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Offline Steve Walmsley

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Newtonian Aurora - Rules
« on: November 09, 2011, 04:24:31 PM »
I am going to use this topic to post rules as they are created. This will provide players with an easy reference point. I'll sticky and lock the topic so please post any questions and/or comment in the main threads. I'll try to keep these posts updated as rules change due to ongoing development.
 

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Re: Newtonian Aurora - Rules
« Reply #1 on: November 09, 2011, 04:24:53 PM »
Engines

The concept of Military Engine, Commercial Engine, Fighter Engine, etc has been removed and Hyper Drives have been removed. The five elements of engine design are now:

Engine Technology: As before, except the base values are different and those values are expressed in Meganewtons of thrust per HS of engine. One Meganewton (MN) is equal to the amount of net force required to accelerate a mass of one ton at a rate of one kilometre per second squared. For example, the Internal Confinement Fusion Drive technology has a rating of 60 Kilonewtons per ton, so an unmodified 250 ton engine (The same size as the standard Aurora military engine) would produce 15 MN of thrust.

Fuel Consumption per MN per Hour: This is similar in concept to the old Fuel Efficiency, although it is now modified by other factors in engine design. Fuel Consumption is critical though and will be far more important than in the past. The initial consumption rate starts at 200 litres per MN per hour and additional technology levels will lower that figure. An Engine is rated in the number of litres of fuel per hour it consumes. This amount is derived from Engine Thrust in MN x Fuel Consumption per MN per Hour. So an Engine with 15 MN of thrust and a Fuel Consumption per MN per Hour of 150 would consume 2250 litres of fuel per hour at full burn.

Engine Size: You can now select the size of engine from 50 tons to 2500 tons. Larger engines are more fuel efficient so fuel consumption is reduced by 1% for every 50 tons of engine. For example, a 500 ton engine reduces fuel consumption by 10% and a 1250 ton engine reduces it by 25%.

Thermal Reduction: As before, this reduces the thermal signature of engines, which is equivalent to 10x thrust in MN.

Thrust / Fuel Consumption Modifiers: There are two new tech lines to research, called Max Engine Thrust Modifier and Min Engine Thrust Modifier. These establish the range within which you can change engine thrust from that provided by the base engine technology. Increasing thrust increases fuel consumption per MN and decreasing thrust can provide significant savings in fuel consumption. Thrust can be increased by up to 300% of normal and decreased to 10% of normal if you have the prerequisite techs. The dropdown on the design window will have options from the minimum possible to the maximum possible in 5% increments. So 40%, 45%, 50%, 55% ...... 180%, 185%, etc. Each engine thrust modifier percentage is accompanied by a fuel consumption modifier, based on the formula Fuel Consumption Modifier = (4 ^ Engine Thrust Modifier) / 4.

For example, assume you choose to increase Engine Thrust to 50% greater than normal. The Fuel Consumption would be (4 ^ 1.5)/4 = 2, so for a thrust increase of 50%, the fuel consumption per MN would increase by 100%. Bear in mind that if the engine thrust has increased by 50% and the fuel consumption per MN has increased by 100%, then the overall fuel consumption for the engine is 3x higher than before. This is shown on the dropdown as "Engine Thrust +50%. Fuel Consumption per MN +100%".

If you had an engine with Engine Thrust +100%. Fuel Consumption per MN +300%, you would have something similar to the FAC engine in Aurora, except now you can have different size engines and you can have more than one per ship.

Here is the design summary for an engine of 250 tons (5 HS in Standard Aurora), using Magneto-plasma Drive technology, with a 25% increase in thrust and no thermal reduction.

Magneto-plasma Drive
Thrust: 12.5 MN     Base Fuel Consumption per MN: 188.1 litres per hour
Base Acceleration: 50 mp/s (5.1G)
Fuel Use at Full Burn: 2351 litres per hour
Engine Size: 250 Tons    Engine HTK: 2
Thermal Signature: 125     Exp Chance: 12
Cost: 62.5    Crew: 8
Materials Required: 15.625x Duranium  46.875x Gallicite
Development Cost for Project: 625RP

Because of the thrust modifier the fuel consumption per MN is increased by 41% and due to the size of the engine the fuel consumption per MN is decreased by 5%.

The Fuel Consumption per MN per Hour is calculated as the base racial technology of 140 litres per hour, x0.95 for engine size, x1.4142 for the 25% engine thrust modifier, which equals 188.1. Fuel use in litres per hour is therefore 12.5 MN x 188.1 = 2351. As that single engine alone would use up a 50 ton (1 HS in standard Aurora) fuel tank in a little over 21 hours, you can already see that fuel tanks are going to be a lot bigger in Newtonian Aurora.

The base acceleration is for the engine accelerating itself with no accounting for where the fuel is coming from. While this is obviously never achievable in practice, it provides a way to rate engines against each other. 50 mp/s is an acceleration of fifty meters per second squared. The 5.1G is the force a passenger on the engine would feel. This subject is covered more realistically in the ship design section. Explosion Chance is based on 10% of the engine thrust percentage, rounded down.

Now lets look at an engine designed with fuel consumption as a priority. This is an engine of 1250 tons (25 HS in Standard Aurora), using Magneto-plasma technology, with an 80% decrease in thrust and no thermal reduction.

Commercial Magneto-plasma Drive
Thrust: 10 MN     Base Fuel Consumption per MN: 34.6 litres per hour
Base Acceleration: 8 mp/s (0.82G)
Fuel Use at Full Burn: 346 litres per hour
Engine Size: 1250 Tons    Engine HTK: 12
Thermal Signature: 100     Exp Chance: 2
Cost: 50    Crew: 1
Materials Required: 12.5x Duranium  37.5x Gallicite
Development Cost for Project: 500RP

The Fuel Consumption per MN per Hour is calculated as the base racial technology of 140 litres per hour, x0.75 for engine size, x0.3299 for the -80% engine thrust modifier, which equals 34.6. Fuel use in litres per hour is therefore 10 MN x 34.6 = 346. So while this engine produces eighty percent of the thrust of the previous engine, the total fuel consumption is eighty-five percent less. However, it is five times larger so the base acceleration is much lower. Even so, you will actually get more Delta-V for the same fuel from this engine than the one above - it will just take longer to do it. More on Delta-V in the ship design section.

