Tear it up?
A lot of grown-ups have a memory of tearing the back of their paper airplanes to create flaps that they would then adjust. So, I get asked quite frequently if that’s a good idea. In general, if your plane requires so much adjustment that tearing the trailing edge is required, your design or your folding is suspect.
No. Don’t rip your plane’s trailing edge. Think of the outer edges of the wings as a tensioning device to hold the shape you’ve created. If you rip the shape, you destroy part of the tension. More tension means more stability. Aside from that simple idea, ripping means you’re bending the wing in opposite directions until it gives up and tears. Notice that tear is spelled the same way as a tear you cry; you’ve just added up and down elevator at the same time. Excess drag, anyone?
The torn flaps will not hold their intended shape during a strong throw or a strong breeze. If you could throw hard enough, the flap would rattle like the reed in a saxophone. While sax players have been known to “tear it up”, it’s far better if you bend it (like Beckham if you please). Unless you’re attempting to turn your paper airplane into a flying hum-a-comb, don’t rip your plane.
When it comes to adjusting a paper airplane, less is more. The fewer adjustments you make the more performance you get. That’s because a bend or tear becomes a source of drag. Better design and better folding will require fewer adjustments. Better performance follows.
Hopefully, you can be the new generation of paper airplane makers who grew up never ripping the tails of their planes. I can dream, right?