Krueger flaps
Encyclopedia
Krueger flaps are lift enhancement devices that may be fitted to the leading edge
of an aircraft wing
. Unlike slats or drooped leading edges, the main wing upper surface and its nose is not changed. Instead, a portion of the lower wing is rotated out in front of the main wing leading edge.
or slots
, they are deployed differently. Krueger flaps, hinged at their leading edge
s, hinge forwards from the under surface of the wing, increasing the wing camber and maximum coefficient of lift. Conversely, slats extend forwards from the upper surface of the leading edge.
The Krueger flaps developed for the Boeing 747
were constructed from fiberglass
honeycomb material and were designed to be intentionally distorted into an aerofoil section on deployment.
in 1954.
Leading edge
The leading edge is the part of the wing that first contacts the air; alternatively it is the foremost edge of an airfoil section. The first is an aerodynamic definition, the second a structural one....
of an aircraft wing
Wing
A wing is an appendage with a surface that produces lift for flight or propulsion through the atmosphere, or through another gaseous or liquid fluid...
. Unlike slats or drooped leading edges, the main wing upper surface and its nose is not changed. Instead, a portion of the lower wing is rotated out in front of the main wing leading edge.
Operation
While the aerodynamic effect of Krueger flaps is similar to that of slatsLeading edge slats
Slats are aerodynamic surfaces on the leading edge of the wings of fixed-wing aircraft which, when deployed, allow the wing to operate at a higher angle of attack. A higher coefficient of lift is produced as a result of angle of attack and speed, so by deploying slats an aircraft can fly at slower...
or slots
Leading edge slot
A leading edge slot is an aerodynamic feature of the wing of some aircraft to reduce the stall speed and promote good low-speed handling qualities. A leading edge slot is a span-wise gap in each wing, allowing air to flow from below the wing to its upper surface...
, they are deployed differently. Krueger flaps, hinged at their leading edge
Leading edge
The leading edge is the part of the wing that first contacts the air; alternatively it is the foremost edge of an airfoil section. The first is an aerodynamic definition, the second a structural one....
s, hinge forwards from the under surface of the wing, increasing the wing camber and maximum coefficient of lift. Conversely, slats extend forwards from the upper surface of the leading edge.
The Krueger flaps developed for the Boeing 747
Boeing 747
The Boeing 747 is a wide-body commercial airliner and cargo transport, often referred to by its original nickname, Jumbo Jet, or Queen of the Skies. It is among the world's most recognizable aircraft, and was the first wide-body ever produced...
were constructed from fiberglass
Fiberglass
Glass fiber is a material consisting of numerous extremely fine fibers of glass.Glassmakers throughout history have experimented with glass fibers, but mass manufacture of glass fiber was only made possible with the invention of finer machine tooling...
honeycomb material and were designed to be intentionally distorted into an aerofoil section on deployment.
History
Invented by Werner Krüger in 1943 and evaluated in the wind tunnels in Goettingen, Germany but one of its earliest uses wasn't until the Boeing 367-80Boeing 367-80
The Boeing 367-80, or "Dash 80" as it was called within Boeing, is an American prototype jet transport built to demonstrate the advantages of jet aircraft for passenger transport over piston-engine airliners....
in 1954.