The NATO STO Task Group AVT-201 on ‘Extended Assessment of Stability and Control Prediction Methods for NATO Air Vehicles’

Abstract

The ability to accurately predict both static and dynamic stability characteristics of air vehicles using computational fluid dynamics (CFD) methods could revolutionize the air vehicle design process, especially for military air vehicles. A validated CFD capability would significantly reduce the number of ground tests required to verify vehicle concepts and, in general, could eliminate costly vehicle 'repair' campaigns required to fix performance anomalies that were not adequately predicted prior to full-scale vehicle development. This paper outlines the extended integrated experimental and numerical approach to assess the of stability and control prediction method capabilities as well as the design and estimation the control device effectiveness for highly swept low observable UCAV configurations. The aim of the AVT-201 Task Group is to provide an assessment of the CFD capabilities using model scale experiments and transferring this knowledge to real scale applications. Nomenclature  = AoA, Angle of attack [] s = Half span [m]  = AoS, Angle of side slip [] x = Chord wise coordinate [m]  = Flap deflection angle [] z = Vertical coordinate [m]  = Pitch angle [] y = Span wise coordinate [m]  = Yaw angle [] q  = Dynamic pressure coefficient [c ref ) RSM = Reynolds-Stress turb. model C my = Pitch moment coefficient (MF) [-] M y /(q   A s) A = Reference relation area [m 2 ] C mz = Yaw moment coefficient (MF) [-] M z /(q   A s) c ref = Reference length [m] c r = Root chord [m] LOB = Left Outboard Trailing Edge Flap LE = Leading Edge LIB = Left Inboard Trailing Edge Flap SLE = Sharp Leading Edge RIB = Right Inboard Trailing Edge Flap RLE = Round Leading Edge ROB = Right Outboard Trailing Edge Flap RLE-FT = Round Leading Edge -Fixed BL = Base Line (no CS deflection) Transition CS = Control Surface CAWAPI = Cranked Arrow Wing AVT = Applied Vehicle Technology Aerodynamics Project Inter.

Validation of Unsteady Aerodynamic Models of a Generic UCAV Using Overset Grids

“…roll moment coefficient in wind axes C m pitch moment coefficient in body axes, M y /q ∞ Sc C mw pitch moment coefficient in wind axes C mα indicial pitch moment coefficient with angle of attack, 1/rad C mδ f indicial pitch moment coefficient with flap deflection, 1/rad C mq indicial pitch moment coefficient with normalized pitch rate, 1/rad C n yaw moment coefficient, M z /q ∞ Sb C nw yaw moment coefficient in wind axes C Y side-force coefficient, Y /q ∞ S C Z z-force coefficient, Z/q ∞ S C Zα z-force coefficient with angle of attack, 1/rad C Z δ f z-force coefficient with flap deflection, 1/rad C Zq z-force coefficient with normalized pitch rate, 1 …”

“…The SA model 32 is the most popular one-equation model that solves a transport equation for a modified eddy-viscosity coefficient. The SA model can be written in general form as 33 (1) whereν is related to the kinematic eddy viscosity, P is the turbulence due to production, D dif f is the turbulence due to gradient of diffusion, and D diss is the near wall dissipation of turbulent kinematic viscosity. The production term is given by…”

“…The main objectives for the Group are to investigate the effects of deflection of control surfaces on the aerodynamic characteristics and dynamic Stability & Control (S&C) and to build S&C data bases from experimental and simulations. 1 The configuration considered is based on the Stability And Control CONfiguration, SACCON unmanned combat air vehicle (UCAV) which was designed and built as part of AVT-161. 2 An extensive series of experiments were carried out at the German-Dutch wind tunnel facility in Braunschweig (DNW-NWB) and 14 ′ × 22 ′ NASA LaRC to understand and analyze the aerodynamic performance of this vehicle.…”

Experimental aerodynamic assessment and evaluation of an agile highly swept aircraft configuration

“…The SACCON baseline configuration, without control surfaces, was subject of extensive experimental and numerical research as part of the DLR internal project UCAV-2010 and the international research group RTO/AVT-161 [3]. For this research, two wind tunnel models had been built, the low speed wind tunnel model of same name, and a high speed model, the DLR-F17E [4].…”

“…Within a first control concept consideration, the generic UCAV configuration SACCON has been equipped with 1 North Atlantic Treaty Organisation 2 Up to Sept. 2012: Research and Technology Organization 3 Reynolds Averaged Navier-Stokes trailing edge control devices, with their hinge lines passing parallel to the trailing edge.…”