**Missile Design**

The missile design window has changed significantly from Standard Aurora and the final layout has yet to be determined. Several missile technologies have been removed and several new ones added. The major changes are as follows:

1) Agility will no longer exist as actual interceptions will be calculated. If the missile manages to intercept the ship it will hit 100% of the time. However, you will be able to try to physically avoid it by changing course. If the missile cannot generate the necessary Delta-V to intercept it is going to miss. However, unlike Aurora, the missile is going to keep trying to hit until you destroy it or it loses its ability to manoeuvre by running out of fuel. Therefore the missile agility tech progression has been removed.

2) Missile engines are now designed in the same way as shipboard engines and you can have multiple engines per missile. The missile engine tech progression has been removed as you use the normal engine tech progression for missiles. (see the earlier section on missile engines

3) The concept of MSP (missile space points) has been removed. In terms of size, missiles are now simply rated in tons and launcher sizes will be adjusted accordingly.

It is difficult to compare Newtonian Aurora missiles in tons to Standard Aurora missiles in MSP though as fuel is far more important and warheads are vastly more powerful.

4) There are no longer missiles, drones and buoys. There are simply missiles. The flexibility in the new design process will allow you to cover the abilities of all three previous missile categories. The drone engine tech progression has been removed.

5) Missiles have to accelerate, just like ships, so they are going to be less effective overall and far less effective at close range. Non-nuclear anti-missiles are going to be less effective too but, due to lower expected missile speeds in many cases, energy-based point defence is likely to become more effective.

**Design Process**

Missile design follows a similar approach to Standard Aurora in terms of allocating space to each component but there are additional checkboxes and dropdowns that make this a more complex process. The decisions that have to be made as part of designing a missile include the following:

**1) Guidance **

Each missile has four options for guidance. No guidance, fire control guidance, onboard guidance or both fire control and onboard guidance. The packages for fire control guidance and onboard guidance are 250kg (0.25 tons) each. Without any guidance the missile will continue moving or accelerating in a straight line after it is released. Fire control and onboard guidance work as they do in Standard Aurora. The actual sensors that will allow onboard guidance must also be added to the missile.

**2) Engine**

As noted above, missile engines are designed in the same way as shipboard engines and you may select multiple engines of the same type for the missile. I will be added some form of advantage for fewer engines, possibly along the lines of a chance of launch failure that increases with the number of engines. This is to prevent the unrealistic strategy of building one tiny engine and using multiples of it for all missiles.

**3) Fuel**

Fuel is allocated in tons, or a fraction thereof. Each ton provides 1000 litres of fuel.

**4) Sensors**

Tonnage may be allocated to active and passive sensors in the same way as Standard Aurora. In Newtonian Aurora, all sensor-related tech lines are rated per ton rather than per HS. This makes it much easier to visualise the sensor strengths for both missiles and ships. For example:

Active Sensor Strength 0.25 per ton

Active Sensor Strength 0.5 per ton

Active Sensor Strength 0.75 per ton

Unlike Standard Aurora, missile sensors must be powered. As with ship sensors in Newtonian Aurora, the power requirement for an active sensor is equal to the strength of the sensor multiplied by five. This reactor tonnage is added automatically but displayed as if it was added by the player. Passive sensors on ships do not require power, primarily to avoid the micromanagement of turning them on and off on those rare occasions where that might be required. The rationale is that they require less power anyway and their power needs can be met from the general power generation of the ship, in the same way as life support. For missiles, which have no innate power generation, passive sensors will be treated in the same way as active sensors and they will need power equal to five times their strength (or sensitivity in this case). On a per ton basis, passive sensors are much less powerful than active sensors at the same tech level so this translates into missiles requiring far less reactor space per ton of passive sensors compared to active.

There is no longer a separate 'buoy' category in Newtonian Aurora but you can create the same effect by designing a missile with sensors and no engine. The necessary reactor tonnage will be added automatically. Missile reactors have unlimited endurance so there will no longer be a need to replace buoys every few years. While unlimited endurance is unrealistic, modern naval reactors have a service life measured in decades so this is a compromise between realism and a desire to reduce micromanagement. Here is an example 'missile' with 5 tons dedicated to thermal sensors. There is no warhead, no engine and no fuel. The extra 0.9375 tons is required for the reactor to power the thermal sensors.

