Multi-Surface Aerodynamics Program Tutorial

Click on “Design”

This brings up the following screen:

Double-Clicking on Surface No. 1 brings up the following screen:

Change the units and lengths as follows:

Go to the “Position/Orientation” tab and input the following:

Go to the “Left Airfoil” tab and press the “Select” button:

Click on the “UIUC Database” button:

Scroll through the available airfoils until you get to “S1223” and select it. Then press “OK”.

Press “OK” when the following screen appears. This selects the Selig 1223 as the Left-Hand Airfoil.

Press the “Right Airfoil” tab:

Press the “Select” button:

The Selig 1223 automatically appears by default, since you chose this airfoil for the left-hand of the

wing. Press “OK” to select it.

Press “OK” again to complete the editing of the wing.

Use the “Zoom” button to magnify the main wing:

Double-click on the blue portion of the screen to create the horizontal stabilizer (Surface No. 2):

The default airfoil (NACA 0012) is the correct selection for the horizontal stabilizer. It is a symmetric

airfoil. Change the dimensions of the stabilizer as follows:

Create an elevator on the horizontal stabilizer by clicking on the “Left Airfoil” tab as follows:

Press “OK” and then click on the “Right Airfoil” tab and input the same information as above:

Press “OK”. The following aircraft has been created:

Press the “Flow” button:

On the “Flow” tab, change the settings as follows:

On the “Forces/Moments” tab, make the following changes:

On the “Weight/CG” tab, make the following changes and then press “OK”:

As you can see, the Center of Gravity (CG) of the aircraft is now at the quarter chord of the main wing.

Click on the “Front” button on the Design Screen shown above to see the front view of the aircraft:

Click on “Stability Report” under the “Reports” button. This causes the program to do some calculations.

The following is the screen that pops up. It tells us that the aircraft is stable in the pitch direction, and

that it is flying trimmed at an Angle of Attack (AOA) of 5.69 degrees:

Now press “Coefficients/Force Report” under “More Results” in the Stability window:

This screen shows that the Lift Force is 22.22 lb. However, our aircraft only weighs 15 lb. Therefore, we

need to adjust the Flap Angle on the horizontal stabilizer until the lift force is very close to 15 lb. Close

the “Coefficients/Force Report” screen and double-click on the horizontal stabilizer. Reduce the flap

angle to -5 degrees as follows:

Remember to do this to the Right and Left Airfoils of the horizontal stabilizer:

Press “OK” and regenerate the Stability Report as before:

The angle of trim has changed to -0.564 degrees. Now bring up the Coefficients/Force Report:

Now the lift force is 10.29 lb. Plot the lift force from the two trials versus the flap angle in excel as

follows:

From the above plot, it appears that the lift force is 15 lb (the weight of our plane) at a flap angle of

approximately -7 degrees. Go back and set the elevator angle to -7 degrees (both the right and left-hand

airfoils) and generate the Stability Report and the Coefficients/Forces Report:

The lift force is now 15.17 lb, which is within 1% of our goal aircraft weight of 15.0 lb. Record the Drag

Force on a new excel spreadsheet as follows:

Go back to the “Flow” menu and change the airspeed to 25 MPH:

With the flap angle still at -7.0 degrees, generate the Stability Report and the Coefficients/Forces

Report:

Now the Lift Force is 10.54 lb. Change the flap angle to -10 degrees to increase the lift. Regenerate the

Stability Report and the Coefficients/Forces Report:

Plot the two data points on the excel graph:

Set the flap angle to -9.8 degrees and rerun the calculations:

Again, the lift force is now within 1% of our target weight for our airplane. Record the Drag Force at this

airspeed and plot it in excel:

Continue this process at airspeeds ranging from 15 to 50 MPH. The aircraft weight can be varied to

generate the following type of plot:

This graph can be used to determine the stall speed of our aircraft, which is vitally important to aircraft

design. The black line indicates the thrust that the engine/propeller is capable of delivering. Therefore,

the area below the black line and above the blue line is the flight envelope of our plane. Similar plots can

be generated that track the aircraft AOA and the flap angle: