Parachute System Research Articles

超音速探测器-刚性盘-缝-带型降落伞系统的大涡模拟研究

The influences of the aerodynamic deceleration performance and the flow field structure characteristics of the capsule-rigid disk-gap-band parachute system at an initial Mach number of 2.0 and different block-structured adaptive mesh refinement were studied. In the unsteady compressible fluid, the hybrid WENO (weighted essentially non-oscillatory) and TCD (tuned center difference) schemes were used to simulate the shock wave and the smooth continuous flow field. The large-eddy simulation method with the stretched vortex subgrid model was used to deal with the turbulence. The results show that, at a low resolution of the block-structured adaptive mesh refinement, it is difficult to accurately simulate the important aerodynamic drag coefficient and capture the flow field characteristics of the parachute system. Subsequently, the convergence of the adaptive mesh refinement of the flow field was verified.

Dynamic Response Analysis of a High Glide Ratio Parachute System

This paper is concerned with the dynamic stability study of a gliding parachute-payload system along its gliding path. To scrutinize the respective dynamic response characteristics after releasing from high altitude, a modified multi-body model is developed. In the stability analysis procedure, the yawing motion of the payload is considered in system dynamics, which in turn creates a state-dependent matrix in the stability analysis and makes the linearization algorithm more cumbersome. To solve the problem, a unified Jacobian-based symbolic differentiation algorithm is implemented and the dynamics is linearized about various operating points along gliding segment of a typical planned trajectory. Based on results, the system has short period and phugoid modes in longitudinal channel just like an aircraft. In addition to dutch roll mode, the system has a low frequency coupled roll-spiral mode in lateral-directional channel which is a result of effective canopy anhedral angle. It is shown, the coupled mode can be decomposed into two distinct roll and spiral modes for small anhedral angles. Based on results, as the parachute descends, both the period and damping ratio for the short period mode were increased by 18 and 30%, respectively. For the phugoid mode the period of oscillations is decreased by 20% and the damping ratio, almost remains constant. For the lateral-directional channel,. As the parachute descends, the dutch roll mode is destabilized whereas the other modes are stabilized. Furthermore, from a practical point of view, lengthening the suspension lines stabilizes the coupled roll-spiral mode whereas destabilizes the other modes.

Experiment informativity in flight tests of parachute systems. Decision making

Experiment informativity in flight tests of parachute systems. Decision making

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.

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.

Calculation of Vibrations in a Tethered Underwater Vehicle–Umbilical Cable System

This article highlights the main factors that determine the oscillation process of an umbilical cable–tethered underwater vehicle system. Cable systems are widespread in various fields of technology: aircraft cable rigging, parachute systems, suspension bridge supports, marine terminal cables, and so on. A mathematical model is constructed for the oscillation process. The calculation results determined the dependences of the oscillation amplitude of the tethered underwater vehicle on the amplitude and oscillation frequency of the umbilical cable attachment point to the vessel. No methodology for calculating oscillations in tethered systems with an assessment of the influence of the design parameters has ever been constructed before now.

Concerning the Application Possibility of Ultrasonic Welding of Textile Materials on the Basis of Synthetic Fibres in the Manufacturing Processes of Parachute Systems

The application possibility of ultrasonic () welding in the technological process of the canopies of braking parachute systems manufacturing for the unmanned aerial vehicles was considered. The subjects of research were parachute fabrics (100 % capron), manufactured by with different surface weight, weave and type of finish. Welding modes were chosen. The obtained welded seams had no defects and met the requirements of technical standard documentation, with the increase of the distance between the welding spots, the welding strength of the welded seam was decreased by 10–40 %. The strength of the seams at the “in shear” test is on the average 2-3 times larger than at the gripping method test. The draft of the nozzle-roll for executing the spotted welded seams was proposed. The calculations suggested that the application of the welded seams instead of sewn seams would allow the reduction of the costs for sewing threads during the manufacturing of the canopy to 50 % and the significant reduction of the labour requirement.

