How does this coanda effect thruster work?
1) The centrifugal pump on top accelerates air away from the center, sideways. This causes a lowered air pressure area in the intake, but that's not creating much thrust, because the pressure of the ambient air filles this void easily.
2) The "Coanda effect".
The accelerated air shoots away from the center, in all directions. Would there be no disc under, the jet of air would just go straight and mix with the ambient air. A jet of air in air mixes its velocity with the ambient air. In this case the ambient air is accelerated away from the center by the jet, and the jet is accelerated towards the center by the ambient air. This may sound strange, but there is no such thing as de-acceleration, nor is there "fast air", because speed is relative and not a property of mass.
But there is a disc under the jet. The disc's surface is an obstruction for the ambient air that wants to fill the void, left behind by the air the has mixed with the jet, air that is accelerated away from the center. At first the air between the jet and and the surface is lowered. Next the jet and the disc's surface are being pushed together by the pressure of the ambient air (about 1.033 kg/cm2 at sea level). Because the jet and the surface come closer together, the pressure of the air in between is reduced even more, causing the two to get closer, reducing the pressure more, reducing the distance, reducing the pressure, reducing the pressure, until there is no more space in between, and the jet "sticks" to the surface.
So; because the air pressure on top is reduced by the "sucktion" of the jet, the pressure of the ambient air is pushing more on the bottom than on top of the disc. This difference in force, is the thrust of the coanda effect.
Note: I don't think a jet of air will stick to a surface in the vacuum of space. Or can air molecules pull as well as push?
3) Secondary air, and Newton.
The jet on top of the disc is also in contact with the ambient air there. This air is accelerated by the jet, causing the jet to lose power, and gain weight. From a Newtonian point of view, the air mass is first accelerated sideways in all directions by the centrifugal pump, then accelerated downwards by the Coanda effect. The result is mass being accelerated downwards and thrust in the opposite direction.
There is this rule that it's more efficient to accelerate a big mass a bit than a small mass a lot. That's why rockets are not efficient for lifting crafts, and wide slim wings are. So why not just throw a big airmass down, and forget about the coanda effect? Good question.
Sometimes people choose a rocket for thrust, sometimes a large rotor. Every situation has its best solutions. Sometimes the best solution might be the Coanda effect, like in the case of a disc shaped VTOL craft. Some think the Coanda effect can have a very high VTOL efficiency at zero airspeed. I haven't seen solid proof of that yet.