Note that there is no detail on exhaust velocity in the engine design. This is a key element in the design of real rocket engines. It has a huge effect on fuel efficiency and will affect the acceleration provided by the engine once the speed of the rocket approaches that of the engine's exhaust velocity. However, I have to draw a line somewhere between realism and fun and in the case of exhaust velocity I decided that having a simpler fuel consumption rating for the engine that could easily be understood by players would be preferable to players having to understand Tsiolkovsky's rocket equation and associated material. I think the current mechanics of engine design allow for a lot of freedom, and provide the players with the feel of a Newtonian game without having to get into serious math.
(http://en.wikipedia.org/wiki/Tsiolkovsky_rocket_equation)

Steve
« Last Edit: November 09, 2011, 05:31:02 PM by Steve Walmsley »
 

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Re: Newtonian Aurora - Rules
« Reply #2 on: November 09, 2011, 05:16:45 PM »
Missile Engines

The four elements of missile engine design are described below.

Engine Technology: Exactly as ship-based engines. However, the base value of thrust is doubled on the basis that missile engines have no radiation shielding or maintenance access requirements. Thrust is rated in Meganewtons. For example, the Magneto-plasma Drive has a rating of 40 KN per Ton, so a missile engine of 1 ton would provide 40 KN x 2 (missile thrust modifier) or 0.08 MN.

Engine Size: Missile engines can be from 0.1 tons to 5 tons in 0.1 ton increments.

Fuel Consumption per MN per Hour: As with ship engines, the fuel consumption of a missile engine is based on Engine Thrust in MN x Fuel Consumption per MN per Hour. So an Engine with 0.08 MN of thrust and a Fuel Consumption per MN per Hour of 150 would consume 12 litres of fuel per hour at full burn.

Thrust / Fuel Consumption Modifiers: Sorium-based missile engines use the same principle as ship engines and use the same tech lines (Max Engine Thrust Modifier and Min Engine Thrust Modifier). However, the upper end of the range is doubled for missile engines. So if the Max Engine Thrust tech is 175%, missile engines can use up to 350%, again with the rationale that these are designed for single use, unmanned craft and therefore have significantly different engineering requirements. As with ship-based engines, increasing thrust has a significant effect on fuel efficiency and decreasing thrust can provide huge savings in fuel efficiency. As the missile modifier is double that of ships, thrust can be increased by up to 600% of normal and decreased to 10% of normal if you have the prerequisite techs. The dropdown on the design window has options from the minimum possible to the maximum possible in 5% increments. So 40%, 45%, 50%, 55% ...... 180%, 185%, etc. Each engine thrust modifier percentage is accompanied by a fuel consumption modifier, based on the formula Fuel Efficiency Modifier = (4 ^ Engine Thrust Modifier) / 4. So a missile with a +200% engine thrust modifier would have a +1500% fuel consumption modifier.

Unlike ship engines, you have the option to use chemical-based rocket engine technology. In this case, the chemical-based technology has its own fuel consumption which is not modified by the Racial base fuel consumption or the Engine Thrust / Fuel Consumption modifier. The engine thrust of chemical technology cannot be modified either. Available as starting technologies are the LOX/LH2 Rocket Engine, which has a fuel consumption of 800,000 and a base engine thrust of 700 KN per ton, and the LOX/RP-1 Rocket Engine which has a fuel consumption of 1,100,000 and a base engine thrust of 900 KN per ton (including the x2 thrust modifier for missiles). There is also an Advanced LPX/RP-1 Engine with a thrust of 1400 KN which can be developed. Actually this was developed by the Soviet Union as the NK-33 but the US didn't develop equivalent tech. In a multi-nation start this could be SM-assigned to Russia. As you can imagine, Chemical engines need a LOT of fuel. Those figures are based on converting modern day rocket engines to Aurora fuel efficiencies and demonstrate how incredibly fuel efficient Sorium-based engines are.

As I have figured out how to convert modern-day rockets in Aurora numbers, there is an option to enter modern-day rocket engines into Aurora and use them as part of missile design. You have to enter name, thrust in Meganewtons, mass of the engine and specific impulse (Isp). Aurora uses the specific impulse to derive the fuel efficiency, which is 367,099,200 / Isp. That number is derived from the formula to convert Isp into thrust-specific fuel consumption (TSFC), which is 101972/Isp. TFSC is used today to calculate fuel consumption per unit of thrust. This is nominally grams per Kilonewton second, but is equally correct for kilograms per Meganewton second or litres per Meganewton second. As Newtonian Aurora hourly fuel consumption is based on engine thrust (in Meganewtons) x fuel consumption, then TFSC multiplied by 3600 is equal to Aurora fuel consumption. Converting in the opposite direction means that (101972 x 3600)/ISP = Aurora fuel consumption.

For example, if you enter the Space Shuttle Main Engine (SSME), which has thrust of 2.18 MN, mass of 3.177 tons and Isp of 453 in vacuum, Aurora uses the name, mass and thrust directly and converts the Isp into a fuel efficiency of 810,373.7. Using that SSME in a missile design shows a fuel consumption rate of 490.73 litres per second. The TFSC of the real SSME is 225, which multipled by the 2.18 MN thrust equal a consumption of 490.73 litres per second. So you can use real rocket engines with real rates of fuel consumption. Of course this is still massively simplified from real world considerations but it will provide the right flavour for the game. It also will be hard to achieve anything major with modern day engine technology but you can try :). As the fuel for chemical rockets will be far more accessible than Sorium, it will be considered to be easily made by ordnance factories and not tracked in terms of cost or storage. Obviously once it is in the missile, the chemical fuel will be tracked.

Anyway back to Sorium-based engines. Here are four two ton missile engine designs using Magneto-plasma engine technology and a base fuel consumption of 140. The first uses Engine Thrust Modifier x1, Fuel Modifier x1.

