Card Stock & Paper Twin Fin Delta Airplane

I used to avoid delta wings, but lately I've been having a lot of fun with them. If nothing else, they have a compelling look! The design at hand is quite simple. It will take 45 to 60 minutes to make.

This glider is best suited for straight flights and should be thrown in calm conditions. I encourage you to use it as a starting point for your own designs. The wing shape could be easily altered; the two fins could be replaced by a central fin; you could add a tail extension; and so on.

It took a while to get this glider right. The first two attempts did not fly well at all, so I shifted to more conventional wing designs. After days of disappointing tests, and many versions, I looked at the original little purple shuttle, smiled, and returned that concept. It worked!

-Sheet of card stock (8.5" x 11", 65 lb.) [see comments for metric conversion; thank you, Peter J.]

-Sheet of paper (8.5" x 11")

-Large vinyl coated paper clip

-Glue stick & liquid white glue

-Scissors

-Hobby knife

-Ruler

Download the PDF file. Print the plans at 100% scale on the sheet of paper. Cut the shapes out, but only approximately. Use the glue stick to adhere them to the sheet of card stock. (Alternatively, if you have a printer that handles heavy card stock, you can print directly onto that; I have not tested this, and it may adversely affect the glider's balance and flight.)

The glue will cause curling, but that's okay. Most of the pieces can be straightened by just working them with your fingers. The main piece does not need to be completely flattened. In fact, it's helpful if the wingtips remain slightly raised.

I've added a JPG in case it is useful to you. Check the comments for some good ideas!

Be careful and patient with this step! Most of the cuts can be made with scissors. You can use the hobby knife to poke the ends of the very thin strips (such as the two points indicated above) in order to remove them, and to make cuts where there are tough angles.

Before starting any crease, think about which side you want to have showing (paper or card stock), and orient the piece accordingly. Carefully line up the dotted line with the edge of the ruler, and push down or pull up, depending on how its oriented. The center of the wing is quite long and you may need to approach it in steps. The wing tips should be about 10 degrees above horizontal.

Add a couple drops of glue to one of the tabs. Use a scrap of card stock to spread it into a thin and consistent layer. Wrap the opposite tab over and pinch the two together. Repeat with the other pairs of tabs. The side pieces, which match the profile of the nose, can be glued on later. If you know you will only be flying indoors, you may not need those extra pieces. They add useful nose weight and durability.

A glue stick is good for attaching the wing braces, but you should use liquid glue for the fin pieces. The wing braces will line up with reference marks, and all you need to do is apply pressure across each piece to ensure it bonds. The fin tabs can be attached to the main piece first, to the fins first, or in some combination, but you should first test fit the fins to make sure they interlock easily with the main piece. You may need to widen the slots a tiny bit.

Curl down the leading edges of the wing a bit. You can do this by repeatedly pinching with your thumb and fingers, using the curve of your fingertips to shape the material. You can also do it by repeatedly pressing and sliding the piece over the edge of a table (while being careful not to damage the fins). Use the pinching technique to flatten the trailing edges, or curl them down ever so slightly.

Test fit the nose/fuselage piece and the main piece, and widen the slots if necessary. Once together, use some dots of liquid glue at the seems to secure the pieces. Slide the paper clip in from the front and clasp it to the wing tab. Depending on the final balance of the plane, which will vary with different materials and glue, the clip should protrude by about 1/8" to 1/2".

Adjusting weight and control surfaces is called trimming. It is a delicate process, so you should conduct the first flights indoors. It is also important that you throw the delta as consistently as possible—straight, level, and gently.

The glider should fly for about 20 feet, gaining a bit of altitude before descending steadily. If it is pitching up too much, bend down the center control tabs located at the trailing edges of the wing. Adjust them in very tiny increments. If the problem continues after several adjustments, you can also bend down the elevons (the outer control tabs of the wing) and/or position the paper clip farther forward.

If the glider is veering to the left or right, compensate with one or both rudders (on the fins). Angling a rudder to the left will nudge the glider's flight to the left, and an angle to the right will nudge it to the right. In theory, the elevons can induce a roll to the left or right, but I haven't found them to be very effective; the inherent stability of the dihedral and convex main piece probably cancels them out. Nevertheless, you can experiment with their influence on roll by adjusting one up and the other down.

Remember that this is a small and light glider that is very easily effected by a breeze. You can expect some rolls, stalls, nosedives, and other catastrophes when flying outdoors. A light tailwind, though, is helpful. Good luck!

In case you want to see some flights and clips of the build, check out the video.