Some airplanes have propellers. Some have one. Some have two. Some have four.

Assignment:

Alter and extend the sample project in the following ways:

1. Change the number of propellers from two to four.
2. You may have to make the size of the propellers a little smaller.
3. Add code to make the airplane move up and down. Control this movement using the up arrow and down arrow keys.
4. Create a button which starts and stops the propellers.