Hello everyone, I’ve been into flying wings since 2000 when I bought a Zagi online. As piloting style I can compare a flying wing to a snowboard ->> COOL. After abusing it greatly, I ended up mounting a couple of small Russian Norvel glow engines on it and eventually I had to bury it, since it became a pack of crumpled styrofoam. In 2005 I built another wing out of packaging tape and foam (see below).
I’ve been dreaming of a build-up flying wing for a while something like a Blended Wing Body covered in translucent film. I finally tried to make a very basic version with few curves and un-swept wings for simplicity.
For airfoil design and moment calculation I use XFLR5 a very nice free aerodynamics software. I started with a high efficiency Eppler airfoil from UIUC database, reflexed it (raised the trailing edge to make it act like a positive momentum generating tail). I also thickened the leading edge (to make it collision proof) and refined it until I got a decent positive moment coefficient while keeping more than half of the gliding ratio of the original airfoil.
After finalizing the profile, I used Excel to draft it. I printed the ribs on a regular home printer. For the larger ribs near the base of the wing I had to splice the sheets of paper. I had some 1/8” and 1/16” plywood in the house as well as some carbon fiber rods from another project.
To the left is a screenshot of the Excel file and to the right there is a photo of my router (7$ from a garage sale) and the rib templates I made using a scroll saw and a 2″ sand drum monted in a drill press chuck. What you see on the top of the rib group (like an elongated letter “S”) is the template for the leading edge.
After gluing the ribs and the carbon spars the wing looked like the upper picture. Of course there was some wood work in the central area played by the ear. The Excel file is not 100% detailed, it contains though the rib shapes and positions. The leading and trailing edge have also an element of improvisation. The pieces to the right of the upper picture are the two elevons and the lids to the radio bay and the servo link bay (close to the stubby tail). The bottom left picture is a detailed view of the central area (radio and servo bays) with the servo mechanisms mounted in. In the lower right photo you can see the antenna as a red wire embedded into the left wing. I have few details to add but not until next spring. This plane is very strong but it will be fairly heavy (ready to fly at about 700 grams and 130 cm span) so I expect it to be quite fast. I used a British thermal-shrink cover type Ultralite.