Estimation of Force and Moment Coefficients for DARPA SUBOFF using USAF DATCOM Method

Hydrodynamic coefficients are essential in the motion prediction of underwater vehicles. This paper presents a study of estimation of force and moment coefficients (Hydrodynamic coefficients) of DARPA SUBOFF model using United States Air Force Digital DATCOM. DATCOM is data compendium which is used to evaluate the aircraft stability derivatives from its geometric shape parameters. It is applied to determine the analogous hydrodynamic coefficients of axisymmetric underwater vehicles by incorporating the properties of water. Digital DATCOM generates the results of Datcom default method and Jorgensen method which can be compared with experimental results published by David Taylor Research Centre (DTRC). In Resistance test, Digital DATCOM results are compared with Experimental results at varying speeds. And in Oblique test, lift, drag and moment results from Digital DATCOM are compared with experimental results at varying angles of attack. Resistance test and Oblique test results of Digital DATCOM show reasonable accuracy with experimental results. MATLAB Aerospace Toolbox generates and invokes the output files obtained from Digital DATCOM. Digital DATCOM can be considered as quick and efficient tool for the estimation of hydrodynamic coefficients in the initial stages of vehicle design. This study on submarine model will be performed as a preliminary step which will be later extended to estimation of force and moment coefficients of a commercially available axisymmetric AUVs.