This is a fast, efficient slope soarer, NOT suitable for beginners.
https://youtu.be/aQ_SdMxxsIY

Update as of 19 January 2019: the Proteusv2
https://www.thingiverse.com/thing:3366296
has more forgiving flying characteristics.

Update as of 9 December 2019: Proteus Plus with 1.8 m span, PW51 airfoil and flaps:
https://www.thingiverse.com/thing:3967057

Note: this Openscad design has a large number of parameters such as sweep, washout, dihedral and many many more. Adjusting these parameters will result in a corresponding outer shell being generated, but may result in some internal structures not being correctly positioned, or possibly puncturing the shell, e.g. increasing the dihedral will cause the ends of the main carbon fiber tube spar to be exposed underneath the wing. These issues are fixable but overall it is a lot of work to get that right for all possible parameters.

Requires OpenSCAD version 2017.01.20 or later.

Update 4 November 2017: Added ProteusFlyingWing.scad. This source file replaces CustomizableFlyingWing.scad and fixes an issue where increasing the noseLen parameter above 90 would cause the hatch to fail to fit properly. Note that fuselages generated with this new scad file will not fit the original hatch and vice versa.

Default specs:
Wing profile: MH-45
Fin profile: NACA symmetrical, 8% thickness
Wingspan: depends on printer max z, 1040 mm for 200 mm, 1160 for 230 mm max z
Root chord: 200 mm
Tip chord: 130 mm
Sweep angle (leading edge): 22 degrees
Washout: 3.5 degrees
Dihedral: 1 degree under each wing (2 degrees total)
Flying weight: 560 g for 1160 mm span version (including 28 g of lead nose weight)

Each wing is printed in 3 pieces, root, tip and fin. I have only uploaded the left-hand wing parts. Create the right-hand parts by reflecting them in the slicer. E.g. for Simplify3D, choose Mesh | Mirror Mesh | Mirror X (or Mirror y).

The length of the root and tip pieces is set by the printerMaxZ parameter. I have only printed and flown versions where printerMaxZ is set to 230 mm. I have added stls for the case where printerMaxZ is set to 200 mm, for the convenience of people with printers limited to 200 in height, but I have not printed them.

The hatch does not depend on the printerMaxZ parameter, all the other parts do, to some degree.

The total span (including fins) of the Z200 version is 1040 mm.

The only pieces I glue together are the nose to the rear fuselage and the servo guards to the wing (both with thick cyanoacrylate). The wing joints are taped, with fiberglass reinforced tape being used for the most important join between the root wing section and the tip wing section.

The OpenScad code calculates the estimated CG position using code from [email protected]:
http://rcwingcog.a0001.net/V3_testing/?i=1

This CG position is used to place 2 small dimples at the correct balance position under the fuselage.

Vitamins:
500 mm x 5 mm OD Carbon fiber tube spar:
https://www.aliexpress.com/item/5pcs-5MM-OD-X-3MM-ID-X-600MM-Carbon-fiber-wing-tube-for-airplane-5-3/32242824992.html?spm=2114.13010608.0.0.dDXTx3

2 mm OD and 3 mm OD carbon fiber rod joiners:
https://www.aliexpress.com/item/1pcs-Carbon-Fiber-Rods-Dia-1mm-2mm-3mm-4mm-5mm-6mm-7mm-8mm-10mm-11mm-12mm/32573564619.html?spm=2114.13010608.0.0.dDXTx3

Servos:
https://hobbyking.com/en_us/hxt900-micro-servo-1-6kg-0-12sec-9g.html

Servo extension leads:
https://hobbyking.com/en_us/10cm-servo-lead-extention-jr-26awg-10pcs-bag.html

Elevon linkages (these are too short for mechanical elevon differential - so use electronic differential, 2 pcs required):
https://hobbyking.com/en_us/extreme-3d-1100mm-replacement-control-rod-1-pc.html

Joining root wing section to tip wing section and holding servos in place:
https://hobbyking.com/en_us/high-stength-fiber-tape-24mm-x-50m.html

Elevon hinging (both top and bottom surfaces) and joining fins to wing tips:
https://hobbyking.com/en_us/1-x-4m-roll-3m-blenderm-tape-hinging-tape-twin-pack.html

Hatch latch:
3M™ Dual Lock™ Reclosable Fasteners (clear not black)

Battery holder bracket mounting:
3M™ Dual Lock™ Reclosable Fasteners (clear not black)

Joining wings to fuselage:
PVC Tape (12mm)

Nose weight:
Lead fishing sinkers (1x 0.5 oz, 2x0.25 oz for the Z230 version)

Weights:
Root wing section (Z230 version): 81g
Tip wing section (Z230 version): 44g
Fin: 18g
Elevon: 11g
Fuselage (nose + rear): 105g
Hatch:17g
Total printed weight (less battery, servos, spar, joiners, tape, etc): 429g

Control throws

These are what I use for the glider version. They are likely to be too large for beginners and for the motorized version.

All measurements relative to the trailing edge at the inner end of the elevons.

Neutral: 1.6 mm of up elevon

Elevator: -4.7 mm to +8 mm

Aileron: - 10.8 to +16.5 mm

In the tx mixer I set the elevator throws to be 45 % and the aileron throws to 100 %.

I set the elevator to 20% exponential and aileron to 45% exponential.

These throws are sufficient to allow a very fast roll, which is why either exponential or dual-rates are needed.

Note, using too much up elevator in a loop will cause the glider to stall at the top of the loop and spin out, so be careful to fly it all the way around the loop to maintain speed (or reduce the maximum elevator throw).