Dogfighting houserules
These are narrative, abstractish, non map-intensive dogfight rules, because I don't anticipate ever owning a table or play area big enough to represent a big chunk of sky at a useful scale. These rules use a d20 modern base, so there is a piloting skill, vehicles have initiative modifiers, maneuver modifiers, hardness, hp, and so on.
2 Plane Dogfighting
Step 1, Encounter:
Start when two planes encounter each other; they are unengaged, but relatively near (within spotting distance of each other, which can be several miles on a clear day). If both planes want to engage, they do so automatically, proceed to step 2 with an initial position of 0. If neither do, they can both withdraw, and no combat occurs. Otherwise, they must make opposed pilot checks.
Note: any time a pilot check is called for, obviously all modifiers are included, such as appropriate feats and the maneuver stat of the plane.
Most planes of the era I'm looking at would qualify as Huge or Gargantuan, and so have a -2 or -4 size modifier, which is both the initiative and maneuver modifier for the vehicle. The maneuver statistic is sometimes modified for high-performance vehicles. In the d20 modern SRD, a Chevy Corvette, size H, has a -2 initiative modifier, but a +0 maneuver stat. I'll need to come up with a table of stats like this for era-appropriate aircraft, eventually. Balloons and zepplins would be collosal (65-128' keel, -8 size modifier), collosal 2 (129-256' long, -16 size mod), and even collosal 3 (257-512 feet long, -32 size mod) (to use the size terminology from FFG's Dragonstar). For purposes of air combat, they're basically set pieces, being relatively stationary compared to planes, and crewmen on them would act on their own initiative scores.
If the aggressor pilot wins the opposed Pilot check by 10 or more, the planes are engaged, go to step 2; the winner gets an initial position of +1. If the avoiding pilot wins by 10 or more, he escapes. Otherwise, the round is inconclusive, and step 1 is repeated.
Option: Surprise: If the DM decides one side has the drop on the other, such as by hiding in a cloud or the sun, or is otherwise unspotted, the surprising plane can choose to withdraw or engage freely. If he engages, then he automatically gets a surprise round to act in, and his Position begins at +1 for each round he observes the enemy before engaging, to a max of his Int bonus. Then continue the engagement normally.
Step 2, Engaged:
Roll initiative; don't forget the vehicle init modifier.
Option: when only a couple planes are involved, roll opposed Pilot checks for initiative, add any miscellaneous modifiers such as improved initiative to this check. The better pilot might deserve a better chance to go first.
Each pilot has a "Position" or "Advantage" score relative to his opponent; these are always the opposite of each other. This starts at 0, unless the planes became engaged by the aggressor winning a piloting check, in which case he has a +1 and his opponent has a -1.
Each round has two phases:
A) Maneuver Phase: At the beginnning of the round, each pilot makes a pilot check. This sets his Defense score for the round. Additionally, the pilot who wins this as an opposed check modifies the Position score 1 point his way; no change occurs on a tie. The maneuver phase takes the place of a pilot's move action for the round.
Option: Position doesn't modify unless you win by 5 or more. For every 5 you win the opposed roll by, get 1 point of Position. If Plane A has position -2 relative to Plane B, but wins the maneuver check by 15, he finishes maneuver with a +1 position.
B) Action Phase: This phase occurs in order of initiative. If more than 1 person is in a plane, like a rider in the observer seat, they act on the pilot's
initiative for simplicity.
Available actions:
Attack: Fire your guns at the enemy. Use the appropriate bonus (BAB + Dex + any feats, -4 for nonproficiency if applicable), but Range modifiers are ignored, subsumed into Position, which also modifies this attack roll. If you are at Position +5 on your enemy, you are right on his tail as he corkscrews through the air, lined up for a great shot. If you are at Position 0, you and your opponent don't enjoy any advantage relative to each other, and if you're at a negative position, you're in trouble. If you have 5 or more ranks in Pilot, you gain a +2 synergy bonus to your attack roll.
- A fixed, forward firing gun gains a +2 to-hit if you are in a positive Position, but cannot fire at all if you are in a negative Position. Guns on a rotating mount can fire from any Position.
- This is a single attack, so iterative attacks or the use of feats like Rapid Shot are not available, though a Burst would be if your gun works that way.
Fly Defensively: You, and everyone in your plane, take a -4 to your attack, and the plane gains a +2 to defense. If you have at least 5 ranks in tumble, the defense bonus is +3. This lasts until your next action. For simplicity, assume the pilot of a plane acts before anyone else on it.
Total Defense: Whip the plane through the air wildly, trying to evade attack. You cannot attack, but your plane gains a +4 to defense, +6 if you have at least 5 ranks in tumble. Anyone else trying to fire from your plane takes a -8 to their to-hit roll.
Maneuver for Advantage: Make a pilot check modified by your Position score, DC 20. If you succeed, you get a +2 to your next Maneuver check.
Aid Another: Make a pilot check modified by your Position score, DC 10, to line up the best shot. If you succeed, your second-seater can get a +2 bonus to his next attack.
Disengage: You can disengage from combat by winning an opposed pilot check, both pilots modified by their Position score, by 10 points or more; if so, return to Step 1 to see whether combat will resume. The pilot you are fleeing from can choose to lose this check automatically.
Actions available for a second-seater:
Attack: If a gun is available to you, as above, modified by any flying tricks the pilot did such as flying defensively. The second-seater gets a +2 synergy bonus to attack if he has at least 5 ranks in the pilot skill, just as the pilot does, representing an educated guess as to the probable path of both his own and the enemy aircraft.
Full Attack: The second-seater has his full round available, and so can make as many attacks as his BAB and feats allow.
Aid another: Using either Spot or Pilot, roll vs DC 10. If you succeed, add +2 to the pilot's next attack or maneuver roll.
Combat runs until one plane goes down, one escapes, or both decide to withdraw.