I was thinking about special arrows. Either mundane (explosive, armor piercing) or magical.

Arrows would require some mechanics changes, while adding cbows is simply adding new models and according xml. Altho having ammo is good idea, with different costs and amounts. So you could have more 'generic' ammo or less amount but more deadly ammo for example.

Arrow should be more powerful at short distance as in they are in the real world. Their damage should be relative to the kind of armor worn by the enemy, but at close range they should still be lethal.

But if all these rules are introduced the UI should clearly state the chances to hit and the possible damage when a cursor is on a target.

The current system only models penetration. Not range, not chance to hit, not moving targets nor moving shooters.

Crossbows could get around that with doing comparably massive damage but firing only every other turn - or less. (on a system like this)
Cbows are good for penetration. Their bolts are thicker, less likely to shatter when hitting armor. (arrows are too thin for that kind of energy transfer)
Their bows are not limited to the (roughly) 150 lbf that a trained shooter can pull.
Cbows don't magically multiply the penetration power but their whole design is far better suited for penetrating armor.
And what's at least as important when running an army:  it's a lot easier to train a crossbowman than an archer. Point and shoot.
(Yes, I like to ramble but you should know that by now)

Personally, I think that the ranged combat tech tree should consist of more than one entire tech.
That's so much wasted potential...
There isn't that much to research about bows. You already listed the 3 likely basic items.  Strings would have some effect but it's usually more about which is more resistant to weather conditions. Not interesting enough on a strategic scale..
Crossbows are an entirely different ballgame. These have constantly been in development but that mostly translated into bigger and stronger bows / pulls. There have been weird ones, though, like pistol crossbows or the cho ku no... a crossbow with a magazine... cbows that would fire bullets or stones - effectively medieval shotguns for bird hunting.
The crossbow tech tree could be very deep. Early cb weren't that much better than bows but late medieval arbalests with steel bows could have several thousand lbf and were on par with modern rifles. Compare that to the 100-150 lbf of a war bow...
The strong cbows weren't entirely safe, either. A snapped string would be the equivalent of a buzzsaw and the soldier (or the man beside him) was uncomfortably close to it when loading / firing.

I like the idea of having multiple arrows but how should that work? Would a unit be able to choose the "proper" arrow for the target?
Select it like a buff?
Creating a ranged units with multiple arrow types would be more expensive but have benefits.
Also, bows could shoot fire arrows, something that doesn't really work well with crossbows.
There shouldn't be a "does everything best" weapon. Choices, choices! =P

Darvin3, I have to agree with you totally.  The stat scaling in Elemental is off by an order of magnitude.  The early stuff game is too variable and the late game system is as well.  Too many one shots or no possible chance scenarios.  But that's for another thread, really.

Robert:  I did some reading on bows and crossbows before posting.  Indeed, most late crossbows were capable of penetrating heavy armor, but were dangerous to use.  Crossbow technology basically ended when gunpowder reached Europe.  Additionally, armor became fare less common when modern ranged weapons would penetrate.  Interestingly, it would be the French in World War I that would bring armor back into the fight (helmets, in this case).  Only recent materials science has made the tradeoff in mobility worth the protection offered by armor.

That said, enchanted bows should affect to-hit rolls, and enchanted arrows should affect damage.  Plus, there should probably be the ability to ignore armor's damage reduction.  But I have an extensive wish list for that, too.

I would start by adding additional types of bows to the tech research tree as suggest by Ishantil;

1. Short Bow (fires 2x turn)
2. Long Bow (fires 2x turn)
3. Recurve Bow (fires 2x turn) (NEW)
4. Light Crossbow (fires 1x turn) (NEW)
5. Heavy Crossbow (fires 1x turn) (NEW)

This would be easy to implement, lengthen the weapons tech tree and make archery effective in the late game against heavily armored units.

I would also add a new building: Archery Training Grounds. Only with this building could the user recruit Expert and Elite archery units.

I like the idea of adding bows and cbows. The archery tree really needs a workout, to say the least. Right now you can get more damage from equipment add-ons than from the weapon itself (Longbow 5 atk, equip 8 atk iirc)

I also like the idea of arrow types. The easiest way to simulate them would be packs (like the vengeance coating). Archers, in a battle field scenario, would only carry a single type of ammo, maybe 2(limited specialty and standard). You wouldn't want 6 types of ammo in your pack, each with different flight, range, damage characteristics, sucks if you grab the wrong one in the chaos of battle. So equipping arrow pack before battle makes more sense than adding a special ability.

As a side note, flaming arrows look cool and set things on fire, but the combustible packing prevents any meaningful penetration. Maybe city attack bonuses, but until elemental damage/weaknesses or Tactical traps are implemented, their use should be limited 

crossbows are almost always inferior to longbows in the hands of a trained user. if you want both then the former cannot be an upgrade to the latter.

It always depends on which era you're talking about.  It seems some people here are talking about classical crossbows, while others are talking about late medieval crossbows.  Big difference; a classical crossbow probably wouldn't even go through chain mail, whereas the late-period stuff were basically hand-held ballistas.  So it really depends on what technology level we're looking at.

Since currently ranged weapons have only advantages over melee weapons and no disadvantages, I think it is important that ranged weapons will always be weaker in attack rating compared to melee weapons in the same number of techs.

Possible ideas for disadvantages can be:

- Limited ammo

- Attacks that take more move points compared to melee

- Limited range and lower attack on close range

- Cannot move and attack the same turn

While true, it's kind of moot because with 2.0001 CS you already get 2 attacks per round...

Add to this:

6. Repeating Crossbows (fires 2x turn, heavy and light) (NEW) (only the light repeating crossbow can be used while mounted).

Longbows should only be usable by Expert or Elite trained units as it requires years of training to use a longbow effectively, whereas a crossbow can be used after a week of training.