Setting angle

from Wikipedia, the free encyclopedia

In aircraft, the setting angle is the angle between the longitudinal axis (see: Flight control ) of the aircraft fuselage and the longitudinal axis of the wing profile (= profile chord of the wing ).

Setting angle

This angle is a design feature and, unlike the angle of attack in today's common aircraft designs, it cannot be changed as a rule. Only in a few designs, such as the Vought F-8 series aircraft, is the angle of attack controlled by changing the angle of attack. This type of control around the transverse axis was earlier z. B. in the aircraft of Henri Mignets , the small aircraft known as sky louse common. Larger aircraft, such as the Messerschmitt Bf 163 built to compete with the Fieseler Fi 156 , could also change the angle of attack in flight. The largest aircraft equipped with such a facility was the Blohm & Voss BV 144 .

In the case of helicopters, the setting angle of the main rotor blades can be adjusted via the control rods and the swash plate within certain limits defined by the design. The same applies to the tail rotor.

The angle of incidence for the wing is chosen in the design so that the fuselage offers the smallest possible frontal area in the most frequently expected flight position of the flow and thus has the lowest possible air resistance .

The term setting angle is also used for the angle between the horizontal stabilizer and the longitudinal axis of the fuselage. The difference between the setting angle of the wing and the setting angle of the horizontal stabilizer results in the setting angle difference (EWD). It is measured between the chord of the wing near the fuselage and the chord of the horizontal stabilizer. For model airplanes, the EWD ranges from minus 2 degrees (Pylonracer F3D, F5D) to plus 5 degrees and depends on the selected profiles and the typical flight speed for the model. For aircraft carrying passengers, the EWD is between 5 and 7 degrees.

In the case of wind turbines , the setting angle describes the angle between the rotor plane and the chord. Modern systems use the rotor blade adjustment for power control.

Longitudinal stability

The aerodynamic stability of the uniform flight is determined by the geometry of the "pressure point center of gravity".

The trim speed of an aircraft is usually set so that the best glide angle is achieved. This is done by adjusting the center of gravity and the horizontal stabilizer.

A glider control means to change this geometry (distance and orientation). This is achieved by moving the center of gravity or - aerodynamically - by changing the angle of attack of the horizontal stabilizer or the rear flaps on the wing.

In order to achieve good flight stability and controllability around the transverse axis, the horizontal stabilizer generates little lift in normal flight position . The trim flight should be able to accelerate as quickly as it can be slowed down. The setting angle of the horizontal stabilizer (compared to the longitudinal axis of the fuselage) is therefore smaller than that of the wing.

literature