Modern aircraft use winglets on the tip of the wings to reduce drag. When air flows past it, due to the difference in curvature of its upper and lower parts, lift is generated, which is responsible for balancing the weight of the plane allowing the body to fly. Wings are the most important lift producing component of an aircraft. They vary in design depending upon the aircraft type and its purpose. During the 1700s, Daniel Bernoulli, a famous scientist, showed that a fluid that flows faster over a surface will create less pressure on the surfacethan the fluid that flows slowly. This concept later came to be known as 'Bernoulli's Principle'. On this page you will find answers to the following questions: How does an aircraft fly?, Why do airplanes leave a trail of cloud? and Why do some aircraft engines have commas?