The Rolls-Royce Spey is a low-bypass turbofan family that served both civil and military aviation. Its civil installations included the Trident, BAC One-Eleven, Fokker F28 and Grumman Gulfstream, while military applications included the Buccaneer, British Phantom and Nimrod. The RAF Museum preserves a Spey 505-5 as an example of this early generation of bypass engines.[1]Rolls-Royce R.B.163 Spey 505-5Royal Air Force Museum · rafmuseum.org.uk · Accessed 2026-09-13Open source details
Compressor arrangement
The Spey 511 and 555 civil variants use a five-stage axial low-pressure compressor and a twelve-stage axial high-pressure compressor. Each compressor is driven by its own two-stage turbine. The combustion assembly contains ten straight-through flame tubes. EASA's type-certificate description records this machinery directly, providing a more specific picture than the broad description of the Spey as a turbofan.[2]EASA E.064: Spey 500 Series EnginesEuropean Union Aviation Safety Agency · easa.europa.eu · Accessed 2026-09-13Open source details
Civil variants
The Spey 511-8 and 511-14 have a published bypass ratio of 0.64:1. The later 555 variants listed in the same certificate have ratios close to 1:1, showing a significant difference in the division between bypass and core airflow. The document records certification dates extending from the 511-14 in May 1966 to the 555-15N and -15P in February 1981. These dates concern particular certified models within a wider family.[2]EASA E.064: Spey 500 Series EnginesEuropean Union Aviation Safety Agency · easa.europa.eu · Accessed 2026-09-13Open source details
Military service
The range of military applications gave the Spey roles in maritime patrol, strike and air defence. British versions of the Phantom used Spey engines, and the RAF Museum distinguishes these from the American-powered F-4J aircraft later acquired by Britain. The latter received British equipment and the designation F-4J(UK), but belonged to a different propulsion configuration from the RAF's Spey-powered Phantoms.[1]Rolls-Royce R.B.163 Spey 505-5Royal Air Force Museum · rafmuseum.org.uk · Accessed 2026-09-13Open source details[3]McDonnell Douglas Phantom FGR2Royal Air Force Museum · rafmuseum.org.uk · Accessed 2026-09-13Open source details
Preserved example
The RAF Museum's 505-5 is displayed at its Midlands site. The collection describes the Spey as a durable and economical engine spanning both airline and military service. That broad application history is its defining feature: closely related bypass-engine technology supported regional transport aircraft, corporate travel and several very different military missions.[1]Rolls-Royce R.B.163 Spey 505-5Royal Air Force Museum · rafmuseum.org.uk · Accessed 2026-09-13Open source details