Fuel Efficient 160 KN Missile Engine
Thrust: 0.16 MN     Base Fuel Consumption per MN: 140 litres per hour
Base Acceleration: 80 mp/s (8.16G)    Per Min: 4.8 km/s    Per Hour: 288 km/s
Fuel Use at Full Burn: 22.4 litres per hour
Engine Mass: 2 tons    Cost: 0.8    Thermal Signature: 1.6
Materials Required: 0.2x Tritanium  0.6x Gallicite
Development Cost for Project: 80RP

Note that while this is more powerful in terms of thrust-weight ratio than a ship-based engine and doesn't use much fuel. It would take an hour to accelerate itself to 288 km/s and that assumes no fuel mass. Shown below are three designs using engine thrust modifiers of x2, x3 and x3.5 respectively. (3.5x requires the max engine boost 175% tech, which is 8000 RP). Note the acceleration rate increases but the fuel consumption goes up very quickly indeed.

320 KN Missile Engine
Thrust: 0.32 MN     Base Fuel Consumption per MN: 560 litres per hour
Base Acceleration: 160 mp/s (16.32G)    Per Min: 9.6 km/s    Per Hour: 576 km/s
Fuel Use at Full Burn: 179.2 litres per hour
Engine Mass: 2 tons    Cost: 1.6    Thermal Signature: 3.2
Materials Required: 0.4x Tritanium  1.2x Gallicite
Development Cost for Project: 160RP

480 KN Missile Engine
Thrust: 0.48 MN     Base Fuel Consumption per MN: 2240 litres per hour
Base Acceleration: 240 mp/s (24.47G)    Per Min: 14.4 km/s    Per Hour: 864 km/s
Fuel Use at Full Burn: 1075.2 litres per hour
Engine Mass: 2 tons    Cost: 2.4    Thermal Signature: 4.8
Materials Required: 0.6x Tritanium  1.8x Gallicite
Development Cost for Project: 240RP

560 KN Missile Engine
Thrust: 0.56 MN     Base Fuel Consumption per MN: 4480 litres per hour
Base Acceleration: 280 mp/s (28.55G)    Per Min: 16.8 km/s    Per Hour: 1008 km/s
Fuel Use at Full Burn: 2508.8 litres per hour
Engine Mass: 2 tons    Cost: 2.8    Thermal Signature: 5.6
Materials Required: 0.7x Tritanium  2.1x Gallicite
Development Cost for Project: 280RP

Finally, here is a 2 ton LOX/LH2 rocket engine, similar in technology to the space shuttle main engine - note the fuel use is shown per minute, not per hour. Also bear in mind all the acceleration figures are for the engine alone with no fuel mass and no payload.

1400 KN Missile Engine
Thrust: 1.4 MN     Base Fuel Consumption per MN: 800,000 litres per hour
Base Acceleration: 700 mp/s (71G)    Per Min: 42 km/s    Per Hour: 2,520 km/s
Fuel Use at Full Burn: 18,667 litres per minute
Engine Mass: 2 tons    Cost: 0.7    Thermal Signature: 14
Materials Required: 0.175x Tritanium  0.525x Gallicite
Development Cost for Project: 70RP

As you can see from the above designs, once you add fuel and payload, getting a missile up to an appreciable speed is going to take some time and there would be little point firing missiles at a fast moving ship if the missiles can't even match its speed for several hours. On the other hand, missiles fired from three or four billion kilometres away will be going pretty fast when they reach their target. Also bear in mind that missiles will be able to switch off the engines mid-flight once they reach a pre-designated speed and use any remaining fuel for course corrections so they have an effectively unlimited range - just as they would in reality. Finally, the missile is going to have an initial speed and heading equal to that of the launching ship so firing at pursuers is going to be tricky. Missile combat is going to require a lot of planning and will depend a lot more on targeting and course correction than missile range.

Steve
« Last Edit: November 09, 2011, 05:34:08 PM by Steve Walmsley »
 

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Re: Newtonian Aurora - Rules
« Reply #3 on: November 10, 2011, 02:09:48 PM »
FTL Drive

FTL Drive Efficiency: This serves the same function as jump drive efficiency, except it starts at efficiency 4 rather than 3 and each level is half the cost in research terms. For example, efficiency 6 is 8000 RP instead of 15,000 RP. In Newtonian Aurora you won't be able to use a gate to get between systems so non-FTL-capable ships can only be moved between systems via squadron jump or in hangar bays. Therefore FTL drives will probably be a lot more common than jump drives in standard Aurora.

Max FTL Squadron Size: The same as standard Aurora, except that squadrons will travel through hyperspace together rather than through jump points. There will only be squadron jumps as there are no jump points to hold open. Creating drives that can jump multiple ships is easier though as the base drive can handle four ships and the research costs are half as much as before.

Hyperspace Dimension: The hyperspace dimension through which the ship or squadron will travel. Higher dimensions bring real space locations closer together and increase effective speed. Each dimension is rated for the speed multiplier it provides. The Alpha Dimension is 2500x speed, the Beta Dimension is 5000x, Gamma is 7500x, etc.

Base Size: The base size of the FTL drive. This is comparable to the size of a military jump drive in standard Aurora, although there is no distinction between military and commercial drives in Newtonian Aurora. Unlike Standard Aurora, larger drives are less expensive in terms of build points per ton.

The cost of an FTL Drive is equal to (Sqrt(FTL Drive Size) * Sqrt(FTL Speed Multiplier) * Sqrt(FTL Squadron Size)) / 50

FTL Travel
Travel between different star systems is only possible using an FTL drive (although you never know - sub-light generation ships might make an appearance at some point). Stars have a hyper limit, inside which it is not possible to activate an FTL drive. This limit is equal to primary star mass squared, multiplied by three billion kilometres. For Sol, this is about the orbit of Uranus. In order to reach another star system, the FTL-capable ship or fleet has to align itself with the destination system. This can be done using the new "FTL Align and Jump" order. Until the ship is on an exact course for the destination it will be unable to jump. Aurora will automatically make course corrections (using any available DeltaV) in order to align while this order is in effect. You will are able to optionally specify a minimum jump speed so the ship will not enter FTL until it reaches the desired speed. Otherwise, the minimum jump speed is 200 km/s.

