About this Plan
SW-107. Unlimited or Open Sailplane. Wing area 620 sq in. For 4 channels.
Quote: "SW-107. A mixture of new and old ideas has produced a mid-wing sailplane with excellent performance for multiple-task competition or fun-flying. By Harley Michaelis.
One of the nicest things about sailplane design is that for most of us, we never arrive. There is always something yet to try - new size, a different configuration, an innovative control linkage, an interesting airfoil, some construction technique, or some adhesive, tool, fitting, material or radio component - the possibilities never end!
The SW-107 includes a mix of new ideas and good things used before. Let's walk around it. Of special interest is the control system. It has genuine tip ailerons that operate differentially, coupled with rudder. This permits a coordinated turn without skid or yaw. Lightweight nylon coated cables operate these controls from two small servos set up in a unique manner in the fuselage. Spoilers operate a pitch compensator, avoiding unwanted pitch changes when thrown. In precision events, altitude loss is controlled with spoilers while con-stant speed is maintained. With the ailerons the nose stays right on track, rather than bobbing around as with rudder control, a luxury previously found only in much larger, more costly and more com-plex ships.
In appearance, it differs being a mid-wing, having both tapered and swept wing and tail surfaces, along with a very racy profile. The result is a distinct configuration that is different and eye-catching. Since wing sweep has a dihedral effect, along with ailerons, a much lower than usual dihedral is used which looks good. The stock fiberglass fuselage is beautifully engineered and superbly custom-molded. It is very light at the rear, reinforced up front where needed, and made of a resilient resin. Shoulders are perfectly aligned to facilitate true alignment of panels to each other, and are angled to fit flush to the roots. The fuselage, while hav-ing a semi-scale look, is still slim and sleek and sized to permit a firm grip at launch without danger of collapse as the tension builds up. The hatch is fiberglass, with no base, and just squeezes on and off.
The opening is long and provides easy access to the innards. A skid is molded in to protect the rudder bottom and the fin is shaped to protect the top. The 10% thick airfoil is inherently stable, allows high speeds, and has excellent stall charac-teristics. The tip used eliminates wash-out, so panels can be built flat and in high-speed runs the outer portions won't twist and bend downward as may be exper-ienced with wash-out. No nuts, bolts, dowels, rubber bands, switch, canopy hold-down, or receiver antenna mar the clean exterior. The new Air-Flow hinge allows fin, rudder and ailerons to be of very soft balsa. The stab is also light but when covered is firm, and with the rigid support used it doesn't flutter. The wing support uses lightweight spring steel blades that slip into a laminated center piece with dihedral built in. Ribs are simply and ac-curately made from a ply root cap, so no patterns are needed. Vertical webbing is sandwiched between spruce spars to make a sturdy 'I' beam, and a ply brace about a foot long lies against this to further in-crease strength and rigidity in this critical area. With an otherwise sturdy set of panels, the thermal can be safely escaped by a terminal dive!
With a proper choice of balsa and the current midget type servos, the all-up weight can be about 34 oz for a 7.8 az wing loading. The nose is shaped so a 225 or 450 mil cube-shaped battery can be placed well forward. With the light tail end, the ship will balance out without lead..."
SW-107, MAN, May 1981.
Direct submission to Outerzone.
Supplementary file notes
Article pages, thanks to RFJ.
Did we get something wrong with these details about this plan (especially the datafile)?
That happens sometimes. You can help us fix it.
Add a correction
Do you have a photo you'd like to submit for this page? Then email email@example.com
User commentsNo comments yet for this plan. Got something to say about this one?
Add a comment
* Credit field
The Credit field in the Outerzone database is designed to recognise and credit the hard work done in scanning and digitally cleaning these vintage and old timer model aircraft plans to get them into a usable format. Currently, it is also used to credit people simply for uploading the plan to a forum on the internet. Which is not quite the same thing. This will change soon. Probably.
This model plan (like all plans on Outerzone) is supposedly scaled correctly and supposedly will print out nicely at the right size. But that doesn't always happen. If you are about to start building a model plane using this free plan, you are strongly advised to check the scaling very, very carefully before cutting any balsa wood.
© Outerzone, 2011-2022.
All content is free to download for personal use.
For non-personal use and/or publication: plans, photos, excerpts, links etc may be used, provided that full and clear credit is given to Outerzone with appropriate and specific direction to the original content i.e. a direct hyperlink back to the Outerzone source page.
Unauthorized use and/or duplication of this material without express and written permission from this site's owner is strictly prohibited. If we discover that content is being stolen, we will consider filing a formal DMCA notice.