Propulsion Systems

Combustion Engines

• Originally, the piston combustion engine was used since the Wright Brothers.
  • These were similar to the engines cars used but with cooling systems
  • They originally had a poor power to weight ratio
• Then came the rotary piston engine
  • This was an engine that was lighter, more powerful and cheaper to produce.
  • But they were very difficult to fly due to the gyroscopic effects of the pistons.
• They're still used today, and they are usually lighter, simpler to maintain and cheap to obtain.
  • Which is good on small-scale/recreational aircraft.
  • They cannot fly very fast as these engines are not as powerful as others.

Turboprops

• Turboprops drive a propeller through a gas turbine engine.
• This engine works by sucking in air, then compressing/heating and ejecting it.
  • The ejection part of the process spins a turbine that turns the propeller.
• A gear is sometimes used to control the speed of the propeller as it can waste energy if flown too fast.
• Turboprops are fairly powerful, often used by small airliners.

Turbojet

• A similar turbine engine is used here.
• This engine works by sucking in air, then compressing/heating and ejecting it.
• The concept is similar to that of a depleting balloon, merely shooting out high speed gas to propel the plane.
• These power the fastest and most powerful aircraft in the form of turbofans.
  • This is when a fan is put at the front to suck in air.