Air_is_a_liquid Posted January 4, 2006 Share Posted January 4, 2006 Hi Everyone; Newbie here. Wondering why so many people are building Canards? I've managed to find short lists of the advantages and disadvantages of Canards in general, however, what made you choose a canard over a traditional design for your home-built? Here's a list from Desktop Aero: Advantages Possibility for very good stalling characteristics without elevator stops. Sometimes a desirable layout from the packaging standpoint: Main wing carry-through behind cabin, pusher engine installation simplified. Synergistic use of winglets for directional stability. In certain cases a simplified control linkage is possible. When wing flaps are not desired (for simplicity as in ultralights, or competition rules as with standard class sailplanes for example) the CLmax of a canard may exceed that of an aft-tail airplane. For unstable aircraft, canard designs may have a CLmax and/or drag advantage. Control authority is larger for unstable canard aircraft at high CL than for unstable aft-tail designs. Disadvantages Fuel center of gravity lies farther behind aircraft c.g. than in conventional designs. This means that a large c.g. range is produced or that the fuel must be held elsewhere (e.g. strakes near the wing root.) CLmax problems with flaps or margin on the entire wing: Flaps produce a larger pitching moment about the c.g. on a canard aircraft. This results in the need for both large canard aerodynamic incidence change and high maximum canard lift coefficient. Note that since the value of a S is usually larger for canard designs, Cm0 has a greater impact on L than it does on aft-swept designs. Induced drag / CLmax incompatibility: Canard designs can achieve equal or better CLmax values than conventional designs, and similar values of span efficiency. However, the configurations with high CLmax values have terrible values of e and those with respectable e 's have low maximum lift coefficients. Directional stability: The distance from the aircraft c.g. to the most aft part of the airplane is usually smaller on canard aircraft. This poses a problem for locating a vertical stabilizer and may result in very large vertical surfaces. (Note, however, that winglets may be used to advantage in this case.) Wing twist distribution is strange and CL dependent: The wing additional load distribution is distorted by the canard wake. Power effects on canard - deep stall: Accidents have been associated with tractor canard configurations for which the propeller slipstream has prevented canard stall before wing stall. The result is a possible deep-stall problem. Finally, and perhaps most importantly, canard sizing is much more critical than aft tail sizing. By choosing a canard which is somewhat too big or too small the aircraft performance can be severely affected. It is easy to make a very bad canard design Quote Link to comment Share on other sites More sharing options...
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