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    Wing Strut General Principle Engineering Question

    We discussed this recently in this thread: Lift strut question At post #15 in that thread I provided a spreadsheet for analyzing a stepped column along with an un-stepped column for comparison. Use that to compare the old and new configurations. This should work ok ... however my main...
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    Composite wing spar web design - composite webs, foam webs, etc.

    I took these to be elastic modulus and if so GPa would be the correct unit. However, these convert to 24,600,000 Psi (24.6 Msi) and 20,300,000 psi (20.3 Msi) and are high numbers for modulus ..... well high for standard carbon uni but they are in the range that might be expected for a high...
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    Composite wing spar web design - composite webs, foam webs, etc.

    Billski, Firstly, my apologies for the quality of the uploaded images. My originals were clear ... looks like the forum software reduced the resolution on upload. I will attach a PDF to this post containing a copy of the original files at original resolution. The calculations I presented were...
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    Solidworks Student - Flattening curved sheet metal?

    I cannot comment on the student version of Solidworks. However, I have commercial licences for Solidworks Standard and Professional and these both flatten sheet metal. The software can in general flatten parts folded from a flat sheet using flanges etc or lofted bends between cross sections...
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    Composite wing spar web design - composite webs, foam webs, etc.

    All composite structures I have worked on have a much higher FOS than 2.0. This assumes that we define the FOS as the ratio between the limit loads (i.e. max loads expected in service) and the failure load (i.e. the same definition used in FAR 23 etc to define the minimum FOS of 1.5). I think...
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    Composite wing spar web design - composite webs, foam webs, etc.

    OK ... here is an example analysis for a composite spar generalized for any tapered wing planform. I have included both bending and shear stresses. I have simplified it by assuming that the loading on the wing is constant over the surface (i.e. no spanwise lift distribution which is...
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    Twin-VW engine Push-Pull design idea (The "Beetlemaster")

    A twin push pull VW design has been built - the Ganzer Gemini from 1982. Whilst not in the configuration of a C337 but it might provide some idea of the likely performance - especially on one engine. This aircraft used 2 x Type IV VW engines. Here is an article on the Gemini from Homebuilt...
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    Jarvis Turbit

    The basic 1200 or 1300 cc VW engine used in these light weight Turbulents is about 130 lb and is likely about 35 hp. So yes I think a B&S conversion could work. Also some of the bigger / better 1/2 VW engines are putting out more power than this and weigh about 85-90 lb with aluminium cylinders...
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    Short span gliders? (Motorglider)

    Here is another interesting short wing glider. The Pascoe EP-1. The EP-1 was built in Australia in 1955 and is of wooden and fabric construction with a steel streamline strut. Span is 36.9 ft and wing area 103 sq ft. Empty weight was 189 lb and gross 390 lb. Max L/D was 1:23 or 26 depending on...
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    Jarvis Turbit

    Thanks Billski. Looks like we lost a couple of posts in the move. No problem, I can recreate my original response here. The question was asked about plans. There are no plans available. The Turbit was built from a set of Druine D.31 Turbulent plans with modifications to reduce weight. There...
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    Composite wing spar web design - composite webs, foam webs, etc.

    Getting back to the original question ... more specifically the question about how to design a web. I have had a look through some old stress reports. Some typical numbers for allowable shear strength for a +/- 45 deg wet layup of Rutan Style 7715 Uni E glass / epoxy on two core materials are...
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    Jarvis Turbit

    A bit off topic but: That blue aircraft is the Jarvis Turbit. He built two of them - a yellow one as well. It was basically a D31 Turbulent built very light with no slots on the outer leading edge, a lower turtledeck and a spring landing gear in lieu of the original telescopic leg. The goal...
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    Short span gliders? (Motorglider)

    I know this is an old thread but .... The threaded started off with mention of Irv Culver's Screaming Weiner (later renamed Lil Dogie). There was also Culver's Rigid Midget. There are however quite a few other small sailplanes with spans in the 30 ft range. One of those is the late Keith...
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    Jarvis Turbit

    I know this is an old thread but .... The threaded started off with mention of Irv Culver's Screaming Weiner (later renamed Lil Dogie). There was also Culver's Rigid Midget. There are however quite a few other small sailplanes with spans in the 30 ft range. One of those is the late Keith...
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    Composite wing spar web design - composite webs, foam webs, etc.

    Apologies I should have clarified this in my original post: Strain = Extension / Length (non dimensional) Strain (%) = Strain x 100 1 microstrain = 1 x 10-6 (usually denoted by a Greek mu and epsilon but cannot do Greek font here) 1000 microstrain = 1 x 10-3 = 0.001 = 0.1% (as...
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