Introduction: Tailless Delta & Stndrd. Config. Mechanical Pencil Gliders
Welcome! To make these gliders, you’ll need fine motor skills, attention to detail, and patience. If you're new to making flying things, the guidance of someone who knows about aircraft and flight will come in handy, especially when it comes to testing and trimming the gliders.
If you are a teacher and plan to use these for a class project, you may want to have students work in pairs or small groups. Note that the tailless delta is easier to build than the other. For fun and some additional learning, I recommend a distance competition, a control competition (such as flying through a ring at a certain distance), or a combination of the two.
Here are some possible prompts for builders to answer.
- What is the mass of each glider?
- What is the wing span of each? (Once the glider is constructed, measure a straight line from tip to tip.)
- What is the wing area of each? (As with the wing span, you should be referring to a planform.)
- Using the mass and wing area, calculate the wing loading of each glider.
- Which design seems to have more yaw stability? What might account for this?
- Which seems to have more roll stability? What might account for this?
- Which seems to have a better glide slope?
- If you were a pilot, and these were full scale aircraft, which would you rather fly? Explain.
- What modification do you plan to implement, and on which glider? What do you hope the modification will do for the glider?
- If designing something entirely new, what considerations are foremost in your mind?
- Sheets of 8.5" x 11" card stock; 65 lb. or 180 gsm
- Plastic mechanical pencils with a clip on the main tube; 15 cm long (more information below)
- Pencil tip erasers
- Glue stick
- Metal ruler and hobby knife (not entirely necessary, but helpful)
- Clear adhesive tape; 2 cm wide
Step 1: Prepare Pencil
Find a mechanical pencil, preferably one that has a broken spring or is just plain worn out. It should measure 15 cm long, have a hexagonal shape, be made of light plastic, and have a pocket clip adjoined to the main tube. OfficeMax and Bic are two brands that I used, and I preferred the Bic because it seemed a touch lighter.
Remove the eraser and graphite. Take out the rod, which will probably require removing the tip of the pencil and making a cut to free a small rubber stopper. Remove the spring, and put the cap back on. Cover the other end with a pencil eraser.
Step 2: Delta—Print Plans & Cut Out Shapes
Print the plans onto a sheet of card stock. Use 65 lb. card stock, or 180 gsm. Gluing two sheets of lighter material together, such as some decent quality 90 gsm paper, could work (and thank you codemind).
Carefully cut out the shapes. If you plan to use a hobby knife, make sure it's very sharp. Younger builders should get permission from an adult before using a hobby knife.
Step 3: Glue & Make Creases
Before using your glue stick, double check that you're working on the correct side of the card stock piece. Applying a thin and consistent layer of glue, and attach the brace piece to the top of the main wing. Use a straightedge to start creases on all of the dotted lines. Start with the center line. In so doing, you will make the wing dihedral. The wingtips should rest about 5 degrees above horizontal.
Raise the interior elevons by about 5 degrees. Raise the slim outer elevons by just a few degrees. Carefully check for symmetry of the left and right sides.
Step 4: Finish Wing
Increase the angles at the wing tips to 90 degrees, thereby defining the vertical stabilizers / winglets. Now, use your thumb and fingertips to gently pinch along the leading edge to curl the card stock down slightly. Repeat several times, working incrementally, until the card stock holds the shape.
Before sliding the wing into place, check that the notch at the forward point of the wing is wide enough. Depending on the brand of pencil you're using, the clip may be too wide and you'll need to widen the notch.
Step 5: Secure Wing to Pencil
Get a strip of tape measuring 8 cm and make a reference mark in the middle. Find the point on the bottom of the fuselage (the pencil) that is 7 cm back from the very front of the wing. This is as far forward as the strip of tape will reach. Carefully adhere the tape to the fuselage (sticking to the sides) and then the bottom of the wings. Avoid pulling down on the wings while doing this.
Step 6: Standard Config.—Print, Cut Out Shapes, & Make Creases
As you will quickly notice, this standard configuration glider (that is, having a tail at the aft end) is more complex to build. Expect to spend 40 to 60 minutes working on it.
Cut out the shapes carefully, and then start creases on the dotted lines. The elevator (at the trailing edge of the horizontal stabilizer) should be raised about 8 degrees. The crease at center line of the wing and wing brace can be very mild, for now.
Step 7: Fuselage & Fin Work
Glue the long narrow fuselage strip to the top of main piece. Next, glue the shorter strip, which is 8.5 cm long, to the bottom of the tail boom. This one should end 1 cm before the trailing edge of the stabilizer.
Glue the shortest and narrowest strip across the bottom of the horizontal stabilizer. It crosses over the strip that was attached previously, and is flush with the end of it.
Bend the tabs at the bottom of the two vertical stabilizer pieces to 90-degree angles. Apply glue to one of the vertical stabilizers (i.e. fins), but not to the bottom tab. Unite it the two halves. After the glue has set for a couple minutes, apply glue to the tabs and attach the stabilizer to the tail of the glider. Use the reference lines.
Step 8: Wing Work
Glue the wing brace to the top of the wing and let the glue set for a minute. Re-establish the crease on the center line. The wing tips should be about 7 degrees above horizontal.
Apply glue to the wing roots. Carefully attach the wing. Make sure it is perpendicular to the fuselage.
Cut the four short black lines near the center. Now give the wings a slight undercamber by repeatedly pinching along the leading and trailing edges. Go slowly and check the left and right often for symmetry. A reference curve is in the plans.
Step 9: Secure Main Piece to Pencil
Slide the wing into place on the pencil. Get a strip of adhesive tape measuring 7 cm. Find the point on the bottom of the fuselage (the pencil) that is 5 mm back from the leading edge of the wing, and mark it. This is as far forward as the tape will reach. Adhere the tape to the pencil (stick to the sides) and the bottom of the wings. Lastly, get a 2.5 cm strip of tape and attach it to the top of the fuselage, a few millimeters in front of the vertical stabilizer. Pinch the tape to the sides. Be careful not to bend the tail boom.
Step 10: Test Flights and Trimming
Trimming refers to small adjustments of an aircraft's control surfaces and/or weight distribution in order to achieve a desired flight path.
If possible, do the test flights and trimming indoors. Throw the gliders gently and level. It's unlikely that they are tail heavy, but you'll notice it pretty quickly if they are. A tail heavy aircraft flits and flops through the air, and tends to crash quickly and violently. If your glider is flying pretty stable flight but is descending quicker than you'd like, increase the deflection of the elevons or elevators a tiny amount. You can also experiment with shifting the center of gravity back, either by pushing the eraser further onto the pencil or by swapping it out for a used eraser.
A tendency to roll left or right is most likely a result of asymmetrical wings. Inspect the wings meticulously and try to correct any inconsistencies. If the standard configuration glider is gently turning to the right or left with just a slight roll, you can address that with the rudder. With the delta, you should be able to counteract the tendency with adjustments to the outer elevons. You could also warp the trailing edges of the stabilizers a small amount, like tiny rudders. For the sake of brevity, I'm not offering a full explanation of how to adjust rudders and elevons. Maybe you can support your local library by checking out a book on the basics of flight.
Lastly, don't forget to have fun! I hope they fly well for you. If they don't, keep in mind that everyone who ever made a glider has gone through the same frustration you're feeling. Keep at it, and you will get better!
Step 11: Video [optional]
If you are a student, do not watch this! No, seriously, you shouldn't. Preserve your objectivity for testing and comparison of the two gliders.
Grand Prize in the