the two most compelling configurations are electric helicopter and eight fan tilt-wing. the estimated electricity cost is $0.12 per kw-hr. for both configurations the hover performance estimates were based on blade element momentum theory. for now the electric helicopter configuration is shown to be more compelling at low ranges, while the tilt-wing configuration is more compelling at longer ranges. the designer has not finalized the vahana project and hope that "the electric tilt-wing configuration provides a doc advantage and many other advantages such as reduced noise and enhanced safety for urban mobility".