Thermal Sensor Buoy

Missile Mass: 5.9375 Tons Guidance: None

Thermal Sensor Strength: 0.75 Detect Sig Strength 1000: 750,000 km

Cost Per Missile: 1.1844

Materials Required: 0.0594x Tritanium 0.375x Boronide 0.75x Uridium

Development Cost for Project: 118RP

Note that unlike Standard Aurora, a missile can now have an engine and a reactor, so you could choose to have a 'buoy' with a small engine and minimal fuel, allowing it to travel to its ultimate destination, rather than using the two-stage missile/buoy option. Fire controls will be able to specify a zero-zero option for missiles, which will instruct the missiles to slow down and stop when they arrive at their target.

**5) Max Speed and Reserve Delta-V**

A missile can be designed with a maximum speed and/or a reserve delta-V. If a maximum speed is set, the missile will not accelerate beyond that speed and will retain fuel for course changes or decelerations. If an amount of reserve delta-V is specified, the missile will cease to use fuel for acceleration when its remaining delta-V is equal to or less than that amount. If both are set then a missile will only accelerate if it is currently below max speed and its remaining delta-V is above the reserve amount.

**6) Warhead type**

The most fundamental decision for a missile is the type of warhead. There are several options for missile warheads, including conventional, kinetic, shrapnel, nuclear and nuclear with laser rods. As well as the type, the size of the warhead in tons must be specified. The size can be specified to several decimal places and theoretically could be much smaller than one ton. The details of each warhead type are described below.

**a) Conventional Warhead **

The option of a conventional missile warhead is included because the possibility of role-playing a multi-Earth start that maintains the existing treaties regarding nuclear explosions in space. The power in megajoules for a conventional warhead is based on the equivalent tonnage of TNT. One ton of TNT has an explosive energy of 4184 megajoules. There is a tech line for conventional explosives which so far includes:

RDX Conventional Warhead: 1.5x Mass (starting tech)

HMX Conventional Warhead: 1.75x Mass

CL-20 Conventional Warhead: 2x Mass

ONC Conventional Warhead: 2.5x Mass

The multiplier for the conventional warhead tech is used in conjunction with the mass of the warhead. So a 2 ton HMX warhead would have an explosive power of 14,644 Megajoules. Conventional warheads require a direct hit on the target.

Below is an example of a conventional anti-ship missile. The engine selected has a mass of 2 tons and has engine power of 240 Kilonewtons. Based on the mass of the missile, this allows for a launch acceleration of 48 m/s. CL-20 Conventional Warhead technology is available and 1.25 tons has been devoted to the warhead, giving it a strength of 10,460 MJ. The other 1.5 tons is used to provide 1500 litres of fuel. Assuming no deviation in course, the maximum possible speed of the missile is 2285 km/s, although against an evading target the max speed is likely to be lower due to the need to devote fuel to manoeuvres rather than acceleration. It would also require over eleven hours of flight covering forty-seven million kilometres to achieve the maximum speed.

**Conventional Anti-Ship Missile**

Missile Mass: 5 Tons Warhead Strength: 10,460 MJ Guidance: Fire Control

Engine Power: 0.24 MN Fuel Use: 134.40 litres per hour

Launch Acceleration: 48 m/s (4.89G) Per Hour: 172.8 km/s Per Day: 4147.2 km/s

Final Acceleration: 68.6 m/s (6.99G)

Fuel Mass: 1500 litres Delta-V Budget: 2,285 km/s

Full Burn Duration: 11.15 hours Distance Required for Max Velocity: 47m km

Cost Per Missile: 2.023

Materials Required: 0.823x Tritanium 0.25x Uridium 0.9x Gallicite Fuel x1500

Development Cost for Project: 202RP

The power of the conventional warhead is expended in the same crater shape as standard Aurora but the damage per armour column is derived in a different way. The total explosion size in megajoules is divided by 100 to provide a rough number of affected armour 'boxes'. The square root of this number (rounded down) provides the depth of the damage in boxes at the centre of the explosion. The width of the damage is equal to (depth x 2) -1 in boxes. The armour column at each edge of the explosion suffers one box of damage, the next column inwards at each side suffers two boxes, the next column inwards suffers three boxes of damage, etc. until max damage is reached at the centre of the explosion. Now the total original damage in megajoules is divided by the damage depth squared (which is the total number of boxes in all the affected columns). This is the damage per 'box' and the number of affected boxes in each column multiplied by the 'per box' damage gives the total damage applied to the column. Of course, because armour in Newtonian Aurora doesn't have a set amount of damage resistance per box, the actual number of armour boxes destroyed by the explosion in each column will probably be different than the rough calculation. However, the 'shape' of the explosion will still be correct and there will no longer be 'sweet spot' warhead sizes because the optimum amount of damage for a warhead will vary depending on the armour type of the target.

