All current LD plans are efficient : "Voyager" of course, but also U. Kitzberger design like the "Lorenz" series and his model "Tibor" (maybe the easiest of all his designs) On his website www.lightboom.net
you will find interesting designs too (with narrow trailing arm and wider leading arm, which produces a nice flight in my opinion).
All variations of these shapes do work more or less good/ The most important is maybe not the shape but the airfoils and tuning.
- not too sharp leading edge (ovoid shape)
- not too sharp trailing edge (a bit sharper than l.e, thought)
- Don't work too much under the leading edge. Too much undercut produces too much lift, and then a shitty flightpath that you have to correct with shitty diheadrals and tunings...
For good beginning you airfoils must be smooth but simple, not too sharp, with slightly (I mean slightly!) negative incidence (which you achieve with few leading edge undercut as I said before).
If your booms lays down too early and comes back to the right, then add a slight (1-2mm max.) degative dihedral on the leading arm and that's it : you a have a reasonnably competitive and esay LD boom.