• Journal of the Korean Society for Aviation and Aeronautics
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• v.12 no.2
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• pp.71-81
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• 2004

There are four methods of landing of B747-400 during the crosswind condition. Pilots can choose either one of them. Those are: Sideslip/Wing low, De-Crab during Flare, Touchdown in Crab, Combining Crab and Sideslip. They decide to use one method by what they have learnt before. During the flight, the pilots choose the method, which depends on the weather forecast, and then try to land according to it. However, the weather condition always changes. In other words, the weather during planning and landing can be different, which can provide a difference between the previously expected situation and the actual one. Therefore, it is very important for the pilots to have the situation awareness. This study shows the direction and the prevention to avoid those errors, which are based on actual landing data of B747-400.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.30 no.3
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• pp.37-45
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• 2002

The vortex flow and aerodynamic load characteristics of a $65^{\circ}$ sweep delta wing with the leading edge extension in sideslip condition is investigated experimentally. The freestream velocity is 40 m/sec, which corresponds to a Reynolds number per meter of $1.76{\times}10^6$ based on the wing root chord. The angles of attack range from $12^{\circ}$ to $28^{\circ}$, and the sideslip angles treated are $0^{\circ}$ , $-10^{\circ}$, $-20^{\circ}$. The LEX vortex of the leeward side. The LEX and wing vortics coalesce to to become a concentrated strong vortex or to break down at down at downstream position. Due to the interation of the LEX and wing vortices, a high suction pressure is maintained on the windward wing surface, and a low suction pressure is formed on the leeward wing surface

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.43 no.3
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• pp.224-231
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• 2015

An experimental study on aerodynamic coefficients of a lambda wing configuration was performed at the low speed wind tunnel of Agency for Defense Development. The main purpose of this study was to investigate the effects of sideslip angle on various aerodynamic coefficients. In the case of $0^{\circ}C$ sideslip angle, nose-up pitching moment rapidly increases at a specific angle of attack. This unstable pitching moment characteristic is referred to as pitch break or pitch up. As the sideslip angle increases, the pitch break is found to be generated at a higher angle of attack. Rolling moment is found to show similar behavior pattern to 'pitch break' style with angle of attack at non-zero sideslip angles. This trend gets severer at greater sideslip angles. Yawing moment also shows substantial variation of the slope and the unstable directional stability with sideslip angles at higher angles of attack. These characteristics of the three moments clearly implies the difficulty of the flight control which requires efficient control augmentation system.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.33 no.12
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• pp.9-17
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• 2005

An experimental study of the vortical flow over a yawed delta wing with leading edge extension(LEX) was conducted to investigate the effects of the existence of a centerbody configuration on the flow characteristics of the wing and LEX vortices using off-surface visualization and PIV measurements. The qualitative investigation using these two techniques indicated that the effect of the centerbody existence on the vortex formation was minimal at somewhat low range of angles of attack and sideslip angles. However, the quantitative analysis of the surface pressure measurements revealed the effect of centerbody existence to be prominently increased for the cases with higher angles of attack and sideslip angles. It was also found that the centerbody effect was not significant compared to the effect of sideslip for the present LEX-delta wing configuration.

• Journal of Aerospace System Engineering
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• v.7 no.2
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• pp.23-28
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• 2013

This is a research on the method of how to improve lateral stability for the small general aviation airplane to meet the FAR part 23 requirements. This research is based on the experience of certification flight tests of KC-100 airplane for Korea first type certification. KAS/FAR Part 23.177 is the static lateral and directional stability requirement. And, 23.177(b) requires to show the tendency to raise the low wing in steady heading side slip maneuver. However, it is very difficult for the low wing to be raised at the low speed during the steady heading side slip maneuver. So, the requirement allows not be negative at the $1.2V_{S1}$ speed and takeoff configuration. (static stability requirement requires low wing picked up at any speed except $1.2V_{S1}$ speed and takeoff configuration) In this paper, the static lateral stability requirements and the lessons & learned of KC-100 airplane certification flight test results are shown.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.30 no.4
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• pp.38-43
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• 2002

A study on the test, design and fabrication of wind tunnel model for measurement of air load distribution on wing surfaces is presented. 447 pressure taps are installed normal to the wing surfaces, and measured by PSI-8400 system using total 8 ESPs modules installed in the model. The test was performed at 50 m/sec constant speed in the low speed wind tunnel of Agency for Defense Development. Tests were carried out to determine effects of angle of attack, angle of sideslip and flap and stores for the load distribution of wing. The test results in this paper can be applied to the design optimization of structure and validation of computational fluid dynamics.