Example: A missile with a warhead of 9000 MJ hits a ship. The depth of the crater is SQR(9000/100) = 9.49 (rounded to 9) and the width of the crater is 17. Total armour boxes affected is 81 and the damage per box is 111 MJ. So the outermost affected armour columns are hit by 111 MJ each, the next column inwards at each side is hit by 222 MJ, the next column inward is 333 MJ, etc. until the centre column which is hit for 999 MJ. A total of 8991 MJ. Penetrating damage is calculated on a per column basis and then added together.

**b) Nuclear Warheads**

The yield of nuclear warheads is based on their size in tons multiplied by the Nuclear Warhead Yield per Ton tech line. The first four levels of this tech are 100KT, 150KT, 200KT and 250KT. Missiles with nuclear warheads can be set to detonate within a specified range of their target, which means a direct hit is no longer necessary. They are also an area-effect weapon, which means any ship within the damage radius will be affected. Due to the incredibly high damage output of nuclear warheads, a single missile could easily take out a capital ship if the detonation is very close. However, despite their potentially massive damage capability, nuclear warheads have a far more localised effect in space as there is no atmosphere to transmit heat and blast effects. Their effective damage range is likely to be less than one kilometre.

Below is an example of an anti-ship missile with a nuclear warhead. This is identical to the conventional missile except that the warhead is based on nuclear warhead technology of 200 KT per ton and the proximity detonation range has been set to 250 meters. Two new lines appear on the missile design summary. Fireball Radius shows the distance from the detonation at which different amounts of damage are inflicted. 1000 MJ/m, which is effectively 1000 MJ per armour column, would be inflicted if a ship was exactly 289 meters from the explosion, That would drop to 100 MJ/m for a ship 912 metres from the explosion. The Proximity Detonation Range (PDR) for this missile is set to 250 metres, which means it will detonate if it moves within that range of the target. In terms of actual mechanics, during each increment the minimum distance which the missile will be from its target at any point during that increment will be checked. If that is less than the PDR, the exact location of the minimum distance is calculated and the nuclear detonation will occur at that point. Therefore the missile could actually explode much closer than the PDR in some circumstances. The amount of MJ/m at the PDR is shown on the same line.

**Nuclear Anti-ship Missile**

Missile Mass: 5 Tons Warhead Strength: 250 Kilotons Guidance: Fire Control

Engine Power: 0.24 MN Fuel Use: 134.40 litres per hour

Launch Acceleration: 48 m/s (4.89G) Per Hour: 172.8 km/s Per Day: 4147.2 km/s

Final Acceleration: 68.6 m/s (6.99G)

Fuel Mass: 1500 litres Delta-V Budget: 2,285 km/s

Full Burn Duration: 11.15 hours Distance Required for Max Velocity: 47m km

Fireball Radius: 1000 MJ/m: 289m 300 MJ/m: 527m 100 MJ/m: 912m

Proximity Detonation Range (PDR): 250m Damage MJ/m: 1331

Cost Per Missile: 2.75

Materials Required: 1.55x Tritanium 0.25x Uridium 0.9x Gallicite Fuel x1500

Development Cost for Project: 275RP

*Note: There are also radiation effects from nuclear detonations, which can affect both the crew of a ship and its electronics. In the case of radiation, the lack of an atmosphere means the nuclear detonation has a far greater radius of effect. I'll include the mechanics for this at a later date.*

**c) Nuclear Warhead with Laser Heads**

Due to the limited damage radius of nuclear weapons, it may be more effective to add laser rods to the warhead. These channel the x-rays created by the explosion in order to generate powerful x-ray lasers. An array of rods is added to the warhead, centered on a primary rod that will be aimed at the target, with the direction of each additional rod separated by a fraction of a degree of arc. Each laser rod, including the rod itself and the deployment system, has a mass of 100 kg (0.1 tons). Laser warheads are technically challenging and there are several different tech lines required for their successful development. These include:

Maximum Lasing Rods: The number of laser rods in the warhead. 5, 7, 9, 11, etc.

Lasing Rod Length (m): Longer rods result in less beam divergence. 1m, 1.25m, 1.5m, 2m, etc.

Lasing Rod Efficiency: The amount of energy channelled by a single rod. 0.000125%, 0.00015%, 0.0002%, etc.

Lasing Rod Arc Separation: The degrees of arc separating the beam from each rod. 0.25 degrees, 0.2 degrees, 0.16 degrees, 0.12 degrees, etc.