Flight Trajectory Simulation and Aerodynamic Parameter Identification of Large-Scale Parachute

In this paper, the multibody parachute-payload system is simplified and analyzed. A six-degree-of-freedom rigid body flight dynamic model is established to calculate the flight trajectory, attitude, velocity, and drop point of the parachute-payload system. Secondly, the random interference factors that may be encountered in the actual airdrop test of the parachute system are analyzed. According to the distribution law of the interference factors, they are introduced into the flight dynamic model. The Monte Carlo method is used to simulate the target and predict the flight trajectory and landing point distribution of the parachute system. The simulation results can provide technical support and theoretical basis for the parachute airdrop test. Finally, the genetic algorithm is used to identify the aerodynamic parameters of the large-scale Disk-Gap-Band parachute. The simulation results are in good agreement with the test results, which shows that the research method proposed in this paper can be applied to study practical engineering problems.

Parachutes: a crossroads between physics, mathematics and computing

In this article, physical quantities related to the motion of a parachute system in the framework of Newton’s law of mechanics guide an informal approach to the mathematical concept of function. Furthermore, a graphical simulator that enables visualization of the fall of object-parachutes system is presented.The article is aimed at students and teachers of basic physics courses at the high school and undergraduate level.

Современный подход к проектированию иностранных десантных парашютных систем

Landing parachute systems are among the most demanded samples of parachute equipment. The purpose of the study was to find new principles for developing parachutes with increased stability according to the analysis of the results of numerical and experimental studies of canopies of various shapes. The paper proposes to supplement a traditional definition of the stability of a parachute system with the obligatory consideration of the system’s ability to maintain a given trajectory of movement with a neutral canopy, regardless of the change in the payload mass. It is the expanded concept of stability that is taken as the basis of the modern approach to the design of foreign landing parachute systems. The study substantiates the main criteria for choosing the optimal cutting shape for parachute systems of increased stability of various types at the stage of preliminary design. The results of numerical modeling of canopies are presented: quarter-spherical, hemispherical, polyconic canopies and a T-11 type parachute canopy. Based on the analysis of these results, the study was first to propose a hypothesis that a decrease in the intensity of vortex formation in the wake leads to an increase in the stability of the parachute descent. The results of numerical modeling of canopies of various shapes, as well as experimental studies of a model polyconic parachute, which prove the correctness of the proposed hypothesis, are presented.

Statistical Engineering for Wind Tunnel Testing of Mars Parachute Designs

Formal experiment design and analysis techniques featuring design of experiments were applied to a Mars parachute wind tunnel test. The experiments were part of an extensive study conducted in 2014 by the NASA Engineering and Safety Center to evaluate the performance of two candidate parachute systems. Reduced scale models of the legacy Disk-Gap-Band (DGB) parachute and new Supersonic Ringsail (SSRS) were compared for both model fidelity and performance measures. Two tests, conducted in the NASA Langley Transonic Dynamics Tunnel, are described with emphasis on statistical engineering principles. The first test compared drag coefficients between models of the same canopy at Earth atmospheric pressure but at mission dynamic pressures. The experiment proved that any manufacturing differences between models were not detectable in drag coefficient measurements. The second test focused on parachute drag coefficient modeling for both canopy designs and two fabric permeabilities over a representative range of mission dynamic pressures and Mach numbers. The SSRS was found to have higher drag coefficients in comparison to the DGB for both canopy material permeabilities over the operational range of Mach numbers and dynamic pressures.

