I had a long career as an early morning paperboy thanks to my older brother vouching that I could do the job at a young age. It was a hilly 10km with 120 customers every day. I did the job for 8 years until leaving for University. It was at times heartbreaking in deep snow and sub-zero winter. Dogs were a constant threat. Human relations could be trying. But, it rewarded me in a number of ways. Strong legs, iron-man stamina, perseverance and an exceedingly strong throw plus sufficient funds to support my model airplane habit and later on, ground school for my pilot's license.
Being interested in flying things, I became obsessed with boomerangs. First it was just a toy I found at the local Five and Dime. It did not last long being lightly and poorly built and more appropriate for a small child. But, I was hooked by the many varied and interesting flight patterns all of which seemed to arrive at the same place. I thus began a long career of boomerang design and construction. I first made 4-bladed crosses like the toy I had bought. They were easy to make but less satisfying to throw being too 'lifty' with a tight flight path and less durable. I eventually settled on the more traditional angular two-bladed type and began experimenting with the angle of the blades, heft and wing profiles and the materials to make them of.
Marine plywood was by far the best in 10-12mm thickness being quite durable and with more layers than normal plywood. The all important profile could be easily seen during the shaping process by the darker glue layers forming a sort of topographical surface-line map. As time and prototypes passed I eventually settled by experimentation on the best angle and wing profiles to provide a long, arcing flight with a subtle progressive flattening which ended in a lasting hover within a few meters from the start. I could vary the flight path by the angle of the release and wind. Every throw was slightly different but the cool thing was how they invariably returned to the start given a decent start. It is all about the release and the combination of spin, speed and direction.
Like many things, the novice designer tends to adapt a philosophy of 'more is better' and I was guilty as charged. I made them bigger and heavier and they became dangerous as a result. The flight paths became large and extensive with the speed of a well-thrown fastball. I became adventurous throwing them first around trees in the park and later garages and houses. Dogs and people became endangered. I got 'clocked' myself more than a few times. Broken windows happened. One was particularly interesting because the pane remained intact but a small profile-shaped hole was clearly left along with the boomerang inside the house. It had arced through the window perfectly! The owner was not particularly happy and that window cost me a couple months of paper money. Somehow I thought it was extremely cool. I became the 'boomerang guy.' I gave formal demonstrations at school. I did a senior project on the physics of boomerangs. It is a very interesting subject combining aerodynamics, torque, precession and momentum with a common result.
But, what do boomerangs have to do with kites? My boomerang obsession taught me that subtle, almost imperceptible changes can have a big effect. The boomerang arm angle would stretch or compact the flight path and effect the spin rate. The profile was extremely critical. Too thick or draft forward created a lot of lift (and drag) and the boomerang would start out great but eventually It would not penetrate and die before it had a chance to return. Too thin or draft aft made for a fast, long stretched out flight but insufficient lift to keep it airborne long enough to return. In either case, throwing it harder would help but at some point would prove to be insufficient.
It just would not work properly. With Felix and Marc, we have done a lot of subtle 'tweaking' which no one could even begin to notice by looking at a Combat in the sky or on land. This also applies to the Element, Nitro and Method all of which have improved as time goes on because we can collect feedback from more users and 'tweak' to satisfy a larger realm of use. It is interesting because the small changes make such a big difference. Somehow I like to think that thousands of hours spent making and throwing boomerangs was beneficial. Maybe it was a waste of time but I don't think so...
More on boomerang physics here: http://large.stanford.edu/courses/2007/ph210/moon2/