Designing a Rudder

Discussion in 'Boat Design' started by UoNMEng, Mar 4, 2012.

  1. Frosty

    Frosty Previous Member

    No and Im not 100% sure it was the 380 ive seen it on something. I think it was the 380.
     
  2. Frosty

    Frosty Previous Member

    Nope sorry its not the 380 0r the 787 Dreamliner I don't know where ive seen it but I saw it on some jet liner.
     
  3. daiquiri
    Joined: May 2004
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    Location: Italy (Garda Lake) and Croatia (Istria)

    daiquiri Engineering and Design

    Frosty, perhaps you have seen something similar to this:

    [​IMG]

    These are not tubercules but a noise-suppression system. They basically mix the outside (cold) air with the hot jet, creating low-scale turbulence and shifting the frequencies of the noise from low to high range. High frequencies are (relatively) quickly damped by the athmosphere, while low frequency waves keep their energy over much longer distance and hence cause more disturbance. For that reason it's advantageous to transform the low-frequency noise into high-freq one.

    Sounds complicated, I know. Such are many aerodynamics-related stuff. ;)
     
  4. rwatson
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    rwatson Senior Member

    I saw a 380a with funny bumps around the outlet in a brochure for the RR Trent engines, but it was to indistinct on the photo to see what they were.

    We can keep looking
     
  5. daiquiri
    Joined: May 2004
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    Location: Italy (Garda Lake) and Croatia (Istria)

    daiquiri Engineering and Design

  6. UoNMEng
    Joined: Mar 2012
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    UoNMEng New Member

    Wow! thanks for all your replies.

    We are only using the rudder for slow speed application when the craft is supported by the buoyancy of the hull rather than the hydrofoils.

    The aim is to reach 9.7m/s (current world record) in a straight line. The rudder is only used at a maximum velocity of 5m/s when the hydrofoils become active. At this point, the whole boat lifts out the water including the rudder reducing drag. Personally, I'd rather not have a rudder at all but it is required for the business plan.


    On an alternative tangent, you guys wouldn't know any useful guides for fiberglass composite building for hydrofoils.

    Basically the way we were thinking is to create a foam core, shape it by hand using a template to the naca0012 and h105 for alternative applications and then hand wrap it in E type fiber glass unidirectional cloth.
    6 layers rotating by 45 degrees each time.
    The problem is I can't find out how thick this will become or whether it will create a sufficient Yield stress (UTS) which is needed to resist the UDL bending stress created on the foils.

    Any suggestions?

    Also if the fiberglass is said to be 200gm, what does that mean?!

    Many thanks
     
  7. daiquiri
    Joined: May 2004
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    Location: Italy (Garda Lake) and Croatia (Istria)

    daiquiri Engineering and Design

    Sorry for speaking frankly, but your posts so far are saying that you currently probably don't have the necessary technical knowledge to beat the record established by Mark Drela's team.

    I would take this project as an easy-going journey through some of the aspects of human-powered vessels design, with no serious aims at the current speed record. ;)
     
  8. UoNMEng
    Joined: Mar 2012
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    UoNMEng New Member

    yeah, we know, they spent $6000 and multiple iterations over several years to produce theirs.
    We have half a year and £500

    Can't blame us for aiming high though.

    Also, the internet is a powerful thing.
     
    1 person likes this.
  9. Leo Lazauskas
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    Leo Lazauskas Senior Member

    Indeed! But I can't see that installing a web browser on-board will help you
    to beat Drela's record. :)

    My only suggestion (and it's admittedly a bit loopy) is to consider some
    form of boundary layer control on the hull and/or hydrofoils. Many human-
    powered vessels are propelled with the legs alone. I think it might be
    beneficial for the crew to use their arms to drive a small pump to suck the
    boundary layer at the stern or from near the trailing-edge of the hydrofoils.
    OTOH, it would add considerably to the complexity and there's no
    guarantee it would work.

    I also suspect that you don't have much time for such complicated devices.

    Good luck!
    Leo.
     
  10. SamSam
    Joined: Feb 2005
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    SamSam Senior Member

    In California, motorcycles were required to have rear view mirrors. Bikers didn't like that but they complied by sticking small dental mirrors on the handlebars. If the rudder isn't needed but only required, why waste time asking about that?

    How is this thing to be propelled? By how many people? Is there any pics of past attempts?
     

  11. rwatson
    Joined: Aug 2007
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    Location: Tasmania,Australia

    rwatson Senior Member

    Heck - just copy the design from their web site :)

    200 gsm means 200 grammes per square metre of fabric (16oz per square metre in the old world)

    You can get lighter than that, but not much.

    For a Kayak - its just as easy to build a few rough test rudders and stand on them to see if they break, its easier than getting all caught up in numbers.

    You will be amazed how strong high density foam wrapped in a layer of 200gsm fibreglass is. I bet it would be strong enough to do the job.
     
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