Airflow hazard prediction for helicopter flight in icing condition

Abstract

A methodology to predict the airflow hazard of helicopter flight in icing conditions is developed. By incorporating the existent ice accretion codes into an established basic helicopter flight dynamic model and considering airflow disturbance that mainly covers downdraft, head/tail wind, and left/right wind, the hazardous effects on trims, stability, and controllability of UH-60A single rotor helicopter in icing/ice-free conditions and within/without different types of wind field are investigated. The stability and controllability of helicopter that encounters airflow disturbance from wind velocity of 0 to 2.5–5.0 m/s for forward flight are examined. The indications of all the work are summarized at the end of this article. Furthermore, this method can be used to helicopter inflight safety prediction or airflow hazard avoidance analysis in icing conditions. It can also be laid as the foundation of the further research about the more complex airflow hazard prediction in icing conditions for helicopter flight safety.

Gust loads on aircraft

“…In addition, this deviation directly causes the difference in the aircraft position and orientation in its subsequent flight even after Figure 34. Longitudinal and lateral/directional dynamic responses of UH-60A helicopter to winds at different directions (177) .…”

“…One group of the current authors, Cao et al investigated the influence of wind shear on both helicopter flight characteristics (176,177) . It was found that left wind, tail wind and downdraft decrease the longitudinal stability, while the left wind, right wind and downdraft decrease the lateral/directional stability, as shown in Fig.…”

The measurement of the adhesion of glaze ice.

“…The acoustic power of the tones was not measured but was considerable: the model could be heard two buildings over during use. 32 The data in the zero to three minute range shows pre-loading prior to the initiation of the test. The H23 sample was noted to be well attached, with the operator noting that the manual application of approximately 20 lbf normal force was required to separate the ice from the coupon post-test.…”

“…The run conditions for these tests are shown in APPENDIX A, and images of the XT model after a glaze ice spray during the third test are shown inFigure 73, which was similar to run conditions during the first test 32. This was anticipated during the design process; suitable countermeasures could not be identified.…”

“…The NTSB determination for the probable cause of the accident was "The pilot's inadvertent encounter with localized icing conditions and his subsequent in-flight loss of helicopter control." Icing on rotor blades has been shown to be a significant problem to safety [32][33][34][35]. In response, a variety of anti-icing equipment has been utilized and tested, with electro-thermal and pneumatic systems showing the most promise [36].…”