ITC/USA 2010 Conference Proceedings / The Forty-Sixth Annual International Telemetering Conference and Technical Exhibition / October 25-28, 2010 / Town and Country Resort & Convention Center, San Diego, California / The development and qualification of personnel and cargo aerial delivery parachute systems present unique challenges to the instrumentation and data analysis engineers. Some of the areas that must be addressed include: a) system must be low in cost, b) system often has to be operated on ranges that have limited telemetry or other range instrumentation and support (i.e. commercial skydiving centers), c) system is often rigged and operated by parachute support personnel and test jumpers rather than instrumentation engineers, and d) system must be able to be reconfigured in the field to support a variety of test card requirements during a typical test day, e) data must be available for review and the system be prepared for the next test within a few minutes of parachute recovery, and f) system must withstand ground impact velocities as high as 50 ft/sec (15.24 m/sec) without damage. This paper describes such a system as it is being used for the development and qualification testing of a number of parachute systems for sport skydiving, military personnel, as well as cargo parachute systems. This modular system has been developed as a result of previous experience in other parachute development and qualification projects to address the need for a flexible Data Acquisition System (DAS) system that meets the above requirements. This paper describes some of the tools used to meet these requirements.

Thesis (MScEng)-- Stellenbosch University, 2013. / ENGLISH ABSTRACT: This thesis presents the development of a flight control system (FCS) for an unmanned, unpowered parafoil and the integration with an existing parafoil system in collaboration with a team at the University of Cape Town (UCT). The main goal of the FCS is to autonomously guide the parafoil from an arbitrary deployment position to a desired landing target. A nonlinear 8 degrees of freedom (8-DOF) parafoil model by C. Redelinghuys is incorporated into a MATLAB Simulink simulation environment. The non-linear model is numerically linearised and modal decomposition techniques are used to analyse the natural modes of motion. All modes are determined to be stable but a poorly damped lateral payload relative twist mode is present which causes large payload yaw oscillations. The FCS is divided into stability augmentation, control and guidance subcomponents. Stability augmentation is proposed in the form of a yaw rate damper which provides artificial damping for the oscillatory payload twist mode. For control, a yaw rate controller is designed with the aim of a fast response while not exciting the payload twist oscillation. Subsequently, an existing guidance method is implemented for path following. Autonomous path planning and mission control logic is created, including an energy management (EM) method to eliminate excess height and a terminal guidance (TG) phase. The TG phase is the final turn before landing and is the last chance to influence landing accuracy. A TG algorithm is implemented which generates an optimal final turn and can be replanned en route to compensate for unknown wind and other disturbances. The FCS is implemented on existing avionics, integrated with the parafoil system and verified with hardware in the loop (HIL) simulations. Flight tests are presented but are limited to remote control (RC) tests that verify the integration of the avionics and the parafoil system and test preliminary FCS components. / AFRIKAANSE OPSOMMING: Hierdie tesis dra die ontwikkeling voor van ‘n vlug-beheerstelsel (VBS) vir ’n onbemande, onaangedrewe valskerm-sweeftuig (parafoil), asook die integrasie daarvan met ’n bestaande stelsel. Die projek is in samewerking met ’n span van die Universiteit van Kaapstad (UCT) uitgevoer. Die VBS se hoof doel is om die sweeftuig outonoom vanaf ’n arbitrêre beginpunt na ’n gewensde landingsteiken te lei. ’n Nie-lineêre 8 grade van vryheid sweeftuig model deur C. Redelinghuys is in die MATLAB Simulink omgewing geïnkorporeer. Die nie-lineêre model is numeries gelineariseer om ’n lineêre model te verkry, waarna die natuurlike gedrag van die tuig geanaliseer is. ’n Swak gedempte laterale draai ossillasie van die loonvrag is geïdentifiseer. Die VBS is opgedeel in stabiliteitstoevoeging, beheer en leiding. ’n Giertempo-demper (yaw rate damper) is as stabiliteitstoevoeging om die loonvrag ossillasie kunsmatig te demp, voorgestel. ’n Giertempo-beheerder is ontwerp met die klem op ’n vinnige reaksie terwyl die opwekking van die loonvrag ossillasie terselfdetyd verhoed word. Daarna is ’n bestaande metode vir trajekvolging geïmplementeer. Outonome padbeplanning en oorhoofse vlugplan logika is ontwikkel, insluitend ’n energie-bestuur (EB) metode, om van oortollige hoogte ontslae te raak, asook ’n terminale leiding (TL) metode. Die TL fase verwys na die finale draai voor landing en is die laaste kans om die landingsakkuraatheid te beïnvloed. ’n Bestaande TL algoritme is geïmplementeer wat ’n optimale trajek genereer en in staat is om vir wind en ander versteurings te kompenseer deur die trajek deurgaans te herbeplan. Die VBS is op bestaande avionika geïmplementeer, met die sweeftuigstelsel geïntegreer en met behulp van hardeware in die lus (HIL) simulasies geverifieer. Vlugtoetse is voorgedra, maar is egter beperk tot radio beheer vlugte wat die korrekte integrasie van die avionika en die voertuig toets, asook ’n beperkte aantal voormalige VBS toetse.

