SK-Hang Glider Model with Mamo II Control System

The very simple Jeldsky-style construction makes it easy even for beginners to get a feel for this interesting category. The build time of about 20 hours is also significantly shorter than that of a standard sailplane of the same size. Precise construction is essential for good flight performance.

Use a soft Pavatex sheet measuring 140 x 20 cm as your building board. Rub soap onto the blueprint so that the glue spots don’t stick to it (you can also cover it with tracing paper, etc.). First, we glue the nose strip (Item 3) to the profile board (Item 1). Make sure the profile is correct: the nose radius should face the straight underside of the profile board. All wood-to-wood and wood-to-balsa joints are secured with white glue. Use Brittfix only for balsa-to-balsa joints. The drying time is at least 20 minutes. We temporarily secure item 1 to item 2. Now we can fold open the wing board like a hinge and apply glue to the resulting joint. Close it immediately, pin it to the plan, and use the first, middle, and last ribs (item 5) to fix the exact profile alignment. The remaining ribs can then be inserted. The wing board must be cut to the exact width beforehand. The end strip (4) is glued in place in the same manner as items 1 and 3. After constructing the hinge box (items 15 and 16), glue the parts together. The dimensions must be adjusted to fit the sash profile. Cut out rib (17) accordingly and glue both pieces to the sash. It is best to secure it with two screw clamps and appropriate shims (to prevent indentations). The aluminum tab (19) can be easily cut out with a small metal saw blade so that it can later be riveted with No. 33. To do this, drill two holes ( $∅$ 3 mm) diagonally through parts No. 19 and 33. Countersink both sides diametrically at $90^\circ$ until a countersunk rivet (3 x 5 mm) fits. Using a vise, we can now press the rivet flush with parts No. 19 and 33. The end rib (18) is first sawed out in a rectangular shape

. Only the slot for the tab is cut precisely. Next, we insert the end rib (18) with the tabs (19 and 33) into the tab box, allowing us to transfer the exact shape from the wing side. After cutting it out completely, glue it in place in the same manner and secure it with clothespins. Once it has dried sufficiently, we can turn our attention to the wing end. First, we attach rib (6). Then we cut the wing board (13) exactly to size and attach the end strip (14). A 35 mm sweep is applied to the airfoil board (1). Now we first glue on the ribs (7, 8, 9, and 10). This provides a good support for the wing board and also ensures the correct angle of attack. Since an SK model is very delicate during flight testing, I strongly recommend—especially for beginners—cutting out the trim tabs (12) and reattaching them with the hinge plates (32). These should be only just movable afterward.

The final step on the wing is to glue on the end rib (11) and sand the entire airframe smoothly.

First, we cut the stringers (21 and 23) and frames (24) to size. Next, we secure the right stringer (21) to the template and glue both stringers in place at the same time using the frames (24). After the glue has dried, sand the top surface and glue the left stringers (21) in place. Using a large flat file, we file out the recesses for the reinforcements (22). The slots in the reinforcements are cut into each other. After gluing them in place, we can cut out the slots in the balsa wood (21). Fit and sand the fuselage ends (25) and fuselage nose (20).

Same design as the Luckystar. Description in MFS No. 10, October 1973.

The entire model is coated with a special clamping varnish (e.g., Kö-C), sanded with 160-grit sandpaper, and coated again. Watch out for drips! After coating, the model should be clamped for about 1 week to minimize warping as much as possible.

Assemble the entire model. You may need to pull the wings together with a rubber band. To do this, you can attach two wood screws (M3) to the bottom of the wing box.

Now fill the lead chamber at the rear of the fuselage until the model is balanced at the center of gravity (S). The model should also be balanced along its longitudinal axis. This can be corrected by adding a small amount of lead to the corresponding wing tip. Set the trim tabs (12) and the rudder (29) to neutral. Calm winds and flat terrain are essential for a successful first flight. You can now attempt the first flight. Hold the model by the fuselage at the center of gravity. It requires significantly more run-up than standard models. If the model dives too steeply toward the ground: Add more lead! If the model pitches up, remove lead until you achieve a glide of about 20 meters with an outstretched arm. Course corrections can now be made using the trim tabs. The trim tabs are also used for fine-tuning the glide. To do this, we must adjust both tabs equally upward or downward.

I hope you enjoy building and flying this model. W. Heise

Construction plans are available from the editorial office or directly from the author, W. Heise, Im Isengrind 35, 8046 Zurich