Merging H105

Discussion in 'Hydrodynamics and Aerodynamics' started by revintage, Jul 17, 2020.

  1. revintage
    Joined: Nov 2016
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    Location: Sweden

    revintage Senior Member

    The foils I am building has the lower part limited to NACA0012 for the first 30% and then flat. I have designed the foil using the added lower and top coordinates of 0012 and fine tuned the profile in JAVA-Foil to an acceptable level. Doug Halsey then ran it in XFoil.

    The upper part can be milled to some extent but not the lower. Just out of curiousity, using Excel, I merged the H105 coordinates at the top half to the lower half with the NACA0012 for the first 30% and then flat at the bottom. It runs with better Cpcrit figures in JAVA-Foil than the initial profile. I have just begun learning XFLR5 but I am not sure I got it right.

    Question is: Will it work IRL and if so, will it be worth the extra work by milling the top?
     

    Attached Files:

  2. jehardiman
    Joined: Aug 2004
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    Location: Port Orchard, Washington, USA

    jehardiman Senior Member

    Ok, NACA 00xx profiles were designed as high stall angle aerodynamic control surface with good stall characteristics. They work, and have a lot of data as hydrodynamic control surfaces as well. Realistically, as a lifting hydrofoil, 00xx sections have their maximum section too far forward and their included aft angle is too small. Your H105 variant seems too move the maximum section slightly aft but significantly increases the included angle aft as well as looking like it has more more camber. So it should be a better lifting hydrofoil.
     
  3. revintage
    Joined: Nov 2016
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    Location: Sweden

    revintage Senior Member

    The camber is very close, but as you say maximum is moved slightly aft. Stall is around CL=1.1 for H105, CL=1.2 for H105flat and CL=1.4 for N12flat according to Java-foil. About Cprit all of the foils are well above the range the foils be used, at 42, 40 and 39 knots. Off course H105 is superior to the two above in every respect.

    Anyway decided to go for the original N12FLAT as the nose profile is already milled.

    105n12.png
     
    Last edited: Jul 19, 2020

  4. revintage
    Joined: Nov 2016
    Posts: 279
    Likes: 48, Points: 28, Legacy Rep: 10
    Location: Sweden

    revintage Senior Member

    The NACA0012 nose profile. By milling it down the H105 profile can be achieved with some tricks.
    A2CA82CB-3456-4A0D-8DA0-E2DCBA7FD001.jpeg
     
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