The Pegasus is the only production engine that makes fixed-wing VTOL practical: its four nozzles can rotate from downward thrust for hover to rearward thrust for forward flight. The Mk 105 variant powered the Harrier GR.5 and AV-8B, representing the mature development of a concept Rolls-Royce proved with the original Pegasus in the 1960s .
Pegasus Mk 105 Vectored-Thrust Architecture
The primary subject of this technical guide focuses on the Rolls-Royce Pegasus Mk 105 engine, engineered specifically for Vectored-Thrust Turbofan applications. Below is an essential digest of this powertrain configuration.
• Vectored-thrust turbofan
• ~21,500 lbf thrust
• Four rotating nozzles
• Powered AV-8B and Harrier GR.5
Pegasus Mk 105 Specification Data
Twin-spool turbofan; bypass ratio approximately 1.4; thrust approximately 21,500 lbf; four rotating exhaust nozzles; dry weight approximately 1,470 kg .
The Pegasus’s bypass air is split between the front and rear nozzle pairs, with the fan supplying the front nozzles and the core exhaust supplying the rear. Rotating all four nozzles together vectors the thrust vector from vertical to horizontal. This arrangement gives the Harrier its unique ability to hover, transition to forward flight, and land vertically—capabilities no other production fighter has matched without complex lift-fan systems .
| Type | Vectored-thrust turbofan |
|---|---|
| Bypass Ratio | ~1.4 |
| Thrust | ~21,500 lbf |
| Nozzles | 4 rotating (2 front, 2 rear) |
| Weight | ~1,470 kg |
| Fuel | JP-8 / Jet fuel |
Aircraft Powered by the Pegasus Mk 105
This engine model is deployed across various operational frameworks. Here is a breakdown of the typical machine or vehicle applications using this unit:
McDonnell Douglas AV-8B Harrier II, British Aerospace Harrier GR.5
Pros & Advantages
Unique VTOL capability; proven in combat; mature development of vectored-thrust concept.
Cons & Disadvantages
Complex nozzle mechanism; high fuel consumption in hover; limited payload compared to conventional fighters.
Frequently Asked Questions (FAQs)
Q1: How does the Pegasus enable vertical takeoff?
A1: Four rotating exhaust nozzles vector thrust downward for hover and transition to rearward for forward flight .
Q2: What aircraft use the Pegasus Mk 105?
A2: The AV-8B Harrier II and Harrier GR.5 .
Q3: What is the Pegasus Mk 105’s bypass ratio?
A3: Approximately 1.4 .
Approximately 1,470 kg .