|A major design driver for ES1 is low aerodynamic drag. Typical modern sportbikes have a drag coefficient of 0.65 and a frontal area of 0.5m2 giving a CdA of around 0.32. This drag coefficient is double that of other streamlined vehicles such as sports cars and is actually closer to the drag coefficient of a truck! The reason that conventional bikes have high drag coefficients is that although the fairing gives a streamlined shape to the front of the bike, the back of the bike has very poor aerodynamic properties which leads to a wide and turbulent wake. The fundamental problem is the conventional riding position ó where the width of the riderís legs far back on the bike ó which creates the opposite of the teardrop shape we ideally want for good aerodynamic performance.
For ES1, we have sought to create this ideal aerodynamic shape by significantly reducing the width of the foot and leg position and by fully enclosing the rear wheel. The fairing is at its widest point close to the front of the bike and the cross section tapers progressively from here to the trailing edge of the rear tire. We have also reduced frontal area with a slightly narrower fairing around the engine and by allowing a much lower tuck position. The fuel tank is repositioned and the front suspension leaves plenty of space for the riderís helmet where it would normally be hitting the top yoke. The narrow front suspension legs and radiator ducting also contribute to efficient aerodynamics.
Overall, we have achieved a 20% reduction in frontal area and computational fluid dynamics analysis tells us that drag coefficient is 0.4, not as good as a sports car but a 40% improvement over a conventional superbike! This translates to a 50% reduction in CdA (total drag) which equates to a 26% increase in top speed!