At this point, you will lose contact with the ship and be unable to communicate until it reaches its destination system, which may be a period of weeks or months. If a full gravitational survey of the destination has been carried out, the ship will arrive with approximately the same speed at which it entered hyperspace, on a bearing from the primary within six degrees of the direct course from the start system and at a range from the primary between 100% and 110% of the hyper limit radius. If the destination system has not been surveyed at all, the location of arrival could be anywhere in a toroid, between 100% and 170% of the hyper limit distance, on any bearing from the star. The heading of the ship will still be directly away from the start system so you could end up on a course perpendicular to your destination, or even beyond it and heading away. A partial survey of the destination will result in a scenario somewhere between the two extremes. A lack of survey information could also result in the ship arriving slower or faster than expected, although within 30% of departure speed, and correspondingly earlier or later than expected. Because the ship is out of contact, you will be unable to determine the likely arrival point ahead of its arrival.

This uncertainty will make assaults on unsurveyed systems 'interesting' to manage. As well as the obvious issue of coordinating multiple squadrons, it will be a lot harder to pull out of an assault if things are not going well. To return to their starting system, ships will have to slow to zero and then begin accelerating along a reciprocal course. Another option may be to escape to another system that is on an easier escape course, fuel permitting. One other result of the above is that there will be far more 'spreading out' of civilian traffic rather than the current situation where ships tend to travel in large groups.

The speed at which interstellar travel takes places is equal to the speed at which you enter hyperspace multiplied by the speed multiplier of the FTL Drive. For example, if a ship using an FTL drive with a 10,000x speed multiplier entered hyper at 1600 km/s, its effective speed would be 10,000 x 1600 km/s, which is about 53x light speed. A journey to Alpha Centauri would therefore take about a month and a journey of ten light years would require about ten weeks. Ships cannot accelerate or decelerate within hyperspace so the decision is whether to expend fuel and time to reach a high speed before entering hyperspace, or to enter at lower speed, saving fuel but extending journey time.

A few examples, using generally level 4 tech, which is FTL Drive Efficiency 8, Minimum Drive Size 500 tons, Speed Multiplier 10,000 and Squadron Sizes up to 7. The crew requirement is based on sqrt(Size)

Survey Ship Drive
Max Ship Size: 4,000 tons     Max Squadron Size: 4     FTL Speed Multiplier: 10,000x
Jump Engine Size: 500 tons     Efficiency: 8    Jump Engine HTK: 2
Cost: 89    Crew: 22
Materials Required: 17.8x Duranium  71.2x Sorium
Development Cost for Project: 890RP

Destroyer Drive
Max Ship Size: 8,000 tons     Max Squadron Size: 4     FTL Speed Multiplier: 10,000x
Jump Engine Size: 1,000 tons     Efficiency: 8    Jump Engine HTK: 4
Cost: 126    Crew: 32
Materials Required: 25.2x Duranium  100.8x Sorium
Development Cost for Project: 1260RP

The next two examples are the same size drive but with squadron sizes of four and seven respectively

Cruiser Drive
Max Ship Size: 16,000 tons     Max Squadron Size: 4     FTL Speed Multiplier: 10,000x
Jump Engine Size: 2,000 tons     Efficiency: 8    Jump Engine HTK: 8
Cost: 179    Crew: 45
Materials Required: 35.8x Duranium  143.2x Sorium
Development Cost for Project: 1790RP

Command Cruiser Drive
Max Ship Size: 16,000 tons     Max Squadron Size: 7     FTL Speed Multiplier: 10,000x
Jump Engine Size: 2,600 tons     Efficiency: 8    Jump Engine HTK: 10
Cost: 270    Crew: 51
Materials Required: 54x Duranium  216x Sorium
Development Cost for Project: 2700RP

Next is a drive for a colony ship plus the same size drive with the minimum speed multiplier. The latter would probably only be worth it for journeys that involved relatively long in-system time and short FTL trips.

Colony Ship Drive
Max Ship Size: 20,000 tons     Max Squadron Size: 4     FTL Speed Multiplier: 10,000x
Jump Engine Size: 2,500 tons     Efficiency: 8    Jump Engine HTK: 10
Cost: 200    Crew: 50
Materials Required: 40x Duranium  160x Sorium
Development Cost for Project: 2000RP

Slow Colony Ship Drive
Max Ship Size: 20,000 tons     Max Squadron Size: 4     FTL Speed Multiplier: 2,500x
Jump Engine Size: 2,500 tons     Efficiency: 8    Jump Engine HTK: 10
Cost: 100    Crew: 50
Materials Required: 20x Duranium  80x Sorium
Development Cost for Project: 1000RP

Now progressively larger drives.

Battleship or Freighter Drive
Max Ship Size: 40,000 tons     Max Squadron Size: 4     FTL Speed Multiplier: 10,000x
Jump Engine Size: 5,000 tons     Efficiency: 8    Jump Engine HTK: 20
Cost: 283    Crew: 71
Materials Required: 56.6x Duranium  226.4x Sorium
Development Cost for Project: 2830RP

Large Freighter Drive
Max Ship Size: 80,000 tons     Max Squadron Size: 4     FTL Speed Multiplier: 10,000x
Jump Engine Size: 10,000 tons     Efficiency: 8    Jump Engine HTK: 40
Cost: 400    Crew: 100
Materials Required: 80x Duranium  320x Sorium
Development Cost for Project: 4000RP

Huge Freighter Drive
Max Ship Size: 160,000 tons     Max Squadron Size: 4     FTL Speed Multiplier: 10,000x
Jump Engine Size: 20,000 tons     Efficiency: 8    Jump Engine HTK: 80
Cost: 566    Crew: 141
Materials Required: 113.2x Duranium  452.8x Sorium
Development Cost for Project: 5660RP

The wat in which the cost of FTL drives is calculated will support the concept that really large freighters and colony ships will be more economical, whereas in Standard Aurora the advantage of building ultra-large commercial ships isn't very great. Commercial ships will generally become more expensive but this is a very different game with longer timescales for the building up of distant colonies so I don't think that is a significant problem.

Steve
« Last Edit: December 10, 2011, 12:21:14 PM by Steve Walmsley »
 

Offline Steve Walmsley

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Re: Newtonian Aurora - Rules
« Reply #4 on: November 10, 2011, 02:18:32 PM »
Railguns

Railgun Maximum MJ Per Ton: The muzzle energy in Megajoules (MJ) of the railgun is based on its size in tons (not HS as I am moving away from HS in Newtonian Aurora) multiplied by this number. So a 200 ton railgun with an MJ per Ton of 12, would have a muzzle energy of 2400 MJ. Damage in Newtonian Aurora will be calculated based on the MJ output of a weapon. For comparison, the recently tested US Navy railgun has a muzzle energy of 33 MJ. This is a tech line starting at 5 MJ per ton.

Railgun Energy Conversion Rate: The efficiency with which the railgun transfers energy stored in homopolar generators (HPG). If this was 35% for example, the 2400 MJ railgun would require 6857 MJ of energy to fire. This is a tech line starting at 25%

Railgun vs. Projectile Maximum Mass Ratio: This is the ratio of the total railgun mass compared to the mass of the projectile. The kinetic energy of each shot is based on the muzzle velocity squared multiplied by half the mass of the projectile (real physics - not my formula). This means that greater velocity is more important than larger projectiles. Also, greater velocity makes fire control easier. So, the question becomes why not spend your muzzle energy on smaller, faster projectiles? Because with a smaller 'calibre' the actual rails become longer and narrower and there is a limit to the aspect ratio between 'calibre' and rail length. As Aurora doesn't really consider how 'long' something is, that design consideration is handled by this parameter. You can exceed the mass ratio if you wish (and therefore increase muzzle velocity) but your energy conversion rate is reduced by maximum mass ratio/actual mass ratio. I'll show an example of this later on. This tech line starts at a mass ratio of 100,000, which is a 1 kg projectile for a 100 ton railgun.

Railgun Heat Dissipation Rate: When a railgun fires, it generates a huge amount of heat. The parameter covers how rapidly the railgun cools down to the point at which another shot can be fired. It is based on the surface area of the railgun, which is based on its mass. The value of the parameter is how much MJ/s per square meter will be dissipated per second (assuming 1 ton = 1 cubic metre). Smaller railguns will have a greater surface area vs volume than larger railguns so they will cooldown a little faster. For example, if this parameter was 0.6 MJ/s and the railgun was 200 tons and 2400 MJ, the surface area would be 165.4, the dissipation rate would be 99.24 MJ per second and the total cooldown period would be 2400/99.24 = 24.18 seconds, rounded to 24 seconds. You can increase rate of fire by either researching this tech line, or you can also reduce the MJ per Ton parameter to create a less powerful but faster firing railgun. For example, changing it from 12 to 5, would create a 1000 MJ railgun that fired every 10 seconds (albeit at about 2/3rds of the muzzle velocity).

Railgun Size: The size of the railgun in tons

Projectile Mass in Kilograms: The size of the projectile, starting at 1 kilogram with 0.1 kg increments to 5 kg and then 0.5 kg increments. When you hit the mass ratio limit described above, if you wish to create a more powerful railgun while retaining as much energy efficiency as you can, then increasing the size of the projectile becomes the best option. However, if muzzle velocity is deemed more important than energy efficiency then increasing mass ratio would be more effective. The following examples assume MJ per Ton of 12, a 200k mass ratio, a conversion rate of 35% and a heat dissipation rate of 0.6 MJ per m2.

Below is a 200 ton railgun with a 1 kg projectile. This makes full use of the maximum mass ratio of 200k. Note that Vendarite is now the required material for kinetic energy weapons (also, the existing research field of missiles and kinetic weapons has been split into two separate fields). The railgun has a Muzzle Velocity of 69,282 m/s (69.3 km/s), which is the maximum that can be achieved with the available technology without sacrificing energy efficiency. While this doesn't seem to be a very high velocity compared to standard Aurora, bear in mind most ships at a similar tech level would require several hours of acceleration to reach this speed from a standing start and if they are moving faster, their own speed may (depending on the ship's heading) increase the relative speed of the projectile and increase its damage.

2400 MJ Railgun
Muzzle Energy: 2400 MJ     Muzzle Velocity 69,282 m/s    Cooldown Period: 24 seconds
Power Requirement per shot: 6,857 MJ    Energy Efficiency: 35%
Mass Ratio: 200k    Energy Efficiency Penalty: 0%
Railgun Size: 200 tons    Surface Area: 165.4    Projectile Mass: 1 kg
Cost: 24    Crew: 20    HTK: 2
Materials Required: 24x Vendarite
Development Cost for Project: 240RP

Now lets look at two options for doubling the size of the railgun to 400 tons. The first has the same 1kg projectile size and the second has a 2kg projectile. Both will inflict the same damage and both take 30 seconds to cooldown, because their surface area to volume ratio has decreased. The former has increased the muzzle velocity to almost 100 km/s but at the expense of reducing energy efficiency to 17.5% and therefore requiring 27,429 MJ per shot. The second has the same 70 km/s muzzle velocity as the 200 ton version and requires 13,714 MJ per shot. BTW, you may be thinking why bother with a 400 ton 4800 MJ railgun and instead have two 200 ton 2400 MJ railguns. I'll explain that when I describe the new shield generators.

4800 MJ Railgun - 1kg
Muzzle Energy: 4800 MJ     Muzzle Velocity 97,979 m/s    Cooldown Period: 30 seconds
Power Requirement per shot: 27,429 MJ    Energy Efficiency: 17.5%
Mass Ratio: 400k    Energy Efficiency Penalty: 100%
Railgun Size: 400 tons    Surface Area: 262.5    Projectile Mass: 1 kg
Cost: 48    Crew: 40    HTK: 4
Materials Required: 48x Vendarite
Development Cost for Project: 480RP

4800 MJ Railgun - 2kg
Muzzle Energy: 4800 MJ     Muzzle Velocity 69,282 m/s    Cooldown Period: 30 seconds
Power Requirement per shot: 13,714 MJ    Energy Efficiency: 35%
Mass Ratio: 200k    Energy Efficiency Penalty: 0%
Railgun Size: 400 tons    Surface Area: 262.5    Projectile Mass: 2 kg
Cost: 48    Crew: 40    HTK: 4
Materials Required: 48x Vendarite
Development Cost for Project: 480RP

Here is a third option using a 1.5kg projectile, which is a compromise between the other two. Bear in mind these are just the options for two different sizes at one tech level. You will be able to create a lot of different designs, of different sizes, even at just one technology level. With multiple tech lines involved, there are many possibilities for railgun design.

