A distinction is made between real duck planes, in which the height control is carried out exclusively with the horizontal stabilizer in front, and modern traffic machines and fighter jets, which have auxiliary control surfaces in addition to conventional elevators . These planes are mostly delta-wing aircraft ; the canards are mainly used for flight maneuvers with extreme angles of attack . The Soviet Tupolev Tu-144 , for example, had retractable canard wings that were used for take-off, landing and slow flight.
Definition of terms
The name canard comes from the French word for duck, whose flight pattern is somewhat similar due to the wings far back. Especially abroad, the term canard is often used for the tailplane itself.
The basic idea was first used by the Wright brothers , and in the following decades there was a constant preoccupation of the designers with the subject, which can be seen from the fact that many record performances were achieved with duck planes. On the other hand, there was no commercial success in civil aviation. So far, no large series of duck planes have been brought onto the market. Most of the few Beechcraft Starship business jets sold were bought back by the manufacturer and some of them were given to museums. Burt Rutan helped the duck plane gain a certain popularity with his VariEze and LongEz designs . His design Voyager , with which a non-stop circumnavigation of the world without refueling was possible for the first time , also caused a stir . Paul MacCready's team managed the first crossing of the English Channel with the Gossamer Albatros duck flying machine . The German Museum in Munich is showing Günter Rochelt's Solair-1, the first usable solar airplane in Germany. Towards the end of the Second World War there were attempts in Japan with the Kyūshū J7W and the USA with the Curtiss XP-55 to produce single-engine duck-style fighters.
In modern combat aircraft such as the Dassault Rafale or the Eurofighter , which are designed to be aerodynamically unstable, canards are used to control the flight position during extreme maneuvers beyond the stall.
While in conventional aircraft the horizontal stabilizer has to generate a downward force for reasons of longitudinal stability , in canard aircraft it generates lift across all stationary flight conditions . The same applies to aircraft in tandem design, although it is difficult to differentiate precisely between “ tandem ” and “duck”. B. Scaled Composites Proteus . What they all have in common is the center of gravity somewhere between the center of lift of the front and rear lift surfaces, whereas in normal aircraft and flying wings the center of gravity is usually within the wing geometry, depending on the sweep.
Advantages of the canard construction
- In certain flight conditions, the canard construction can result in a more favorable ratio of lift to drag .
- A better stall behavior is created because the maximum angle of attack of the horizontal stabilizer in front is always reached first in a correctly designed duck plane. As a result, the nose of the aircraft lowers itself again, which prevents a stall on the main wing.
- The center of gravity, which is far forward, allows the engines to be arranged at the rear of the aircraft. This can reduce the noise level in the passenger cabin .
- Due to its center of gravity, the fuselage can usually be used in its entire length for passengers, freight, etc.
- A canard wing can have a positive effect on the flow to the main wing and the vertical stabilizer at high angles of attack .
- Combat aircraft increase the control authority around the pitch axis by combining a delta main wing with a canard wing.
Disadvantages of the canard construction
- Limited use of landing flaps on the main wing (generate a top-heavy moment that has to be compensated by the duck tail and is compensated by a deflection in the same direction). The canard must generate more lift. In a conventional aircraft, the top-heavy torque is compensated for by increased downforce on the tail unit.
- Influencing of the airflow around the wing by the duck tail (on the other hand, in the modern combat aircraft mentioned below, this effect is used to improve the performance of the delta wing and the vertical tail)
- Difficult design because the stall behavior of the duck tail and wing must always be coordinated and the profile selection of the horizontal tail influences the type of stall behavior
- As a rule, larger vertical stabilizers are necessary because of the short lever arm to the center of gravity . For this reason, very large winglets (some with built-in rudders) are used on the wing tips in many modern duck aircraft in order to increase the lever arm and at the same time reduce the induced drag of the wing
- Often the pilot's field of vision is restricted by the duck tail.
- The independent nodding of the aircraft's nose in slow flight is necessary when landing in the high angle of attack range. U. dangerous. Landing at minimum speed (maximum lift) should therefore be avoided.
- Michael Schönherr: High-performance lightweight ducks, developed around 1975–1985. www.m-schoenherr.de, accessed on August 19, 2018 .
- Beechcraft Starship - Marian Aldenhövel. In: marian-aldenhoevel.de. Retrieved February 6, 2019 .
- Michael Schönherr: Presentation of high-performance lightweight ducks. Retrieved September 7, 2012 .
- Canard Pilots. The advantages of the canard aircraft. (No longer available online.) Formerly in the original ; Retrieved September 7, 2012 . ( Page no longer available , search in web archives ) Info: The link was automatically marked as defective. Please check the link according to the instructions and then remove this notice.
- The mirror. Tail off. April 23, 1984. Retrieved September 7, 2012 .