Re: What is a "conventional engine"?

In <URL:news:local.spelljam> on Wed 09 Mar, Danton May wrote:
> Whether a flitter moved its wings or not would not
> really make a difference.  That only has meaning when
> you are flying through an atmosphere, with air to push
> against your wings.  If a flitter leaves the
> atmosphere, true it brings an air buble away with it,
> but moving its wings would not make a difference
> because pushing against the air is not the issue.  The
> air bubble it brought with it would not be big enough
> to have enough air to push against.  A bird flys
> because it is "swimming" through an ocean of air.
> Imagine there is a column of air inderneath the bird's
> wings, with the earth all the way at the bottom of it.
>  The land on the other side of the column of air holds
> the other side of the air colum steady and pushes it
> back.  But with no land, ocean bottom, or other stable
> platform a the edge of a free floating bubble of air
> there is nothing to push on "the other side" of the
> air the flitter's wings would push on if they moved,
> the air at the edge of the bubble would just move away
> as the flitter's wings moved, giving them no
> resistance or motive force.  The edge of the bubble
> would just distort and ripple, and the flitter would
> go nowhere.
[snip]

I though the idea of wings was they provided lift, by being
shaped so that there is a lower pressure above them, than below.
This would work even in an air bubble, and if some magical force
dragged the air along with you...

Or, if not shaped this way, wings at least provide more surface
for air resistance to work against, to slow down your falling.

Isn't that why small things can get away with falling long
distances and not get hurt? They have a big surface area for air
resistance to work against compared with how much they weigh?

But, I've never been sure how SJ physics affects things like what
wings do for you, in terms of lift and gliding. Hence my original
comment, that implied wings worked by sympathetic magic: birds
and insects have wings, they fly, so if we want something that
will fly, we make it with wings. "It flies because it looks as
though it ought to."

It should be easier to make things with wings fly, because they
look as though they ought to, rather than things like carpets,
brooms and cauldrens, which don't seem to have any excuse to stay
up in the air. Or, maybe even worse, magic-users with just a Fly
spell on them, and not even a object mythologically associated
with flying to hold them up!

Presumably, this makes it easier to enchant a giant statue of a
bird to fly, rather than, say, your house?

So, your spelljamming ship moves through the air because a ship
looks as though it should move when the wind blows, and the idea
of one that uses the wind so well it can be blown though the air
doesn't seem that far fetched?

I suppose this means the dwarves have to work even harder, to
make their rocks fly...

--
Dreamer
dreamer@??????.?????.??.uk
http://www.romsys.demon.co.uk/