Introduction: 20-Minute Aeroplane

About: I have always loved the feeling of finishing the construction of an object and if I don't have something I need or want I usually give it a go to build it from what I have. Usually though, I look at a boring o…
This is a very basic polystyrene glider made almost entirely from stuff you can find in rubbish bins. It should take about 20 minutes to get it flying, but there is no need to rush through it if you want it to work better.

In this instructable I will also explain the jobs of most of the control surfaces of an aeroplane and how to use them to make your plane fly the way you want it to. These basic control surfaces control (and stabilize) almost all aeroplanes and have been used for over one hundred years with relatively few changes.

To make this instructable, you will need:
- Polystyrene foam (Mine is from food packaging)
- A sharp knife
- Scissors
- Tape
- A pen to draw/trace the design onto the foam
- Ballast (I use Prestik but you can also use a coin or putty or anything of the correct weight which can be applied to the foam)

Click on the last picture in this step to get the full sized image and from there copy and print it to trace onto your foam. Re-size the image if you want to make your plane a different scale.

Here is a short video of it, It would fly for longer but I don't have the space to fly it in.

Step 1: Trace and Cut the Parts

Cut the four sides off the sheet of polystyrene you have. Your usable polystyrene may be less than mine shown here so consider this and re-size the plan accordimg to this.

Print the plan and cut the 3 parts out of it. Use them as a stencil and draw a line around each of them onto the foam. I do not have a printer so I held the translucent foam over my screen and traced it like that.

Cut these parts out of the foam.
The fuselage (in the plan) has 2 thick black lines on it, cut these out. The thickness of your foam will determine the vertical thickness of the lines you cut out.

The Control surfaces are marked in the plan with Orange for hinges and Green for cuts. Make slits in the foam where green lines are shown in the plan.
Cut along the Orange line in the fuselage(body) only. This will remove the rudder from the fuselage. Don't cut along any other orange lines.[Picture 3]
Remember to also cut a small piece out of the front of the horizontal stabilizer.[Picture 4]

I have added a Google Sketchup model of the three cut-out parts in this step for you to download for reference if you want.

Step 2: The Tail

Slide the horizontal stabilizer into the slit in the back of the fuselage.

Put tape onto the rudder and tape it back onto the fuselage. If it doesn't fit properly, trim it or the horizontal stabilizer until it does. Only tape the vertical cut you made, leave the horizontal cut as it is. Test that the rudder can be rotated along the taped axis. The top part of the rudder should stick out when the rudder is moved to the left or right.

Step 3: Wings

Make sure you have the correct slits in the trailing edge of the wings.[Picture 2]
Bend both of the wings up from the centre line.[Picture 3] This angle is called Dihedral. If the wings slope downwards that is called Anhedral, but in this model they slope upwards to the tips of the wings. This allows the aeroplane to stay upright while it flies and it would otherwise tend to wobble in flight.

Simply slide the wings through the hole in the fuselage and ensure that they are facing the right way. They should fit well with the centre line of the wing hidden by the fuselage.

Use the pictures and/or the sketchup model in the next step to see how the wings should look when they are in place.

Step 4: Ballast and Balancing

Add ballast to the nose in the form of anything you have which appears to be the correct weight. I used two small blobs of Prestik (stuck on either side of the nose) but a small coin taped to one side of the nose can work equally well.

To balance the aeroplane, add or remove weight on the nose until the plane can balance like a see-saw with a point on the wing being the balancing point or pivot. This point (Centre of Gravity) is located about one quarter of the wing's breadth back from the leading edge of the wing. Allow the aeroplane to balance between two fingers, each under the wing at this point on both sides. When it no longer falls forward or backward, it is properly balanced.

(The CoG is shown in the Google Sketchup model as a circle under the left wing)

I have added a Google sketchup model of the complete aeroplane in this step for you to download if you want to use it. It is shown with a coin taped to the nose as ballast.

Your glider is finished! to fly it, simply hold it under the wings and chuck it in the direction you want it to fly. The next step explains how to make it fly straight or any other way you want it to.

Step 5: "Trimming" the Aeroplane (Pitch Axis)

Test fly the aeroplane and observe its motion.

If it flies straight, you do not need to trim it. I will speak about up-down motion first. This axis is called PITCH. To change the pitch, you will be using the Elevators found on the horizontal stabilizer. They stay in the same position as one another, so if one is up, the other will be too.

If the aeroplane climbs and then falls quickly, it has too much nose-up pitch. To correct this, bend the elevators down a little bit and try again until it flies in a level, stable manner.[See Pictures 1 and 2]

If the aeroplane just dives, it has a nose-down pitch. Correct this by bending the elevators up a little bit and fly it again until it flies level.[See Picture 3] You can also try reducing the ballast weight on the nose. 

If you want the aeroplane to do a loop, bend the elevators up and throw it fast.

Step 6: Trimming (Roll Axis)

The aeroplane may tend to "lean" to one side as it flies and fly in a circle. (Like a motorcycle turns left or right.) This axis is called ROLL. This can be fixed by using the Ailerons found on the wings. The ailerons do the opposite thing to one another, so if you bend the left one down, the right one must be bent up.

If the aeroplane rolls to the left, bend the Right aileron Up and the Left one Down and fly it again to see if it flies straight yet. [See Picture 1]

If the aeroplane rolls to the right, bend the Right aileron Down and the left one Up. Fly it again to test if it flies properly and keep trimming until it flies straight. [See Picture 2]

If you want the aeroplane to do a Barrel-Roll while it flies, bend the ailerons as described above but bend them more and throw the aeroplane hard.

Step 7: Trimming (Yaw Axis)

The third plane of motion of an aircraft is its direction, ie. North, South, East, West. (It is the same kind of motion as steering in a car.) This axis is called YAW. To control the direction the aircraft faces, we use the Rudder. It is bent left or right depending which way the aeroplane needs to be facing.

If the aeroplane turns to the Left, bend the rudder to the Right. [See Picture 1]

If the aeroplane turns to the Right, bend the rudder to the Left. [See Picture 2]

If you want the aeroplane to fly in a circle, just bend it to the side you want it to turn to.
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