This Instructable is a thank you for all those who liked the Staple Sailplane and were looking for something a little more challenging. Many pilots will tell you that the planes they remember the most are the ones they first learned in. Because of this, I decided to do my next glider in the shape of a Cessna 172 Skyhawk, the plane I am currently using for my private pilot. This glider is smaller than its sailplane brother, measuring 40 millimeters in fuselage length, 53 millimeters in wingspan, and 8 millimeters in height. It is also slightly less aerodynamically adept than its sailplane counterpart, due to its short and wide wings and stubby empennage. It is, however, fairly stable and forgiving, much like the real C-172. Hope all of you enjoy it and post any suggestions, concerns, corrections, recommendations, and pictures in the comments section!
Step 1: Materials
- Most paper or post-its will work.
- The piece should be at least 4x6 centimeters.
- The piece should also have about the same thickness and weight of computer paper.
- Use standard staples. They are approximately 1.5 centimeters in length.
- Use a small, sharp pair.
4) Metric Ruler
- Small, clear rulers work the best for this project.
- Mechanical pencils or a well-sharpened wood pencil is ideal.
Step 2: Fold Paper in Half
Fold the piece of paper you will be using in half. If you are using a Post-it Note, fold the two sticky sides together. This will hold the sides steady during the next steps.
Step 3: Draw the Design
Draw the design onto the piece of paper using the template provided. Start from the bottom, and work you way upward, making sure you draw the reference lines. 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, the dotted lines indicate reference lines, and the solid lines indicate cuts. Draw the nose as a rectangle first, and then draw in the curve afterwards.
Step 4: Cut Out the Design
Unlike the previous Instructable, the glider has to be cut out before the staple is attached. Carefully cut out the design, remembering to cut out the black lines specified on the diagram. Cut out the nose as a rectangle for now. 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.
Step 5: Fold the Ballast and Tail
Fold the ballast inside the fuselage as shown in the pictures. Snip off one of the horizontal stabilizers and fold the other one inside the fuselage as shown. Be careful not to cut or tear off the other stabilizers in the process. Fold the entire cutout in half when finished.
Step 6: Add the Staple
Carefully add the staple to the design as indicated, pressing the layers together so that they don't get warped. 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. After the staple is applied, cut out the shape of the nose.
Step 7: Fold the Wings Down
Fold the wings down as indicated by the dashed lines. Again, be as accurate as possible. Adjust the vertical stabilizer so it is parallel with the fuselage of the aircraft.
Step 8: Add Camber
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. You can also use a pencil or sharp object to create the curvature.
Step 9: Add Up Elevator
This next step is extremely important in ensuring that the glider will fly. Bend the trailing edge of the horizontal stabilizer about one-eighth 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.
Step 10: Add Dihedral
Although it may not appear like it, the C-172 does have dihedral. The Cessna 172S Pilot's Information Manual states that the wings have a 3.5 degree dihedral. For this model, you will have to add extra dihedral to increase the roll stability of the glider. 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.
Step 11: Preflight and Solo!
Every student pilot anticipated the moment the instructor hands them the controls, exits the airplane, and tells them to be safe and have fun. While it is not the same excitement of flying a real aircraft, there is no doubt that anticipation has been building during the tedious construction of this paper glider, and now is the time to reward your hard efforts!
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 on the Staple Sailplane Instructable
Step 12: Decorate Your Cessna!
To turn the glider into a C-172 look-a-like, draw details on the glider, such as windows, wingtip stripes, and tail numbers using permanent markers 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. You can also add details such as landing gear and wing struts by cutting them out and gluing them on with superglue. 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 :-).
However, exercise extreme caution, as the side-effects of obsessive detailing can be irreversible. This is an example of what happens when one gets too excited about the whole process and goes completely overboard. With all the extra weight, its a miracle it still flies. As for the livery, well, I saw these planes at some random flight school and thought they looked cool ;-). I might attend... after I get my social life back.
Here is a link to a YouTube video
of this C-172 flying.