4800 MJ Railgun - 1.5kg
Muzzle Energy: 4800 MJ     Muzzle Velocity 80,000 m/s    Cooldown Period: 30 seconds
Power Requirement per shot: 18,240 MJ    Energy Efficiency: 26.32%
Mass Ratio: 266k    Energy Efficiency Penalty: 33%
Railgun Size: 400 tons    Surface Area: 262.5    Projectile Mass: 1.5 kg
Cost: 48    Crew: 40    HTK: 4
Materials Required: 48x Vendarite
Development Cost for Project: 480RP

Fire control for railguns isn't finalised yet but I will likely be tracking each projectile as if it were a missile with no manoeuvring ability and checking if it intersects the same space as the target (or anything else that gets in the way) at the same time.

 

Offline Steve Walmsley

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Re: Newtonian Aurora - Rules
« Reply #5 on: November 10, 2011, 03:21:04 PM »
Armour and Shields

Armour
The general principle for armour remains the same in Newtonian Aurora, although the specifics have changed. Rather than the abstract nature of armour in standard Aurora, Newtonian Aurora measures armour thickness in centimetres and calculates the amount required based on the surface area of the hull. For the purposes of armour, shields and chance of weapon impact, the hull is assumed to be spherical and each ton of displacement is 10m3. So a ship of 5918 tons would have a volume of 59,180 m3, which is a sphere of approximately 48m in diameter. The surface area is 7344 m2 so a layer of armour 1 cm thick would mass 73.44 tons (rounded to 73). If the armour thickness is increased to 3cm, the hull volume is 60,690 m3 (including the armour), surface area is 7468 m2, sphere diameter is 49m and armour tonnage is 224. All this information is shown in the armour section of the class window. Each cm of armour means 1 row of armour boxes. The width of the armour is equal to the twice the diameter of the sphere, which means an armour width of 98 in the latter case. In effect, this means one armour box for every metre of diameter on both sides of the ship. In reality it should be diameter x PI, as that would be the circumference of the ship but this way is less confusing for damage resolution.

Armour is rated in the amount of megajoules required to destroy one box. For example, High Density Duranium Armour is rated at 80 MJ per box while Ceramic Composite Armour is 125 MJ.

The total amount of armour boxes in Newtonian Aurora is now much greater than for the same tonnage of armour in Standard Aurora, perhaps 3-4 as much and the depth is perhaps a little less than twice as much. So a ship that used to have 3 layers of armour would now have 5-6 layers for about the same tonnage. It's not an exact conversion though as Standard Aurora uses the concept of Armour Strength to require less tonnage for the same number of boxes at higher armour levels. That concept doesn't exist in Newtonian Aurora where you will always need the same tonnage of armour for the same number of boxes. Better armour in Newtonian Aurora is more resistant to damage though. Damage is rated in Megajoules rather than an abstract damage rating so 1 box will subtract a set number of megajoules from the total damage amount, rather than 1 box stops 1 damage. Bear in mind that some of the weapons in Newtonian Aurora are far more devastating than their Standard Aurora counterparts so the improvement is armour is not as dramatic as it might seem at first.

The way in which damage is applied to armour is still armour boxes removed due to damage but the way in which the boxes are selected will change. Assume for the purposes of these example, there are no active shields. Lasers (which are totally different than standard Aurora and I will cover the details in a later post) will affect an area of armour depending on the diameter of the beam when it hits the target. The megajoule output of the laser will be divided between the number of armour boxes covered by the beam, which means once the beam widens to a certain amount, it will only warm up a large section of the armour rather than vapourising a smaller section. For example, if the armour is rated at 100 MJ and the laser output is 1200 MJ, it could penetrate 4 layers of armour by three columns if the beam is only 3 boxes wide, or penetrate two layers by six columns if the beam is 6 boxes wide, etc. If the beam is 13 or more boxes wide, it wouldn't damage the armour because the megajoule damage per box is less than 100. The width of the beam will depend on the range between firing ship and target and on the wavelength of the beam in nanometers (more on that in the forthcoming laser post). Lasers won't be able to affect more than half the width of the armour (one whole side of the ship) so any beam width beyond that will be wasted.

Kinetic weapons such as railguns will punch a hole one column wide straight through the armour. If they penetrate through the entire armour belt, they will damage a limited number of systems depending on the size of the ship and then potentially punch their way out again, damaging armour from the inside outwards. Of course, it will be much harder to hit with a railgun due to the speed of the projectile but the potential for damage is much greater, especially if the target ship is moving at high speed.

Nuclear weapons in Newtonian Aurora are area-based and missiles may be set for proximity detonation. If a ship is close enough to be within the blast radius, any damage that penetrates the shields will be applied to half the width of the armour, which will be the side of the ship facing the explosion. To determine the damage applied per box, the total MJ output of the explosion (which for 1 megaton would be 4,184,000,000 Megajoules - ouch!), is applied across the total surface area of a sphere with a radius equal to the range from the ship to the detonation point. The total energy output for 1 square metre of that explosion at the given range will be applied to each affected armour column. This isn't quite as bad as it sounds unless you are very close to the explosion because the rate at which damage falls off for nuclear detonations in space is far greater than in atmosphere.

For example, if you are 500 meters from a 200 kiloton detonation (which is a 1 ton warhead at tech level 3), the total damage applied per armour column will be 266 MJ. At 100 meters though it is 6659 MJ per column, which wouldn't be good. And yes, this means it is possible to take out a ship with a single missile if you get close enough, so I suggest anti-missile defence should be a priority. I thought a lot about this but decided to go with the realistic option. Lets face it - if the Nimitz took a direct hit from a 200 KT nuke, it would be in some difficulty. Don't forget though that you can also use nuclear detonations defensively and a single small nuke could take out a lot of attacking missiles with a proximity detonation. Also missiles will generally be much slower than in Standard Aurora. Targeting will be different too but I will cover that in another post.

