C# Aurora Changes List v1.00

[Steve Walmsley (OP)]

Planet X in the Sol System

In recent years, several theories have been published regarding a potential planet affecting some Kuiper Belt objects, possibly a distant but undetected gas giant. Therefore, a new game option is to "Add Planet X to the Sol System".

The planet will be located at a distance between 125% and 225% of the orbit of the most distant dwarf planet. 10% of the time it will be a terrestrial body, 60% a gas giant and 30% a superjovian. Moons, Trojan asteroids and a Lagrange point may also be generated depending on the type of planet generated. If Planet X has a Lagrange point, a Lagrange point will also be generated for Jupiter. While very distant from the inner system, this could add an interesting variation to the Sol system.

Currently Planet X is named Minerva, although I haven't created any moon or Trojan asteroid names. Suggestions welcome.

Here is one version of Minerva - a superjovian with eight moons, orbiting at 145 AU.

[Steve Walmsley (OP)]

Resupply Changes

In C# Aurora, resupply is no longer instant and ships without cargo shuttles cannot exchange maintenance supplies in space. A ship can only resupply at a population with a spaceport, a cargo shuttle station or at least one maintenance facility, or from a ship with cargo shuttles.

Maintenance supplies are transferred at the rate of 10 per hour, multiplied by the number of cargo shuttle bays and the racial shuttle technology. Spaceports, cargo shuttle stations and maintenance facilities can resupply an unlimited number of ships simultaneously. However, the ships being resupplied must be stationary.

Resupply order types will be adjusted to deal with the new requirements. Maintenance supplies can be transferred by supply ships during each movement increment as time passes until the target ship has reached capacity (in the same way as underway replenishment of fuel).

[Steve Walmsley (OP)]

Combination Orders

Given the number of new logistics options, I am adding some combination orders to C# Aurora where functions can happen simultaneously. For example, "Refuel and Resupply from Colony" will carry out both activities simultaneously, assuming that the ships / colony are equipped with the necessary logistical facilities. The order will complete when the activity with the greater duration is complete.

Other combination orders so far (I will edit here as more are added):

Refuel, Resupply, Load Ordnance from Colony
Join, Refuel and Resupply Target Fleet
Join, Refuel, Resupply, Add Ordnance to Target Fleet

I will add more combination orders during play testing, depending on which are useful, although I can't go overboard or I risk cluttering the orders list.

[Steve Walmsley (OP)]

Minimum Fuel and Supply

Because of the new rules for transferring fuel and supplies, ship classes can be given a minimum maintenance supply level and a minimum fuel level. Ships will not unload or transfer fuel and supplies beyond these levels. These functions replace the VB6 rule where a tanker would only unload 90% of its fuel.

[Steve Walmsley (OP)]

Damage Control

Damage Control functions in a similar way to VB6 with a few exceptions.

• There is no longer any separation between the current damage control assignment and the queue. In C# there is just a damage control queue and the highest priority item will be worked on first.
• The ship damage control rating is equal to the total value of engineering, damage control and commercial damage control systems, boosted by five times the Engineering bonus of the Chief Engineer (if one is assigned). So a Chief Engineer with a 20% bonus would double the damage control rating
• If the ship being repaired is in a hangar, the damage control rating of the mothership will be added to the damage control rating of the ship and the mothership maintenance supplies will be used first (although they will not be used past the specified minimum level). While this allows the mothership DC rating to be potentially used on multiple ships simultaneously, I decided that was preferable to having repair priorities per ship. The micromanagement isn't really worth the extra realism.
• If the top item in the damage control queue is too expensive to repair (due to lack of maintenance supplies), other items will be checked in order to see if they can be repaired instead.
• The percentage chance of repair is equal to ((Increment Length in Seconds / Repair Cost) *  Damage Control Rating) / 1000. For example, Geological Survey Sensors cost 100 BP so have a repair cost of 200 MSP. If a ship has a damage control rating of 5 and the increment is one hour, the repair chance for the sensor would be ((3600 / 200) * 5) / 1000 = 9%
• All ships have the option to engage Automated Damage Control, in which case the ship will assign its own damage control queue based on the same repair priorities as NPRs

Below is the new damage control tab for the Ship section of the Naval Organization window. The Repair Chance on the rightmost column is the chance for the ship to repair the component in the time specified at the bottom of the screen in the Repair Chance Time text box. SM Repair All is only visible in SM mode and will repair everything, including armour. Auto Queue will queue everything using the automated damage control rules. Clicking the Automated Damage Control checkbox means the ship will automatically queue and repair damage (the queuing is done just prior to damage control in the sequence of play).

