Millions of paper airplane designs exist; every kid seems to know a different one. But by far the best paper airplane I have ever flown was taught to me by my dad, who learned it from his dad when he was a kid in the 60's. In fact, my grandpa invented this design (he was a draftsman, an airplane mechanic in WWII and the Korean War, and holds several patents). So I made this sound like my family's secret paper airplane legacy, but we've taught it to tons of people over the decades so it can hardly be called a secret. Now I'm going to teach it to you.
One more thing: This instructable is an entry in Paper Airplane Contest 3 (http://www.instructables.com/community/Paper-Airplane-Contest-3-Open/). <--- check it out !
Step 1: Materials needed....
That's it. This isn't one of those fancy cut-cut-tape-tape-fold-fold paper airplanes; this is pure old-fashioned paper folding.
If you are fanatical about your creases, you could also use the edge of a ruler to run along them, but your fingers should do well enough for most people.
Step 2: Construction - Step 1
Step 3: Construction - Step 2
Step 4: Construction - Step 3
Repeat with the upper left corner. [Pic. 2]
Everything should be lined up as close to perfectly as possible. Exactness counts.