Essay About Concept Of Winglets And Small Airfoils

Winglet
Winglet
Winglets are one of the most successful examples of a NASA aeronautical innovation being utilized
around the world on all types of aircraft.
Winglets are vertical extensions of wingtips that improve an aircrafts fuel efficiency and cruising
range. Designed as small airfoils, winglets reduce the aerodynamic drag associated with vortices that develop
at the wingtips as the airplane moves through the air. By reducing wingtip drag, fuel consumption goes
down and range is extended.
Aircraft of all types and sizes are flying with
winglets — from single-seat hang gliders and
ultralights to global jumbo jets. Some aircraft are
designed and manufactured with sleek upturned
winglets that blend smoothly into the outer wing
sections. Add-on winglets are also custom made
for many types of aircraft.
The concept of winglets originated with a
British aerodynamicist in the late 1800s, but the idea
remained on the drawing board until rekindled in
the early 1970s by Dr. Richard Whitcomb when the
price of aviation fuel started spiraling upward.
Whitcomb, a noted aeronautical engineer at the
NASA Langley Research Center, refined the winglet
concept with wind tunnel tests and computer studies.
He then predicted that transport-size aircraft with
winglets would realize improved cruising
efficiencies of between 6% and 9%. A winglet flight
test program at the NASA Dryden Flight Research
Center in 1979-80 validated Whitcombs research
when the test aircraft — a military version of the
Boeing 707 jetliner — recorded an increased fuel
mileage rate of 6.5%.
The Benefits of Winglets
Since the 1970s, when the price of aviation
fuel began spiraling upward, airlines and aircraft
manufacturers have looked at many ways to improve
the operating efficiency of their aircraft. Winglets
have become one of the industrys most visible fuelsaving
technologies and their use continues to
expand.
Winglets increase an aircrafts operating
efficiency by reducing what is called induced drag
at the tips of the wings. An aircrafts wing is shaped
to generate negative pressure on the upper surface
and positive pressure on the lower surface as the
aircraft moves forward. This unequal pressure
creates lift across the upper surface and the aircraft
is able to leave the ground and fly.
Unequal pressure, however, also causes air at
each wingtip to flow outward along the lower
surface, around the tip, and inboard along the upper
surface producing a whirlwind of air called a wingtip
vortex. The effect of these vortices is increased drag
and reduced lift that results in less flight efficiency
and higher fuel costs.
Winglets, which are airfoils operating just like
a sailboat tacking upwind, produce a forward thrust
inside the circulation field of the vortices and reduce
their strength. Weaker vortices mean less drag at
the wingtips and lift