Piston vs Turboprop vs Jet
Currently there are 3 major types of engines: piston, turboprop, jet (or Turbofan).
Turboprop is basically a jet engine connected to a propeller.
Both piston and turboprop are propeller driven, however
- piston: low cost, low fuel burn.
- turboprop: simpler, lighter, more powerful, but with a higher cost and higher fuel burn.
AvGas vs Jet Fuel
Similar to gas cars vs diesel cars, aircraft fuel falls into roughly 2 categories: AvGas and Jet Fuel.
|Engine||Piston (AvGas)||Piston (Diesel) / Turboprop / Jet|
High-octane gasoline, piston-engine powered aircraft; leaded, unlike car gas
AvGas is similar to car gas, but still with lead. The most common in US is 100LL, where "LL" means "low lead". The availability is limited, especially outside of north america. Why lead? in many piston engines, lead in avgas prevents damaging detonation that can result in a sudden engine failure. For general aviation aircraft that need 100-octane fuel to prevent detonation, the only current option is 100LL.
There are plans to remove lead from all aviation fuels. 100LL replacement: UL94 is a 94 octane unleaded avgas.
Jet Fuel is a highly refined Kerosene, ignited by pressure and heat; cheaper, more available, and can run in diesel engines.
Low-octane. Jet A and Jet A-1, for gas-turbine engines. Most jet fuels in use since the end of World War II are kerosene-based.
- Jet A: only in US and a few Canada airports, freezing point is −40 °C (−40 °F)
- Jet A-1: in the rest of the world other than the former Soviet states, freezing point is −47 °C (−53 °F), lower than Jet A
- Jet B: enhanced cold-weather performance, freezing point is −60 °C (−76 °F)
Jet and gas turbine (turboprop, helicopter) aircraft engines typically use lower cost fuels with higher flash points, which are less flammable and therefore safer to transport and handle.
Jet fuel is very similar to diesel fuel, and in some cases, may be burned in diesel engines. Avgas is leaded, so some small general aviation piston engine aircraft are equipped with diesel engines to use jet fuel. A diesel engine may also potentially be more environmentally friendly and fuel-efficient than an avgas engine.
Kerosene vs Diesel
Kerosene is extracted from crude oil first, then diesel, as kerosene has a lower boiling point than diesel.
Diesel is a reddish colour while kerosene is colourless
Kerosene is typically cheaper than diesel, and it burns at a lower temperature than diesel which prevents gelling in freezing temperatures,
The big 3 engine makers:
- GE Aviation (GE), a subsidiary of General Electric, largest market share
- Rolls-Royce (RR), 2nd largest
- Pratt & Whitney (PW), a subsidiary of Raytheon Technologies
And 2 joint-ventures:
- Engine Alliance (EA) is a 50/50 joint venture between GE Aviation, a subsidiary of General Electric, and Pratt & Whitney, a subsidiary of United Technologies.
- CFM International (CFM) is a 50-50 joint venture between American GE Aviation and French Safran Aircraft Engines. CFM makes LEAP ("Leading Edge Aviation Propulsion") engines
Here's a summary of the current and future airliners (that's why you do not see 757 or 747-400 here):
A few observations:
- EA only makes GP7200 for A380. Once A380 is discontinued in the near future, would this joint venture dissolve?
- Trent engine family covers the most of the wide-bodies: A330, A340, A350, A380, B777, B787.
- LEAP is used in all next generation mainline narrow-bodies: LEAP-1A for A320neo, LEAP-1B for B737 MAX, and LEAP-1C for the future C919
- PW covers smaller jets, except for (soon to be deprecated?) PW4000. PW1000G competes with LEAP.
Regional Jets: the older generations were using GE's CF34, while the newer generations are using PW engines.
Almost all still in production turboprop airliners chose Pratt & Whitney (PW)
|ATR 42-600||PW127M||1,953 kW|
|ATR 72-600||PW127M||1,953 kW|
|Dash 8 Q400||PW150||3,782 kW|
Light aircraft: MTOW <= 12,500 lb (5,670 kg)
Light piston aircraft engines can either use AvGas or Jet Fuel (with a Diesel engine). Leaded AvGas will eventually go away, but unleaded gasoline is not widely available. Many brands come up with diesel versions (e.g. Piper Archer DX).
The FAA recently estimated that nearly 170,000 aircraft operate today on 100 low lead (LL) fuel, burning 150 to 175 million gallons annually.
The most common engines are Lycoming and Continental. Both have AvGas and Diesel engines.
To decode the engine type:
- A: Aerobatic (dry sump)
- AE: Aerobatic (wet sump)
- E: Electronic
- G: Geared (reduction gear)
- H: Helicopter
- I: Fuel Injected
- L: Left Hand Rotation Crankshaft
- M: Designed for unmanned drone
- O: Opposed Cylinders
- R: Radial Cylinders
- S: Supercharged
- T: Turbocharged
- V: Vertical installation (usually for helicopters)
- X: X-type engine
- Y: Experimental
AvGas Engine vs Diesel Engine
Diesel engines are heavier than AvGas engines (~100kg), but have better fuel economy.
Diesel engines and more costly to build, especially the fuel delivery system is much more expensive than fuel injection systems for gasoline pistons, since diesel fuel systems run at a much higher pressure to cause atomization of the fuel for a clean burn.
Powers more than half the world's general aviation fleet, both rotary and fixed wing. A subsidiary of Textron, the parent company of Cessna and Beechcraft.
- Number: displacement (in cubic inches).
- O: Opposed engine.
- I: fuel Injection.
- T: Turbocharged.
- AE: Aerobatic.
- IO-360: 361 in³ (5.92 L) displacement, four-cylinder air-cooled horizontally opposed engine; used by Cessna 172S, Piper Archer LX.
- IO-540: 541.5 in³ (8.9 L) displacement, six-cylinder air-cooled horizontally opposed engine; used by Cessna 182, Cessna 206.
Part of Aviation Industry Corporation of China (AVIC). Also owns Centurion engines as the result of Thielert aquicision.
Builds both AvGas engines and Jet Fuel (Diesle) engines.
Offer both four-stroke and advanced two-stroke engines. Often used in light aircraft.