Review of Launch Vehicle Related Aeroelastic Instability Studies at HAL

Upadhya, AR and Somashekar, BR (1984) Review of Launch Vehicle Related Aeroelastic Instability Studies at HAL. In: Analysis of Structures - A Commemorative volume published on the occasion of the 60th Anniversary of Dr. S.R.Valluri, Dec 1984, NAL, Bangalore, India.

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Modern launch vehicles are long slender bodies with high flexibility and hence are prone to aeroelastic instabilities during their flight. These instabilities may adversely affect the performance of the vehicle or may even cause its failure, It is therefore necessary that a rigourous investigation of the aeroelastic behaviour of the vehicle is done at the design stage itself to ensure that the vehicle is free from such instabilities during its atmospheric flight, Important among the instabilities that a launch vehicle may experience are response to ground wind loads, divergence,flutter 06 control surfaces and panels, buffeting, coupled oscillations and fuel sloshing, Because of the complex nature of the aerodynamic input forces and aerodynamic-elastic-inertial interactions involved in most of these phenomena, it is often difficult and at times almost impossible to predict accurately the behaviour of the flight vehicle through theoretical means, Hence the designer has to take recourse to experimental means involving design and testing of aeroelastically scaled models, In this technique an aeroelastic model in a suitable wind tunnel is used as a mechanical analog of the mathematically complex problem requiring solution, The model in the wind tunnel first generates the correct aerodynamic input forces, and the measured response of the model to these input forces is then used to predict the response of the actual vehicle using appropriate scaling laws, The importance of scaled models in the study of aeroelastic problems of launch vehicles is amply demonstrated by the work done in this direction at the aerospace research Laboratories of NASA and elsewhere, With the importance of aeroelastic problems in the design of aerospace vehicles in mind, the Structures Division of the Laboratory, with active support from the Aerodynamic Division* initiated work on aeroelastic model studies in the early 1970's, mainly to understand the technique of aeroelastic model design and fabrication and to gain experience in aeroelastic testing. Early works in this direction were related to aircraft, involving design and testing of flutter models of typical aircraft wings (Ref.1&2).The know-how gained out of these studies was thus very useful while undertaking studies related to aeroelastic problems of launch vehicles for the ISRO in the early 1970°s, This paper gives a brief review of the past and current aeroelastic studies at NAL on Satellite Launch Vehicles SLV3, ASLV and PSLV developed/being developed by the ISRO.

Item Type: Conference or Workshop Item (Paper)
Uncontrolled Keywords: Launch vehicles;Aeroelastic instability;Wind tunnel
Subjects: AERONAUTICS > Aerodynamics
ENGINEERING > Structural Mechanics
Depositing User: Ms. Alphones Mary
Date Deposited: 18 Nov 2010 03:54
Last Modified: 18 Nov 2010 03:54

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