sideslip

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(車・スキーなどが)横すべりする / 横すべり,横転

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出典(authority):フリー百科事典『ウィキペディア（Wikipedia）』「2012/07/09 16:40:58」(JST)

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"Sideslip" redirects here. For the angle of sideslip, see Sideslip angle.

A slip is an aerodynamic state where an aircraft is moving somewhat sideways as well as forward relative to the oncoming airflow. In other words, for a conventional aircraft, the nose will not be pointing directly into the relative wind (in the side-to-side sense).

A slip is also a piloting maneuver where the pilot deliberately puts the aircraft into a slip.

Background

Flying in a slip is aerodynamically inefficient. Inexperienced pilots will often enter slips unintentionally during turns by failing to coordinate the aircraft using the rudder; however there are common situations where a pilot may enter a slip deliberately by using opposite rudder and aileron inputs, most commonly in a landing approach at low power^[1]. Without a slip it is difficult to increase the steepness of the glide without adding significant speed. This excess speed can cause the aircraft to fly in ground effect for an extended period, perhaps running out of runway. In a slip much more drag is created, allowing the pilot to dissipate altitude without increasing airspeed, increasing the angle of descent (glide slope). Additional airspeed will further increase the steepness of descent.

Slips are especially useful when operating aircraft that have neither high-drag flaps nor spoilers (typically pre-1950s training aircraft, or in aerobatic aircraft such as the Pitts Special), or in any aircraft in which the flaps cannot be extended due to a system failure, or when finer control is needed.

As with any low altitude maneuver it is important to maintain correct airspeed in order to prevent a stall. However, if an airplane in a slip is made to stall, it displays very little of yawing tendency that causes a skidding stall to develop into a spin. The airplane in a slip may do little more than tend to roll into a wings level attitude. In fact, in some airplanes stall characteristics may even be improved. ^[2]

Forward-slip vs. Sideslip

Two forms are employed, the forward-slip and the sideslip. Aerodynamically these are identical once established, but they are entered in different manners and will create different ground tracks and headings relative to those prior to entry. Slips are particularly useful in performing a short field landing over an obstacle (such as trees, or power lines), or to avoid an obstacle (such as a single tree on the extended centerline of the runway), and may be practiced as part of emergency landing procedures. These methods are also commonly employed in flying into farmstead or rough country airstrips where approach hazards are present.

Forward-slip

The forward slip will change the heading of the aircraft away from the down wing, while retaining the original track (flight path over the ground) of the aircraft.

A forward-slip is useful when a pilot has set up for a landing approach with excessive height or must descend steeply beyond a tree line to touchdown near the start of a short runway. Assuming that the runway is properly lined up, the forward slip will allow the aircraft track to be maintained while steepening the descent without adding excessive airspeed. Since the heading is not aligned with the runway, the slip must be removed before touchdown to avoid excessive side loading on the landing gear, and if a cross wind is present an appropriate side slip may be necessary at touchdown as described below.

In the United States, student pilots are required to know how to do forward slips before embarking on their first solo flight. The logic is that in the event of an engine failure, the pilot will have to land on the first attempt and will not have a chance to go around if the aircraft is too high and/or too fast.

Sideslip

The sideslip also uses opposite aileron and rudder. In this case it is entered by lowering a wing and exactly enough opposite rudder so the airplane does not turn (maintaining the same heading), while adding airspeed as required.

In the sideslip condition, the airplane's longitudinal axis remains parallel to the original flightpath, but the airplane no longer flies straight along its original track. Now, the horizontal component of lift forces the airplane to move sideways toward the low wing.

A sideslip is also one of the methods used by pilots to execute a crosswind landing. In order to land crosswind using the sideslip method, the pilot puts the airplane into a sideslip toward the wind to maintain runway centerline position while maintaining heading on the centerline with the rudder, touching one main landing gear, followed by the second main gear, and finally the nose gear (or tail gear if employed). This allows the wheels to be constantly aligned with the track, thus avoiding any side load at touchdown.

The sideslip method for cross-wind landings is not suitable for long winged and low sitting aircraft such as sailplanes, where instead a crab angle (heading into the wind) is maintained until a moment before touchdown.

Uses of the slip

Other uses

There are other, specialized circumstances where slips can be useful in aviation. For example, during aerial photography, a slip can lower one side of the aircraft to allow ground photos to be taken through a side window. Pilots will also use a slip to land in icing conditions if the front windshield has been entirely iced over — by landing slightly sideways, the pilot is able to see the runway through the aircraft's side window. Slips also play a role in aerobatics and aerial combat.