Lasing Rod Targeting Jitter: The maximum potential targeting error in degrees for the primary rod. 0.1 degrees, 0.09 degrees, 0.08 degrees, etc.

Below is an example of a nuclear anti-ship missile with laser rods added. As there are nine laser rods in the missile, an additional 900 kg has been added to the mass of the missile. Together with an additional 100 litres of fuel this increases the total mass to six tons, reduces the acceleration to 40 m/s and reduces Delta-V to 1989 km/s. The proximity detonation range has been increased from 250m to 50,000m.

**Laser Warhead Anti-Ship Missile**

Missile Mass: 6 Tons Warhead Strength: 250 Kilotons Guidance: Fire Control

Engine Power: 0.24 MN Fuel Use: 134.40 litres per hour

Launch Acceleration: 40 m/s (4.08G) Per Hour: 144 km/s Per Day: 3456 km/s

Final Acceleration: 54.5 m/s (5.56G)

Fuel Mass: 1600 litres Delta-V Budget: 1,989 km/s

Full Burn Duration: 11.9 hours Distance Required for Max Velocity: 44,040,538 km

Fireball Radius: 1000 MJ/m: 289m 300 MJ/m: 527m 100 MJ/m: 912m

Proximity Detonation Range (PDR): 50,000m Damage MJ/m: 0

Lasing Rods: 9 Output Per Rod: 1569 MJ Maximum Jitter: 0.07 degrees Max PDR Jitter: 61m

LR Arc Separation: 0.125 degrees PDR Beam Width/Separation: 1m/109m MJ/m: 1569

Cost Per Missile: 3.66

Materials Required: 1.55x Tritanium 0.25x Uridium 0.9x Corundium 0.9x Gallicite Fuel x1600

Development Cost for Project: 366RP

Two new lines have been added to the missile summary. The information contained is those two lines is as follows:

Lasing Rods: The number of laser rods included in the warhead

Output Per Rod: The amount of energy channelled through each rod in the form of an x-ray laser.

Maximum Jitter: The maximum targeting error in degrees

Max PDR Jitter: The maximum resulting targeting error in metres at the PDR

LR Arc Separation: The arc separation of each rod in the array

PDR Beam Width/Separation: The width of each beam at the PDR and how far apart those beams will be in metres.

MJ/m: The damage per affected armour column, based on the beam width at the PDR

So what the above really means is that in addition to the normal effects of the nuclear detonation, nine x-rays, each of which has an energy of 1569 MJ, will be directed toward the designated target. At 50,000 meters, the primary rod could miss the centre of the target by up to sixty-one meters. Of course, if the target has a radius greater than sixty-one meters then the beam can't miss. If the target radius was thirty meters, then the chance of a hit would be 49%. Also, if the target was closer, the 0.07 degree jitter would translate into a smaller error in terms of distance from the centre of the target. At 25,000 metres, the max jitter would be 31m.

Each of the other eight beams will be 109m apart at the PDR (or 55m apart at 25,000 meters). So, assuming the target was at the PDR of 50,000m, if the beam from the primary rod was 20m to the left of the centre of the target, there would be additional beams 129m to the left, 238m to the left, 347m to the left, 456m to the left, 89m to the right, 198m to the right, 307m to the right and 416m to the right. Other ships in the same area could also potentially be hit, as well as ships closer to the detonation or further away who happen to be in the path of one of the beams. All nine beams will be one metre in width at 50,000m (or closer), which means they would drill down a single armour column. Beyond 53,000m they would be 2m in width, which would result in the 1569 MJ energy output being divided across 2 armour columns. Beyond 89,000m the beams would be 3m wide, etc. Playing around with the PDR value in the missile design window will allow the designer to check the beam width and beam separation at different distances.

While the 1569 MJ damage per rod is reasonable, a larger nuclear warhead would result in correspondingly more powerful beams. Below is a missile using identical technology that has three engines, 4850 litres of fuel and a one megaton warhead. Bear in mind that while 17 tons sounds like a lot, this is equivalent to a size 6.8 missile in Standard Aurora.

