R&D Blog
- 03/06/09 Winglet experiment
I was inspired by a show presented by Richard Hammond which looked at inventions throughout history that made the design of the Airbus A380 possible. The main item that I was interested in was the winglets, it had great footage of tests done in wind tunnels and full sized examples explaining the benefits of having winglets on the end of a wing. The shortened reason is that vortices are created at the end of normal wings. Winglets move the vortex away from the end of the wing to the tip of the winglet. Therefore making the entire wing surface more efficient and providing more lift. A lot of research and testing was done in the 70s and the theory is now applied to many new commercial jets including the A380, not a new concept at all. It mentioned that winglets can increase a wings' lift capaiblity by 10%. Seeing the smoke move over the wings in the wind tunnel got me thinking it would be worth experimenting on the OzPrey.
To create my winglets I shaped a piece of corflute and attached it to be flush with the top surface of the wing. Underneath I flexed a thin sheet of balsa and taped it to all edges of the corflute winglet and then made it flush with the bottom surface of the wing. The kicked up winglet has a natural wing shape (curved). Once completed it increased the wing span from 50 inches to 56 inches.
I tested it today at the Wreck at Woody Pt, I was really eager to see the difference but it was fairly light when I first arrived. I almost pulled out as I really felt there wasn't enough lift to fly. I had tried in similar conditions a month or two ago and crashed three times in a row. My common sense disappeared as my eagerness took over and away she went .... wow! It behaved so well in the light conditions and it was so stable. The OzPrey is a stable plane by nature but I could really sense a sufficient difference. It was smooth to fly and didn't show any of the normal unsettled behaviour that is displayed in lighter lift.
In summary it stayed afloat in conditions which I wouldn't normally fly at the Wreck and as the wind increased it started to get decent height. Even the landings where much smoother, like a stone skimming across water, not the common one bounce then flip.