loss in air core inductors

["Tesla list" <tesla-at-pupman-dot-com>]

Original poster: "Jim Lux by way of Terry Fritz <twftesla-at-qwest-dot-net>" <jimlux-at-earthlink-dot-net>

I'm looking for some decent approximation equations for losses in air core 
RF inductors.  Single layer solenoids and flat spirals, with skin effect 
(Rac vs Rdc) and turn proximity effects taken into account. Wire diameters 
are on the order of the skin depth (or smaller), so the first approximation 
using the infinite flat sheet equation isn't quite enough, but it doesn't 
need much more sophistication. Something of the complexity/simplicity of 
the Wheeler equations is what I'm looking for.

It has to be an analytical expression (no table lookups with "factors").

Thanks in advance..