hovercraft

Discussion in 'Boat Design' started by whitepointer23, Oct 11, 2014.

  1. whitepointer23

    whitepointer23 Previous Member

    I have a set of plans for a little uh10 hovercraft I would like to build as an introductory to hovercraft. my question is about lift. the plan shows a choice of twin fans where you use a vertical shaft engine on the lift fan and a series of idlers and a belt to drive the propulsion fan. the other option is a horizontal shaft engine driving the propulsion fan and filling the skirt through a duct . I would have thought the latter would be superior because it has only 1 fan and no belts. am I missing something here, why do they offer 2 options. its not really a boat question although I have to register it as a boat.
     
  2. Saqa
    Joined: Oct 2013
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    Saqa Senior Member

    Maybe they list that as then you can use the design for which you would easily find an engine?

    With the duct, will the lift vary due to various fan speeds at various boat speed?
     
  3. whitepointer23

    whitepointer23 Previous Member

    good point , maybe the separate lift fan flows enough to keep the skirt inflated at idle without trying to move forward.
     
  4. Nick_Sinev
    Joined: Aug 2014
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    Nick_Sinev Junior Member

    I'm not a specialist, my opinion could be a mistake.

    According to I-net discussions on hovercrafts.
    Pasticipants insist, that a hovercraft should have 2 separate engines: one for lift and one thrust, to control lift and thrust independently.

    Yes, it can be done with a single engine (variable pitch propellers / shutters), but the resulting hovercraft would be more compicated and more expensive.
     
  5. rwatson
    Joined: Aug 2007
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    Location: Tasmania,Australia

    rwatson Senior Member

    two engines would be a big confidence booster on long trips to awkward and remote locations.
     
  6. WestVanHan
    Joined: Aug 2009
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    WestVanHan Not a Senior Member

    Kaachi65 i think was the guy always posting hovercraft pix and building them in his shop.
     
  7. WestVanHan
    Joined: Aug 2009
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    WestVanHan Not a Senior Member

  8. whitepointer23

    whitepointer23 Previous Member

    thanks for the replys. I have been reading the universal hovercraft forums since I posted. apparently my plan is the uh10 super, the uh10 standard uses 1 fan with a duct for lift. the super uses the 2 fans which makes less noise and more thrust.
     
  9. whitepointer23

    whitepointer23 Previous Member

    it would be if they did both jobs but 1 is lift and 1 is thrust.
     
  10. whitepointer23

    whitepointer23 Previous Member

  11. whitepointer23

    whitepointer23 Previous Member

    that's pretty much what I have read to.
     
  12. BMcF
    Joined: Mar 2007
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    BMcF Senior Member

    I have the full plans for the UH10 that uses a dedicated propulsion engine and separate vertical shaft engine forward for lift. My experience with designing, building and operating various hovercraft strongly supports that configuration as being the better way to go:

    1. Not having independent control of lift and thrust is always a PITA with a hovercraft. Single-power-source craft that do not have controllable pitch propulsion props or closure doors on the ducts if ducted props are used can be a real handful to safely control.

    2. A rear cushion air supply results often in a craft that is "tippy"; On cushion and at speeds over hump, they have a nasty tendency to suddenly pitch forward and plow in.

    We owned and operated a British SH-2 5-person enclosed cockpit craft for several years. It had one 400HP engine that drove both the aft-located lift fan and the twin ducted props. It was a truly dicey handful of a machine to operate (very fast..too fast) and, despite adequate operator skill and foreknowledge, still managed to stuff her beak rather violently at speed on more than one occasion.
     
  13. whitepointer23

    whitepointer23 Previous Member

    thanks . Thats what I needed to know. My plans don't show a front engine option but it should be pretty easy to do. I prefer that to running the thrust fan off the lift motor. Is it worth fitting an elevator to help prevent plow in.
     
  14. BMcF
    Joined: Mar 2007
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    Location: Maryland

    BMcF Senior Member

    We modified our UH10 design to include an elevator ...for overall trim control, not just to prevent plow ins.

    The design of the SH-2 with its reversing slats and steering vanes left no room for an elevator...alas. I'll see if I can dig our the old blueprints for the UH10. It was going to be rather "extreme" because we adapted a 2-stroke Mercury 150HP powerhead to be the main propulsion engine. It might be just as well that the project was never completed....we moved on to build a 43-foot hydrofoil instead.
     

  15. whitepointer23

    whitepointer23 Previous Member

    Sounds cool. The merc would have launched it into space. What size lift motor do you recommend to carry 1 large adult.
     
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