Fan shroud dimensional drawings??

[haybayian]

Hello boat designer friends,
I am now about to design and build a power train for my 4 m hydrofoil. I have bought a 8 blade 45 "fan which will be hooked up to my 92 hp engine via a flat belt. What I need is a set of dimensional drawings to guide me in the making of the shroud. Basically I know little to nothing about fan/shroud aerodynamic requirements and I would rather copy, adapt an existing shroud rather than to design my own. Your guidance will be welcome.

Thanks.

Haybayian

[daiquiri]

Is there some particular reason which made you choose the air prop?
Guess that, since it is a hydrofoil, it is not a matter of draft...

[kach22i]

Some of the airboat and hovercraft sites have information posted on designing and building them, do a Google search and find a method which appeals to your skill set.

I find starting with an "image" search to start really helps to find drawings and photos.

[Guest625101138]

There is some useful test information and design data on this blog:
http://www.mickaircraft.com/fan.htm#fan1

If you work though it you might find something useful.

You can also use JavaProp to determine the velocity ratio at your design conditions and then design the ducting area to suit. For the low pressure differential you will experience it is reasonable to assume that the air is incomprossible. Hence the area ratio is the inverse of the velocity ratio.

There are other threads on how to use JavaProp.

Rick W.

[kach22i]

Originally Posted by Rick Willoughby

There is some useful test information and design data on this blog:
http://www.mickaircraft.com/fan.htm#fan1

Nice find, thanks.

[haybayian]

Thanks Rick for posting this remarkable site. I read it with a great deal of interest.

Haybayian

[haybayian]

Originally Posted by daiquiri

Is there some particular reason which made you choose the air prop?
Guess that, since it is a hydrofoil, it is not a matter of draft...

Yes, several reasons.
I want this craft to be "beachable". With retractable foils I will be able to move it in 4 " of water.
The other reason is simplicity. My fan will be driven directly from the engine's flywheel end, via a 3 to one pulley arrangement. This is the most effective indirect drive I am aware of. By contrast, a water prop would require a lot more engineering, would be difficult to retract and altogether would be more difficult to build in a hobby situation (mine).

Haybayian

[kach22i]

Haybayian, just admit that you just love foils and hovercraft skirts give you a rash.

Just about any outboard motor will flip up in shallow water, and some are designed for it.

http://www.nauticmotors.com/T2.html

[haybayian]

Originally Posted by kach22i

Haybayian, just admit that you just love foils and hovercraft skirts give you a rash.

Just about any outboard motor will flip up in shallow water, and some are designed for it.

http://www.nauticmotors.com/T2.html

I did not want an outboard: Cost of purchase, need to lengthen the drive shaft and once tilted up an outboard leaves you pretty well without propulsion. I have a pretty good 1.5 L DOHC automobile Mazda engine capable of 92 hp @ 6000 rpm strapped to and 8 blade prop I think that I will get all the thrust I need for less trouble than I would with a water prop arrangement.
These are my reasons
Haybayian

[kach22i]

Sounds cool, you may wish to look at the Sea Phantom, they went from outboard to inboard. Outboard was just quicker to get it off the ground for testing.

http://www.seaphantom.com/