Sorting through possible solutions to the wingsail, and water testing them on the model, one at a time, took several years, and over 20 wings were built. It seemed impossible...
Robert Bray - South Africa
Robert Bray has been designing and building his own model aircraft from the age of 12 years old. His particular interest was aerofoil sections, and the affect these sections had on the performance of aircraft. By using only one model aircraft engine the characteristics of different airfoils became clearly evident. He investigated how slowly he could get an aircraft to fly, and the designed wing sections got thicker and more cambered until the drag was so high that the plane would not move fast enough to become airborne. This was a study in airfoils specific for low speed flow, which is an almost untested area of the scientific field.
As a commercial retail specialist architect for most of his career, he redirected his energies to the invention of a morphing wing solution, aware that the world needed a solution to the rigid wing compromise that had become entrenched in aeronautical thinking. He established a company in 2008 to find a wing that could be every known section instantly on command, and began investing in research and development. The journey produced remarkably simple solutions.
Instead of building an aircraft, he decided to build a yacht with a wingsail as the demonstration platform and test bed. The certification process for a full sized aircraft is arduous and lengthy and requires more resources than are available to an individual.
Before long it was realized that the full size testing process was time consuming, so it was necessary to speed up R&D at model scale. He built a perfect replica of the full size trimaran yacht at 1⁄4 scale. The yacht was scanned and replicated by 3D machining in a model-makers studio requiring many hundreds of hours to create a lightweight accurate model of the real version. Fabricating morphing wings at this same scale, he then embarked on the morphing wing technology research. Sorting through possible solutions to the wingsail, and water testing them on the model, one at a time, took several years, and over 20 wings were built. It seemed impossible to build a fully morphing wing that was simple, lightweight and economic, and the attempts became increasingly complex.
The sinusoidal shape required, together with the simultaneous incremental reflexing of the section, was a highly complex problem to solve. The surfaces needed highly intricate and heavy internal machinery to configure the correct form, and there were serious problems with sliding joints in these surfaces.
A solution was eventually found, and refinement over a few more prototypes sorted out many complex issues experienced on yachts in wave action.
Destructive dynamic oscillation was a big issue, and the forward rake of the wingsail was found to solve this fundamental problem. By aligning the axis of rotation behind the mid point of the wingtip, an opposite moment was created, and this eliminated the ever-increasing flag waving action caused by the inertia of the wing. The model yacht with the autonomous wingsail was highly successful, faster than any model Robert had ever seen. It was powered by an autonomous sail of incredible simplicity, and operating on only a two-channel radio control, one for steering, and the other for forwards and reverse (by controlling only the camber of the wing). A fisherman watching the silent model maneuvering with dexterity remarked- “has that boat got an electric engine?” The speed and ease with which the model can move is unlike any other yacht.