--- an email I wrote to Jan and the list ----------------------------

Hi Jan,

as I wrote last week, I'm currently reworking a big part of the code.
It is about LaRCSim mainly, but involves separating the physics of the plane
(one class) from its visual and audible representation (another class).

I first made some mistakes when I wanted to do this, so it takes longer than
neccessary. Hopefully I can check something in the next days (I think so).
It is not finished by then, but should work and the structure should be
quite stable by then.

About coordinates systems: LaRCSim uses geocentric and geodetic coordinate
system, plus 'runway' coordinates and other things. Lots of stuff which we
don't need. Regarding our short-range simulation the non-flat character of
the real world is not important at all.

So I want to use only two coordinate systems:
 1. local (inertial, earth, world, whatever you call it)
 2. body (aligned to stability axes of the plane)
And both of them are set up like one can find it in lots of textbooks:

local:
  x -> north positive
  y -> east  positive
  z -> down  positive (so we'll have negative values)

body:
  x -> nose
  y -> right wing
  z -> down

Euler angles phi, theta, psi as usual, too.

No more latitude, longitude, earth radius, geocentric and geodetic, ...

So x and y of this local frame are aligned to your axes. Can you agree to
use z like described above (negative values up)?

Best regards,
Jens


--- current state (east-south-down) ---------------------------------

(as visible at davis)
  east:  x positive
  south: y positve
So, the system in use is: east-south-down

--- how it should be (north-east-down) ------------------------------

Davis: see davis.jpg
Cape Cod: seems to be 'Wellfleet - Great Island National Seashore Area',
where the cliff faces to the west.

north: x positive
east:  y positive

Wind:
  Direction of air molecule travel: where do they come from?
    0/360: from north
    90   : from east
    180  : from south
    ...
    
