e (Smith 77). All of the different kinds of drag play a great role in the designing of the aircraft, and its efficiency. Drag has its biggest effect on the fuselage, or the body of the aircraft because of its large size. Since all types of aircraft have mass it is impossible to eliminate all drag; therefore aircraft must be designed to use drag to their advantage, or be efficient enough that lift over powers drag.ThrustAnother extremely important element in flight is thrust. For flight to ever occur there must be some kind of initial force to force air over the wings creating lift. This initial force is usually found in the form of a propeller or a jet engine. An exception to those forms of thrust is a glider. A glider still needs an initial force to begin flight, which is usually found in a tow plane. The most commonly used thrust mechanism is a propeller. The propeller will continue to be the most commonly used because of its effectiveness and cheapness. Due to the jet engines high cost and high speeds it will remain primarily a military aircraft power plant. The physics of thrust used in aircraft is semi-complicated. Firstly, in the case of the propeller the propeller must be large enough to displace or pull enough air to keep the aircraft in flight. On the other hand jet engines must be able to displace a small amount of air at much higher speeds than the propeller. As an aircraft speeds up in must displace air at faster amounts causing more drag. This factor creates a barrier of speed within the Earths atmosphere. Although some aircraft do come extremely close to this barrier of speed such as the SR-71 and the space shuttle. The SR-71 or surveillance aircraft can reach speeds of over mach two, or two times the speed of sound approximately 14,000mph. The space shuttle on the other hand can reach speeds of over mach five, or 36,000mph while orbiting the Earth. Both are extremely fast and made of strong, lightweight...