[Steve Walmsley (OP)]

Electronic Intelligence Gathering

A new concept in C# Aurora is ELINT, or Electronic Intelligence Gathering. This is performed by a new line of ship components, the Electronic Intelligence and Analysis Modules. These start at strength 5 and follow a similar strength progression to EM Sensors. One of the prerequisites for each module is the corresponding EM Sensor strength technology.

The ELINT Modules are 10 HS, require 15 crew and cost 20x their strength (this is subject to change as a result of play test). They have a secondary function as an EM Sensor, although a dedicated EM sensor of the same size would be far more effective. Their primary function is to gather electronic and signals intelligence on alien populations and active sensors (and I will add ground forces at some point). Increased strength, through research or multiple modules, can increase the range at which intelligence is gathered but the base rate is fixed. Multiple ships cannot increase the intelligence gathered from a single source, although a single ELINT module can gather intelligence from multiple sources.

If the target can be detected by the ELINT modules' built-in EM Sensors, intelligence can be gathered. The rate is 1 intelligence point per day, boosted by the Intelligence bonus of the ELINT ship commander. For populations, the intelligence is also multiplied by (100 - Population Species Xenophobia) / 100. In other words, it is much harder to gain intelligence when a population has high xenophobia. If the alien language is not translated, all intelligence is reduced by 80%.

Intelligence is gathered per population and per active sensor design (if multiple sensors of the same type are monitored, you only gain intelligence at the same rate as one sensor). Specific alien sensors will now be associated with specific alien classes.

Alien active sensors will initially be displayed with just a strength and not a range or resolution. Once 100 intelligence points have been gathered for a particular design of active sensor, its range and resolution will be displayed. Note that in VB6 you only have an approximation of the alien sensor range. I plan to add active jammers and passive stealth capability, both of which will become more effective against alien sensors based on the intelligence gathered on those sensors (no limit to intel points). I'll provide the detail for this when I post the jammer and stealth rules.

Alien populations will be initially be displayed as they are now, with EM and thermal signatures. Once 100 intelligence points have been gathered, the population size in millions and the number of installations will be displayed. Additional information becomes available at higher intelligence levels:

200 Points:
Number of factories and mines and whether a spaceport and/or a cargo shuttle station are present.

300 Points
Number of refineries and maintenance facilities and whether a refuelling station and/or an ordnance transfer station are present.

500 Points
Number of research facilities and ground force training facilities and whether a naval headquarters and/or a sector command are present.

The intelligence points for a specific population will reduce at approximately 25% per year if ELINT monitoring ends. The information that was gained while intelligence points were at their highest point will remain and is shown in red when viewing the alien population on the Diplomacy window. Current information is shown in green.

Any intelligence gained on a population is also used at the racial level for the purposes of espionage. Each Alien Population Intelligence Point adds one Alien Race Intelligence Point. If the population is less than 100m, the translation of Population Intelligence to Race Intelligence is modified by Population in millions / 100. When 100 Alien Race Intelligence Points have accumulated, a check is made for any intelligence gained. This is the same check as in VB6 for espionage teams and can result in new technology, survey data, new system knowledge or details of an enemy ship class. I will probably add information on alien sensors, ground units and populations to that list.

As a result of these changes, espionage teams have been removed from C# Aurora.

A couple of design examples for the ELINT Module

[Steve Walmsley (OP)]

Interrogation of Survivors

In VB6 Aurora, you can gain espionage points from interrogating the survivors picked up from life pods. In C# Aurora, the same principle applies, although they are now Race Intelligence Points and are added to those gained via ELINT.

The rate at which Race Intelligence points are gained from survivors is Crew / 10 + the cube of the rank number of any captured officer (so R3 would provide 27 points). This is more important than the same algorithm in VB6, because there are now potentially multiple officers per ship.

