Strake (aeronautics)

Lore & Background

Strakes appear in various forms on both subsonic and supersonic aircraft. Nose strakes, such as those on the Concorde, are applied to the forward fuselage to control airflow at high angles of attack and improve directional stability. Wing strakes, also known as leading edge root extensions (LERX), are seen on double delta wing aircraft like the Concorde, Tupolev Tu-144, Boeing 2707, and Lockheed L-2000 SST projects, providing additional vortex lift at high angles of attack. Nacelle strakes are added to engine nacelles slung under wings to energize airflow over the wings during takeoff and landing, improving wing effectiveness. Ventral strakes under the fuselage, as on the SOCATA TB family and Lockheed F-104 Starfighter, act as large vortex generators to enhance tail surface efficiency. Rear strakes or tail fins, such as those on the Piaggio P.180 Avanti, Learjet 60, and Beechcraft 1900D, provide stability at high angles of attack when the tail fin is shielded. The Grumman X-29 featured rear fuselage lateral fins continuous with the main wing trailing edge, enabling a three-surface configuration. Anti-spin strakes at tailplane roots on aerobatic aircraft like the de Havilland Tiger Moth and Scottish Aviation Bulldog help prevent spins; a dorsal fillet was added to the North American P-51 Mustang D variant for tail strength and lateral stability. Munitions strakes, fitted as bolt-on collars to 500-pound bombs, normalize aerodynamics for greater accuracy, and are also used on guided munitions to stabilize slipstream for predictable control surface action.

Reader's Guide

Strakes are notable for their versatility in improving aircraft performance across a wide range of applications. They serve as vortex generators to control airflow at high angles of attack, enhancing lift and stability during critical phases like takeoff and landing. On supersonic aircraft such as the Concorde, nose strakes improve directional stability, while wing strakes on double delta designs provide vortex lift. Nacelle strakes increase wing effectiveness by energizing airflow over the wings. Ventral and rear strakes improve tail surface efficiency and stability when the tail fin is shielded. Anti-spin strakes on aerobatic aircraft enhance safety by preventing spins. In munitions, strakes significantly improve accuracy by stabilizing the weapon's glide and making control surfaces more predictable. The legacy of strakes lies in their simple yet effective aerodynamic contribution, from early designs like the North American P-51 Mustang to advanced research aircraft like the Grumman X-29, demonstrating their enduring value in aviation.

Did You Know?

• The Concorde had small nose strakes to get better directional stability.
• Leading edge root extensions (LERX) are sometimes referred to as wing strakes.
• Anti-spin strakes are placed at the tailplane roots of aerobatic aircraft such as the de Havilland Tiger Moth.
• Bolt-on strake sets are used on 500-pound dumb bombs to improve accuracy.