747
Unfortunately, you'll have to install a wing, too. That might take up a few excess parking spaces ....
Eagles
It's not just a question of reducing drag caused by the vortices; the energy in the vortices represents excess work done, and so drag. A device which simply destroyed the vortex would arguably reduced the energy in the vortex and hence the drag "caused by the vortex". The nifty trick is to redirect some of that wasted energy in the vortex back into providing something useful. If you were to instrument a winglet appropriately you would really find there was a propulsive force acting. It's not just an elimination of drag force.