Nutjob

The wing is made from EPS foam. A fully symetrical section was chosen, and cutting templates made and placed in a jig. Clean-cut panels 24" long and 12" wide were produced, since blocks of foam that size were available. A 1/4" x 1/4" slot was added top and bottom, for hardwood spars, and a "fishmouth" was added to the leading edge to accept a 3/8" hard balsa stick, which will be planed and sanded to give the correct leading edge profile.

Several more of the same-sized foam blocks were available and a second pair of wing-panels were produced for another pilot. Even more panels can be produced as needed.

The top and bottom 1/4" sq. hardwood spars and the 3/8" sq. hard balsa spars were scarf-joined for extra strength. The wing will be flat (no dihedral -- hope I don't regret that!) so the spars can function as joiner braces.

I didn't join two pieces of wood in the middle. I used a solid central spar with extensions scarf-joined on each end. This makes the spars at the center of the wing integral pieces of wood, and moves the joins out close to the wingtips, where the stresses should be far lower.

While surfing on Tower, I spotted these fuel tanks for sale. They are replacement tanks for the Hobbico Twinstar MkII ARF (which looks suspiciously like a twin version of my old Sky Vista). With a capacity of 4-oz., and an approximate size of 2"x1-7/8"x1-3/4" these tanks are perfect for a little, sratch-built .25 like the Nutjob!

I paid US$2.85 for these tanks, and for that price you get two! Seeing as just a clunk can cost as much $1.99 and you're lucky if you can find a fuel tank stopper for under $1.79, two complete tanks with all hardware for $2.85 is an absolute bargain. I bought three sets (six tanks). No, you can't have one! Get your own!

I'm using built-ip ailerons, shown here with their triangle-stock leading edges not yet attached. Note the blocks into which holes will be drilled for the Du-Bro torque rods (shown).

Originally, I thought I would sheet the rear part of the wing, and hinge it as the aileron. After removing the trailing edge section of the wing with the hot-wire cutter, it appeared too flimsy and flexible. So without any suitable aileron stock to hand, I decided on this built-up approach.

The center-section of the wing is fitted with a light-ply half-rib. This leys back into the top and bottom main-spars, as well as the 'fish-mouth' leading edge spar. It is cut with an integral wing pin that locates the front of the wing into a slot in the fuselage, in front of the wing saddle.

Torque-rods allow a single, centrally located () servo to operate the ailerons.

I had a misfortune here! After fitting the torque rods and gluing them into the wing, I noticed one was slightly bent. While trying to 'coerce' it straight, it snapped! Fortunately, I had another torque-rod kit available, but this lead to some ugly, butchery of the woodwork covering the assembly.

The 1/16" ply plate has a mate on the under-surface of the wing. These will eventually be drilled to accommodate a 1/4-28 nylon wing bolt.

Small hard-balsa blocks are glued into each wing-tip, to accommodate dowel/pins and machine screws. (The middle block has a 4-40 blind nut behind it.) These are to accommodate any lightweight attachments that may come to mind. Shown here: a pair of vortex-reducing tip-plates.

The fuselage is built up from a number of hand-cut parts made of thin ply and balsa. It resembles a 3D jigsaw.

The parts are slotted and equipped with tongues so that they lock together in place. Entire fuselage sub-assemblies can be put together without adhesive for testing.

I think this sort of design should not be attempted without some sort of 3D drafting or CAD software assistance!

Far from being finished, the model is barely started! Here's a look at the engine and wing mocked up. No fuse or tail feathers as yet.

A friend says "Forget the tail! Build a flying-wing!" Hmmm. The mockup does look like it would fly, doesn't it? No! Maybe later, Ian, but for now, I want something a little more conventional, and equipped with landing gear!