Any rules for Air/Weather spells on flyers?

[SolemnGolem]

The Magic book has decent spells for the Air and Weather colleges, with details of how they affect people on the ground (a fair enough assumption, given that most PCs typically are landbound).

But are there any rules about how these whirlwinds, air vortices, storms, wind walls etc. affect flying creatures?

[mlangsdorf]

Most realistic flyers have Cannot Hover. A lot of air/storm spells cause knockback or loss of footing. If your prone move while flying is less than 1/4th your maximum flight speed and you have Cannot Hover, you fall (B398).

Large scale weather spells like Wind or Storm explicitly have GM defined effects. I'd generally rule that a flyer with Cannot Hover can't fly with the wind coming from behind him if the windspeed is more than 3/4s his maximum move, and can always fly with the wind coming from in front of him if the windspeed is more than 1/4th his maximum move. But those are judgment calls and I don't think the GURPS has a robust set of rules for flyers.

Flyers without Cannot Hover are mostly immune to the effects of weather.

[Anthony]

Originally Posted by mlangsdorf

Large scale weather spells like Wind or Storm explicitly have GM defined effects. I'd generally rule that a flyer with Cannot Hover can't fly with the wind coming from behind him if the windspeed is more than 3/4s his maximum move, and can always fly with the wind coming from in front of him if the windspeed is more than 1/4th his maximum move.

Realistically, performance for aerodynamic flight is relative to the air. You can implement this by moving a flyer downwind by the wind speed (mph/2 hexes) in addition to regular motion; for spells with no wind speed (whirlwind/etc) just automatically move them to the edge of the area. This forced motion has no effect on stall, max speed, etc, so a flier with stall 3 and move 10, in a 10 mph wind, can fly 15 hexes downwind or 5 hexes upwind, and will stall if velocity is 3-7 hexes downwind.

It looks like the Flight advantage is by default aerodynamic, unless bought as Space Flight (balloons have no stall, but would still work as above).

[Humabout]

A quick and dirty way of handling penalties would be to treat dirty air as difficult terrain for flyers. I would also do as Anthony suggests and have sustained winds act just like currents on boats - your move is relative to the current, but your move relative to the ground is the sum of both your move and the air's move. This largely doesn't affect aerial battles, but it does matter when you have flyers and walkers attacking each other.

[SolemnGolem]

Thanks for the feedback! I have a powerful arcane lich who is squaring off against an Angelic Emissary (from DF 11 Summoners) and I'm trying to find ways of counteracting the high Flying movement rate of the angel.

The Air college has spells that apparently create very dramatic winds and tornadoes, but obviously they're written with grounded adversaries in mind. So I was wondering how a fast moving flyer would be affected by buffeting winds from a maelstrom.

[mlangsdorf]

Originally Posted by SolemnGolem

The Air college has spells that apparently create very dramatic winds and tornadoes, but obviously they're written with grounded adversaries in mind. So I was wondering how a fast moving flyer would be affected by buffeting winds from a maelstrom.

Poorly? I'm assuming you mean hurricane force winds.

If I were the GM, I would do this:
at the start of every turn that the angel is in the storm, the heavy winds move the angel in a random direction.
roll 1d6: 1 is the direction the angel is facing, 2 is one hex facing clockwise, 3 is two hex facing clockwise, and so forth.
roll 1d6: on a 1-2, the winds don't effect his altitude. on a 3, his altitude drops in additional to the horizontal movement. on a 4, his altitude drops instead of his horizontal movement. on a 5, his altitude increases in additional to the horizontal movement. on a 6, his altitude increases instead of his horizontal movement.
roll 1d6 and multiply it by another 1d6: that's how far the angel moves. If the total movement is more than 10 yards, the angel needs to make a Body Sense roll at +3 or be stunned. If the total movement is 25 yards or more, the angel does not get a bonus on the Body Sense roll. Add this movement to the angel's speed for any collisions that occur during the angel's turn, including falling into the ground.

Depending on the angel's Flight power, he might fall when he's stunned. If so, there's a reasonable chance that when flying too close to the ground - within 50 yards or so - he gets buffeted by a strong downwind, gets disoriented, and plows into the ground at 70+ mph which will probably hurt.