However, unlike VB6, this point gain is reduced if the survivors are from a non-hostile power. The intelligence points gained from neutrals is halved, friendly reduced by 80% and allied by 90%. This is to simulate that aggressive interrogation is unlikely to be used against survivors from a friendly power.

As with other intelligence gains, there is a further 80% reduction if the alien language has not been translated.

[Steve Walmsley (OP)]

Ground Force Logistics

Ground Units have two separate logistics requirements. The first is Maintenance, which applies to all units at all times and has a wealth cost equal to 12.5% of Ground Unit cost per annum. The second is Ground Supply Points (GSP), which applies only to combat units during ground combat.

The GSP requirement for a weapon component is equal to Penetration Value * Damage Value * Shots. For example, Personal Weapons is (1 x 1 x 1) = 1. Crew Served Anti-personnel is (1 x 1 x 6) = 6. Medium Anti-Vehicle is (4 x 6 x 1) = 24. Heavy Bombardment is (2 x 6 x 3) = 36.

The GSP requirement for a Ground Unit Class is the sum of its weapon components. For example, a tank with a Medium Anti-Vehicle component and a Crew Served Anti-personnel component would have a GSP requirement of 30. The GSP requirement for a Formation Element is the GSP for the Ground Unit Class in the element multiplied by the number of units. The GSP requirement for a Formation is the sum of the GSP for its constituent Formation Elements. In all these cases, that is the GSP cost to provide sufficient supply for ten combat rounds.

Two new ground unit components have been added; the Logistics Module, which is Size 50 and provides 500 GSP, and the Logistics Module - Small, which is Size 10 and provides 100 GSP. The standard module is available for light vehicle and infantry base types, while the small module is only available to infantry.  Here is an example of a light vehicle with the Logistics Module.



Ground units with either logistics module can be added to any level of the ground force hierarchy, either embedded with the front line combat formations or held at a superior formation, such as a headquarters.

Each Ground Unit has sufficient inherent supply points to fight ten rounds of combat (currently one round takes place every eight hours). After that point, only one quarter of units in a formation element that is out of supply will fire in each round. In addition, a formation with out of supply elements cannot use a field position of 'Front Line Attack' (more on this when I publish the full ground combat rules). However, if units with logistics modules are available, ground units can draw supply to both fight the current combat round and replenish supplies used in previous combat rounds.

Ground Units will attempt to draw supply from the formation that sits highest in their hierarchy and is at the same population. If no supply is available, they will move down the hierarchy to their own parent formation, checking at each stage. However, when drawing supply from outside their own formation, units can only draw on logistic modules mounted on light vehicles. Logistics modules with an infantry base type can only supply their own formation.

For example, a formation element of 10 tanks engaged in combat is part of an armoured formation with a brigade HQ formation above it and a division HQ formation above that. The tanks will check for a vehicle-based logistics element within the division formation first, then a vehicle-based logistics element within the brigade formation and finally either type of logistic element within their own parent formation. If no logistic elements are available, the tanks will use their inherent supply, although they can only use that inherent supply for ten combat rounds, unless resupplied. If a unit does not require a full resupply (for example, it still has sufficient inherent supply for eight combat rounds), it will only draw an appropriate fraction of its normal GSP requirement (in this case 20%).

When a formation element of logistics units provides supply, a number of units will be consumed based on the supply required. For example, assume the 10 tanks above each have a GSP requirement of 100, which is 1000 for the whole element. If they draw on a logistics element using light vehicles with normal logistics modules (which have 500 GSP each), two of those logistics vehicles would be consumed. When the GSP requirement does not neatly fit into the 500 point granularity, there is a chance of an additional logistics vehicle being consumed. This chance is dependent on the fraction of supplies required. For example, if there were 12 tanks with a requirement of 1200, then two logistic vehicles would be consumed and there is 40% chance (200 / 500) than a third vehicle will be consumed. This adds an element of uncertainty, as supplies may be consumed faster or slower than normal (although it will average out over time), plus it avoids any tracking of partial supplies per vehicle.

Below is an example of a Formation Template for a Brigade Headquarters that includes 50 Supply Vehicles.



