Aerodynamics Assignment 3 - Airfoil sim PDF

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Sangeeta Khialani APPLIED FLIGHT DYNAMICS I

Professor Maureen McFarland GRADUATE ASSIGNMENT - 3 LESSON 3 - DRAG

In the last lesson, we went through the changes in values of Lift on an airfoil under various conditions, and I hope by now you are familiar with the software functions and how to change the inputs and calculate the outputs in this for Lift and Drag. In this lesson, we will talk about Drag and various factors affecting Drag. We will calculate Drag changes for airfoil by changing its shape and dimensions, flight changes as well as the size of airfoil, same as we did in last lesson for Lift.

FoilSim III Student Version 1.5a 1. Open

the

website

in

Java

enabled

browser

(preferably

Internet

Explorer)

:

https://www.grc.nasa.gov/www/k-12/airplane/foil3.html 2. You will see a popup or prompt from java, click Run/ Run this time.

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Sangeeta Khialani APPLIED FLIGHT DYNAMICS I

Professor Maureen McFarland GRADUATE ASSIGNMENT - 3

3. You can see the following:

Changing foil dimensions:

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Sangeeta Khialani APPLIED FLIGHT DYNAMICS I

Professor Maureen McFarland GRADUATE ASSIGNMENT - 3

1. By default, it is an airfoil with 5 degree AOA, maximum chamber zero and maximum thickness as 12.5%. 2. Drag in this case is 131 lb. 3. Now, change the AOA to 6%. Note the change in Drag now. (Question 1) Change AOA back to 5. 4. So we notice, a increase in AOA, increases the Drag on the aircraft. 5. Now, we change the maximum chamber which is zero right now. Input value "2" in Camber%c. What is the increase in Drag? (Question 2) 6. The little change in maximum chamber increases the Drag value. 7. Change AOA back to 5. 8. Now, Increase the thickness of foil to 15. What is the new value of Drag now? (Question 3) 9. So, we conclude when the dimension of airfoil is increased in values the Drag on the airfoil also increases. They are directly proportional.

Now, we change the conditions of Flight and see its impact on Drag on aircraft.

1. Reset the software. 2. From the Control Panel select Flight. In the Input window, the by default condition is of flight-test is Earth-Average day. 3. The airfoil in this condition is at zero Altitude and at a Speed of 100 mph. Drag in this condition is 131 lbs. 4. Increase the speed by 15 mph. What is the change in Drag? (Question 4) 5. Keeping speed at 115 mph, change the Altitude of flight.

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Sangeeta Khialani APPLIED FLIGHT DYNAMICS I

Professor Maureen McFarland GRADUATE ASSIGNMENT - 3

6. Change Altitude to 500 ft. What is the new Drag? (Question 5) 7. As we increase the speed of flight the Drag increases. 8. With an increase in altitude of flight, the Drag gradually (slowly) decreases. 9. Keeping the Altitude and Speed value constant at 115 mph and 500 ft, Change the Flight test to 'Mars- Average day' from the drop down menu. What is the new Drag at the surface of Mars (Question 6). 10. Note: The values of Lift and Drag and their difference from Earth. 11. Now, change the speed to 150 mph and Altitude to 750 ft. What is the new Drag value? (Question 7) 12. Reset the software. Select Flight from Control Panel. 13. From Flight Test drop down menu select 'Specify Air T & P'. This will enable you to enter values of temperature and pressure manually. 14. Reduce the Pressure in Press lb/in 2 tab to 12, it will automatically take it to 11.995 nearest point, which is just a round-off for other values. Also, change the Temp F to 65 degree. What is the new Drag now? (Question 8) 15. Reset the software. Now select Size tab from the Control Panel. It will enable you to input Chord length and Span, and also change the Area of wing. 16. Now, change the Area-sq ft from 100 to 150. It automatically change the Length and Span to adjust to aspect ratio. What is the increase in Drag? (Question 9)

This lesson will give you a better understanding of how the changes in size of airfoil and conditions around the airfoil affect its Drag values. Also, you will practically see and visualize what conditions can help increase and decrease the Drag on our airfoil. And, will

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Sangeeta Khialani APPLIED FLIGHT DYNAMICS I

Professor Maureen McFarland GRADUATE ASSIGNMENT - 3

help you in design of aircraft such that it has minimal drag, and what flight conditions we can fly at for minimum values of Drag affecting the aircraft. In the next lesson we will talk about the effects of same conditions on Lift & Drag on the airfoil simultaneously.

Answer key 1. D = 2. Drag increased by ___ lbs

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Sangeeta Khialani APPLIED FLIGHT DYNAMICS I

Professor Maureen McFarland GRADUATE ASSIGNMENT - 3

3. D = 4. D increases by ___ lbs. 5. Drag = 6. D = 7. D = 8. D = 9. Drag increases by ___ lbs.

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