[ODE] OT: Tumbling

[Russ Smith]

> When there's no net torque on an object, its angular momentum is 
> conserved.

true.

> The axis it rotates about is constant.  But is it constant 
> in body coordinates, or world coordinates?

the axis of rotation is not constant, except if the inertia tensor is
dynamically symmetric (i.e. some constant times the identity matrix).
the expression you are looking for is:

	I * dw/dt = - w x (I*w)

where w is the body-relative angular velocity and I is the 3x3 intertia
matrix. if I=identity*k then the cross product reduces to zero and w
doesn't change.

i'm just writing the above from memory so if anyone knows better feel
free to correct me!

russ.

-- 
Russell Smith
http://www.q12.org