NASA’s Dragonfly mission uses Quadcopter technology but they are not variable blade. If each blade has an independent motor as well as ability to tilt blade angle independently this would enhance mission capabilities. Most quadcopters that are variable blade alter all 4 blades simultaneously and in an identical manner. So far there are no commercial drones that have variable blade function for each motor and blade pair. This is a mistake because it’s omitting efficiencies that can be gain at various altitude and atmospheric pressures/densities for all kinds of aerodynamic flight maneuvers.