1:12 Scale Schempp-Hirth Discus Sailplane Glider

The Schempp-Hirth Discus is a high-end German sailplane designed in the 1980s that has racked up six World Gliding Championships over its lifetime. It is an aircraft known to be easy and graceful to fly with great performance and handling.

For this project I made a 1:12 scale Schempp-Hirth Discus inspired glider using foam board and cardstock paper. I decided not to include a motor or any form of thrust to the aircraft to highlight the aerodynamic qualities of this glider. This is a simple project that can be completed in a few hours and requires minimal tools and technical skills.

I am a grade 11 student at the Virtual Learning Centre and hope you enjoy this build.

For this project I used:

• x2 foam boards 28" x 22"
• x1 Bristol board (cardstock) 28" x 22"
• x1 wood dowel 5/16” x 36"
• x3 sticker paper sheets 11" x 8.5"
• Scotch tape
• Fishing sinkers
• Black acrylic paint (optional)

As well as the following supplies:

• Hot glue gun + glue sticks
• Razor blade + scissors
• Paintbrush (optional)

Before you begin this project, it is a good is a good idea to familiarize yourself with the aircraft.

I began by designing the aircraft in Fusion 360. Above are some templates I created to help with the design and build process. It includes all the measurements for this project. The stl. file for the aircraft is downloadable below.

The first step of this project is to make the fuselage. To minimize the weight of the aircraft, we will use foam to create ribs and connect them using a dowel. This will provide structural strength and also keep the weight of the aircraft at a bare minimum.

Begin by cutting out ribs of the cross section of the aircraft. I've included a template that can be traced onto a foam board. The aircraft will have a total of 13 spars about 1.5 to 2 inches apart and up to 4 inches apart at the rear end.

Once the ribs have been cut out, cut out holes in the spots marked to create a passage to slide the dowel through.

Cut the dowel in two pieces; 16" and 10" respectively.

Next slide the ribs onto each dowel in order by number. Some ribs will have two holes to accommodate an overlap of the dowels for increased strength. Once they are in place, adjust till it matches the rough shape of the glider and hot glue in place.

With the skeleton of the fuselage complete, the next step is to wrap it with cardstock paper. Measure and cut out strips of cardstock to fit between each rib. Fitting each strip is a tedious task and requires a bit of trial and error to get each piece to fit. Make sure to test fit each piece before gluing and make any adjustments to the shape.

Despite my best efforts, the skin of the aircraft did not end up perfect, so I used some sticker paper and scotch tape to fix any blemishes and imperfections.

The tail on this glider is of a T shape and consists of a horizontal and vertical stabilizer.

To make these, simply trace out the shapes onto the foam board and cut them out.

To create elevators and a rudder, cut out the back portion of the stabilizers and tape them back on with scotch tape. Make sure to leave some room between the two cut portions when attaching them to allow movement. Creating a rudder and elevators will allow you to set trim on the aircraft when flying to allow for minute changes in airflow.

Next you want to attach the horizonal and vertical stabilizers by gluing them to one another. It is important that they are aligned at at 90 degree angle and that all moving parts can move freely without being restricted by other components. For example, the elevators movement was restricted by the rudder, so I cut out a small notch between the elevators to allow both to move.

Once the tails construction is complete, it can be attached to the rear end of the fuselage. Once the glue has dried and it is attached securely you may use some cardstock to blend the shape of the fuselage into the tail.

Before moving onto the wings there is one last detail to address: the nose cone.

Cut out a few small pieces of the foam board and glue them to each other. Slide and glue this onto the nose of the aircraft. Next use a razor blade to taper it down and shape it into a nose cone. Now the fuselage looks complete.

This step is for aesthetic purposes only. Paint a canopy onto the front of your glider using black paint. Feel free to add any other details such as aircraft registration, panel lines etc.

The wingspan of this glider is more than double its length. The Discus has very long, flexible, narrow wings that bend upward when in flight.

To create an airfoil shape, I used an unconventional way by stacking two layers of foam board and rounding the leading edge.

To begin you will need to cut out two wings 28" in length and 3" in width. Mark the wings 12" from the ends and taper the wing down to 1". Make sure both wings are symmetrical when cutting.

To create an airfoil shape, cut out two more pieces of foam board 16" x 2.5", and glue it on top of the wing from the last step. Glue it so that the leading edge of the smaller wings is 1/4" behind the edge of the main wing (refer to the second image). Once it is all aligned and glued, round all three edges of the leading edge with a razor blade. Cut out strips of sticker paper and stick it along the leading edge to create a round airfoil shape.

Repeat this on the trailing edge, but rather than rounding the corners, taper them down gradually (refer to image 5). Cover the trailing edge with sticker paper as well.

Cut out small winglets from the foam board roughly 1" x 2" x 0.25" or whatever the size of the end of the wing is. Using a razor blade, cut the edge of the inside of the winglets and glue them to the ends of the wings.

Now that the wings are complete the only step left is to attach them to the fuselage. Run a 6" dowel through the center of the aircraft as marked on the template. The dowel should be resting on the a rib and the other dowel running down the length of the aircraft. Slide the wings onto each side and glue them in place. Take your time on this step making sure the wings are aligned with the rest of the aircraft.

The glider should now be complete! There are just a few steps left before it can take to the skies.

1.Determining the center of gravity

To find the center of gravity, place the belly of the aircraft on your finger and find the point where it balances without dipping forward or backward. The center of gravity for this aircraft should be about an inch behind the leading edge. To adjust this, add fishing sinkers to either the nose or tail to counter the extra weight of the opposite side. This will take a little bit of trial and error, but is integral for the aircraft to fly.

2.Adjusting trim

Adjust the pitch and yaw of the aircraft by trimming the elevators and rudder. You can make minor adjustments to the flight path and correct the flight path if there is wind, or if the aircraft is not flying straight.

Since this glider has no form of thrust, it requires some initial speed to glide. You can either give it a running head start or release it from a high elevation (hill, window etc.) to allow it to build up speed before gliding.

I hope you enjoyed this build. Experiment with your glider and make sure to have fun.

Happy flying!