This instructable, inspired by the proliferation of micro-sized paper airplanes, contains instructions for building a miniature sailplane out of paper and a staple. It has a fuselage measuring 40 millimeters, a wingspan of 60 millimeters, and a height of 7 millimeters. Despite its small size, it has surprisingly good aerodynamics, which is due to the fact that it shares similar dimensions and attributes with full-size sailplanes. This includes:
- High aspect-ratio (long and thin) wings for increased lift with less induced drag
- Slender and streamlined fuselage for less drag
- T-tail empennage/stabilizers for effective pitch and yaw stability
- Dihedral for roll stability
Due to these attributes, this small glider can glide for substantial distances, perform tight aerobatics, and even gain some altitude on thermals created from heaters.
Much effort, time, and prototyping has been done on this design to ensure that it is easy to build, easy to trim, and flies well. If there is any flaw or area that could use improvement, do not hesitate to put recommendations in the comments section. In addition, I have designs for smaller and more complicated paper gliders, and these can be made into instructables upon community request ;-).
Draw the design onto the piece of paper using the template provided. Make sure to be as accurate as possible and ensure that bottom of the fuselage is touching the folded side of the paper. Also make sure NOT to draw the design over the sticky portions of the Post-it Note if you are using one. The dashed lines indicate folds. CameronSS has created a PDF of the plan that can be printed out and attached to the sheet of paper being used. Thanks again, CameronSS!
Carefully add the staple to the design as indicated. The staple functions as a nose ballast to shift the aircraft's center of gravity forward. Make sure it is centered in the space provided. If not, remove it and insert another staple in the correct position. It is recommended to test the stapler on scrap paper to determine the exact location of the staples.
Carefully cut out the design. Ensure not to slice off the wings, cut too deep, or leave excess paper on the cutout. Also, it is important to make sure that the paper is perfectly flat to ensure symmetry of both sides. Any folds or curves on either side will result in an asymmetrical glider that will not fly. Discard the excess paper.
In order for the glider to fly well, you must add camber. Camber creates Bernoullian lift (lift formed by the pressure difference between the top and bottom of the wings) as well as strengthening the wings. Pinch the leading edge and the trailing edge of the wings to add camber. The max camber should be about half of a millimeter and be located halfway across the chord of the wing (NACA 7500). Make sure to apply the same camber for the entire wingspan.
This next step is extremely important in ensuring that the glider will fly. Bend the trailing edge of the horizontal stabilizer about one-fourth of a millimeter higher than the leading edge. This produces a positive angle of attack that points the wings upward in relation to the air around it. It is this angle between the wings and the "relative wind" that produces the majority of lift, and without it, the glider will not fly. The measurement is only approximate as you will have to adjust it later on.
Bend both wings upward until the wingtips are even with the top of the vertical stabilizer. Make sure both wings have the same dihedral and that the camber was applied evenly. In addition, ensure even up-elevator on the horizontal stabilizer and that the fuselage and the vertical stabilizer are straight and without warps.
Now its time to enjoy your hard work! Grab your glider by the fuselage and give it a very light toss. Note the direction of flight. If the glider dives, add more up elevator and decrease the dihedral. If the glider pulls up and stalls, decrease the up elevator and increase the dihedral. If the glider curves or spirals in one direction, curl the vertical stabilizer opposite to the direction it turns. If it still spirals, reduce the dihedral of the main wing. Keep repeating the process until the glider flies in the desired direction. If you need help, watch the videos below.
To turn the glider into a scale model of a real-life sailplane, draw details on the glider, such as a canopy, wingtip stripes, and tail numbers using permanent marker and/or pens. For working control surfaces, cut slits into the wings and outline with a pen. These can be used to trim the glider or perform aerobatics. When adding details, be careful not to add too much weight or alter the shape of the glider substantially. A detailed glider always looks better when it flies :-).