Below is an order of battle for a divisional formation. At the divisional level are 240 Supply Vehicles, indicated by LOG 120k (120,000 supply points) in the Formation Attributes column, with smaller numbers within each brigade headquarters formation. The GSP column shows the resupply requirement for each formation or formation element. The total divisional organisation requires 40,338 GSP for a complete resupply and there are sufficient supply vehicles (410) in that organisation to resupply five times. With the inherent supply as well, the entire division can stay in combat for sixty rounds before additional supply vehicles are required.



Finally here is a view of a single population, with the order of battle tab in Location mode.

[Steve Walmsley (OP)]

Base Ground Combat Rules

Ground combat is conducted after the naval combat phase of each increment. One combat round will be performed for every eight hours that passed in the increment. Combat potentially takes place on any system body where populations exist from two or more hostile powers. If only one side has ground forces present, there may be a conquest (rules and code TBD). If ground forces are present from two or more hostile powers, ground combat will take place.

Ground forces can be assigned one of four field positions; front line attack, front line defence, support and rear echelon. Units in support and rear echelon positions cannot directly attack hostile forces but if they possess elements with bombardment weapons they may be assigned to support a front line formation. Support and rear echelon formations can also potentially provide anti-air cover (more in a rules post on ground-space interaction) and supply to front line units. Only formations with all elements supplied can be placed in front line attack mode. Formations placed in front line attack mode lose any fortification bonus.

Each race involved in a combat on a system body creates a list of its own formations on that system body (even if in multiple populations), plus a list of hostile alien formations, even if they are from multiple alien races in multiple populations. Hostile formations are checked for their weighted size.  This is based on actual size for front line size, 25% for support and 5% for rear-echelon. Each hostile formation is given a range for potential selection, based on its weighted size.

Each front line friendly formation randomly targets a hostile formation. Friendly units with front line defence can target hostile front line formations. Friendly units with front line attack can target any hostile formation, although support and rear echelon are less likely given their smaller weighted size. In fact, the more formations that are pushed into front line positions, the less likely it is that rear areas will be attacked.

Support and Rear Echelon formations that contain formation elements with bombardment weapons can be assigned to support front line formations that are part of the same organisation. Formations in a support position with light bombardment weapons will fire with the front line formations (see next paragraph). Formations in a support position with medium/heavy bombardment weapons or formations in a rear echelon position with heavy bombardment weapons will fire in a subsequent phase - see below.

Once a front line formation (or a light bombardment element in the Support position) has been matched against a hostile formation, each friendly individual unit (a soldier or vehicle) in that formation engages a random element in the hostile formation, with the randomisation based on the relative size of the hostile formation elements. The targeting on an individual unit level represents that the different elements in a front line formation will generally be attacking in conjunction (infantry supporting tanks, etc.).

Once all front line attacks have been concluded, each unit in each element providing supporting bombardment will engage either the hostile formation being targeted by the friendly formation they are supporting, or one of the hostile formation's own supporting elements (counter-battery fire). If the hostile formation is targeted, each unit in the supporting artillery element engages a random element in the hostile formation, with the randomisation based on the relative size of the hostile formation elements (the same as front-line vs front-line). If a hostile supporting element is targeted, all fire is directed against that element. This represents the difference between providing supporting fire in a combined arms front-line battle and targeting specific hostile artillery for counter-battery fire. The decision to target the hostile front-line formation vs hostile support elements is based on the relative sizes.

Supporting medium artillery will choose between hostile forces in Front-Line or Support field positions (and will ignore any elements in Rear Echelon field position for purposes of relative size), while heavy artillery can select targets in any field position. In other words, if the enemy has supporting heavy artillery in a rear echelon position, you will only be able to target those elements with your own heavy artillery (or ground support fighters, or orbital bombardment support).

