After a few evenings of testing the previous wing and securing a good winglet solution I decided to put it up for sale because I wanted something smaller, that would light up so I could fly in the calm night air - there isn't enough room in my place to have all of the planes I make so every time I make a new one I have to let another one go. I like the idea of an extremely efficient and capable SAL flingy toy. The old 2000's hotwired EPP Alula did a good job of being this but still had that fragile element about it because of the fuselage and the depron tail, and the weak control rods and horns, and that configuration just doesn't like rolling as much as a delta.
Reducing the wingspan to 30", and the weight to (?) both resulted in the necessity of a thinner airfoil in my mind to achieve the flying characteristics that I want. The official science would state otherwise but I don't know really, how much science has been done on the exact thing I'm doing, I don't think any. The worlds of aviation and model aviation aren't the same thing and stuff works in a weird alice in wonderland sorta way when it comes to Physics when you go small and light. I think at these sizes its best to go even thinner than is normally prescribed, its just the way the air works in my experience, while the trouble often comes from the difficulty in building things this thin in a precise way while keeping them lightweight and rigid.. Thinning the airfoil also reduced the mass of the EPP cores. Reducing the wingspan, and thinning the airfoil (from 8-9% to 5-6%), thereby reducing the overall weight of the plane and naturally increasing the rigidity allowed the implementation of lighter weight carbon fiber reinforcement which also reduced the weight proportionally. Then I decided to go with a thinner laminate instead of the 3mil thickness I was using, once again, a weight decrease. The smaller wingspan, lower weight of the airframe allowed the use of smaller servos (3.7g instead of 9g) to, again, reduce the weight. We're now working with something that is about as much of nothing as possible, while still having an actual airfoil. The foam is thin enough to see through at the rear 50% of the chord..
I added four 5mm LED's using random gauges of wire in the tool box.. for the UFO enthusiasts out there, and now we're ready to install servos, cut and hinge the elevons & create some tip fins & mounts. I would like to do some kind of RDS system for the elevons or some kind of torque rod pull/pull system in order to keep the wing totally clean, but I think I will go the regular route this time because I don't know how to do that stuff yet and I want to fly. I also need to see how much length I can afford to lose on the servo arm and still get the roll rate I want. The length of the servo arm will determine what ability I have to bury the elevon connections. This is a finicky thing to figure out with tiny servos and tiny planes because slop becomes a big deal pretty easily in several different ways, and then when you go and change the geometry of things, the size of the elevon horns, you wind up with different mechanical leverage values and when enough throw is managed then other issues come into play that not even solidworks will forsee, like the structural properties of the foam itself surrounding the hinge and control horn areas, and so on and so forth. I had determined a long time ago that the best route is a long servo arm AND a long horn on the surface side, in order to battle aerodynamic forces on barn door surfaces that rotate 180 degrees. There are however aesthetic and aerodynamic issues when those techniques are used, compromises I've been willing to make because of the nature of the craft I was producing and its ability to actually take advantage of excess drag, while this flying wing DLG is the opposite.
I need to work on my cutting system to get more consistent cuts when cutting out these ultrathin airfoils *it's thickest point is only 1/2 and tapers to nothing"* because as you can see the trailing edge lost a little material. It's so thin back there, that it actually vaporized. Not a big deal other than aesthetics because the foam is so thin anyway that the laminate laminated to itself at the trailing edge takes care of the lost surface area without complaint. I'll probably put a sticker over it, and you will all be none the wiser. While I did manage to cut out a set of very clean cores alongside these, it required spectacular robot-like athleticism to accomplish on my part. Cutting EPP is difficult, cutting EPP to tolerances its never seen before by hand is really, really really difficult! I'll be switching to top & bottom templates instead of the full airfoil center templates for the next iteration, or better yet I'll get the CNC cutter running that I've been printing parts for after I win the lotto..
