Types of Aircraft Engines EO M232.01 Types of Aircraft Engines 1x30 with FSgt Aikens

Importance Why would we want to know about aircraft engines? Well, the engine is a key part of the airplane, counteracting the force of drag and creating the speed necessary for lift. It is important to understand aero engines in every aspect of the aviation industry. Also it will be important to know what’s in this class, so you will be more prepared when we add more complex details in the next few classes.

Engines We have three main types of engines: Rocket Engines Gas Turbine engines This includes Turbojets, Turbofans, Ramjets, and Turboshafts Piston engines

Rockets Overview By far the simplest propulsion method, one of the least common, and certainly the oldest, rockets burn fuel in a controlled explosion, throwing exhaust gasses back, and pushing the engine onwards.

Rockets Overview The earliest known form of rocket was a black powder rocket used to power Chinese fire arrows. Rocket engines have the advantage of not needing air to burn. They also have minimal lag on command, and good acceleration. They are not very fuel efficient. Nowadays, rockets are used principally for space exploration and launching satellites. Rockets, and most engines require Newton’s third law of motion: When one body exerts a force on a second body, the second body simultaneously exerts a force equal in magnitude and opposite in direction on the first body.

Piston Engines Overview Piston Engines are the most popular engines. They can be found on many planes, cars, helicopters, hovercraft... We’ll really be focusing on this kind of engine, because of its popularity. Piston engines were invented in the late 19th century, they were readily available (if not somewhat unrefined) to Orville and Wilbur Wright, who used one in the 1903 flight of the Wright Flyer.

Piston Engines Overview The piston engine is one of the more complicated ways to get an aircraft moving. It works by burning compressed fuel and air together to push a piston, that connects to the powertrain, where it is eventually transferred to the propeller, or in the case of a helicopter, the rotors. Piston engines are categorized by their capacity, piston layout, and number of cylinders. Ex; This 7.2L I6 Engine (Ranger L-440)

Gas Turbine Engines Overview Ramjets!: A very basic and somewhat crude form of jet, the ramjet is a tube with fire in it. Advantages: You can get going very fast. Disadvantages: The ramjet requires high velocity airflow to start, meaning it can’t start when sitting still.

Gas Turbine Engines Overview Turbojet: It’s kinda complicated to explain, lets look at a picture. The intake fans take in air, then it gets compressed. It then gets combined with fuel in the combustion cam, before being expelled. The hot air leaving pushed the aircraft forward, but also spins the turbine blades, with drive the intake blades.

*Side note* We can inject fuel directly into the exhaust to create a bit of a boost. We call that an afterburner. (As you can imagine, it’s not that fuel efficient) Fuel

Gas Turbine Engines Overview Turbojets are commonly found on military aircraft, small civilian jets, and older commercial jets. Pros: Good high speed and medium efficiency. Cons: Loud, and high control lag due to spool up/down. This is also called a “low bypass jet engine”

Gas Turbine Engines Overview Turboprops: Now imagine the engine we just looked at, but in front of the intake fan, we attach a propeller. Enter the turboprop. Pros: Good engine response, and much quieter. Good performance at lower speeds.Good fuel efficiency Cons: Not as fast as the turbojet, can’t operate at high altitudes. Commonly found on medium airplanes of almost any type.

Gas Turbine Engines Overview Turboshaft: A turboshaft is a turboprop with the driveshaft extending from the engine, and going through a gearbox, so that the speed of the shaft is not necessarily tied to the main engine. We see this a lot in helicopters.

Gas Turbine Engines Overview Turbofan: The intake fans of the turbojet are extended, and the air passing through this extension exits the back of the engine without being burned. This is called “high bypass engine”. It’s much more fuel efficient, a bit quieter, and produces much more thrust for its weight. We see this on all modern commercial jets for its tremendous advantage.

Question Time Where were rockets first used? Where do we use them now? Ramjets! What are they really good at? What’s the difference between a low bypass and high bypass engine? What engines do we find in helicopters?

Combustion Fuel and air explode in a process called combustion. The capture and direction of this explosion is where we get our engine power. In each engine it happens in a different location. The heat of this ignition gives off heat and the air rapidly expands

Combustion There is a difference between fuel burning, and fuel exploding. Burning alone is like a candle, it works, but it’s slow and doesn’t work very well in engines. When combined with a specific mixture with air, we get an explosion, something with much more force, much more capable of moving things...like airplanes. Getting more bang for your fuel, which can be up to $7.00 per litre.

Oxidization Oxidization is the process of getting the air into the engine. In Piston Engines The air is brought through an intake by the natural vacuum of the piston, and the airflow of the aircraft's speed.

Oxidization Oxidization is the process of getting the air into the engine. On Rockets: Rockets bring their own oxygen with them. Because space has none.

Oxidization Oxidization is the process of getting the air into the engine. On Gas Turbine Engines: The air is brought through the front intake, and into the engine.

Oxidization Oxidization is the process of getting the air into the engine. In all these cases, the air is compressed first for better performance and more explosion. Piston Engines: The piston closes and compressed air Rocket engines carry the oxygen in an already compressed form Gas Turbine engines use spinning fans and narrowing passages

Question Time Why do rockets carry oxygen? What is oxidization? How does a turboshaft get its air? How about a piston engine? What is a slower process, fuel burn, or fuel explosion? Because there’s no O2 in space Through intake blades Through the intake and the natural vacuum of the piston Fuel burn

Case Study Piston Radial

Case Study Turbojet (low bypass)

Case Study Turboprop

Case Study Turboshaft

Case Study Rocket (notice the lack of intake)

Case Study Turbofan

End of Class Engines are super important to everyone in aviation, from designers, ground crew, fuel makers, mechanics, pilots, even passengers. Hopefully this class has queued up your interest in this ever advancing topic. Right now, major corporations are working on electric, hydrogen, and hybrid engines in the aviation field.