Rollers (longitudinal axis)
| Roll-Nick-Yaw angle ( Euler angle ) | |
|---|---|
 |
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| Rotation axes : | Move: |
| ↙ Longitudinal axis (roll / roll axis) : | Roll , sway |
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| ↖ transverse axis (pitch axis) : | Nod, stamp |
| ↓ vertical axis (yaw axis) : | Yaw (roll) |
Rolling refers to the movement of a watercraft , aircraft or spacecraft around its longitudinal axis . In land vehicles , the movement is known as swaying .
Planes
Aircraft roll motion is triggered by operating the ailerons or shifting weight , usually to initiate a change of direction. The elevator is pulled at the same time so that the aircraft does not lose altitude . Helicopters roll through the cyclic blade adjustment using the control stick .
A (sailing) pilot does rolling exercises to get a feel for the interplay of aileron and rudder. The student pilot must try to control the aircraft nose with ailerons and rudders around a point on the horizon so that the nose swings approximately 45 ° to the left and 45 ° to the right around this point. The thread should stay in the middle.
Ships
Ships are mainly caused to roll by rough seas . Attempts are made to prevent this in particular on modern passenger ships in order to enable passengers to travel comfortably without seasickness . For this purpose, ballast water , for example, is pumped back and forth between rolling tanks on the side . If this happens with the correct frequency, it corresponds to the damping effect of a pendulum absorber .
There was also an attempt to pivot the saloon of a ship around the longitudinal axis so that it would remain in a horizontal position at all times ( prototype experimental steamship according to Bessemer from 1875). The desired effect was not achieved, so development was discontinued.
Today both large cargo ships (container ships) and passenger ships are partially equipped with so-called stabilizers. If necessary, these stabilizing fins are moved out of the ship to the side and below the waterline and work in the opposite direction to the ship's movements. These stabilizers, which look like lateral fins, are driven hydraulically. When using the stabilizers, the fuel consumption of the ship increases significantly, since the shape resistance of the ship increases and the ship's propulsion system requires more power to achieve the same speed.
Heavy rolling of cargo ships carries the risk of the cargo slipping, especially if it is not properly secured . This results in the list and thereby sometimes to capsize and sink of the vessel. It is therefore important to secure cargo correctly when loading general cargo. It is particularly dangerous for large amounts of liquid to slosh around, for example through water that has penetrated into rooms. It can quickly get to the other side of the ship with every movement and amplify the movements. For this reason, tanks must not extend across the entire width of the ship; they are to be divided by longitudinal bulkheads because they can lead to capsizing of the ship when half-filled. This corresponds to the baffle plate .
Parametric rolling is understood to mean spontaneous, uncontrollable rocking of the ship up to damage or loss of the cargo. This is caused by a large number of parameters such as ship length, draft , wave height and frequency etc .; it is most likely to occur when a ship is running or lying across the waves. The parametric excitation can rock a ship from a roll angle of less than ± 5 degrees to a roll angle of over ± 45 degrees within 5 or 6 oscillation periods.
The violin , which is feared in sailing, is similar , a swaying rolling motion to both sides that only occurs on a downwind course , mostly under spinnaker . It can capsize .
The static inclination around the longitudinal axis of ships is called heeling .
See also
literature
- Ernst Götsch: Aircraft technology . Motorbuchverlag, Stuttgart 2003, ISBN 3-613-02006-8 .
- Peter Kemp: Encyclopedia of Ships & Seafaring . Stanford Maritime, London 1980, ISBN 0-540-07194-3 .
Individual evidence
- ↑ Securing of general cargo . (PDF; 3.1 MB)
- ↑ Peter Kröger: Simulation of the rolling movement of ships in the sea . (PDF) 1987, p. 49 f.
- ↑ Parametric scrolling. In: TUHH Maritime Systems. TU Hamburg-Harburg: Research focus on maritime systems, accessed on March 28, 2019 .