Q:

Dyson Air Blade as a propulsion system?

I've read from many sources that Dyson Air Multipliers are more efficient and quieter than normal fans. Now, with the proof of concept, is it possible to use its principles as a propulsion system for, say, a quieter helicopter? 

A:

Unlike John Rennie, I think that the problem is not in the efficiency of this system but in the fact, that it will not generate considerable lift. So even if marketing materials are completely true and Dyson Air Multiplier is more energy efficient than conventional fans this efficiency only applies to moving air (which is its intended use) but not to the lifting force.
The principle behind Air Multiplyer (see this video) is creating the flow around the surface of the duct which induces considerably greater flow through the duct. However the resulting flow would be nearly potential and the net force on the duct would be quite small.
Somewhat similar effect does occur in helicopters: Vortex ring state, where under certain conditions  increasing the air flow through the rotor does not produce additional lift. In helicopters this is harmful and could even cause the crash, but the Air Multiplier effectively creates similar 'vortex' around the duct for the purpose of moving air.

