Inlet passage shapes (water and air)

I think air takes better to changing direction (as in intakes) than water due to it's specific weight. If I remember right, the cooling air intake on a Porsche is like that of my Corvair engine. It's actually a centrifical pump (fan).

 

Yea, I'm just waiting for someone else to scale it up from 3" to the 36" I want.

 

Yea, true.........but does water increase in velocity and decrease in pressure when it's constricted in a venturi tube like air?

 

Well there ya go...build it!

 

You mean like the fans in a hovercraft?

 

Yes, right now everyone seems to make their own from scratch.

Smitty Hairplane took a mock up of a ducted fan to Oshosk about five years ago for the Kit=Plane market. A few others like some blimp makers keep their products to themselves.

If I could find a duct and fan which could be driven with a common automotive engine and could be hooked up to via belt or gear drive, all I would have to figure out is the inlet design.

I don't want a hovercraft that looks like an airboat or airplane, I think something safer for ground application can be developed.

 

Fans like these?
http://www.hoverhawk.com/

 

The housing is normally tapered into a nozzle to increase the speed of the water, which also creates a Venturi effect in which low pressure behind the impeller pulls more water towards the blades, tending to increase the speed.

According to Wikipedia...

 

The water presure exiting the nozzle is astranomical..at idle, you could not hold a hand or foot behind the nozzle on my jet boat..

 

You can buy fans, you can make ducts...........but it's not going to be Pratt & Whitney quality/tolerances.

I'm looking/have been looking for a fan/duct combination. I find it hard to believe lawyers and the FAA have kept them from coming to market. I think the market for use on airboats and hovercraft is limited.

Something like they make for HVAC systems for buildings, only light weight and optimized for thrust.

Model:



Building:

 

Oh...your talkin rocket science. In that case, just get the real thing.
I saw some GPU turbines for sale awhile ago fairly inexpensive.

 

...and here ya go...
http://cgi.ebay.com/NEW-GARRETT-GTP...ryZ26261QQssPageNameZWDVWQQrdZ1QQcmdZViewItem

 

more power???...no problem...
http://cgi.ebay.com/ebaymotors/Jet-...015QQitemZ250152151553QQrdZ1QQsspagenameZWDVW

 

I could not afford to feed it all the kerosene it would demand. Nice find though, thanks.

Back about 13 years ago there was a short article in KIT PLANES magazine about a young guy in Florida (mid-30's) who was bringing a 4-stoke driven turbofan like thruster to the market. He actually had one built. He used to work for one of the big jet engine companies and said about 80% of the turbojets's thrust is from the fan not the hot expanding gases. I found the article a few years ago and tried looking his name up with no results. I kind of figured he had to go underground to hide from creditors or something.