EFFECT OF AIR PERMEABILITY ON STABILITY OF SUPERSONIC PARACHUTE

A compressible air permeability model is developed to simulate the aerodynamic performance of the supersonic porous canopy. And a single-degree-of-freedom model is applied to analyse the static stability of the parachute. By using this method, the flow structure of the parachute system with big attack angle is obtained. The aerodynamic moment coefficients of porous and nonporous canopies are compared to discuss the effect of air permeability on stability of the supersonic parachute. The numerical results show that aerodynamic moment coefficient of the system with air permeability has larger oscillation amplitude and value than that without air permeability. This method can be developed as a potential method to select the supersonic parachute initially.

Effects of Aerodynamics on Line Sail During Parachute Deployment

This paper presents a dynamic model to numerically simulate the parachute deployment for space vehicle recovery system. In the proposed dynamic model, the deployment bag and the space vehicle are treated as a six-degree-of-freedom rigid body with mass varied and a regular six-degree-of-freedom rigid body, respectively. The parachute system is considered as the mass spring damper model, in which the canopy, suspension lines, risers and bridles are discretized into some three-degree-of-freedom segments with their centralized mass on the end points. During the deployment a notable phenomenon can be observed and so-called line sail. The line sail generally occurs during a deployment in which the relative wind is not parallel to the deployment direction. The line sail has been known to cause or contribute to the following problems: increased deployment times, changes in snatch load, asymmetrical deployment, friction damage, and unpredictable canopy inflation. To understand its mechanisms, the effects of aerodynamics such as angle of flight path, deployment bag ejection velocity, Mach number, air density and wind velocity are numerically investigated.

Use of the parachute system for the collective rescue of passengers and aircraft crew

This study covers the issues of the security system in civil aviation. The relevance of the topic is conditioned by a qualitatively new approach to the design of civil aviation, since the modern equipment has the means intended for rescue directly in the area of contact of an emergency aircraft with the ground. When hitting the ground, as a rule, the lower part of the airframe is crushed, the fuselages break in the centre wing section, and the interior equipment breaking off is very traumatic to passengers, the engines are extremely fire and explosion dangerous, which leads to an emergency situation developing into a catastrophic one. The purpose of the study is to investigate the existing security system of a civil aircraft and develop the modification of aviation equipment with the help of collective rescue systems. Two main areas of application of collective rescue systems in aviation technology are analysed. As a solution to the problem at hand, a modification in the form of a parachute system of collective rescue is proposed. A detailed description of the system operation with the use of the necessary calculations for weight, aerodynamic and similar costs is given. The system under study relates to aviation technology and can be used in the development of transport (passenger, cargo, business class, etc.) aircraft. The proposed modification would significantly increase the level of flight safety due to a preventive measure that would exclude the contact area of the emergency aircraft with the ground.

Paraglider Reserve Parachute Deployment Under Radial Acceleration

INTRODUCTION: The paragliding reserve parachute system is safety-critical but underused, unstandardized, and known to fail. This study aimed to characterize reserve parachute deployment under radial acceleration to make recommendations for system design and paraglider pilot training.METHODS: There were 88 licensed amateur paraglider pilots who were filmed deploying their reserve parachutes from a centrifuge. Of those, 43 traveled forward at 4 G simulating a spiral dive, and 45 traveled backward at 3 G simulating a rotational maneuver known as SAT. Tests incorporated ecologically valid body, hand, and gaze positions, and cognitive loading and switching akin to real deployment. The footage was reviewed by subject matter experts and compared to previous work in linear acceleration.RESULTS: Of the pilots, 2.3 failed to extract the reserve container from the harness. SAT appeared more cognitively demanding than spiral, despite lower G. Participants located the reserve handle by touch not sight. The direction of travel influenced their initial contact with the harness: 82.9 searched first on their hip in spiral, 63.4 searched first on their thigh in SAT. Search patterns followed skeletal landmarks. Participants had little directional control over their throw.CONCLUSIONS: Paraglider pilots are part of the reserve system. Maladaptive behaviors observed under stress highlighted that components must work in harmony with pilots natural responses, with minimal cognitive demands or need for innovation or problem-solving. Recommendations include positioning prominent, tactile reserve handles overlying the pilots hip; deployment bags extractable with any angle of pull; deployment in a single sweeping backward action; and significantly increasing reserve deployment drills.Wilkes M, Long G, Charles R, Massey H, Eglin C, Tipton MJ. Paraglider reserve parachute deployment under radial acceleration. Aerosp Med Hum Perform. 2021; 92(7):579587.

