Hydrofoils: Pleasure (Engines and Human Powered)
  Human powered hydrofoils 07-18-14

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       Human powered hydrofoils - (Dumith)     07-18-14 - 11:27 AM
     Hi,
    I am a mechanical engineering undergraduate student and currently involved with a designing of a pedal powered hydrofoil boat. When i look into the designs of hydrofoils, was able to find out so many hydrofoil sections (actually they are airfoil sections, but since the only difference is density, they were selected for hydrofoil sections). But the thing is that i cannot select one section design for the task.
    So what will be the best section of hydrofoil to be used with human powered boats (actually in low Reynolds Numbers) ?
     

    Date=07-18-14    Name:Dumith [Msgid=2325434]Click here to Modify or Delete this message    ModifyMsgClick here to Delete or Modify this message   
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Hydrofoils: Pleasure (Engines and Human Powered)
     Human powered hydrofoils (Dumith) 07-18-14
         Hydrofoil profiles (Martin) 08-07-14

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       Hydrofoil profiles - (Martin)     08-07-14 - 5:45 AM
    Personally, I wouldn't get too hooked up on the foil profile shape initially. For such a project, you have to first determine some other overall design parameters such as what total weight you are looking at supporting (which means estimating the weight of the craft and determining the weight range of the operator it will be intended for), what constraints to you have on foil span, foil construction material (and hence available strength), available propulsive power, taking into account all the losses in the propulsion system from the operator down to the propeller.
    Then you should familiarise yourself with lift and drag estimation equations for wings (which also apply for hydrofoils). You will for example see that for a human powered hydrofoil, it is critical to try to maximise the aspect ratio of the foils in order to maximise the overall Lift to Drag ratio of the craft. Tabulating equations in a spreadsheet will help you to understand how varying design parameters will influence performance. You can then start to scan through a text book such as "Theory of Wing Sections" by Abbott and von Doenhoff to find a foil profile which has the best 2D lift to drag ratio at the lift coefficient you are aiming for. The charts are provided for a range of Reynolds Numbers so you should be able to interpolate or extrapolate from them to some degree.  

    Date=08-07-14    Name:Martin [Msgid=2330682]Click here to Modify or Delete this message    ModifyMsgClick here to Delete or Modify this message