
Lift vs. Airspeed Answers


Step 2.
Using the chart below, record the Airspeed and the
Lift. By changing the Airspeed, make at least 9
additional readings. Record these in the chart.
Answers will vary. Samples are
shown below:
Airspeed (km/hr)

Lift (Newtons)

0

0

38

401.5

56

919.8

95

2647.0

126

4437

171

8577

228

15,250

308

27,820

359

37,800

400

46,930

Step 3.
Enter your data into the Lists in your calculator. Set up
Stat Plot so that the Airspeed is your independent
variable and the Lift is the dependent variable. Graph the
data on your calculator and make a sketch in the graph below.
Answers will vary, depending on the
answers in Step 2.
Step 4.
In FoilSim, push the Plots output button and select Lift
vs. Speed. How does this graph compare to yours?
The graph should be very
similar.
Step 5.
Which kind of function does this graph represent?
The graph represents a
parabola.
Step 6.
Using the regression
equations (http://www.ti.com/calc/docs/act/pdf/marcus09.pdf) from
your calculator, determine the equation of best fit.
a = .295
b = .455
c = 8.901
R^{2 }= .999
equation: .295X^{2}  .455X 
8.901
Step 7.
What does this equation tell you about the relationship between
the change in Lift and the change in Airspeed?
As the airspeed increases, the lift
increases by more than the square of the airspeed.
Step 8.
Using the graph and/or the equation, what would you predict the
lift to be given an airspeed of 300 km/hr.?
equation: .295(300)^{2}  .455
(300) 8.901
Lift = 26,404.59 Newtons
(Note: Have students
check their answers using FoilSim: lift = 26,400 Newtons. Then take
it one step farther and show the regression equation on a
calculator.)