Експериментальне визначення стану текстильних матеріалів десантної парашутної системи Д-5 серії 2 після тривалого зберігання. Повідомлення 1. Фактичний стан міцності текстильних матеріалів основного парашуту

The subject matter of the article is a comparative analysis of indicators of strength and elasticity of textile materials of the main parachute canopy before and after long-term storage. A simplified approach proposed by N. A. Lobanov and P.O. Fomichov was used, the coefficients of degradation of the strength characteristics of the textile materials of the main parachute of the D-5 landing parachute system of series 2 after its long-term storage were experimentally determined. These coefficients are defined as the ratio of the strength characteristics of individual elements of the parachute system in the design sections after the operation or long-term storage to their initial value adopted in the design of the parachute. The goal is to obtain an array of data to assess the state of the physical and mechanical characteristics of the main parachute materials. It is known that in the process of long-term storage there is a deterioration (degradation) of the strength characteristics of the strongest elements of the frame of the parachute canopy, lines, canopy fabrics, reinforcing tapes, etc. Further operation beyond the established period while maintaining sufficient safety factors is possible only with the availability of modern data. Tasks: to develop and test a method of sampling materials, experimentally determine the characteristics of materials, choose an effective algorithm for calculating safety factors. The following methods and equipment were used. The actual value of the indicators was established by destructive strength measurements. The methodology for preparing test samples of D-5 series 2 landing parachute systems, taking point and elementary samples of textile materials of individual elements of the parachute system in design sections for laboratory research to determine mechanical characteristics (strength, elongation, and air permeability) has been improved. The tearing machine is equipped with specialized clamping devices. The batch size was 25 parachute systems. The breaking load and the relative elongation were measured for slings and braids, for fabric - along the warp and weft, a total of 1250 elementary samples. Degradation coefficients were calculated. The array of empirical data was processed by mathematical and statistical methods of the Descriptive Statistics software package from the add-in of the MS EXCEL Analysis Package. The following results were obtained. In terms of breaking load, the fabric of the main parachute canopy slightly (up to 3 percent) exceeds the standard value. The elastic characteristics of the fabric fully meet the requirements - exceeding 1 ÷ 4 percent. During storage, the slings of the main parachute lost up to 21% in strength, but at the same time retained their elastic properties - exceeding up to 3 times. The tapes have satisfactory strength characteristics (exceeding from 3 to 12 percent), in terms of elongation at break, they have lost from 15 to 25 percent. Conclusions. The novelty of the results obtained is as follows: for the first time, the strength characteristics were measured and evaluated in the design sections of the fabric, reinforcing tapes of the power frame of the canopy and lines of the main parachute of the D-5 landing parachute system of series 2 on a large sample of 25 parachutes; it is shown that the obtained data will be correct for all parachute systems produced in 1973-1974.

Investigation of droplet impact on inclined fabric based on CMOS imaging technology and FSI numerical method

In order to study the impact characteristics of droplet on inclined fabric, the relevant experiment was setup in this paper.The process of a single droplet (2.12 mm) impacting inclined fabric (45°) was captured by CMOS (ComplementaryMetal-Oxide Semiconductor) imaging technology. It could be found that there was a second impact phenomenon duringspreading stage, which was very different from impacting horizontal fabric. Then a two-way coupling method was usedto simulate that impacting process. The numerical results were basically consistent with the experimental results. Inaddition, the reaction force and vibration characteristics of fabric which couldn’t be collected by experiments were alsoobtained. Finally, the effect of inclination angle on impact characteristics was analyzed by numerical method. The biggerthe inclination angle was, the longer the stability time of droplet was, and the smaller the reaction force on fabric was.The change law conformed to the momentum theorem. The method and conclusions could provide some references forthe design of parachute system.

Investigation of droplet impact on inclined fabric based on CMOS imagingtechnology and FSI numerical method

In order to study the impact characteristics of droplet on inclined fabric, the relevant experiment was setup in this paper.The process of a single droplet (2.12 mm) impacting inclined fabric (45°) was captured by CMOS (ComplementaryMetal-Oxide Semiconductor) imaging technology. It could be found that there was a second impact phenomenon duringspreading stage, which was very different from impacting horizontal fabric. Then a two-way coupling method was usedto simulate that impacting process. The numerical results were basically consistent with the experimental results. Inaddition, the reaction force and vibration characteristics of fabric which couldn’t be collected by experiments were alsoobtained. Finally, the effect of inclination angle on impact characteristics was analyzed by numerical method. The biggerthe inclination angle was, the longer the stability time of droplet was, and the smaller the reaction force on fabric was.The change law conformed to the momentum theorem. The method and conclusions could provide some references forthe design of parachute system.