A modern passenger plane is a very complicated mechanism, where designers use the most advanced technologies to ensure a stable flight. One of the know-how, relatively recently appeared on the wings of airliners, is the vertical aerodynamic tips to increase the aerodynamic quality of aircraft - winglets.
This story tells about the history of the appearance and development of this technology in the passenger aircraft industry.
History of the invention of technology
The wingtip is called the vertically curved tip of the plane. It smoothly bends almost 90 degrees vertically at the place where the wing spar ends. The basics of the wing tip bending technique were laid in the work of NASA engineer Richard Whitcomb. At the beginning of the seventies of the last century, he proposed the design and fundamentals of the aerodynamics of the wingtip, which was mounted perpendicular to the wing with a direction up or down. Research and experimental flights lasted a decade and a half. In 1985, the Boeing 747-400, the world's first passenger airplane with wings equipped with wingtips, took off.
Five years later, the head of the aerodynamic department of Aviation Partners received a patent for a blended winglet, which smoothly bends upward. Exactly so, leaving only the second word, experts began to call the wingtip.In 1991, winglets were used in the United States to modernize a private jet liner. This allowed to reduce fuel consumption by 7%.
At the turn of the century, passenger liners of leading companies began to be equipped with wings with vertical winglets. Among the most famous:
- Boeing - 737-700, 737-800, 747-400, 777;
- Airbus - A 310-300, A 320, A 330, A 340, A 350, A 380.
- Tu - 96-300, 204, 214, 334.
Absolutely unique winglets are installed on the French giant A 380. They occupy only part of the length of the end of the spar, bending down and up. Airbus engineers first tested this technology in 1985, using double-sided tips to reduce the inversion footprint of the A 310-300. Chinese engineers managed to equip the tips of the wings of such "ancient" by modern standards of Soviet developments, as the An-2 (Y-5C) and An-24 (Xian Y-7).
What are winglets for?
From a technical point of view, the wingtip is a hollow design such as monocoque or semi-monocoque. Winglets are installed not only on the main planes, but also on the keel and stabilizers in the rear of the fuselage. In addition to aerodynamic functions, they can perform a number of tasks. Designers install various equipment on winglets:
- navigation lights;
- charge strikers to combat lightning.
From the point of view of physics, the wingtip provides a natural extension of the wing, without changing the magnitude of its wingspan. Another main task of winglets is to reduce the energy costs of movement during the formation of vortices at the tips of the wing due to the pressure difference below and above. Exactly the desire to increase the elongation of the wing and its effective area was the main reason for the appearance of new elements in the design.
Disadvantages
However, one should not think that winglets have only positive aspects. Their main disadvantages include:
- negative effect of strong wind in take-off / landing mode;
- susceptibility of the aircraft to turbulence.
Currently, engineers at Boeing Corporation are in full swing developing an aircraft that could effectively compete with the Airbus A-380. He received the marking of the B 777X. Folding winglets can become one of the novelties used to increase efficiency and reduce fuel consumption. The approximate length of the folding wing section is 7.3 m. The experiments have two goals: optimizing the load distribution of the wing in flight, during takeoff and landing; increase in wing lift of the Boeing 777X. The folding winglet design should include a drive and a strong lock.
