Low Reynolds number aerodynamics of leading-edge and trailing-edge hinged control surfaces: Part I statics

Abstract

The use of a leading-edge hinged control surface, as opposed to a traditional trailing-edge hinged control surface, is investigated in the context of improving control authority of fixed-wing Micro Air Vehicles when subject to gusts. Static and dynamics forces are considered in two separate papers (Part I and II). In Part I we document the static lift characteristics of two flat-plate airfoils, having either a 30% chord leading- or trailing-edge hinged control surface, resolved from surface pressure measurements captured at angles of attack ranging from 0∘ to 30∘ and control surface deflections from 0∘ to ±45∘. The lift response of the airfoil with the leading-edge control surface was complex with a reversal in lift noted beyond specific control surface deflections (for e.g., at α=0∘, CL reversed beyond ψ=±20∘). The use of a trailing-edge control surface was found to be more effective than the leading-edge control surface. Analysis of the CP and CL fluctuations at fixed α and control surface deflections revealed the fluctuations were significantly less with leading-edge control surfaces than trailing-edge control surfaces. Furthermore, a simple potential flow model exhibited good correlation of CL against experimental results at small angles of attack and control surface deflections.