Picture an aircraft: the wings, the tail, the cabin - visualize it flying overhead as it displays its prowess and heads for the open skies. Did the aircraft you imagined have straight wings? It is a common misconception that all aircraft wings that protrude straight out from the cabin, perpendicular from the plane itself. However, a swept wing is one that angles backwards from its root and points towards the tail of the aircraft.
Bernoulli’s principle of lift demonstrates how airflow over the top of a wing is faster than below. When an aircraft travels fast enough it can cause the airflow to become supersonic, which makes the air flow off the wing as opposed to sticking to it, lowering the amount of lift. This is called the critical Mach number. With straight wings, this speed is relatively low since all of the air flows over the wing. Swept wings utilize their shape to direct part of the airflow along the front edge of the wing, reducing the amount of air flowing over the wing. This ultimately increases the critical Mach number because less air is available to create a supersonic effect.
When a swept wing travels at high speeds, the airflow has a short amount of time to react to the oncoming force, which causes it to flow over the wing from front to back. At lower speeds, the air is able to react, and pushes the air across its length towards the wing tip. With increasing spanwise flow the boundary layers on the surface of the wing have a longer distance to travel, making them thicker and more susceptible to flow separation. The result is that wing components based towards the rear operate at increasingly higher angles of attack, creating a nose-up pressure on the aircraft. To combat this issue, a wing fence was added on the upper surface of the wing to direct the flow of air to the rear. Other modern solutions include adding leading edge slats and compound flaps. Fighter jets have added leading edge extensions that assist in maneuverability in high speed situations.
When designing high speed wings, engineers consider compressibility. This is the effect on a wing caused by passing through the speed barrier and entering different speeds. An aircraft can suffer negative effects of compressibility which leads to malfunctions. The next time you see a swept wing, consider its purpose and application.
Remember Us the Next Time You’re Looking for NSN Parts. We Can Get You Some of the Quickest and Most Competitive Quotes In the Industry.Request for Quote