The modern day arrow that you see used in the Olympic Games has changed somewhat from the ancient design, and employs some of the latest modern technology.
Arrows can now
be made from a thin hollow tube of aluminium, carbon fibre, or even a hybrid of the two where the aluminium is wrapped in carbon fibre. The thin, stiff shafts; perhaps only 6 mm thick are very light, giving great speed and a flat trajectory. Their small cross-section and short time-of-flight also gives good perfomance in the wind. The manufacturing process ensures each batch has almost exactly the same stiffness and weight.
The feathers have been replaced with plastic, often shaped to catch the air and spin the arrow to give
increased stability of flight.
The point, or "piles"; to give them their proper name are small and fit flush, with no part projecting out past the circumference of the arrow. Usually they are made from steel for the part that penetrates the target, with a brass potion that inserts into the hollow shaft where glue can hold it in place. Piles come in various weights to help you "tune" your arrows to the bow.
Getting exactly the same flex is important; as the arrow is accelerated by the string, the inertia from the weight of the pile causes the arrow to bend along it's length. As the arrow leaps forward from the bow, this bending does die away, but the process *will* affect the flight of the arrow in different ways for different stiffnesses. Modern bows have spring loaded "buttons" in the handle of the bow, perpendicular to the arrow rest. By adjusting the tension of the spring in this button, varying amounts of energy can be taken out of the arrow flexion as it moves past. This coupled with left-right and up-down adjustment of the arrow, ensures the mode of the arrows vibration is in perfect alignment with the shot; and the same from shot to shot. (This has been described as 'giving the arrow a good clean kick up the arse.')
Fired from a modern recurve or compound bow great accuracy can be achieved with the modern equipment, hitting a head-sized area consistently at 90 metres.