK for now, you just select the size of the magazine. The ejection and efficiency are set to the best available. For example, I have set the Commonwealth to 90% for the Ejection System and 85% for the Efficiency. So if they select a 3 HS Magazine (same size as the existing Standard Magazine), the storage space available would be equal to 3 HS x 85% efficiency = 2.55HS. As each HS is equal to 20 missile size points, this translates to a magazine capacity of 51 (the existing standard magazine has a capacity of 50). Because of the 90% chance of successful ordnance ejection when damaged, the magazine has a 10% of an internal explosion. If the magazine was 10HS (as per the existing large magazine), the internal storage space would be 10 x 85% = 8.5 HS and the capacity would be 8.5 x 20 = 170. This is less than the existing large magazine (180 capacity). This can be improved with technology and larger magazines also become more attractive when armouring is considered.
The old internal armour system is no longer consistent with the updated external armour system so I decided to replace it with a method of improving HTK (hits-to-kill) instead. All magazines are assumed to have a base HTK of 1, regardless of size. You have the option of choosing a higher HTK if you wish. In this case, an amount of internal armour is added to make the magazine harder to destroy. The amount of internal armour added is based on exactly the same formula as that used for ships, except that for each additional point of HTK you only need armour strength equal to one tenth of the surface area of the magazine. This is because you are only increasing the chance for the magazine to survive a hit rather than adding armour strong enough to absorb hits. The amount of space required for the armour is deducted from the size of the magazine before internal space is calculated. This sounds complex so an example should make it clearer.
Lets assume a 1 HS magazine using the tech of the Commonwealth (90% Ejection System, 85% Efficiency, Composite Armour). With a normal HTK of 1, the magazine has internal storage space of 0.85 and therefore a capacity of 17.
If we increase the HTK to 3, then some internal armour is required. Determing the surface area of the magazine based on its volume (or HS) is straightforward maths
Radius = ((Magazine HS * 0.75) / PI) ^ (1 / 3)
Surface Area = (Radius ^ 2) x 4 x PI
In this case the radius is 0.6204 and the surface area is 4.8368
The armour strength required is equal to one tenth of the surface area multiplied by the total HTK - 1. In this case: 2 x (4.8368 / 10) = 0.9674
Once the amount of armour strength required is determined, the actual HS of that armour is a simple matter of dividing the required strength by the strength per HS of the best available armour, which is 8 for composite armour. So, in this case, the amount of armour required in HS is 0.9674 / 8 = 0.1209.
That 0.1209 HS worth of armour is deducted from the size of the magazine before internal space is calculated: 1 - 0.1209 = 0.8791
Which means that when the efficiency of 85% is applied to the remaining space, the capacity of the magazine drops accordingly: Internal Storage: 0.8791 x 85% = 0.7472, Capacity = 0.7472 x 20 = 14.944, rounded down to 14. So an increase in HTK for the 1 HS magazine from 1 to 3, decreases its capacity from 17 to 14. If the HTK was increased to 5, then the capacity would drop to 12.
As objects get larger, the ratio of their surface area to their volume decreases, which is why in Aurora larger ships require less armour tonnage on a per HS basis for the same thickness of armour than a smaller ship. This also applies to magazines, so the percentage of capacity lost by larger magazines is less for a given HTK. For example, the 3HS magazine with a 51 capacity described earlier would have a capacity of 46 for 3 HTK and a capacity of 42 for 5 HTK. A 10 HS magazine with a 170 capacity would have capacities of 160 and 150 for HTKs of 3 and 5. If you increased it to a HTK of 10, the capacity would fall to 127.
This gives the player some real decisions to make, both in terms of how much research time he wants to spend on magazines and in how much protection against secondary explosion is emphasised over magazine capacity.
Steve