Thursday, September 4, 2014

Rubber-powered Planes

Here's a short-lived hobby of mine.  In 8th grade, I joined the Science Olympiad team and signed up for Wright Stuff, an event where we were to build rubber-band powered airplanes and have them stay circling around in the air as long as possible.

I first had to buy a kit containing instructions, two propellers, rubber band hooks, and the rubber itself.  I bought a 16:1 gear ration rubber winder.  The white plane was my first and my friend and I accidentally ruined the delicate Mylar so I used grocery bags to cover the wings.  I also used delicate balsa to make the lightweight frame, following the instructions.  The most challenging part perhaps was getting the dihedral angle correct, in other words, the shallow angle at which the wing is V'd upwards.  The two sides are also twisted to make the plane fly in a circle.

Being myself, I thoroughly enjoyed building the planes.  It was very difficult to get testing time even inside the school gym - the teacher running the Science Olympiad team wasn't very involved.  There was a bunch of drama between parents and teachers which I stayed away from - I only cared about building and flying the plane.

In the above photos, there are detailed shots on the rubber hook, bendable tail attachment point, and the propeller which looks to be made of milk jug material.

During the first regional competition, my friend, myself, and our fathers went in without having tested the plane at all.  My friend's dad actually accidentally snapped the "main bar" of the plane in half.  Thank goodness for super glue.  We ended up scoring 2nd place by some stroke of luck, our plane circling around in the air for either 8 or 12 seconds.

Floating on the good vibes, I quickly built a second plane using the second set of equipment now that I knew what I was doing.  I also built a third one of a different design for my friend and his father to test by themselves but for whatever reason, that one wasn't successful.  My father and I brought both of my planes to the gym to test one night and to our astonishment, the planes made large, lazy circles in the air for almost 100 seconds consistently during many runs.  We experimented with rubber bands that were 0.94 and 0.99 (not sure what units they used) wide and I think we ended up using the 0.94 because it unwound more slowly.  We weren't as confident during the state competition after seeing many wild-looking, self-designed machines, but we still scored 7th place later that day with the Home Depot plane.

I had my attention turned to detail and, of course, decided to align the logos on the grocery bags with the wings of the plane.  In the photo to the right, you can see how the wings were made detachable via thin plastic tubing glued to a slice of balsa, which itself was taped to the main bar to allow for fore-aft adjustment.  This would have made transportation easier, but I still used a large cardboard box that supported both planes fully assembled.

After the season was over, I first made styrofoam stands to hold the planes horizontally for display but I later realized less strain would be placed on all parts if I just hung them from the basement ceiling. The summer after the season, the idea of flying rubber-powered gliders was still hot on my mind so based on everything I learned, I designed a faster-flying version to accept the thicker rubber band.  I never got around to building it because the flame died quickly.  I simply lost interest because I have more of a preference for vehicles that I can control myself, like remote control ones.

The planes have been hanging there for years now and before leaving for school, I repaired them after a recent incident when my parents accidentally knocked them down.  I doubt they're in operable condition anymore because of the relatively damp basement air.  Just like old, tired race cars, their fatigued frames were left languishing in less-than-ideal storage conditions.  I don't know what to do with them now - their fragility makes them hard to transport and store, yet they have served me well and given me great memories.  Now that I think about it, I could make a nice, compact display case for them so they can be moved and stored easily while being supported at many points.