The SOARBIRD series of designs are intended to be 'stylized' powered soaring RC aircraft. Some aspects are optimized more for flight performance, rather than for a 'perfect' eagle / hawk silhouette.
After achieving exceptional glide performance with the "DANCER" wing designs [ with their Kline-Fogleman variant wings with the steps on the top surface at 50% of chord], I decided to design a new 48" span Bluecor winged SOARBIRD4, utilizing a variation of the same wing build approach.
One of the main reasons is that the multi-layered KFv wings can be built to have excellent strength, are easy to build well-aligned on a flat building surface, and hold their shape under heavy flight load conditions. The heat-forming / tempering / thinning techniques that I developed recently are being used on all Bluercor wings and tailgroup members now. This allows shaping the leading edge areas into more of an airfoil contour, and thinning the trailing edges substantially to minimize drag while firming and tempering the foam- all without any added weight!
(For more details on the SLIM BEAGLE and DANCER designs, CLICK HERE
An EPP body / fuselage will be added once the wing and tail are completely built out; the wing will be mounted to this body with screws to keep it solidly positioned.
[Above]: Initial layout is done using the fold between two panels of Bluecor as the leading edge. Span is 48", Chord is 8". The tip half (12") of each wing is swept back 3" at the leading edge. A cutting mat is then slipped between the bluecor layers to do the upper layer cut at 50% of chord. You can see that the ailerons are laid out, 16" long with a minimum width of 1.5".
Also, the spacer strips that will go between the bottom and top wing layers are marked on the cut-away pieces, ready for cutting. The remainder of the cutaway pieces could still be cut again to add a secondary step at ~70% of chord, similar to what was done on the third DANCER wing prototype. (That wing has proven to be the most efficient of the three wings for slow speed thermal gliding performance to date.) This wing's airfoil will be just under 9% thick at the step / thickest area.
[Above]: Next, the upper surface portion of the wing was rolled over a 4" diameter tube to start shaping the curvature for the upper wing surface.
[Above]: The spacer strips are ready to be glued to the edges of the upper wing surface. I used foam-safe CyA glue for this.
[Above]: The trailing edges of the wing and ailerons have been extensively heat-formed / thinned in this photo. The elevator has been cut and tape-hinged. The 1mm diameter x 36" long C.F. rod cap spars have their rounded depressions formed & 'wood-peckered', ready for gluing the spar caps in place on the top and the bottom surfaces. These are located at 40% of wing chord, relative to the inboard wing panels.
In a manner similar to the DANCER wings, these wing tips will be upswept somewhat and further shaped to a 'feathered' tip profile as the build process progresses. These upswept wing tips perform two valuable functions; they provide some flight stability similar to conventional dihedral, and they effectively move the wing tip vortexes up away from the outer wing panel's surface, allowing more of the wing surface to generate more lift.
I'll add more photos and details as the build process continues.