Building a Propeller Driven Vehicle Lesson 11 Building a Propeller Driven Vehicle

Materials Goggles Propeller (per group) Bucket of building pieces (per group) 3 rubber bands connected (per group) Materials for teacher to assemble propeller units: 10 propellers 10 hooks 20 brass eyelets 10 white connectors Colored markers Masking tape Pictures of propeller driven vehicles Bucket of building pieces The teacher may want to go ahead and assemble the propeller driven vehicles for each group.

Overview You will brainstorm what you know about propeller driven vehicles. You will discuss design features you think are needed for propeller driven vehicles. You will build propeller driven vehicles from a technical drawing. You will discuss your initial observations.

Background Propellers create a force that moves airplanes and boats forward. Even when an airplane is on the ground, the force from the spinning propellers enables it to taxi on and off the runway. Airboats are propeller driven vehicles that skim over shallow water. Because the propeller blades are in the air, not the water, these vehicles can move over water less than 30 cm or 1 ft deep.

When a propeller mounted on a vehicle spins, its blades push the air backward, like a fan. According to Newton’s 3rd law, the air pushed backward causes the propeller and its attachments to move forward. A close look at the propeller used in this lesson shows how the blades curve. The force of air against the spinning, curved blades pushes the vehicle forward.

Today, you will use a technical drawing to build a vehicle that has a twisted rubber band attached to a propeller. As you turn the propeller, you store energy in the rubber band. You will notice a regular series of knots of identical size forming in the rubber band as you tighten it. Letting go of the propeller releases the stored energy, spins the propeller blades, pushes air back, and pushes the vehicle forward.

Each time you wind your propeller another turn, the amount of energy stored in the rubber band increases. When you release the propeller, the stored energy changes to energy of motion of the vehicle. Initially, the vehicle might move with a burst of speed. This is because the rubber band is at its maximum tension. When first released, the rubber band produces the greatest force and therefore the highest propeller speed.

Propeller must be strong enough to withstand high speeds and great force. Airplane designers much carefully match the size, shape, and number of blades with the aircraft and its engine to ensure top performance and safety. As you observe the propeller driven vehicle in this lesson, look at how you mounted the propeller on the vehicle and discuss why it is positioned in this way. For example, you may notice that the propeller is mounted high so the blades can turn freely without hitting the table below.

Describe what you know about propeller driven vehicles. You will use a technical drawing to build a propeller driven vehicle. You will also analyze your design. Think about vehicle design features that might be necessary to move your vehicles with a propeller. The propeller must be high in the air so it will not hit the ground as it spins. Propeller must be in the front.

Assemble Propeller Driven Vehicle and try to make it move

Present your complete vehicles to the class. What difficulties did you have? What successes did you have? How was it easier and more difficult to build this vehicle with a technical drawing than it was in Lesson 2?

Discussion How did you get your vehicle to move? How did you get the propeller to spin? What happened to the rubber band as you wound the propeller? What happened when you let go of the propeller? Why do you think this happened?

Clean Up Do not disassemble the propeller driven vehicle. Return all materials.

Extensions Use self stick dots and adding machine tape to test how far your vehicles will move with various turns on the propeller. Measure, record, and graph the distance. Research a general aviation airport or a museum that displays propeller airplanes. Compare the planes you see with the vehicles you built. Use a timer to measure how long it takes the propeller to spin down after winding it various numbers of times. Graph results.

The End!!!