How Many Revolutions Do Different Aircraft Engine Types Complete Per Minute?

Jun 06, 2024

Not all parts of modern jet engines rotate at the same speed.

Jet engines comprise thousands of moving and stationary parts. Modern jet engines are typically mounted on aircraft wings, while some airplanes may feature tail-mounted engines. Irrespective of the location, engines must produce enough power (thrust) to lift the aircraft off the ground. On large modern airliners, the speed of the jet engine fan is between 2,500 and 4,500 revolutions per minute (RPM). However, not all engine parts rotate at the same speed.

Engine parts are grouped into the same rates of rotation. The groups are called N1 and N2. The N1 is the rotation speed of the low-pressure (LP) system (fan, LP compressor, and LP turbine). The N2 is the rotation speed of the high-pressure (HP) system (HP compressor and HP turbine). Both N1 and N2 are expressed as a percentage of the maximum allowed rotation speed (RPM).

N1 speed indicates how much air the engines take in. N2 speed indicates the amount of power the engine-driven systems are receiving. Hydraulic, fuel, and electrical systems typically receive power from the N2 system of the engine. Engine displays in the cockpit show both the N1 and N2 values to the pilots. These values are essential for flying the aircraft safely.

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The typical N1 speed of typical turbofan engines ranges between 2,500 and 4,500 RPM. Typical N2 speeds can be anywhere between 10,000 and 15,000 RPM. It is noteworthy that the N2 speed of special-purpose (military, surveillance, etc.) engines may be as high as 30,000 RPM.

It is noteworthy that on three-spool engines, such as the Rolls-Royce Trent 1000, the N2 speed represents the intermediate pressure (IP) system and N3 represents the HP system.

The fan RPM (N1) of the CFM International CFM56 engine installed on Boeing 737 aircraft is 3,200. The N2 speed of the engine is as high as 13,000 RPM. The International Aero Engines (IAE) V2500 installed on the Airbus A320 family aircraft has an N1 speed of 3,500 RPM and an N2 speed of 11,000 RPM.

The CFM LEAP engines installed on the Airbus A320neo family (LEAP 1-A) and Boeing 737 MAX (LEAP 1-B) have N1 speeds approaching 4,600 RPM, and N2 speeds up to 20,000 RPM. Notably, the smaller the engine, the higher the RPM to achieve the required blade tip speed. Blade-tip speed determines the maximum pressure ratios that can be obtained by the turbine and the compressor. Therefore, larger engines' maximum N1 and N2 speeds are relatively lower.

The N1 of the General Electric CF6-80 engines installed on Boeing 747s and 767s is 3,300 RPM, while the N2 speed is 10,500 RPM. The GE90 for Boeing's 777 rotates at a maximum of 2,850 RPM for N1 and 10,850 RPM for N2. Another engine option for the 777 is the Rolls-Royce Trent 800 engine, which has similar speeds. The N1 speed of the Trent 800 engine is 3,300, N2 speed of 7,000 and N3 speed of 10,600 RPM.

The Rolls-Royce Trent 1000 installed on Boeing 787s has N1 speed of 2,700 RPM, N2 speed of 8,400 RPM and N3 speed of 13,300 RPM. The Trent XWB engine installed on Airbus A350 has an N1 speed of 2,700 RPM, N2 speed of 8,200 RPM and N3 speed of 12,600 RPM.

Rolls-Royce Trent 7000 installed on Airbus A330neo have an N1 speed of 2,900, N2 speed of 8,900, and N3 speed of 13,400 RPM. It is notable that while the maximum RPM of an engine is a design parameter, the RPM is typically limited by the aircraft Electronic Engine Control during flight to prevent engine damage.

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Writer - Omar is an aviation enthusiast who holds a Ph.D. in Aerospace Engineering. With numerous years of technical and research experience under his belt, Omar aims to focus on research-based aviation practices. Apart from work, Omar has a passion for traveling, visiting aviation sites, and plane spotting. Based in Vancouver, Canada