Hovercraft

Step 3 The Thrust Engine

The thrust engine was a little bit harder than the lift. It has a larger fan, a pulley reduction and a large fan duct. I started off with the fan. It was hand made with a welder and some steel. This is not a good idea, the fan has to be perfectly balanced and the pitch of the blades has to match the power of the engine. I you are going to build a hovercraft do not build you own fan. I was lucky that my fan did not fly apart and kill me. Do not do what I did here and get a good fan to use.

So once you have a fan you need to build a duct. I used more lauan plywood to cut out the shape and screwed in a bunch of 1x2s to hold the two pieces together. Then I wrapped more aluminum flashing around the whole thing to make the duct.

The fan was mounted to a 1/2in shaft that ran through two brass bushings with a pulley on the other side. This was all mounted on a 2x4 and plywood frame. Then a smaller frame was made to hold the engine up so that the belt would fit. No type of clutch was used on the engine which is typical for most hovercraft. This finished the thrust engine and fan.

Comments

[charles61]

Propeller has flat blades : much noise , bad aerodynamic and poor thrust.
You have to wharp the blades so that they have the same diametral pitch (at any distance of the center) . Furthermore, it shoud be good too to give the blades some curve (put a look on an airplane wing ) and to sharpen sligtly their trailig edge ...and make the leading egde 'round' . As a result you will obtain MUCH better performances : much thrust for less power !

[ravingking2008]

a safety gaurd would be a really good idea . safety first n all that. nice project

[bayaan19]

what did you use to make sure your carborator is facig upward?

[yrmoma]

I wonder if you could make this fan Collective Pitch, that way you could have a way to better control the speed as well as have reverse... Anyone ever try this or have an idea how feasible it would be?

[Nfiltr8]

In order to have a duct that affects the air flow significantly, the margin between the fan and duct has to be under .25". You would have been better off putting the aluminum flashing on the inside of the duct's frame.