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 ∘ , C L 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 C P and C L 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 C L against experimental results at small angles of attack and control surface deflections.