Re: Why do some paper airplanes stay up way longer than others?

Hello Tanya:

Paper airplanes depend on the design of their wings and placement of the ballast (usually a paper clip) to get most flying time. They also depend on the initial trajectory (angle of launch) and the launch velocity. Three factors also are very important when making a "long range" paper plane. First is it must be symmetrical, meaning both wings must be closely the same. Second, the choice and placement of the ballast (paper clip) must be compatible with the size and wing shape of the plane. Too heavy ballast for the amount of wing area will make a poor glider. Too light the ballast and it will have no range.

Placement of the ballast determines whether the glide is too steep or too shallow. Steep glides mean the ballast is too far back, the plane glides steeply, stalls, usually recovers and speeds up to stall again. With the ballast too far forward, the plane is "nose heavy" and won't glide well. Third is the angle of launch and the speed of the launch. Too steep a launch causes the plane to go up high but it either stalls on recovery or just comes down nose first. Speed of launch determines how much energy it has on release. Again, the more energy, the further it will go, but not necessarily stay up the longest.

Paper planes have a big drawback in their design. The wings have no camber, therefore the only lift is derived from the angle of incidence of the wing with respect to the free air.

If you are interested in the dynamics of flight, get back to me. I too like airplanes and have been around them all my life. There is a lot of fun stuff to learn and you will see why it took us a long time before we learned how to build airplanes. A lot has to do with the placement and shape of the wing, and location of the ballast.

For now I will just leave you a little about real airplanes: There are all types of airplanes flying around but with different jobs to do. Looking at commercial airplanes, some are built to fly long distances and others just short hops. Also they might not fly with fully loaded fuel tanks because it costs to carry extra fuel. Also there are restrictions on how long a crew may fly, so long flights might require to have two crews on-board. Military airplanes can fly the longest missions because they are capable of refueling in flight. Normally the smaller the plane, the shorter time it can fly, but there are exceptions. Some carry external fuel tanks and some glide at very high altitudes and may be up without refueling longer than most people would care to sit in one place.

There are two brothers named Rutan that live in the Mojave Desert in California. One in particular is a brilliant aeronautical engineer. In the mid 80s they built a very special airplane to set a world record. That is probably the longest flight a single crew ever made. Dick Rutan did most of the flying; he was so fatigued that he let one of the engines run out of oil and it seized. The second engine brought him and his companion home. I will quote an article concerning that flight. "On December 23, 1986, Rutan's Voyager aircraft returned to its starting point at Mojave, California completing a twenty five thousand mile and two hundred sixteen hour non-stop and un-refueled around the world flight, the first in history." They averaged 115.74 miles/hour (very slow) and had 300 gallons of fuel left on the end. The world fastest is the SR71 Blackbird. Ship SR-71A #64-17972 flew Los Angeles to East Coast (Speed Over a Recognized Course): Coast to Coast Distance: 2,086 miles...Time:1hr 7min 53.69secs...Average Speed: 2,124.5 mph. Top speed UNCLASSIFIED 2,195+ mph. If you like to look at a Blackbird here is a web site for you:

http://www.wvi.com/~lelandh/srlink~1.htm

Keep your interest up. Airplanes are great!

Yours, MAD.SCI Micro