Throwing Paper Airplanes from the Roof

One of the great pleasures in life is throwing a paper airplane off a roof. Presenting the Kite and Rocket Research Five Rules of Paper Airplanes:

1.) Never throw a paper airplane without first test-flying and trimming it to adjust for a perfect flight.
2.) After a test-flight, never pick up a paper airplane by it's tail. This will warp the tail surfaces, which will make the information gained from the last test-flight useless. Instead, pick up the airplane from it's center section.
3.) Once an airplane is perfectly trimmed, STOP THROWING IT. Every test-flight runs the risk of warping the delicate tail surfaces. Instead, carefully set the airplane upside down on a table top with the tail surfaces hanging off the edge, and begin folding your next one.
4.) When launching an airplane, your hand should move in a straight line like it's on rails, not in an arc like you're throwing a baseball.
5.) You can never bring enough paper airplanes to the launch site. Once you've thrown your last one, there is a one-hundred percent certainty that you will wish you had brought more.