It is impossible to depart to space by helicopter or the plane. Because in space there is no atmosphere. There is a vacuum, and air is necessary for planes and other flying means. And here it is not obligatory for a rocket for flight at all. It is moved by only reactive force.
The jet engine quite simply is arranged. In it there is a special camera in which fuel burns. During combustion it turns into gas. From the camera there is the only exit - a nozzle. It is sent to the direction, opposite to the movement. Gas escapes from a nozzle with an enormous speed and pushes a rocket. There is an air or not — it does not matter at all. The main thing that force of pushing away of gas was rather powerful to lift and move the mass of the aircraft. The rocket conclusion to an orbit requires huge amount of fuel and speed which will help to overcome force of terrestrial gravitation. Therefore it is necessary to accelerate the device to eight kilometers per second. But besides fuel, air also has to come to the engine, otherwise fuel will not be able to burn. Therefore in a rocket there is an air reserve in liquid state. Liquid it becomes due to very strong cooling. Except air as oxidizer it is possible to use fluorine. However, this gas is very poisonous. The rocket has the form similar to a spindle. It is connected with the fact that it should fly through the atmosphere before reaching space. Air is a hindrance to fast flight. Its molecules brake the movement for the account of friction force. And to make air resistance it is less, a rocket form streamline and smooth. But not all space. Its part is lost even in flight. As the rocket has very big tank, and fuel reserve in it quickly decreases, it is irrational to transport a thin fuel compartment. The scientist Konstantin Tsiolkovsky resolved this issue as follows: invented multistage rockets. They are several rockets in one. The first step and its engines are responsible for start. It the biggest and powerful in all design as the difficult task is assigned to it: to lift a rocket in air. Upon termination of fuel the step separates and following begins to work. Engines in it are weaker because the rocket is already much easier and resistance of air constantly decreases. And so a step behind a step. In space there is a smallest of them to which the spaceship fastens.