Alexander V. Nebylov
State University of Aerospace Instrumentation
St. Petersburg, Russia
1.1 General Considerations
1.1.1 Types of aerospace vehicles and missions
Aircraft are designed to fly within the atmosphere, which makes possible the creation of motion, lift, and attitude control. Spacecraft are designed for travel in open space; the presence of air is not necessary because the thrust is created by rocket engines. There are three main ways for an aircraft to gain lift within the atmosphere: the fixed wing for normal airplanes, the rotor (or rotary wing) for helicopters, and an envelope filled with any gas less dense than the surrounding air for aerostats such as balloons or airships (dirigibles).
There are also ...