Vortex Generator
Vortex generators (VGs) are small, angled plates or vanes installed on aircraft wings and other surfaces to improve airflow and reduce the risk of flow separation. Originally used on large transport aircraft to address localized buffet issues at high speeds, they have evolved to improve low-speed handling and stall characteristics in various aircraft types, including general aviation and STOL aircraft.
Early Development & Purpose
- VGs were first used on aircraft to address localized airflow problems, especially on swept wings at transonic speeds.
- They were initially used to alleviate shock-stall problems on aircraft like the Harrier and Gloster Javelin.
- The concept of VGs was proposed by Taylor in 1947 to enhance lift and reduce drag by facilitating energy exchange between the boundary layer and the free stream.
- Boeing was among the first to use VGs, initially on the 707.
Evolution and Applications
- VGs gained prominence in the 1970s and 80s, with more aircraft manufacturers incorporating them to improve low-speed handling and stability.
- They have been used on transport jets, business jets, and various general aviation aircraft.
- Ex-Boeing engineer Paul Robertson pioneered the use of VGs in general aviation to address low-speed handling issues.
- VGs are now commonly used on aircraft to reduce stall speeds, improve low-speed handling, and enhance stall characteristics.
- They are particularly beneficial for multi-engine aircraft, as they can reduce minimum control speed (VMC).
- VGs have also been found to improve aileron and rudder authority at low speeds.
How VGs Work
- VGs create vortices, or swirling patterns of air, which interact with the boundary layer (the thin layer of air near the aircraft surface).
- These vortices re-energize the boundary layer, preventing or delaying flow separation, which occurs when the airflow detaches from the surface.
- By maintaining a more attached airflow, VGs improve lift, reduce drag, and enhance control effectiveness.
- The effectiveness of VGs depends on their placement relative to the point where flow separation is likely to occur.
- They are typically positioned near the leading edge of the wing or control surface.
Benefits
- Lower stall speeds: VGs can reduce the speed at which an aircraft stalls.
- Improved low-speed handling: VGs can make an aircraft easier to control at low speeds and high angles of attack.
- Reduced drag: By delaying flow separation, VGs can reduce drag, improving efficiency.
- Enhanced stall characteristics: VGs can make stalls more predictable and less severe.
- Improved control effectiveness: VGs can enhance the effectiveness of control surfaces at low speeds.
- Shorter takeoffs and landings: VGs can enable slower approaches and touchdowns, allowing for shorter landing distances.
In summary, vortex generators have significantly advanced aviation by improving low-speed handling, stall characteristics, and control effectiveness. Their use has evolved from addressing specific airflow problems to becoming a common feature on various types of aircraft, especially those operating in challenging conditions or requiring enhanced safety margins.