Another example. A 1 megaton nuke would cause 83 MJ per column at 2000 meters, 332 MJ at 1000 meters, 1331 MJ at 500 meters and 5327 MJ at 250 meters. At 100 meters it would be 33,295 MJ per armour column!! You definitely need to keep the location of any fleet bases and shipyards a very closely guarded secret! In fact, I think dispersing shipyards may be a good idea. In a way, I am designing Newtonian Aurora without a really detailed idea of how the combat is going to play out. I am trying to create realistic systems and then I will see how everything interacts and how that drives tactics. It will be fun to find out

Other types of warhead will include non-nuclear conventional warheads, bomb-pumped laser warheads, inert warheads for kinetic attack and shrapnel heads.

Shield Generators
Shields have changed for Newtonian Aurora. There are three parameters in the design window.

Maximum Shield Energy Per Ton: This parameter is rated in Megajoules (MJ) and the tech line starts at 25 MJ per ton. This is the maximum shield energy that can be sustained by the shield generator. So if the Maximum Shield Energy Per Ton was 100 MJ and the generator was 50 tons, it could sustain a shield energy of 5000 MJ.

Shield Generation Rate: This is the rate in MJ/s per ton at which the shields can draw energy from the ship's homopolar generators (HPG) to replenish shield energy. The tech line starts at 0.1 MJ/s. For example, if this tech was 0.25 MJ/s, a 50 ton shield generator could replenish shield energy at 12.5 MJ/s.

Shield Generator Size: Between 10 and 500 tons. Each 10 ton increment adds a 1% bonus to maximum shield energy, on the basis that the larger installations are more efficient. So a 50 ton generator would have a 5% bonus.

Here is an example 200 ton shield generator using Maximum Shield Energy Per Ton = 100 MJ and Shield Generation Rate = 0.25 MJ/s

5250 MJ Shield Generator
Maximum Shield Strength: 5,250 MJ
Maximum Recharge Rate: 12.5 MJ/s    Minimum Recharge Time: 420 seconds
Cost: 10.5    Crew: 3     HTK: 1
Materials Required: 10.5x Corbomite
Development Cost for Project: 1050RP

Multiple shield generators can be added to a ship, although they must be all of the same type. The Maximum Shield Strength of the ship is equal to their combined strength and is the total amount of incoming energy (damage) that the shields can withstand. However, as well as a maximum overall strength, a ship has a Maximum Point Strength for its shields as well. This is the maximum damage than can be absorbed from a single hit from a railgun or a narrow beam from an energy weapon weapon. This depends on a combination of the size of the ship and the overall strength of the shields. The shields are assumed to encompass a spherical volume that has 1.1x the radius of the spherical volume of the ship. In other words, if the ship is a 40 meter sphere, the shields are a sphere with an 44 meter diameter. For the purposes of shields (and armour), every ship is assumed to be a sphere, even if for role-playing reasons (and for the Length displayed on the class summary) they are described as different shapes.

Shield Area is in square meters and the point strength is equal to the total shield strength multiplied by (200/shield area). In effect, I am assuming that the energy contained in 200m2 of the shields will be applied against any single kinetic strike or against a beam strike with a beam width of one metre or less.

For example: A ship of 4895 tons has 6cm thick armour and 72 GJ shields. The hull volume is 48,950 and the spherical diameter is 46 meters. The surface area is 6647m2, which is multiplied by 0.06 for 6cm of armour, giving 399 tons of armour. The armour is 6 layers by 46 columns and is Ceramic Composite with a strength of 125 MJ per box. The radius of the shields is 10% greater than for the armour, which gives a surface area of 8044m2. The 72 GJ total shield strength (72,000 MJ) is multiplied by (200/8044), to give a point strength of 1790 MJ.

If the ship was hit by a 1000 MJ railgun shot, its shields would absorb 1000 MJ and be reduced to 71,000 MJ and no damage would penetrate.
If the ship was hit by a 2400 MJ railgun shot, its shields would absorb 1790MJ and be reduced to 70,210 MJ. The other 610 MJ would be resolved against a single column of armour
If the ship was hit by a 4800 MJ railgun shot, its shields would absorb 1790MJ and be reduced to 70,210 MJ. The other 3010 MJ would be resolved against a single column of armour

This means that larger ships may have a greater total shield strength than their smaller opponent but may not necessarily have a greater point strength. Although given the reducing ratio of surface area to volume as ships become larger, larger ships will be more efficient in terms of point strength vs. total strength. In a battle between two railgun-armed, shield protected ships, the ship that is able to penetrate the shields of its opponent more effectively is likely to prevail. In a sense, such a combat would resemble that of two WW1 dreadnoughts.

Steve
 

Offline Steve Walmsley

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Re: Newtonian Aurora - Rules
« Reply #6 on: November 19, 2011, 03:16:08 PM »
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
« Last Edit: December 06, 2011, 02:17:33 PM by Steve Walmsley »
 

Offline Steve Walmsley

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Re: Newtonian Aurora - Rules
« Reply #7 on: November 25, 2011, 12:37:56 PM »
Active Sensors

Target Cross Section (TCS)
In Standard Aurora, the active signature of ships is based on their volume, with 1 HS (50 tons) equalling 1 point of resolution. So an 800 ton ship has an active signature of 16 and a 5000 ton ship has an active signature of 100.

In Newtonian Aurora, the active signature is based on the cross-section of the ship and known as the Target Cross Section (TCS). For resolution purposes, this is calculated as one tenth of the surface area of a circle that has the same radius as the ship. For example, a ship with a mass of 5952 tons and therefore a volume of 59,520 m3 has a radius of 24m. This is rounded to an integer because the number of armour columns is equal to twice the diameter of the ship (96 in this case). The area of a circle with a radius of 24m is 1809.5616. This is divided by 10 and rounded to 181. So 181 is the active signature or TCS of the ship. In Standard Aurora it would have been 119.

