Introduction: Foam Walkalong Glider

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This instructable shows you how to make a walkalong glider by thermoforming a styrofoam sheet. The foam sheet used here was obtained from the Owens Corning Raft-R-Mate product available in the insulation department of most home building supply stores. Here's a video of the X-Surfer foam walkalong glider inside:


...and when there is no wind outside, here's a flight down the sidewalk:


It is reccomended that first timers start with the tumblewing walkalong glider design as it is much simpler to build and easier to fly because it is slower.

Step 1: Cut Out the Pattern Outline of the Wings

First print out the half wing outline twice and cut each form. Turn one of the outlines upside down and tape the two pieces of paper together at the wing root. The resulting outline should have a wingspan of about 28cm (14 inches):

Attachments

Step 2: Cut Out Piece of Raft-R-Mate Material

the Owens Corning Raft-R-Mate product can be found in the insulation department of most home building supply stores. Alternatively, thin (1mm) depron or other foam may be used. If the material is already in sheet form, this and the next step on thermoforming the Raft-R-Mate into a sheet can be skipped.

The Raft-R-Mate product does not come in nice flat sheets and must be cut and thermoformed. The pink foam is cut so all bends are parallel to each other. This makes thermoforming the material into a flat sheet easier. Here's how to cut the foam:

Step 3: Thermoform Raft-R-Mate Into a Sheet

Using a house hold iron set to a temperature suitable for acrylic, Gently heat each bend in the Raft-R-Mate material. Do not apply pressure, but wait until the material gives. Rock the iron to evenly heat the bent material, holding the iron flat against the seam. If the iron is melting the material, it will get sticky and the iron should be set at a slightly lower temperature. Not enough temperature and the material will not give when heated. Just the right temperature and the material will give and the iron will still slide over the material. Applying too much pressure or force on the iron will buckle the foam, creating creases which will affect the material's structural integrity. Here's a video of the cut material being thermoformed into a sheet:

Step 4: Cut Out Foam Sheet According to Pattern

In this step the flattened foam sheet is cut according to the pattern created in step 1. There should be enough material for 2 gliders in the Raft-R-Mate material used in the video (if the cut lines do not overshoot the angles too much):

Step 5: Draw Lines for Elevon and Airfoil Bends on Top and Bottom of Wing

In this step the lines creating the elevons are drawn on the top of the wing cutout and lines creating the airfoil are drawn on the bottom of the wing:

Step 6: Thermoform Dihedral and Washout Angle

Step 6 involves thermoforming a twist and upward bend (also called [http://en.wikipedia.org/wiki/Dihedral_(aircraft) wing dihedral]) to each wing. The wing root will have a higher angle of attack than the with tip which prevents tip stalls when applying control inputs about the [http://en.wikipedia.org/wiki/Roll_(flight) roll axis] (also called the [http://en.wikipedia.org/wiki/Washout_(aviation) wing washout angle]). The dihedral in an airframe design makes the aircraft more stable in the roll axis.

It is important to do this step before bending the airfoil.

Step 7: Thermoform Airfoil Shape to Wing

In step 7, an airfoil shape is thermoformed in the wing. Here's a video of making the first bend along the line closest to the leading edge of the wing:


Do the same for the remaining two lines:


Step 8: Thermoforming Elevons

Thermoform the elevon surfaces to the trailing edge of the wing:


Step 9: Flatten Out Airfoil, If Needed

If needed, flatten out the airfoil and elevon surfaces. This thermoformed model has airframe design features exagerated for clarity and needs to have them flattened out to improve its glide ratio.

Step 10: Fabricate a Nose Boom Ballast

A paper clip is straightened out to make a forward ballast to be attached to the nose. This weight will allow adjustment of the weight and balance:

Step 11: Test Flights

The following step involves elevon and ballast adjustments to get the glider flying slowly, smoothly and in a straight line. Initially, the ballast should be as forward as possible.

Test fly the glider, launching it with a slight nose down attitude and at approximately walking speed:


adjust the elevons to get the glider flying straight. In the last video, the glider flies too much to the right, so the left elevon needs to be flattened:


The turning tendency has been corrected. Here is the second test flight:


In the last video, the elevons are trim too nose up and need to both be flattened:


How does it fly now? Let's see:


After more elevon trimming, the glider flies like this:


For general flying information, see the instructions at:
How to fly the x-surfer type walkalong glider

Step 12: Flying Lessons

For general flying information, see the instructions at:
How to fly the x-surfer type walkalong glider

Step 13: First Controllable Soaring Flight

The launch of the glider should be as close to the glider's trim speed and altitude as possible to avoid pitching the nose up (too fast) into a stall or entering too steep a dive (too slow). The glider should keep flying straight out of your hand. Once the glider is in stable flight, bring the controllable slope (here a 50cmX70cm piece of cardboard) so as to position the glider in the rising wind at the top edge of the controllable slope. Here's a video of an indoor flight (same as from first page):