PROCEDURE FOR EVALUATION OF THE APPLICATION’S EFFICIENCY OF THE PARACHUTE SYSTEMS FOR THE AIR DROPPING

The article proposes a procedure for evaluation of the application’s efficiency (AE) of parachute systems (PS) for the air dropping (AD). Based on the analogy with the index of combat effectiveness of armament and military equipment, the AE of PS can be evaluated by using the typical mission performance probability of AD - personnel or cargo positioning to site, while maintaining their combat capability to accomplish a mission of the parachute assault force.
 In this formulation, the process of accomplishing the typical mission of AD consists of the following stages: delivery of cargo to the airborne objective area, the exit of the aircraft to the computed air release point, the actual air dropping. Further analysis showed that the most influential factors affecting successful accomplishment of the typical mission of AD by the stages are: the reliability of the aircraft, the ability to overcome the enemy air defense without consequences for the accomplishment of AD, the property retention of PS while in flight considering flying conditions of the aircraft to the area of ​​the AD, problem solving of determining of the computed air release point under the actual conditions, the accuracy of the aircraft's exit to the computed air release point, the reliability of the PS, the covertness of the AD, the accuracy of cargo’s landing to the size-defined site, speed of the cargo’s landing. For each of the factors, the calculating formulas were defined in the article in the form of the probability of a positive influence on the successful accomplishment of the mission of the AD. The product of all these probabilities is evaluation of the AE of PS.
 For example, the calculations of the AE of PS DPS and Status-CH types in equal conditions of AD and Status-CH by using various tactical techniques of AD were made. The results of the calculations are completely consistent with the logical considerations and practice of the PS application, which testifies to the adequacy of the proposed procedure and the feasibility of its application.

Research on Reliability Assessment Method of Emergency Escape Parachute

Aiming at the problem that emergency escape parachute cannot meet the requirements of the index using the binomial evaluation method, combined with the characteristics of emergency escape parachute products, comprehensively using emergency escape parachute components and system test data, the emergency escape parachute Bayesian reliability assessment method is proposed to solve the problem of reliability assessment in the case of small sample size of emergency escape parachute system test, which effectively reducing emergency escape parachute test expenses and development cycle.

Fluid–structure interaction simulation based on immersed boundary-lattice Boltzmann flux solver and absolute nodal coordinate formula

Large deformation fluid–structure interaction (FSI) is a typical nonlinear problem in aero elastics. Engineering applications can be found in aviation, marine engineering, and bio-fluid mechanics. A three-dimensional (3D) parallel FSI solver based on an immersed boundary-lattice Boltzmann flux solver (IB-LBFS) and absolute nodal coordinate formula (ANCF) is established. The computational efficiency of the parallel IB-LBFS with moving boundaries is improved by several acceleration techniques, including Euler–Lagrangian interpolation matrix parallel assembling and sparse matrix solving methods. Structure dynamics simulation discretized in high-order ANCF elements distinctly reduces the number of finite elements compared with the standard finite element method. A multiple body dynamics (MBD) solver including a rigid body, ANCF cable elements, and ANCF plate elements is developed. The IB-LBFS, MBD solver, and coupled FSI solver are tested by the corresponding validation examples. A framework of solving 3D FSI problems of complex multiple flexible structures with large deformation in incompressible flow is presented. An implicit boundary condition enforced method is applied to achieve a strong coupling approach. For application demonstration, the inflation process of several types of parachute systems is simulated in which different Young’s moduli of the parachute canopy are considered. The interaction between dynamic deformation and an unsteady vortex is obtained and discussed.

Features of parachute systems testing during their creation

The article describes a number of stages in the creation of parachute systems for military and special purposes and some features of executing their testing. The necessity of development flight tests and their peak modes are analyzed in details. The feasibility of recovery parachute system creation for saving the weight model during the flight tests connected with checking of parachute systems strength is proved. The procedure of putting the recovery parachute system into the action scheme of the tested parachute system is suggested. The sequence and the stages of three-cascade recovery parachute system operation consisting of the auxiliary parachute, the drogue parachute and the main one are given. The analysis of this system operation considering the phase trajectories of the recovery parachute system and the tested parachute system movement is conducted. Development of possible emergency situations of the tested parachute system including the phase trajectories of motion at all stages is considered. The phase trajectories of motion are given taking into account test envelope with overlapping of the maximum operation conditions and acceleration modes. Development of emergencies is analyzed considering time buffer to put the recovery parachute system into operation. The article considers the example of creating the emergency detection system and its operating procedure when putting the recovery parachute system into action. Positive results from introduction of the recovery parachute system into the flight tests when creating parachute systems for different purposes are predicted. A new strategy of executing flight tests with the introduction of an updated (by the decision of the Chief Designer) test program is proposed. Extension of the test envelope will enable to significantly advance information awareness of the flight experiment, efficiency and quality of its results. Introduction of the emergency detection system will considerably improve reliability of the tested parachute system operation.