Notable employment of the slip

Gimli Glider - a 767 captain who happened to have glider experience made a successful engine-out landing despite excessive approach altitude by employing a slip

How a Slip affects flight

When an aircraft is put into a side slip with no other changes to the throttle or elevator, the pilot will notice an increased rate of descent (or reduced rate of ascent). This is usually mostly due to increased drag on the fuselage. The airflow over the fuselage is at a sideways angle, increasing the relative frontal area, which increases drag.

External links

Video of a slip from camera mounted on landing gear
FAA Airplane Flying Handbook Chapters 7-9

References

^ John S. Denker, See How It Flies. http://www.av8n.com/how/htm/snaps.html#sec-intentional-slip
^ http://www.faa.gov/library/manuals/aircraft/airplane_handbook/media/faa-h-8083-3a-4of7.pdf

English Journal

Development of a small sucker manipulator for underwater surgery support.

Tsuchiya N, Sekine M, Kita K, Wenwei Yu.
Conference proceedings : ... Annual International Conference of the IEEE Engineering in Medicine and Biology Society. IEEE Engineering in Medicine and Biology Society. Annual Conference.Conf Proc IEEE Eng Med Biol Soc.2014 Aug;2014:384-7. doi: 10.1109/EMBC.2014.6943609.
WaFLES (Water-Filled LaparoEndoscopic Surgery) is an operative method suggested by Igarashi et al., which has several advantages, such as, preventing the drying of inner organs, and being able to use ultrasound devices for real time monitoring. However, grasping of inner organs with usual forceps fo
PMID 25569977

Comparative study on a solving model and algorithm for a flush air data sensing system.

Liu Y1, Xiao D2, Lu Y3.
Sensors (Basel, Switzerland).Sensors (Basel).2014 May 23;14(5):9210-26. doi: 10.3390/s140509210.
With the development of high-performance aircraft, precise air data are necessary to complete challenging tasks such as flight maneuvering with large angles of attack and high speed. As a result, the flush air data sensing system (FADS) was developed to satisfy the stricter control demands. In this
PMID 24859025

A multibody approach for 6-DOF flight dynamics and stability analysis of the hawkmoth Manduca sexta.

Kim JK1, Han JH.
Bioinspiration & biomimetics.Bioinspir Biomim.2014 Mar;9(1):016011. doi: 10.1088/1748-3182/9/1/016011. Epub 2014 Jan 22.
This paper investigates the six degrees of freedom (6-DOF) flight dynamics and stability of the hawkmoth Manduca sexta using a multibody dynamics approach that encompasses the effects of the time varying inertia tensor of all the body segments including two wings. The quasi-steady translational and
PMID 24451177

Japanese Journal

Lateral Slope Effect on Tipping Behavior of a Tractor Encountering an Obstacle (Model Development)

Li Zhen,Mitsuoka Muneshi,Inoue Eiji,Okayasu Takashi,Hirai Yasumaru
Journal of the Faculty of Agriculture, Kyushu University 59(2), 345-349, 2014-08-29
… Furthermore, the supporting and lateral friction forces can be examined since they predominantly determine the tractor lateral rollover and sideslip which affect tractor safety to a great extent. … In particular, a specific slope angle of 25˚ was highlighted as a warning parameter because the onset of rollover as well as tractor sideslip were discovered. … It is also found that a tractor is more susceptible to sideslip than rollover along with the slope increasing. …
NAID 120005472187

車体横すべり角が操舵に与える影響について

鈴木雄太,風間恵介,孕石泰丈,毛利宏,菅沢深
日本機械学会論文集 80(815), TL0217-TL0217, 2014
… In order to investigate the influence of the sideslip angle to drivers steering behavior, driving simulator is employed to realize various vehicles with different side slip characteristics. …
NAID 130005004940

Influences of Angles of Attack and Sideslip on the Flow Field of a Cantilevered Ramp Injector in Supersonic Flows

, , [他],
TRANSACTIONS OF THE JAPAN SOCIETY FOR AERONAUTICAL AND SPACE SCIENCES 57(4), 195-200, 2014
… The effects of the angles of attack and sideslip on the flow field of a cantilevered ramp injector have been studied, and the predicted axial distribution of the maximum injectant mole fraction shows good agreement with the available experimental data in public literature. …
NAID 130004735456

Related Pictures

Supermonk Sideslip by astir698 flight were determined with zero sideslip Name: Medicop sideslip.jpgViews: 367Size Sideslip Aerodynamics.gif Metodo Sideslip لغت وارد شده : angle of sideslip must, therefore, eliminate the sideslip