Once all the initial combat is complete, there is a chance for a breakthrough. Each defending formation is checked according to the following procedure:

• A Cohesion Damage value is determined for each formation element using the following formula: Element Class Size * Units Destroyed in Combat Phase * (100 / Element Morale)
• The total Cohesion Damage is summed for all elements in the formation and compared to the formation size. This value, from 0 to 100%, is the Formation Cohesion Rating
• For each front line formation that attacked the defending formation, a Breakthrough Value is determined for each formation element
• Static elements have zero Breakthrough Value. Vehicle elements use the following formula: Element Class Size * Element Units * (Element Morale / 100). Infantry elements use the same formula as vehicles with a further modifier of 0.5.
• The total Breakthrough Value is summed for all elements in the attacking formation and compared to the formation size. The value is multiplied by 2 if the formation has a field position of Front Line Attack. This value, from 0 to 200%, is the Formation Breakthrough Rating
• A Breakthrough Potential value is determined for the attacking formation by multiplying the defending Formation Cohesion Rating by the attacking Formation Breakthrough Rating. If this value is equal to or greater than 30%, a breakthrough has occurred for that attacking formation.
• Each formation that creates a breakthrough mounts a second attack. This attack does not benefit from supporting artillery or fighter support. However, it functions as if the attacking formation has a field position of Front Line Attack, which means all hostile formations are potential targets, not just those on the front line.

The breakthrough rules mean that defending formations that suffer casualties may allow attacking formations to penetrate their lines and conduct a second attack. This is more likely under the following circumstances: A single defending formation is attacked by multiple attacking formations, the defender suffers a high casualty percentage in a single ground combat round (potentially because the formation is small in size), the defender suffers disproportionate casualties to elements with larger unit classes, the defender is low morale, the attacker is primarily vehicle-based, the attacker is on front-line attack, the attacker is high morale.

When a formation element is engaged in combat against a hostile formation element, supply is checked. If supply is not available, the number of units firing will be 25% of normal. Each attacking unit uses the following process:

• The To Hit Chance is determined. The base chance is 20% multiplied by the 'Dominant Terrain To Hit Modifier', the firing element morale / 100 and, if the target is not fortified, the base to hit chance for the target element unit class.
• The Fortification Modifier for the target element is determined, which is the current fortification level of the target multiplied by the 'Dominant Terrain Fortification Modifier'. If the target is not fortified, the Fortification Modifier is 1.
• The Environment Modifier is calculated, taking into account gravity, pressure and temperature and whether the firing element has capabilities in those environments. Each environment for which the element is not trained has a x2 modifier.
• The Terrain Capability Modifier is calculated. If the element is trained to fight in the dominant terrain, the modifier is 0.5.
• The Final Chance to Hit is calculated as To Hit Chance / (Fortification Modifier * Environment Modifier * Terrain Capability Modifier)
• The unit fires each weapon it has (except for non-bombardment weapons on units bombarding from support and rear-echelon field positions). If the to-hit roll is equal or less than the final chance to hit, the weapon has struck the target.
• If a hit is scored, the armour-piercing (AP) value of the weapon is checked against the armour of the target. If AP is equal or greater than armour, the shot has penetrated. If AP is less than armour, the percentage chance to penetrate armour is (AP / Armour)^2.
• If the shot penetrates armour, the percentage chance of destroying the target is equal to (Weapon Damage / Target Hit Points)^2.
• If a target is destroyed, the firing element gains morale and the target element suffers a loss of morale. This morale gain/loss is doubled if the firing unit is in front-line attack mode.

All combat is conducted simultaneously and losses are applied once all firing is completed. Because of the way the above is structured, multi-way conflicts with multiple races on each side are possible.

I will post separately on how spacecraft interact with ground combat.

[Steve Walmsley (OP)]

Setting Ground Formation Support

Here is a screenshot of the UI for setting support relationships between superior and subordinate formations. You drag the superior formation on to the subordinate formation. If the Support checkbox is checked, the supporting formation is shown in blue-grey with the name of the supported formation. Any supported formation in shown in orange. Support can only be provided when the supporting formation is a superior formation in the hierarchy of the supported formation, or is directly subordinate to a superior formation in the hierarchy of the supported formation and does not itself have any subordinate formations (an independent artillery formation for example). Supporting formations must be on the same system body as the supported formation. In combat, the support relationship will only function if the supporting unit has suitable bombardment units and is in a support or rear echelon position and the supported unit is in a front line position.

The drag-drop is intelligent and can distinguish between setting support relationships, reassigning formations to a new headquarters, removing headquarters assignments, moving formations from one population to another (on the same system body) and moving elements between formations (more on that last option in the next post).

