Activity 2.2.1 Action and ReactionIntroduction

Newton determined that for every action there must exist an equal and opposite reaction. An aircraft has four groups of forces acting on it. When all of the forces are balanced, the aircraft will fly at a constant velocity. When two opposing forces are not equal, the aircraft will accelerate in the direction of the greater force. For example if lift exceeds weight, an airplane will ascend. If weight exceeds lift, it will descend. In this activity you will see how a propeller creates thrust to overcome drag. You will also see how thrust can be improved.

Equipment Engineering notebook Pencil PC with Logger Pro and ROBOTC software AE VEX kit Small "A" base 45 cm stainless steel rod Dual-Range Force Sensor Vernier Go Link adapter Activity 2.2.1a Action and Reaction Construction Guide

Procedure1. Construct the propeller test stand using Activity 2.2.1a Action and Reaction

Construction Guide. Confirm that the ROBOTC program is downloaded to the Cortex.

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2. Download the program to turn the propeller to the Cortex.

a. Start ROBOTC software.

b. Ensure that the Cortex is powered off.

c. Connect the USB cable between the PC and Cortex.

d. Power on the Cortex.

3. Confirm that the Vernier Dual Range Force sensor is set to +/- 10 N.

4. Align propeller with center of hook or bolt depending on which method of preparing the Styrofoam target was used. The plane of the propeller rotation should be parallel to the face of the Styrofoam target.

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5. Start Vernier Logger Pro software.

6. Connect the Dual Range Force Sensor to the Go Link. Connect the Go Link to the PC USB port. The software should recognize the sensor.

7. Prepare to gather data.

a. Double click the Force title to change sensor parameters.

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b. Click Experiment in the menu at the top of the screen. Click Data Collection to set acquisition parameters.

c. Change Length to 30 seconds.

d. Click Zero on the menu as shown below. This will reset the force to zero before collecting data.

8. Gather data.

a. Click Collect on the menu.

b. Press the bump switch to begin the propeller rotation.

c. After the data collection ends, release the bump switch.

d. Save the data and record the average force in your engineering notebook.

9. Remove the Slow Flyer Propeller, 8x3.8SF.

10.Compare the Slow Flyer Propeller, 8x3.8SF and Slow Flyer Propeller, 8x6SF. In your engineering notebook, record your observations and how the force data may change when testing this other propeller.

11. Install the Slow Flyer Propeller, 8x6SF using the instructions in the Activity 2.2.1a Action and Reaction Construction Guide.

12.Repeat the data acquisition in step 8.

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13.Measure the impact of increasing distance between propeller and the Styrofoam target.

a. Click Collect on the menu.

b. Press the bump switch to begin the propeller rotation.

c. Slowly move the propeller back from the Styrofoam target at a rate of 1 in. per second.

d. After the data collection ends, release the bump switch.

e. Save the data and record the average force in your engineering notebook.

f. Record your observations in your engineering notebook. This reaction that you observe is similar to the reaction that is known as ground effect in aviation.

g. . This is a similar reaction that is known as ground effect in aviation.

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Conclusion1. Explain how the propeller pitch affects the force exerted by the propeller.

The greater the propeller pitch size is the greater the force is exerted on the pressure sensor.

2. Explain how a thrust force is generated in this activity.

Thrust force is generated when the propeller turns helping the plane move forward.

3. Explain how a drag force is generated in this activity.

Drag force is generated when the propeller is pulled back in the opposite direction which with a real plane would cause drag.

4. Explain what ground effect is and provide three examples.

Ground effect for an aircraft is the increased lift and decreased drag that an aircraft’s wings generate when they are close to a fixed surface. An Australian Sea Eagle (WIG craft), a Chinese DXF100 (Tianyi-1), and a Russian Beriev Be-1.

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