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    my part 103 ultralight build -thread

    I found T88 sufficiently viscous so fillers aren't necessary provided your joints are tight. Do butter both parts to be joined and even let the epoxy go a little green and you won't have dry joints.
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    my part 103 ultralight build -thread

    How Big The Tail (eaa62.org) should be helpful. The coefficients suggested by Raymer are for a general cross-country plane, not an ultralight. The tail coefficients for the Minimax ultralight are approximately Vhorizontal = 0.36 and Vvertical = .023, about the same as a J3 Cub. The Minimax...
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    Tillotson 212cc and 225cc on efficient ultralights?

    A slightly different approach. The engine creates thrust moving the airplane forward. Drag retards the plane and the climb angle is determined by (thrust - drag)/weight in radians. If the Skypup has a takeoff weight of 400 lbs and an L/D of 10 at 40 mph, then the drag might be 40 lbs. To climb...
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    Heavily inspired ultralight

    Regarding tail size, I believe the Skypup has low horizontal tail loading owing to the low moment coefficient of the NACA 43018 airfoil. Compare your proposed 4418 airfoil's -.09 Cm with -.013 of the 43018 airfoil. The 43018 allows for a cantilevered, low-drag, light horizontal tail and...
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    Lift Strut and Cabane Strut loads

    The specified loading in the simplified design criterion occurs at VA, point A of the Flight envelope - Wikipedia . Another good reason to define the envelope for the Pietenpol. So one wing is lifting its share of about 3g while the other is lifting its share of 4.4g for a utility category...
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    Lift Strut and Cabane Strut loads

    Your "Understanding fwd component of lift" is correct up to the last sentence about "transfer to the fuselage/cabanes". The fuselage pulls down on the wing while the wing pulls up on the fuselage. Its the same pull. The wing struts will take care of the pull(s) perpendicular to wing chord...
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    Lift Strut and Cabane Strut loads

    There is drag of the wing and drag of the whole airplane. The wing drag is composed of form and friction drag as well as induced drag from producing lift. The drag coefficient of the wing can be broken down into a zero-lift drag coefficient plus an induced drag coefficient. When you...
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    Minimax wing load spreadsheet

    Fenix, I supposed that since the Himax exists, a parasol should be doable. After all, remove the Himax windows and you have a parasol. But I didn't want to build a center section, so I gave up some wing span and built a root tube supported by angled struts. This was somewhat complicated...
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    Minimax wing load spreadsheet

    Thanks for your considered critique, Billski. The spreadsheet was an attempt to understand the calculations behind an analysis report published by Tennessee Engineering and Manufacturing (TEAM). The report describes the method in general terms and does include shear and moment diagrams but no...
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    Lift Strut and Cabane Strut loads

    There is a tool called "scenario manager" in Excell that allows for substituting several cell contents with alternate values. The spread sheet has sets of values for both airplanes.
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    Lift Strut and Cabane Strut loads

    This is an excel spreadsheet I did using Hiscocks' "Design of Light Aircraft". One can toggle between Minimax and Himax parameters. With it one can examine symmetric positive loading and with some assumptions maybe negative and asymmetric loads. Minimax wing load spreadsheet
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    Minimax wing load spreadsheet

    Iteration is a common numerical method of obtaining an ever more accurate approximation of a set of values that satisfy a series of equations . In this case, we have a guess for lift and in the first iteration the tail force is assumed to be zero. This results in an approximation of the...
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    Minimax wing load spreadsheet

    The spreadsheet does have a circular reference in the balance equation section where the lift calculation and the tail force calculation reference each other. The spreadsheet program (Excel) must be set to allow circular reference and the number of iterative calculations is specified, a hundred...
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    Minimax wing load spreadsheet

    What are you trying to accomplish? You would probably be better served finding a beam calculator. This spreadsheet is specific to the Minimax. That's not to say it couldn't be used for most two-spar, fabric covered, strut braced monoplanes with some modification but one cannot simply change a...
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    Minimax wing load spreadsheet

    Thank you and sorry for not replying sooner. The angle of attack is one of the inputs to the calculations. The Minimax airfoil is supposed to have a maximum lift coefficient of 1.5 unflapped and 2.0 with the flaps fully deployed. If the lift curve slope is 0.1/° then the 2 dimensional alphas...
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    Dumb question #34567: Pitching moment polars

    I thought Cm doesn't change with changes in angle of attack.
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    Minimax wing load spreadsheet

    It's my attempt to do the calculations behind the numbers quoted in the TEAM report. It's incomplete as it only examines symmetric loading and points A and D of the flight envelope. The calculations are found in the highly accessible "Design of Light Aircraft" by Richard Hiscocks.
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    Minimax wing load spreadsheet

    attached is a spreadsheet that calculates wing loads for the Minimax airplane.
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    Why can we eliminate wing weight from free body diagrams?

    STRESS WITHOUT TEARS from Aircraft Spruce was a series written for Kitplanes. Very good at explaining origins of loads and beginning of stress analysis.
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