hovercraft

[machinist@large]

anyone see why I cant use this as a lift fan for a hovercraft? http://www.ebay.com/itm/161189080424

Biggest question that has me in doubt is the lack of a CFM rating at a given RPM; the fact that it looks like a standard replacement ventilation fan disk has me leaning to the "Not Worth It" side of the equation. IIRC most hover craft and air boat generally use aviation style propellers, which are designed for max air volume first, noise control second. Ventilation fans are (usually) the opposite; decent air flow, but low noise is a bigger concern.

Not saying you couldn't use it, I just don't think it would be the ideal part for the application......

Pat

 

[qtband]

I'm far from an expert, but that fan blade looks like an A/C condenser fan which turns at 1725rpm's. I wouldn't like to see what happens at 3600+ rpm's. If I were building one, I think this is one part I'd purchase. They're about $125.

 

[exenos]

How about a clutch fan from a truck? They're meant for continuous use at well over 3600 rpm and are designed to create pressure so it would be ideal for your purpose.

 

[fowler]

A fan from a truck

They are usually on a viscous hub that'll only lockup in the mid rev range

So they arnt doing full egmine rpm

Or they're the flexi blade type where the blades flatten out at full rpm
So they can handle the speed but not the force

Or the old solid type
Or which were bolted to engines where 4k was redline anyway

I'd be looking for an aviation type one

Props on places have an expiry date I think
Maybe look for an old one

 

[exenos]

A fan from a truck

They are usually on a viscous hub that'll only lockup in the mid rev range
So they arnt doing full egmine rpm

You sure about that? As far as I know viscous clutch fans will lock up whenever required. They are controlled by temperature more than rpm.

 

[fowler]

It depends

The ones in the big cats are electronic comtrolled based on temp

But pickups and cars are just centrifugal
They are part locked at idle to give good cooling when stationary but allow a smooth idle
Full lock once the revs get up a bit and the engine has a bit more power

Then unlock at full noise because by that point u should be going fast and the fan is just a waist of fuel

 

[exenos]

I'll have to take a look at my truck tomorrow. I would have sworn that I saw wires going to the clutch fan.

 

[fowler]

It's not a thermo fan mounted on the engine is it

Or is it a sensor

If it where computer controlled clutch fan
Then it would have lines running to it and an electronic controlled valve on the engine

The more lockup it wants the more engine oil it pumps in

 

[billyvray]

Howdy folks, first post.

The Sevtec hovercraft Scout model can use an engine this size, and you can buy plans.
https://www.youtube.com/watch?v=XLRKeNWyUGo

another is Universal Hovercraft. I like this prototype of

a WIG craft:
https://www.youtube.com/watch?v=1SoyFWgZGB0

Enjoy!

Bill