Proposed Turtle airships -- solar-powered VTOL with jet engine supplement

Lifted by helium and flying on sunlight. Backed up with Ethanol/Bio-diesel JET engines; 200 mph; able to fly as fast as small airplanes. Able to fly indefinitely, anywhere in the world, without stopping or refueling. Able to hover like a helicopter, and to land straight up or down onto any surface... grass, an airport runway... or on water. Land on lakes, on wide rivers, in harbors... land in the middle of the ocean.
Carry 400 passengers. Carry 300 tonnes of cargo.