ok, some cold logic (though idk about peculiarities of RFC):
The formula for the revenue of a trade mission conducted by your GM in a target city is:
Profit = (500 + 200 * CapitalTradeProfit) * GameSpeedMultiplier
500 =
iBaseTrade, 200 =
iTradeMultiplier for the GM (from CIV4UnitInfos.xml)
GameSpeedMultiplier = the usual 0.67 | 1.0 | 1.5 | 3.0 for Quick | Normal | Epic | Marathon (
iUnitTradePercent/100 from CIV4GameSpeedInfo.xml)
CapitalTradeProfit is the income the target city would get for a
hypothetical trade route to
your capital. It is irrelevant if the owner of the target city has met all necessary requirements to enable a real trade route -->
Mercantilism has no effect (see example below). All modifiers are factored in (Harbor, ToA, TargetCitySize, ConnectionToCapital, Overseas, Foreign, PeaceTime). Thus the ToA-city is often optimal, but not if it is an inland city close to your capital on the same landmass. Since the Base Profit of a trade route is
Max(1, Min(SizeOfOtherCity, PlotDistance)/10
) you should always attempt to have a big capital (wait for growth before starting missions).
Example:
My GM is in Cuzco, Huyana Capac is currently in Mercantilism plus he doesn't have Astro yet (necessary for intercontinental trade to my capital), thus he doesn't have / cannot establish a real trade route. Still the GM's trade mission will yield the nice sum of 4950
(epic speed)!
After giving him Astro and forcing him into Free Market, Bibricate (my capital) shows up as the top trade route in Cuzco's city screen.
Hovering the mouse over the 14
reveals:
- Bibricate is size 22 and far away enough --> Base profit = 22/10 = 2.2
- Harbor +50%, ToA +100%, Overseas +100% all clear
- Population +30% --> Modifier for TargetCitySize = +5% for each population point above size 10, Cuzco is at size 16 --> 6*5 = +30%
- ConnectionToCapital +25% --> Cuzco is connected to Huayna's capital Cuzco
- Foreign +100% --> Cuzco has a Customs House
- PeaceTime +150% --> +3% for each turn at peace (max 50 turns)
Total Modifiers +555% --> Trade route yield = floor(2.2*6.55) = 14
Profit = (500 + 200 * 14) * 1.5 = 4950
I'm not sure about RFC, but your comment that France just spawned lets me assume, that you could not accumulate any percentages for the PeaceTime modifier yet, so you only benefit from the Overseas +100% while your capital is still <= size 10. (Or did you move your palace to the main land?) Inland Paris would only get 2
for a hypothetical trade route to Kyoto --> Profit = (500 + 200 * 2) * 1.0 = 900
.
