1. Purpose:
- APU: An APU is a small gas turbine engine that provides electrical power, compressed air, and sometimes hydraulic power to an aircraft while it is on the ground or in the air.
- Jet Engine: A jet engine is the primary source of thrust that propels an aircraft through the air. It generates thrust by compressing and expanding air and expelling it at high speed.
2. Location:
- APU: An APU is typically mounted in a separate compartment or section of the aircraft, often in the tail or underneath the fuselage.
- Jet Engine: Jet engines are usually located on the wings or at the rear of the aircraft, depending on the type of aircraft and its design.
3. Size and Power:
- APU: APUs are generally smaller in size compared to jet engines. They typically produce a few hundred kilowatts of electrical power and a limited amount of compressed air.
- Jet Engine: Jet engines are significantly larger and more powerful than APUs. They can generate thousands of kilowatts of power and produce enormous thrust to propel the aircraft.
4. Function:
- APU: The main function of an APU is to provide power for various systems on the aircraft, such as lighting, air conditioning, avionics, and certain hydraulic systems. It is particularly useful when the main engines are turned off, such as during ground operations or when an aircraft is parked.
- Jet Engine: Jet engines are responsible for propelling the aircraft forward by generating thrust. They convert the energy from burning fuel into kinetic energy in the form of high-velocity exhaust gases.
5. Fuel Efficiency:
- APU: APUs are generally less fuel-efficient compared to jet engines. They consume a significant amount of fuel to generate electricity and compressed air.
- Jet Engine: Jet engines are more fuel-efficient when it comes to generating thrust. They are designed to optimize fuel consumption during different phases of flight.
6. Noise Levels:
- APU: APUs can generate a considerable amount of noise, especially during ground operations. This is because they operate at relatively high speeds to produce power and compressed air.
- Jet Engine: Jet engines also produce significant noise, especially during takeoff and landing. However, they are typically designed with noise reduction features to minimize the impact on surrounding areas.
In summary, an APU is a вспомогательный источник энергии that provides electrical power and compressed air to an aircraft while a jet engine is the main propulsion system responsible for generating thrust to move the aircraft through the air. They differ in terms of size, power, function, fuel efficiency, and noise levels.
