Dutch Roll

Dutch Roll, tumbling, Dutch roll or yaw oscillation referred to an undesirable aerodynamic characteristics of aircraft in which the engine deflects alternately on both sides about the yaw axis ( vertical axis ) and the longitudinal axis.

Wings above the aircraft center of gravity and positive V -position of the surfaces reinforce the tendency to dutch rolls. Therefore, the wing of high - and shoulder -deckers are often arranged in anhedral. The "Dutch roll " problem can be found on all aircraft with swept wings.

Since Dutch Rolls are usually undesirable, (English yaw damper ) have been developed as a countermeasure yaw damper. These are systems that counteract adverse yaw motions by deflection of the rudder.

Explanation

Dutch roll is a coupling of oscillations about the vertical axis and the longitudinal axis. The tendency to Dutch roll occurs when the effect of the lateral stability is greater than that of the rate stability. When an aircraft is disturbed in its course equilibrium, the leading surface generates more lift and more drag than the trailing surface. Is the effect of buoyancy is greater than the resistance, then a Sideslip maneuvers ( sideslip ) in the opposite direction and the Dutch -roll cycle repeats.

The Dutch roll problem is found with all aircraft with swept wings. Therefore, most aircraft are equipped with a yaw damper. The effect of the Dutch- roll problem can be partially mitigated by reducing the sweep angle and an improvement in the rate stability. The rate stability can be improved by the use of larger vertical stabilizers, but a detrimental effect on the size, weight, structure, and air resistance., An extension of the fuselage, and in particular the extension of the distance between the fin and an aerodynamic focus lengthens the lever arm, thus increasing the force with which the fin is rate stabilizing effect on the aircraft ( Figure 2).

Naming

The term Dutch roll comes from English and means literally " Dutch roll ".

On the origin of the name, there are two interpretations. Most commonly reported, the name goes back to the association with Dutch skaters, one of the yaw oscillation of an aircraft would performs similar movement on the ice. This interpretation is Attributed often an unnamed engineer who had been involved in the development of the Boeing B -47. This type of aircraft reached 1947 launched one of the first critical speed range, occur in the Dutch Rolls.

Another interpretation refers to the English phrase Dutch courage (literally: Dutch courage ) for drunken courage. She alludes to the fact that these oscillations of an aircraft give the impression that it would control under the influence of alcohol.