• Journal of the Korean Society of Propulsion Engineers
• /
• v.21 no.5
• /
• pp.61-70
• /
• 2017

Robust thrust distribution method of solid DACS is researched. For the case of the system which has higher number of actuation nozzles than the degree of freedom of thrust to be controlled, the robust thrust allocation law which accommodate the abnormal operation is suggested. Assuming the situation that some nozzles are uncontrollable, the error between nozzle throat area command and response can be calculated. The error is used for realtime reshaping of weighting matrix. From the weighting effect, the nozzle which operated abnormally has low responsibility for the command then, the thrust error is reduced. The suggested algorithm is verified by the simulation of abnormal operation condition of DCS and ACS nozzle respectively.

• Journal of the Korean Society of Propulsion Engineers
• /
• v.24 no.3
• /
• pp.18-30
• /
• 2020

This study deals an estimation method of thrust measurement uncertainty in solid rocket motors. Guidelines of the force measurement uncertainty estimation have been provided by ISO, domestic and international organizations. However, all of them are described by focusing on the force calibration machines and force transducers with a conceptually-driven way. Thus the guidelines cannot be directly applicable to uncertainty estimation of calibration equation and its linear approximation, which are critical error sources in the thrust measurement. In this paper, the equations taking into account effects of both error sources are derived based on fundamental concepts of measurement uncertainty. These are applied to the real thrust measurement system where a relatively simple estimation method for the thrust measurement uncertainty is proposed.

• Journal of the Korean Society of Manufacturing Process Engineers
• /
• v.15 no.5
• /
• pp.73-79
• /
• 2016

In this paper, the grinding characteristics in thrust internal grinding have been studied using vitreous CBN wheels with a machining center. Grinding experiments have been performed according to grinding conditions such as wheel feed speed, cut depth, workpiece speed, rate of grinding width and number of grinding passes. The machining error, shape of machined surfaces, grinding force, and surface roughness have been investigated though these experiments. Based on the experimental results, the grinding characteristics on the machined surface in the internal thrust grinding are discussed.

• Journal of the Korean Society of Propulsion Engineers
• /
• v.15 no.1
• /
• pp.55-62
• /
• 2011

In this study, we tried to improve the thrust control performance through the thrust control combustion experiment of the hybrid rocket. We constructed the system which controls the oxidizer flow by combining a needle valve with a stepping motor and controlling the stepping motor drive according to the thrust control command order. Gas oxygen was used as the oxidizer for two different propellants, PE(Polyethylene), PC(Polycarbonate), respectively. To improve the slow response time and the oscillation phenomenon in the beginning stage of the thrust control combustion experiment, we measured and analyzed the change of the flow speed of the propellant pipe. The revised thrust control combustion experiment showed that the thrust was stably controlled with the margin or error from the thrust command within ${\pm}1$ N.

• Journal of the Korean Society of Propulsion Engineers
• /
• v.10 no.3
• /
• pp.73-81
• /
• 2006

In order to evaluate the thrust of a propulsion system, generally the captive thrust stand is used Based on the applied propulsion system, the various captive ways between thrust stand and the propulsion system are considered. In this paper, the effect of motor deformation generated during firing in horizontal thrust stand on the measured thrust is theoretically derived from classical beam theory. New flexure performance index is defined and estimated on the basis of the thrust measurement error. Its result is good agreement with numerical result of ABAQUS. This study showed that measurement reliability and safety of test can be highly upgraded, in case of two flexure-type captive thrust stand.

• Journal of the Korean Society of Propulsion Engineers
• /
• v.5 no.2
• /
• pp.38-43
• /
• 2001

In this study, the technique of the performance prediction on the finocyl-type dual-thrust rocket motor is developed, and the predicted data are compared with those of the static firing tests. The prediction is carried out with the separate calculations of the grain burning area and the performance of the rocket motor. When predicting the performance of the dual-thrust rocket motor, the different correction factors should be used at the boosting and sustaining phases. Otherwise, an error of prediction will follow. Reprediction using the separate correction factors shows good agreement with the test data within 0.5% error.

• Journal of the Korean Society of Manufacturing Process Engineers
• /
• v.15 no.1
• /
• pp.68-73
• /
• 2016

In this paper, the grinding characteristics in internal grinding methods(plunge, thrust) were studied with vitreous CBN wheels using machining center. Grinding experiments were performed according to the same material removal rate conditions such as a wheel speed, depth of cut and workpiece speed. And the grinding force, machining error and grinding ratio were investigated though these experiments. Based on the experimental results, the grinding characteristics on internal grinding methods were compared.

• Proceedings of the KIEE Conference
• /
• 1997.11a
• /
• pp.38-41
• /
• 1997

As the LPM is used for position accuracy decision device it is required that both the reason of posion error and the definition of position itself should be cleared. In this study, the precision of the position decision of LPM is affected by the geometrical shape such as tooth shape or processing accuracy. By using the analysis of magnetic circuit, we calculated the permeance come up with the gap. Once the thrust force has been obtained, the permeance due to the mechanical error of the pole pitch and the tooth pitch becomes the error of thrust force. We confirmed as well that it is being affected by the difference due to the variation of the airgap permeance.

• Proceedings of the KSME Conference
• /
• 2007.05a
• /
• pp.1143-1148
• /
• 2007

LRE(Liquid propellant Rocket Engine) is one of the important parts to control the motion of rocket. For operation of rocket in error boundary of the set-up trajectory, it is necessarily to control the thrust of LRE according to the required thrust profile and control the mixture ratio of propellants fed into combustor for the constant mixture ratio. It is not easy to control thrust and mixture ratio of propellants since there are co-interferences among the components of LRE. In this study, the dynamic model of LRE was constructed and the dynamic characteristics were analyzed with control system as PID control and PID+Q-ILC(Iterative Learning Control with Quadratic Criterion) control. From the analysis, it could be observed that PID+Q-ILC control logic is more useful than standard PID control system for control of LRE.

• Journal of the Korean Society of Propulsion Engineers
• /
• v.10 no.1
• /
• pp.9-17
• /
• 2006

The thrust measurement systems(TMS) with high accuracy are required in rockery, according to develop the high precise guided space vehicle. For obtaining high accuracy, the basic concepts and the necessary technology which have been acquired through many experiences of TMS are summarized, and the design methodology for practical use in ADD is presented. In this paper, the parameters against accuracy of TMS are discussed, and the improving methods are suggested. Through this application example, the design methodology of ADD is shown its superiority in TMS.