Fun and easy science experiments for kids and adults.

Trash airplane

Build an airplane from what you find in the trash. Can you make your vehicle fly according to Bernouille's principle or more like a kite?

Gilla:		Dela:

Materials

Trash (for example plastic and paper packaging)
1 pair of scissors
Tape
1 wooden pallet
2 nails
1 hammer
2-4 strong rubber bands

Step 1

First, build the launch pad. Fasten two nails a few centimeters (1-2 in) from one of the sides of the pallet. They should be about 50 cm (20 in) apart. Tie a pair of rubber bands together and thread them over both nails.

Step 2

Place the ramp at an angle, with the launch device facing upwards.

Step 3

Bring forth the pile of trash. Each participant (feel free to make this a competition) is only allowed to take three objects from the pile. From these three objects you will build an airplane that will be launched from the ramp. You may use scissors and tape.

Step 4

Pull the rubber band backwards and place the aircraft in front of it.

Step 5

Release the rubber band and see how far the plane flies.

Short explanation

Your aircraft will fly the longest if you achieve a lot of lift and little air resistance.

Long explanation

Lift is the force that lifts the aircraft upwards into the air. On an ordinary aircraft, that force arises through the shape of the wings. If you look at an aircraft wing from the side, it's straight on the underside and curved on the top. So when the wing cuts through the air, the air that passes above the wing must take a longer path than the air that passes below the wing. Since the air masses meet again behind the wing, the air moving above the wing has the same time to pass the wing as the air below. This causes the air above the wing to move faster than below. Bernouille's principle states that the faster air moves over an object, the less the air pushes on the object (the air pressure is lower). Therefore, the air below the wing pushes more than the air above the wing, and the wing is therefore pushed upwards.

However, if your aircraft achieves lift, it will probably not arise because of Bernouille's principle, but instead because of the same mechanism that lifts a kite. When the aircraft is launched forward/upward, the underside of the wings "collects" a lot of air as they travel through the air. This means that many air molecules are within a small volume and push on each other and what is around them. They therefore push on the wing and the aircraft is pushed upwards.

Since lift is perpendicular to the direction of travel, it contrasts with the air resistance, which is a force that is completely opposite to the direction of travel. Air resistance occurs due to the aircraft colliding with air molecules. These molecules (mainly nitrogen and oxygen molecules) absorb kinetic energy which the aircraft then loses.

Test and improve

You have now built your first prototype. There are probably improvements to be made. In order to keep working on your design, try answering any of the following questions.

What happens if you make the fuselage more rocket-like?
What happens if you make it lighter?
What happens if you make the wings bigger?
What happens if you build the wings according to Bernouille's principle (see above)?
What happens if you change the tilt of the launch pad?
Will a bullet go further than your plane?