What is a Rocket ?
A rocket is a vehicle designed to deliver a specific payload to a particular altitude. But how does it achieve this? Before delving into the principles of rockets, let’s examine the term called “momentum.” While on the internet, you might find it defined as the product of mass and velocity (p = mv), a more detailed expression is possible. Momentum can be thought of as an object’s desire to move. Now, let’s explore the principles behind rocket movement.
Rockets move by expelling heavy masses with high velocity in the opposite direction to accelerate in the desired direction. This is essentially Newton’s third law (every force has an equal and opposite reaction force) and the conservation of linear momentum. Since momentum is always conserved:
(M+m)V0=(M+m−dm)(V+dV)+dm(V−u)
Now that we understand the basic principle, let’s explore the types of rocket engines.
Types Of Rocket Engines :
Solid Propellant Chemical Engines: These engines are powerful and are commonly used in boosters. Fuel and oxidizer are mixed in a solid mixture. However, one drawback is that once ignited, they don’t stop until they are finished. Examples of fuel and oxidizers used in solid propellant engines include:
- Fuel: Aluminum, Magnesium
- Oxidizer: Ammonium Perchlorate, Ammonium Nitrate
2. Liquid Propellant Rocket Engine: In this type of rocket engine, both oxidizer and fuel are in liquid form. These engines are the most complex due to their turbomachinery. Examples of fuels and oxidizers are:
- Fuel: Liquid Hydrogen, Liquid Methane, RP-1 (Refined Kerosene)
- Oxidizer : Liquid Oxygen, Nitrogen tetroxide, Liquid Fluorine
3. Hybrid Rocket Engines: These engines are a mix of solid and liquid propellant engines. The oxidizer is liquid, and the fuel is solid. This is a newer technology compared to the others. Examples of fuel and oxidizers are:
- Fuel: Polyethylene, cross-linked rubber (e.g., HTPB)
- Oxidizers can vary but are often the same as those used in liquid rocket engines.
