Recently, I attempted to give different engineers a thirty second explanation of what design of experiments is and what it could do in science. The results were what an experienced practitioner could expect from such an exercise and a total failure. Perhaps a thirty second introduction to that topic is really unrealistic, but providing a short and concise explanation is possible and having a paper helicopter on hand helps.
The late statistician George E. P. Box, together with Soren Bisgaard and Conrad Fung, used a paper helicopter to teach statistics. The idea originally came from Kip Rogers of Digital Equipment and is useful for demonstrating fractional factorial better designs. Decades after Box, Bisgaard and Fung’s publication, the designed helicopter has become a useful staple of experiments of the training.
The paper helicopter provides a way to quickly explain basic design concepts. It also offers an easy-to-do experiment you can analyze using Minitab. To perform a design with a paper helicopter we need to identify the desired output, which would be our response variable. We can’t just declare that we want a high quality helicopter; quality must be clearly defined.
A good helicopter is one which stays in the air for a longer time, so the response variable would be flight time as measured from the time the helicopter is dropped from a height of 2 meters until the time it hits the floor. Without defining the test conditions it could be possible that sample helicopters would be dropped from different heights, in which case our design results would be not be valid.
Test factors that influence flight time must also be identified. For the helicopter experiment, the factors are paper type, rotor length, leg length, leg width and paper clip. The helicopter experiment levels are varied by using two different types of paper, using longer or shorter leg and rotor lengths and adding or removing a paper clip.