Some more comparisons are shown below. In general, anything larger than about 20,000 tons will have a smaller TCS than before and anything smaller will have a larger TCS than before

Terraformer of 63,003 tons. Standard 1260, Newtonian 882
Freighter of 35,393 tons. Standard 708, Newtonian 608
Colony Ship of 20,313 tons. Standard 406, Newtonian 407
Warship of 5,952 tons. Standard 119, Newtonian 181
Survey Ship of 2,006 tons. Standard 40, Newtonian 91
Fast Attack of 991 tons. Standard 20, Newtonian 53
Fighter of 256 tons. Standard 5, Newtonian 24

Missiles are detected using a similar formula. However, ships are larger in relation to their mass than missiles so missiles use Volume = 3x Mass, rather than the Volume = 10x Mass used for ships. A comparison of different missile TCS between Standard Aurora and Newtonian Aurora is shown below. Bear in mind that Standard Aurora has a minimum contact size of 0.33, which doesn't exist in Newtonian Aurora, and that Newtonian missiles will probably be smaller in tonnage terms than their Standard counterparts.

Standard Size 2 missile (5 tons) - TCS 0.33
Standard Size 4 missile (10 tons) - TCS 0.33
Standard Size 6 missile (15 tons) - TCS 0.33
Standard Size 8 missile (20 tons) - TCS 0.40
Standard Size 12 missile (30 tons) - TCS 0.60

Newtonian 5 ton missile - TCS 0.74
Newtonian 10 ton missile - TCS 1.17
Newtonian 15 ton missile - TCS 1.53
Newtonian 20 ton missile - TCS 1.85
Newtonian 30 ton missile - TCS 2.43

Sensor Range Formula
The calculation for base active sensor range has been changed as well. It is now:
SQRT(Sensor Strength x EM Sensitivity x Size x Sensor Resolution) x 1,000,000 km

For example, a 50 ton Sensor with a resolution of 100, active sensor tech of 1 per ton, and EM tech of 0.2 per ton has a base range of  SQRT(50 x 1 x 0.2 x 100) = 31.62, multiplied by 1 million = 31,620,000 kilometres.

For targets with a TCS smaller than the resolution of the sensor, the maximum detection range modification remains as before, which is:  Maximum Range Modification = (TCS / Resolution) ^ 2

The changes mean that in Newtonian Aurora similar increases in technology or size will yield less of a range increase than in Standard Aurora, while changes to resolution (which was already modified via square root in Standard) will have the same effect. To double the range of a sensor you would have to quadruple a combination of its size, resolution and technology. Conversely, the changes to TCS mean that many ships will have a larger TCS than before so higher resolutions will be normal. Active sensor strengths are higher in Newtonian Aurora but there is also a requirement for a reactor to power the sensor, which is not included the sensor size.

Here are five example sensors. Note the layout of the tech summary has changed to provide more examples of missiles and ships with a TCS less than the resolution of the missile. These are all 150 ton installations, using Active Sensor Strength 1 per ton and EM Sensor Sensitivity 0.2 per ton. The last four lines are omitted beyond the first example as they are the same in each case

Missile Detection
Active Sensor Strength: 150   EM Sensitivity Modifier: 20%
Sensor Size: 150 tons    Sensor HTK: 1
Resolution: 1  (7.9 ton missile)     EM Detection Signature: 150
Maximum Range vs object with TCS of 1 or greater: 5,470,000 km
Range vs 4 ton Missile (TCS 0.63): 2,196,619 km
Chance of destruction by electronic damage: 100%
Cost: 150    Crew: 15
Materials Required: 37.5x Duranium  112.5x Uridium
Development Cost for Project: 1500RP

Fighter Detection
Active Sensor Strength: 150   EM Sensitivity Modifier: 20%
Sensor Size: 150 tons    Sensor HTK: 1
Resolution: 20  (213 ton ship)      EM Detection Signature: 3000
Maximum Range vs object with TCS of 20 or greater: 24,490,000 km
Range vs 4 ton Missile (TCS 0.63): 24,586 km
Range vs 8 ton Missile (TCS 1.01): 61,950 km
Range vs 12 ton Missile (TCS 1.32): 106,388 km

FAC Detection
Active Sensor Strength: 150   EM Sensitivity Modifier: 20%
Sensor Size: 150 tons    Sensor HTK: 1
Resolution: 48  (792 ton ship)      EM Detection Signature: 7200
Maximum Range vs object with TCS of 48 or greater: 37,940,000 km
Range vs 4 ton Missile (TCS 0.63): 6,613 km
Range vs 8 ton Missile (TCS 1.01): 16,662 km
Range vs 12 ton Missile (TCS 1.32): 28,614 km
Range vs 250 ton Ship  (TCS 22): 8,166,570 km

Small Warship Detection
Active Sensor Strength: 150   EM Sensitivity Modifier: 20%
Sensor Size: 150 tons    Sensor HTK: 1
Resolution: 141  (3983 ton ship)      EM Detection Signature: 21150
Maximum Range vs object with TCS of 141 or greater: 65,030,000 km
Range vs 4 ton Missile (TCS 0.63): 1,314 km
Range vs 8 ton Missile (TCS 1.01): 3,310 km
Range vs 12 ton Missile (TCS 1.32): 5,684 km
Range vs 250 ton Ship  (TCS 22): 1,622,185 km
Range vs 1000 ton Ship  (TCS 56): 10,300,388 km

Large Warship Detection
Active Sensor Strength: 150   EM Sensitivity Modifier: 20%
Sensor Size: 150 tons    Sensor HTK: 1
Resolution: 260  (9973 ton ship)      EM Detection Signature: 39000
Maximum Range vs object with TCS of 260 or greater: 88,310,000 km
Range vs 4 ton Missile (TCS 0.63): 525 km
Range vs 8 ton Missile (TCS 1.01): 1,322 km
Range vs 12 ton Missile (TCS 1.32): 2,270 km
Range vs 250 ton Ship  (TCS 22): 647,870 km
Range vs 1000 ton Ship  (TCS 56): 4,113,782 km
Range vs 4000 ton Ship  (TCS 141): 26,121,287 km

Steve
« Last Edit: December 17, 2011, 10:34:15 AM by Steve Walmsley »
 

 

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