The velocity field in the wake of a small scale flexible parachute canopy was measured using two-dimensional particle image velocimetry. The experiments were performed in a water tunnel with the Reynolds number ranging from 3.0-6.0 x 104. Both a fully inflated canopy and the inflation phase were investigated in a constant freestream (i.e. an infinite mass condition). The fully inflated canopy experienced a cyclic“breathing" which corresponded to the shedding of a vortex ring from the canopy. The normalized breathing frequency had a value of 0.56 +/- 0.03. The investigation of the canopy inflation showed that during the early stages of the inflation, the boundary layer on the canopy surface remains attached to the canopy while the canopy diameter increases substantially. The boundary layer begins to separate near the apex region when the diameter is ~68% of the fully inflated diameter. The separation point then progresses upstream from the canopy apex region toward the canopy skirt. During this time period, the force rapidly increases to its maximum value while the separation point of the boundary layer moves upstream towards the skirt. The force then declines rapidly and the separated boundary layer rolls-up into a large vortex ring near the canopy skirt. At the same time, the canopy is drawn into an over-expanded state after which the cyclic breathing initiates. The unsteady potential force was estimated from the rate of change of the canopy volume. It contributed no more than 10% of the peak opening force and was only significant during the early stages of inflation. The majority of the opening force was the result of the time rate of change of the fluid impulse. It accounts for approximately 60% of the peak opening force. This result shows that the formation of the viscous wake is the primary factor in the peak drag force of the canopy.

The study was undertaken to ascertain whether participatory development (PD and) by implication, the Person Centred Approach (PCA) had an impact on change in the communication patterns in the parachute packing section in the SANDF. The study was conducted in a military setting where hierarchical authoritarian structures exist. PCA and PD are used as theoretical frameworks for the study which resulted in changes in the communication patterns at the section. Change occured at two levels viz: Changes in communication amongst the participants which led to teamwork, cooperation and the avoidance of conflict. Changes in communication between management (the Officer Commanding) and the parachute packing section which lead to regular contact with the participants to address their problems. The study further highlighted the importance of learning from the community in order to avoid misinterpretation which could lead to conflict and dissatisfaction / M. A. (Social Science (Mental Health))

The study was undertaken to ascertain whether participatory development (PD and) by implication, the Person Centred Approach (PCA) had an impact on change in the communication patterns in the parachute packing section in the SANDF. The study was conducted in a military setting where hierarchical authoritarian structures exist. PCA and PD are used as theoretical frameworks for the study which resulted in changes in the communication patterns at the section. Change occured at two levels viz: Changes in communication amongst the participants which led to teamwork, cooperation and the avoidance of conflict. Changes in communication between management (the Officer Commanding) and the parachute packing section which lead to regular contact with the participants to address their problems. The study further highlighted the importance of learning from the community in order to avoid misinterpretation which could lead to conflict and dissatisfaction / M. A. (Social Science (Mental Health))