Defence Research and Development Laboratory

About: Defence Research and Development Laboratory is a facility organization based out in Hyderabad, India. It is known for research contribution in the topics: Mach number & Turbulence. The organization has 404 authors who have published 420 publications receiving 4183 citations. The organization is also known as: DRDL.

Estimation of Circular Error Probability of Strapped Down Inertial Navigation System by Propagation of Error Covariance Matrix

Abstract: This paper provides an error model of the strapped down inertial navigation system in the state space format. A method to estimate the circular error probability is presented using time propagation of error covariance matrix. Numerical results have been obtained for a typical flight trajectory. Sensitivity studies have also been conducted for variation of sensor noise covariances and initial state uncertainty. This methodology seems to work in all the practical cases considered so far. Software has been tested for both the local vertical frame and the inertial frame. The covariance propagation technique provides accurate estimation of dispersions of position at impact. This in turn enables to estimate the circular error probability (CEP) very accurately.

Comment on 'Integrated development of the equations of motion for elastic hypersonic flight vehicles'

Abstract: Introduction B ILIMORIA and Schmidt give an integrated development of equations of motion for simulating the trajectory of a vehicle incorporating structural elastic modes, effect of rotating parts, and mass flow rates of air-breathing engines in the equations of motion. This Note shows that the terms containing mass flow rates in the equations of motion of Ref. 1 are erroneous. Further, it is shown that none of the mass-flow-rate terms should be present in the equations of motion because the force and moment attributable to engine thrust are considered as external force and moment acting on the vehicle.

Reliability Demonstration of Safety Actuating Mechanism

Abstract: Development of high technology and high cost weapons system is a difficult task in view of. highreliability goals. It is further compounded in the case of single-shot airborne systems. Overall reliabilityof weapons system depends upon the reliability of systems and sub-systems used. Design of each systemand sub-system is fmalised after preliminary design review, critical design review, etc. and final reliabilityis demonstrated by subeing to functional tests.Warhead is the only sub-system responsible for inflicting damage to the target and all the otherembsystemsassist in delivering the warhead on or near the target. Safety actuating mechanism (SAM) subsystemis a single-shot device which provides safety during handling, launch and flight of a missile and actuatesthe warhead, whenever desired on receipt of firing pulse from radio altitude switch. SAM being critical forsuccessful detonation of the warhead, it is desired that this unit should have very high reliability. SAMunits are subjected to reliability tests and a reliability factor of 0.84 at 90 per cent confidence level is achievedwhich further increases to 0.98 due to redundancy.

Design of Packaging for Microballoon Actuators and Feasibility of their Integration within Aerodynamic Flight Vehicle

Abstract: The microballoon actuators are used for the active flow control in turbulent boundary layer for aerodynamic control of flight vehicles. The packaging, interfacing, and integration of the microballoon actuators within the flight vehicle play a key role for functioning of the microballoon actuators during the flight conditions. This paper addresses the design and analysis of packaging and integration aspects and associated issues. The use of microballoon actuators on the control surfaces and nose cone of flight vehicles has the positive influence of delaying the flow separation from the aerodynamic surface. This results in enhancing aerodynamic effectiveness and lift as well as reduction of drag. A typical control surface is configured with eight microballoon actuators symmetric wrt the hinge line of the control surface and embedded within the control surface. Provision of the Pneumatic feed line system for inflation and deflation of the microballoons within the control surface has been made. The nose cone has been designed to have 32 such actuators at the circular periphery. The design is found to be completely feasible for the incorporation of microballoon actuators, both in the nose cone and in the control surface. Defence Science Journal, 2009, 59(5), pp.485-493 , DOI:http://dx.doi.org/10.14429/dsj.59.1549

Quality Engineering in Aerospace Technologies : A Review

Abstract: Quality assurance and reliability have assumed paramount importance in aerospace technologies due to stringent requirement of weight-to-strength considerations and the need for highly reliable systems. The techniques of inspection and testing have given way to the use of sophisticated reliability engineering, failure mode effects & criticality analysis, deign of experiments and total quality management concepts. The role of failure analysis to improve the quality on a continuous basis has been realised by all engaged in aerospace technologies. The number of simulation runs help to build up quality in design and development phase and obviate the need for extensive hardware testing. The techniques of metrology and nondestructive testing have been upgraded considerably during the last decade. Most of the manufacturing techniques, now being computer-aided, give consistent production and better quality.