Turbofan vs. Turboprop Engines: What's the Difference?
Walk through any major airport and you'll see a variety of aircraft — wide-body jets, regional turboprops, narrow-body airliners. Behind each of those aircraft is an engine designed for a specific mission. Two of the most common engine types in commercial aviation are the turbofan and the turboprop. Though they share a common heritage, they work quite differently and excel in distinct roles.
How a Jet Engine Works (The Basics)
Before comparing the two, it helps to understand the shared foundation. Both turbofans and turboprops are gas turbine engines. Air enters the inlet, gets compressed, is mixed with fuel and ignited, and the resulting hot gas drives a turbine. What happens after that turbine stage is where the two designs diverge.
The Turbofan Engine
A turbofan engine routes most of its thrust through a large fan at the front of the engine. This fan accelerates a massive volume of air around the core (the "bypass flow"), producing most of the engine's thrust very efficiently at high altitudes and speeds. The ratio of bypass air to core air is called the bypass ratio.
- High-bypass turbofans (e.g., CFM LEAP, GE90, Rolls-Royce Trent) power modern commercial airliners. They are extremely fuel-efficient and quiet.
- Low-bypass turbofans are used on military jets and business jets where speed is prioritized over fuel economy.
Turbofans are most efficient at speeds above 400 mph (around Mach 0.75–0.85) and at altitudes above 30,000 feet — exactly where commercial airliners cruise.
The Turboprop Engine
A turboprop also burns fuel through a gas turbine core, but instead of a large bypass fan, almost all of the energy extracted from the combustion gases is used to spin a propeller. A reduction gearbox slows the high-speed turbine shaft down to a speed the propeller can use effectively.
- Turboprops are highly efficient at lower altitudes and lower speeds — typically below 350 mph.
- They excel on short routes, often 300 miles or less, where turbofan jets never reach their efficient cruise altitude.
- Common turboprop aircraft include the ATR 72, Bombardier Dash 8, and Beechcraft King Air.
Side-by-Side Comparison
| Feature | Turbofan | Turboprop |
|---|---|---|
| Thrust source | Bypass fan + core exhaust | Propeller |
| Optimal speed | 400–600+ mph | 250–350 mph |
| Optimal altitude | 30,000–43,000 ft | 10,000–25,000 ft |
| Best route length | Medium to long haul | Short haul / regional |
| Fuel efficiency (short routes) | Lower | Higher |
| Example aircraft | Boeing 737, Airbus A320 | ATR 72, Dash 8 |
Why Does the Choice Matter?
Airlines make careful economic decisions when selecting engines. A turboprop burning less fuel on a 200-mile hop between regional cities makes far more financial sense than a turbofan that never reaches its efficient cruise altitude. Conversely, on a transatlantic crossing, a high-bypass turbofan's efficiency at altitude makes it the only practical choice.
Key Takeaways
- Both engine types share gas turbine technology but extract thrust differently.
- Turbofans dominate medium and long-haul routes due to high-altitude efficiency.
- Turboprops are the workhorses of regional aviation, connecting smaller communities economically.
- The "right" engine is always the one matched to the aircraft's intended mission.
Understanding these differences gives you a new appreciation every time you board a regional turboprop or a mainline jet — each engine is precisely the right tool for its job.