Establishment and Simulation of Twelve-Degree-of-Freedom Model for UAV Parachute Recovery System

In the UAV parachute recovery process, the UAV and the parachute have always been in the state of dynamic balance, so it is difficult to deal with the constraint between them. In order to solve this problem, the UAV parachute recovery system was divided into three parts:the parachute, riser and UAV. The extension length of riser was obtained by the velocity relationships of the riser connection points. The riser tension was obtained by the product of the elastic coefficient and the extension length of the riser. And it was applied to the parachute and UAV systems respectively. Finally, based on the Newton-Euler equation, the 12-DOF model of UAV parachute recovery system was established, in which the unsteady aerodynamic model of the UAV from the forward flight to the steady descents was established based on the ONERA equation. The simulation and test results shows:the 12-DOF model is consistent with the results of the experimental data, which verifies the accuracy of the 12-DOF model. The 12-DOF model is more accurate than the past 6-DOF model. This model established in this paper can provide reference for the selection of parachute in the UAV parachute recovery system and the determination of the landing point of the UAV.

Social Acceptance of Increased Usage of the Ballistic Parachute System in a General Aviation Aircraft.

BACKGROUND: An airframe parachute ("Chute") available in certain aircraft is designed to lower the airplane safely to the ground for emergency situations that occur 500 ft (152 m) above ground level (AGL): the "Chute altitude envelope." This study will explore the change in Chute use before and after 2012 to better understand factors that increased usage and improved accident outcomes.METHODS: Using the public National Transportation Safety Board (NTSB) accident database from January 1, 2001, through August 31, 2018, a regression model was developed to identify factors that may predict Chute use.RESULTS: In accidents occurring after January 1, 2013, pilots were 5 times more likely to use the Chute, while 2.9 times less likely to use the Chute when the accident involved pilot-related causes. The presence of passengers did not predict Chute use. Injuries were likely to be more severe when the Chute was used outside the Chute altitude envelope.DISCUSSION: In contrast to General Aviation (GA) overall, accidents outcomes in aircraft equipped with a Chute have seen great improvements between 2013 and 2018, with increased use of the Chute and improved injury outcomes. Results suggest that changes to pilot training in 2012 have increased the social acceptance of Chute use. Results highlight increased risk of injury outcomes for Chute use in accidents that occur outside the Chute altitude envelope.Kirby J. Social acceptance of increased usage of the ballistic parachute system in a general aviation aircraft. Aerosp Med Hum Perform. 2020; 91(2):86-90.

Optimal appearance determining technique of cargo parachute system at early design stages

Optimal appearance determining technique of cargo parachute system at early design stages

Parameters liable to be defined while a multi-dome parachute system flight-testing for its efficiency stimation

Parameters liable to be defined while a multi-dome parachute system flight-testing for its efficiency stimation

A STUDY OF VISCOELASTIC BEHAVIOR OF A TEXTILE SUSPENSION IN A PARACHUTE SYSTEM MODEL FOR ADVANCED SPACE RE-ENTRY VEHICLES

One of the pressing problems in space industry is providing soft landing on Earth for space re-entry vehicles and stages of launch vehicles for their re-use. This problem could be addressed by using a parachute system option which has an elastic link and tandem separation of the cargo into two tethered parts. The paper discusses determining viscoelastic behavior of the textile tether in a test setup of this parachute system, and constructing a math model of its strain behavior under transient mechanical loads. Obtained in the experiment was viscous friction coefficient for unit length of the tether, while the literature provides damping properties for samples of a certain length. The math model was developed under assumption of the Kelvin-Voigt viscoelestic model. Wave effects produced by shock impact are not simulated. The process of cargo descent was mathematically simulated using parameters of the test-bed experiment. The results of calculations using experimentally obtained coefficients are in satisfactory agreement with experiment with respect to strain and maximum g-load values. Key words: soft landing, re-entry vehicle, viscoelasticity, mechanical properties of textile materials, math model of strain.