**Megaton Anti-Ship Missile**

Missile Mass: 17 Tons Warhead Strength: 1 Megaton Guidance: Fire Control

Engine Power: 0.72 MN Fuel Use: 403.20 litres per hour

Launch Acceleration: 42.4 m/s (4.32G) Per Hour: 152.47 km/s Per Day: 3659.29 km/s

Final Acceleration: 59.3 m/s (6.04G)

Fuel Mass: 4850 litres Delta-V Budget: 2,158 km/s

Full Burn Duration: 12.02 hours Distance Required for Max Velocity: 47m km

Fireball Radius: 1000 MJ/m: 577m 300 MJ/m: 1053m 100 MJ/m: 1825m

Proximity Detonation Range (PDR): 50,000m Damage MJ/m: 0

Lasing Rods: 9 Output Per Rod: 6276 MJ Maximum Jitter: 0.07 degrees Max PDR Jitter: 61m

LR Arc Separation: 0.125 degrees PDR Beam Width/Separation: 1m/109m MJ/m: 6276

Cost Per Missile: 9.92

Materials Required: 5.3x Tritanium 0.25x Uridium 0.9x Corundium 0.9x Gallicite Fuel x4850

Development Cost for Project: 992RP

**Nuclear Detonation Sequence**

If a warhead includes laser heads, the damage from those is assessed first, on the basis that the x-rays will arrive before the wavefront of the detonation. The damage per laser head is checked and the maximum range at which an x-ray would inflict 10 MJ per square meter or higher is calculated.

The bearing of the missile's primary target is checked and the bearing of the primary laser rod (i.e. the rod at the centre of the laser rod array) is determined by applying a random jitter to that target bearing, based on the level of jitter reduction technology in the warhead. Every fleet in the system within the 10 MJ range limit, regardless of race, is checked in order of increasing range from the detonation, to see if the beam intersects the hull of any ships in that fleet. If it does, the actual ship is determined randomly from among those that could be hit. The portion of the beam that hits the hull is determined, based on the width of the beam at the target range, the size of the hull and the point at which the centre of the beam strikes the hull. The damage procedure for a beam strike with the width that actually strikes the target is then carried out. Once the effect of the beam from the primary rod is resolved, the effects of the other laser rods in the array are checked, alternating left and right until every beam has been resolved.

A beam strike has a beam width in meters and a damage per metre. One metre corresponds to one armour column, so a beam width of 6 metres would hit 6 armour columns. Before armour is checked, the effect on any shields on the beam is determined. The point strength of the shields (see the earlier section on shields) is used against a beam up to one metre wide. For wider beams, the available shield strength is equal to the point strength x beam width up to the maximum strength of the shields. If the power of a beam strike is reduced by the shields but not eliminated completely, the reduction in strength is applied equally across the width of the beam. For example, if a 5 metre wide beam with a strength of 3000 MJ is reduced by 1200 MJ, the beam will still be 5 metres wide and the 1800 MJ remaining will be applied as 360 MJ per armour column.

Once the effects of any laser rods have been determined, the nuclear detonation itself is resolved. The range at which the fireball causes damage of 1 MJ per square meter is determined and damage is inflicted on every ship within that range. The total damage for a ship is equal to the MJ damage per square metre of the wave front at the ship's distance from the detonation point multiplied by the ship's diameter in meters. If a ship has shields, the entire strength of the shields may be used to reduce the damage. So if the total damage to a ship was 20,000 MJ and the shields were 35,000 MJ, the shields would be reduced to 15,000 MJ and there would be no damage to the armour.

The damage that penetrates the shields is divided between half of the entire armour width. So if 50,000 MJ penetrates the shields and the ship has an armour width of 80, then the 50,000 MJ is divided by 40 which results in 1250 MJ being applied against each of the 40 armour columns. The other 40 columns are assumed to be on the far side of the ship and therefore not affected by the wave front.

*Example #1: A 4895 ton ship with a diameter of 46 meters is located 500 meters from a one megaton blast, which has a total damage output of over four billion megajoules. The warhead does not include any laser rods. The ship has 72 GJ (72,000 MJ) shields and an armour rating of 6-92. At that range, the damage per square meter is 1332 MJ. Therefore the ship is hit by 61,272 MJ (1332 x 46) of damage. The shields are just able to withstand the blast but are reduced to 10,728 MJ.*

Example #2: An identical ship is 300 meters from the detonation point. The damage per square metre amount is now 3700 MJ, which means the total damage is 170,200 MJ. The shields are blasted down and 98,200 MJs hit the armour. Each of the 46 affected armour columns is hit by 2135 MJ of damage. The armour is ceramic composite, which can absorb 125 MJ per square meter for each cm of depth. As the armour is 6 centimetres thick, each column can withstand 750 MJ of damage. 1385 MJ of damage penetrate each armour column, which is 63,710 MJ in total. The ship is totally destroyed. The moral of the story is: you should try to avoid being close to a nuclear explosion.

*Note: Kinetic and Shrapnel warheads will be explained in a follow-up post*

Steve