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    E-Turbo for an E-UL (a legal 100mph Part 103 UL is possible!)

    ...so long as it only reaches that speed while climbing and gets the power chopped back when in dead-level flight). This is referencing an ultralight glider. In a nutshell, any powered UL glider is an "ultralight" and gets lumped in with the 254lb folks). I spent some time rereading Part 103...
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    An I-beam for a tail?

    Some material testing may be required here, but follow along with me on the basics. Primary gliders just have a truss with two dimensional "spar caps" and some reinforcing at the joints. These tails tend to be rather short, which I assume reduces twisting forces. They may also use some wire...
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    Could sports foam be used for shock absorption?

    I'm speaking about ultralight aircraft here, just to be clear. Rubber donuts, springs, shock cords, and spring steel gear all suffer the same problem - fast rebound. The solution is air oleo struts, but those are heavy. Would it be possible to engineer (or aquire) an off-the-shelf memory foam...
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    Vertical tail volume coefficients - what am I missing?

    I am trying to do some preliminary sizing of a vertical tail for an ultralight glider. I have the following - Swing: 143sqft b: 41.5' Lvt: 10' Cvt: .04 (per Raymer) And it says I need about 24sqft of surface area for the vertical tail. That is ridiculously huge. I looked at other comparable...
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    Ultralight Flaps

    If I've learned one thing in my 30+ years being tangentially (or more) involved in aviation, it's that no matter what you "invent", no matter how clever you are, whatever you think is new has already been done. If it works, it's got a name and it's being used. If it isn't being used, there's...
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    What Could You Do With A 65hp Turbo-Normalized Motor?

    We all know about feature creep in any design. And "hp creep" (Xhp is good, so X+20hp is better). But for a long time, this little engine had my mental gears turning. 65hp, 100lbs, turbocharged. Aerotwin Motors Corporation If you designed a tiny little "speedster" for low altitudes and then...
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    LE Flap Design for a VW-powered homebuilt

    3-view image added in post #3 In life, you can make time or you can make money, but seldom do opportunities present themselves to make both at the same time. Right now, I have more time than I'd like, so I figured I'd go back to that little airplane that's been built in my head for years (we...
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    The spirit of "experimental"

    I was thinking that if I ever successfully designed and flew an aircraft and was asked about plans, I would eagerly supply them. However, being a non-professional, I am aware that it would be viewed with healthy skepticism. You have guys like Mike Arnold who are so acutely aware of this that...
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    In flight forces on the rudder

    Whoops.. the title should have read "In-flight forces on the vertical tail". Sorry... can a mod fix that? I feel silly for not knowing this, but I guess in a way it makes sense that I wouldn't... Why have I never seen anything about calculating forces on the vertical tail? I'm guessing...
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    EXPERImental

    A side discussion on another thread got me thinking about the difference between the planes that are listed as experimental by the FAA, and those that are seriously EXPERIMENTAL. That word... experimental... has twelve letters. Maybe we could create a standard. 12 degrees of demarcation which...
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    Wrapping my head around U/L GLIDER design practices

    Allow me to preface this by saying I'm not constantly changing my mind. I've had my single-seat sport plane on the drafting table for years and it's ultimately something that I want. I am simply exploring other projects which may also interest me either now or else sometime down the line. And...
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    Wrapping my head around U/L design practices

    Coming from a background in certified aircraft, there's a lot about ultralights that scare me. I see some things that you wouldn't be caught dead doing on a normal-speed experimental. Sometimes I think, "well, they'll never see anything above 80mph in a dive, so it should be fine.." Other...
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    Suggested references for "low" Reynolds number airfoil performance?

    I'm looking for references that discuss, or provide equations, or even pretty pictures for standard aircraft airfoils in the Reynolds number range of about 1 million and up... I've seen lots of stuff about wind turbines and R/C models in the under 400K range, however I'm looking for some...
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    Gluing a wing together....

    I'm still toying with ideas to make a plane cheaply. Stuff like selecting fabrics based on the generally-available widths of material is not escaping me... By that I mean I'm considering that if a single ply rolled out across the span can cover from the trailing edge at the top all the way to...
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    Pulling a precision part from a male mold...

    This is what I'm planning to do.... unless someone wiser convinces me that it won't work.... As per my post in the design/structures forum, I am planning on building my wing without twist and without taper. This means that I can use the same mold for both wing halves. My plan is to build a...
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    Creating aerodynamic twist by using a trailing edge slot?

    I'm designing a wing for a very light, mid-performance aircraft with a heavy emphasis on being easy/cheap to build. Sort of a love child between the Hummelbird and the AR5, if you will, with a little bit of Cri-Cri and Questair Venture thrown in. I know those are very different aircraft...
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