Basically the upshot is this. If you are designing a new spell to do something like say... FLY... what determines how fast you can move?
If I were to whip out and pick up a ship with Rego Herbam. How fast can I move while riding the vessel?
Where are the guildelines and rules for determining things like that?
A recent game had a member of our group using Rego Aurum picking up a massive tree that we had sheared into a mast for our ship(we'd lost it recently), and the guy running the game was left with a quandry. Just how fast was this flying caber going to be going exactly? HOw far off the ground, etc...
I realize the old caveat is "if it's not there, make it up yourself." I am an old hand at that, but still. If there is info to work from. I'd like to see it.
I think that you'd want to rely on real world inforamtion (such as regardng ships and windspeeds) balanced against how much benefit the character gets for their spell levels. In my opinion a character who develops a rego auram spell to create winds to transport him to his destination should be moving faster than a character who casts a muto corpus (animal) spell of the same level that transforms him into a flying, fire breathing dragon because the dragon metamorphasis character gets several additional benefits from hs spell beyond mere flight.
I don't know if the frame of ReCo can be used? - which somewhat implies the speed by which you can move the controlled being. The CrAu spell of Wing of the Soaring Wind have been implied to be the only "true" form of flight - which so far have made me think of it, or similar spells, to be the fastest forms of flight.
I know that it's been discussed elsewhere to add some more base levels to the spell guidelines - and I think that this question might be a good candidate too.