[Steve Walmsley (OP)]

Ground Formation Element Transfer UI

Below is the same screenshot as the previous post but with the Elements option selected. Now the formation elements for each Ground Formation are shown in the hierarchy. For formations with no subordinate formations, the formation elements are shown directly under the parent formation. For formations with subordinate formations, the formation elements are shown under their own node, to avoid cluttering the tree view.

To move elements between formations, you can drag and drop elements from one formation to another, although they must be on the same system body. Normally, the whole element is transferred. However, if the Amount checkbox is checked, a popup box will appear after the drag-drop, allowing you to transfer only a portion of the element. If the receiving formation already has an element with the same ground unit class, the additional units will be added to the existing element.

[Steve Walmsley (OP)]

Fighter Pods and Fighter Pod Bays

In C# Aurora, fighter-sized ships can be equipped with a new component, the Fighter Pod Bay, which is similar in function to a small Box Launcher, except it will only hold Fighter Pods (see below).



Fighter Pods are created on the Missile Design window. The various pod options, such as bombardment pod, autocannon pod and air-to air pod, will appear when the requisite technology has been researched. When one of those options is selected, the warhead strength field is replaced by a pod size field. The player can choose the pod size, with larger pods being more effective. The pod capabilities will be similar to the capabilities of equivalent-sized ground unit components, although the fighter pods have more flexibility in design. For example, a bombardment pod will have three shots, armour penetration equal to Racial Weapon Modifier * ((Tons / 20) ^ 0.6) and damage equal to Racial Weapon Modifier * ((Tons / 20) ^ 1.6).

Fighter pods are ordnance, in exactly the same way as missiles. They are built by ordnance factories, transported in magazines and loaded onto fighters. Unlike missiles, they are not expended when fired and will function during ground combat phases.





A fighter can be designed with fighter pod bays. Different pods can be assigned to those bays while the fighter is in a hangar, providing flexibility of loadout. The same fighter could be used for bombardment or autocannon pods, as long as the pods bays are large enough and the parent carrier has both types of pods available. The pods can be assigned to the fighter using the normal ordnance loadout. The pods require a missile fire control to operate, although this can be minimal size (0.1 HS) as there are no range or resolution restrictions.

Pods can also be assigned to normal box launchers, so a fighter designed for space combat can also be used for ground combat in an emergency. However, box launchers are three times larger than the missiles (or pods) they are designed to fire, while fighter pod bays are equivalent in size to the pods, making fighter pod bays are a much more efficient way to mount the pods. Because of this efficiency, the minimal-size fire control and no requirement for active sensors in ground combat missions, dedicated ground support fighters can be much smaller than their space combat equivalents. It is also possible to have hybrid designs mounting both pods and box launchers. Due to the requirement for smaller engines for dedicated ground support aircraft, ship engines can now be designed from 0.1 HS in size.

[Steve Walmsley (OP)]

Ground Support Fighters

Fighters equipped with fighter pods can provide support to ground unit formations during ground combat.

To be eligible, a fleet with fighters is given an order to "Provide Ground Support" with a friendly population as the destination. This order functions in a similar way to a 'Follow' order, with the order remaining in place until removed by the player. On the Ground Combat Window, eligible fleets appear in their own section for each population. These fleets can be dragged and dropped on to formations in the same way as superior and subordinate formations. Fleets with this order that are at their target population cannot be targeted in normal naval combat or by STO weapons.

In combat, the ground support fighters attack at the same time as bombardment elements and have the same target selection options as heavy bombardment.

Ground support fighters have the same chance to hit as ground units, although they are not affected by any negative environmental modifiers (such as high gravity or extreme temperatures). Each fighter's to hit chance is affected by its own crew grade and morale.

Each Forward Fire Direction component in a formation allows support from up to six ground support fighters. If more fighters are assigned to a formation than can be supported, the chance to hit is modified by (Number of FFD * 6) / Number of Fighters.

[Steve Walmsley (OP)]

Ground-based AA Fire

AA units take part in ground combat normally, using their ground combat values. If an AA unit takes part in both ground-ground and ground-air combat, it will draw supply twice.

