PROPULSION FAN

hey guys,
I think Colin did the research about the propulsion fans we can get out in the market I did something different. I basically researched on which type of fan should be used as a propulsion fan.
The propulsion fan should be axial. The benefits of an axial fan are that it provides more thrust and high volumetric flow rate . The levitation fan should be centrifugal because this would generate more pressure and lift the hovercraft.
There are also benefits if the propulsion fan is ducted. A ducted fan provides more thrust and has a smaller diameter than a free propeller. If the diameter is big this would help to catch more incoming fluid and distribute its power and thrust on a larger fluid volume.
Having shorter blades can help to operate the hovercraft at higher speeds.
The disadvantage of a ducted fan is that it is heavy.
A shrouded fan is a good fan because it has a very short ring around the prop to control tip losses.
Here are some websites
http://4wings.com.phtemp.com/tip/tpdduct.html

http://4wings.com.phtemp.com/tip/tpdduct.html

http://4wings.com.phtemp.com/index.html