Fan shroud dimensional drawings??

Discussion in 'Boat Design' started by haybayian, Dec 9, 2008.

  1. haybayian
    Joined: Oct 2008
    Posts: 24
    Likes: 0, Points: 0, Legacy Rep: 10
    Location: canada

    haybayian Junior Member

    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
     
  2. daiquiri
    Joined: May 2004
    Posts: 5,373
    Likes: 254, Points: 93, Legacy Rep: 3380
    Location: Italy (Garda Lake) and Croatia (Istria)

    daiquiri Engineering and Design

    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...
     
  3. kach22i
    Joined: Feb 2005
    Posts: 2,414
    Likes: 111, Points: 63, Legacy Rep: 1222
    Location: Michigan

    kach22i Architect

    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.
     
  4. Guest625101138

    Guest625101138 Previous Member

    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.
     
  5. kach22i
    Joined: Feb 2005
    Posts: 2,414
    Likes: 111, Points: 63, Legacy Rep: 1222
    Location: Michigan

    kach22i Architect

  6. haybayian
    Joined: Oct 2008
    Posts: 24
    Likes: 0, Points: 0, Legacy Rep: 10
    Location: canada

    haybayian Junior Member

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

    Haybayian
     
  7. haybayian
    Joined: Oct 2008
    Posts: 24
    Likes: 0, Points: 0, Legacy Rep: 10
    Location: canada

    haybayian Junior Member

    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
     
  8. kach22i
    Joined: Feb 2005
    Posts: 2,414
    Likes: 111, Points: 63, Legacy Rep: 1222
    Location: Michigan

    kach22i Architect

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

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

    http://www.nauticmotors.com/T2.html
    [​IMG]
     
  9. haybayian
    Joined: Oct 2008
    Posts: 24
    Likes: 0, Points: 0, Legacy Rep: 10
    Location: canada

    haybayian Junior Member

    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
     

  10. kach22i
    Joined: Feb 2005
    Posts: 2,414
    Likes: 111, Points: 63, Legacy Rep: 1222
    Location: Michigan

    kach22i Architect

    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/
     
Loading...
Forum posts represent the experience, opinion, and view of individual users. Boat Design Net does not necessarily endorse nor share the view of each individual post.
When making potentially dangerous or financial decisions, always employ and consult appropriate professionals. Your circumstances or experience may be different.