Clipper : Rubber powered Free flight model

The clipper, a rubber powered free flight model with a folding propeller for longer glides. The design is inspired by the immortal Gollywock design kitted by Midwest. Flies on a 1/8 loop of rubber hand has reasonably long flights. The model seems to be attracted to trees and rooftops, so avoid flying near those.

Rubber Bands: I recommend FAI tan rubber from a free flight supplier ( Peck Polymers , FAI Model Supply ). Two loops of 1/16th inch should do well. 1/8 inch will also work, but keep it to one loop. The hook size makes it hard to fit more rubber.

Printing: I used basic PLA and 30% infill, and I set the first layer to .16mm for that transparent look. This model depends on a good first layer so make sure the z-offset and extrusion rate are dialed in. Print the pins lying perpendicular to the bed to maximum strength. Uses supports and brims where required. If using LWPLA or use the included brace to keep the structural beams aligned. Otherwise your model may have unexpected trim changes due to the rubber band bowing the fuselage. Please take care with the folding propeller assembly: if it were to fail it can launch a propeller blade some distance. A fixed pitch prop is included as an alternative. 

Assembly: Wait for parts to cool then carefully remove from the plate.

1. Snap the wing on in the middle of the ridged section. Take care of the hook tabs, they layers are inline with the force. Too much bending can cause them to fail.

2. At the two widthwise grooves in the wings, carefully crease so that the wingtips point upwards (plate side up). The angle should be about 30 degrees. The crease line is not perpendicular to make the angle of the airfoil lower. Add a drop of glue or a strip of tape to the crease to hold the angle.

3. Snap in the stabilizer next, flat plate side up.

4. place the propellers in the open slots with the concave side  facing the circular ridge in the center of the hub. Insert the pins into the side of the hub with a horizontal line above the hole. If pins are loose, try the opposite hole, it should be smaller. Add a bit of glue to the flat portion of the pin to secure.  Check the propeller periodically and replace if any parts become damaged of loose.(I haven't had any issues after 30 flights)

5. Push the hook through the hole in the front, add the washer to the pointed end. Pre fit the propeller assembly on and check for free rotation. use a file or hobby knife to adjust the fit as necessary. Apply small amount of glue  to the inner hub of the prop, then push it on the hook concave side towards the tail.

6. Optional: add the brace between the top and bottom longerons of the fuselage. This reduces bending with lighter (lower infill) prints.

7. Loop one end of the rubber band (or rubber band chain) around the capstan in the rear. pull that end through the loop to form a hitch. now pull the other end over the hook. If using the optional brace run it through the large center hole.

Test Flying: Make a couple of test glides to verify weight and balance by gently tossing the model. If model stalls or undulates while gliding move the wing back. If model lawn darts or dives steeply, move the wing forward. 

Now wind up the model and let it fly. Add aileron trim to correct for any rolling due to torque. Add rudder to set the direction of the turn and up elevator to increase the climb angle. For more information on trimming free flight models read this trimming article at the National Free Flight Society's library. 

Update 7/26: revised prop pin an hub fit, added a marking. Making sure things are tighter. 

9/13: Updated wing and Prop Hub, All new files named updated. These are some minor tweaks to reduce friction and make the wing easier to print.