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    Senior Member Azmodon's Avatar
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    Rear Diffuser Build

    I've been saying for a long time that I'd make posts about the stuff I'm doing... maybe it's time I actually do that lol

    Today's post: Functional rear diffuser build.

    Parts used at this point:
    2'x4', 1/8 ABS sheet ($20)
    2'x4', 1/4 ABS sheet ($27)
    16"x36", 3/4 Laminated Pine Shelf X 2 ($28)
    1.25"x1.25" Angle Iron - Two 5" lengths (one side has a 1 inch section removed creating a tab, which is bent up to match the required angle (7 deg.) ($scrap)
    Triple corner bracket X 2 (sandwiched by angle iron between front and rear assemblies) ($4)
    3" x 7" Mending Plate X 2 ($6)
    #6x32 Machine Screw X 8 ($2?)
    #6 Washer X 8 ($1?)
    #6-32 Nylock Nut X 8 ($1.50)
    1/4-20 Bolt @ 0.75" X 24 (Box of like 50 for $14)
    1/4-20 Bolt @ 1.25" x 12 ($3?)
    1/4-20 Bolt @ 1.50" x 4 ($2?)
    1/4 Washer X 54 (Box of 100 for $12)
    1/4-20 Nut X sum of ^^that (Box for $8)
    1.5" double wide corner bracket X 4 (for strakes) ($6)
    1.5"x2.5" corner brace X 4 (for wings) ($5)

    Parts being installed next:
    1" wide steel strip - from wing tip back to main body, bent at 90 and up to the ABS, fastened with one 1/4-20 bolt near the wings insertion point. ($9)
    1/4-20 RivNut near the end of the wing ($scrap)
    2" long 1/4" eye bolt mounted to the RivNut ($3)
    3" long 1/4" eye bolt mounted above the 1/4-20 bolt back at the main body through the upper end of the bent steel strip ($3)
    3/16" 7x19 coated aircraft cable attached through thimbles and cable clamps -> the 3" long eye bolt can then be tightened to pre-load the wing. ($6)

    (total cost... very very roughly = ~$160)

    The design:
    Name:  Design stage.jpg
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    The design... again:
    www.youtube.com/watch?v=EDy-UcvuLCM



    The ABS sheets
    Name:  ABS Sheets.jpg
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    The Pine which was cut using printed templates
    Name:  Wood components - pine.jpg
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    the two sections and wings laid in place + front and rear assemblies separately
    Name:  component layout.jpg
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    Assembled
    Name:  assembled components.jpg
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    Underside view
    Name:  Underside complete.jpg
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    Once the cutting out of the parts was complete I shaped the two short sections for the front using a sander (sloped the entrance inwards) -> the mid wing (large black thing - shown in red on the design) was hand planed in to an aerofoil using another template and its angle of attack set to 4.5 degrees.

    The rear pine pieces each diverge from mid-line at 7 degrees - the insertion angle of the rear and front assemblies is tangential, with the ABS sheet on the rear on a smooth curve (25' diameter) - mid point of the curve is 6.5 degree's from horizontal, ending angle is 11 degrees from horizontal. The idea being that, the mid-wing will assist in energising the boundry layer, helping air ride the upper surface - the 6-32 screws are also all offset from each other in this area and left at 0.5" in to the air stream so that their tiny bodies may provide a uniformly spaced set of vorticies.

    Questions / comments / etc. are welcomed - I also have a tonne of pictures regarding the removal of the interior components and carpet to put down dynamat, and I've got flares going on soon... and I'm having custom side skirts, somewhat similar to PCI Racings but "better" being priced right now.
    Last edited by Azmodon; 09-14-2017 at 04:00 PM. Reason: Added video

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  2. The Following 5 Users Say Thank You to Azmodon For This Useful Post:

    Bobaganousch (09-19-2017),Daox (09-15-2017),IMPUL (09-14-2017),MetroMPG (09-20-2017),not_a_bot (11-02-2017)

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