Once all direct combat, bombardment support and ground support fire has been resolved, but before damage is allocated, all AA units will be checked to see if they can fire on hostile aircraft, using the following rules:

1) All AA units in a formation that was directly attacked by aircraft will each select a random aircraft from those that attacked that formation.
2) Medium or Heavy AA units in a formation that was not directly attacked by aircraft but is the direct parent of a formation that was attacked will each select a random aircraft from those that are attacking the subordinate formations.
3) Heavy AA units that are not included in the two categories above will fire on a random hostile aircraft, including those on CAP that are not directly engaged in attacking ground units.

An Environment Modifier is calculated, taking into account gravity, pressure and temperature and whether the firing AA unit has capabilities in those environments. Each environment for which the element is not trained has a x2 modifier. There are no terrain modifiers.

The chance to hit is (10% x (Tracking Speed / Aircraft Speed) x (Morale / 100)) / Environment Modifier.

If a hit is scored, the damage vs the fighter is (Ground Damage Value  / 20)^2 rounded down. For example, an AA unit with a ground damage value of 40 would have AA Damage of (40 / 20) ^ 2 = 4.

All AA damage is applied after all attacks have been resolved.

[Steve Walmsley (OP)]

Ground Commander Bonuses

Ground force commanders have a much greater variety of bonuses in C# Aurora. The most straightforward are:

• Ground Combat Defence (GCD): When elements of a formation are fortified, their fortification level is increased by the formation commander defence bonus
• Ground Combat Offence (GCO): Increases the to-hit chance of all direct-fire weapons in the formation
• Ground Combat Artillery (GCA): Increases the to-hit chance of all indirect-fire weapons in the formation
• Ground Combat Anti-Aircraft (GCAA): Increases the to-hit chance of all anti-aircraft weapons in the formation
• Ground Combat Logistics (GCL): Represents the chance that a formation element will not draw supply during a combat round.
• Ground Combat Manoeuvre (GCM): Increases the chance that a formation will make a breakthrough in combat
• Ground Combat Occupation (OCC): Boosts the occupation strength of a formation
• Survey (SURV): Increases the output of geosurvey modules in ground units
• Production (PROD): Increases the output of construction modules in ground units
• Xenoarchaeology (XEN): Increases the chance of successfully recovering abandoned installations

In addition to the above, each ground commander has a 'Ground Combat Command' rating, which represents the size of the formation he can effectively command. This rating is given a relatively high score for promotional purposes so officers with high command ratings will tend to progress though the ranks.

If an officer is commanding a formation that is larger than his command rating, the effectiveness of his other bonuses will be reduced by (command rating / formation size). For example, an officer with a 20% defence bonus and a command rating of 5000 is commanding a regiment with a size of 7000. The defence bonus is reduced to 14.3%. In addition, if the largest HQ in a formation has a rating less than the formation size, the effectiveness of the formation commander's bonuses will be reduced by (HQ rating / formation size). These penalties (command rating and HQ rating) are cumulative. Note that if all HQ capacity in a formation is eliminated, no commander bonuses will apply.

Finally, ground forces officers have a Ground Combat Training bonus, which affects morale. Each construction phase, any formation element with less than 100 morale will regain that morale at a rate of 100 per year, plus the commander training bonus (so a 20% bonus would increase morale recovery to 120 per year). Formation elements can continue to improve morale above 100, using the following process:

• The training bonus percentage (after any reduction for command rating and HQ rating penalties) is converted into a morale bonus at 1% = 1 morale point (so 10% training bonus = 10 morale bonus).
• Maximum formation element morale is 100 plus 5x the morale bonus
• Formation element morale increases at a rate equal to the morale bonus per year multiplied by the 'Morale Gain Modifier'
• The 'Morale Gain Modifier' is calculated as 1 - ((Element Morale - 100) / (Maximum Morale - 100))

For example, a formation element has 140 morale and the commander of the parent formation has a Ground Combat Training bonus of 30%. However, he is commanding a formation that is slightly too large for his Ground Combat Command rating, so he has a Command Modifier of 0.8. The training bonus is 24% (30% x 0.8), which converts to a morale bonus of 24. The maximum morale for the formation is therefore (100 + (5 x 24)) = 220. The morale gain modifier is 1 - ((140-100) / (220 - 100)) = 0.667. Therefore, the formation will gain morale at 24 * 0.667 = 16 points per year.