Airfoil to Improve Aerodynamic Performance OF Aileron Reduced Spanwise in Combat Helicopter

“La Sapienza” University of Rome, DIMA

^* Contact Author: giovannimaria.depratti@uniroma1.it

Abstract

Combat helicopters frequently operate in the part of Planetary Boundary Layer (PBL) characterised by the presence of dust and many other aggressive agents, particularly, in desertic areas and in marine sites, so the aerodynamic performance of their ailerons reduced spanwise, carrying out weapon systems, may be reduced within unacceptable values and consequent relevant risks for the stability of the copter. According to some experts, ailerons for weapon systems of helicopter are not involved in the global lift of the copter, but their operative function is only to carry the combat systems..Nevertheless, some crash occurred to US combat helicopters suggest a different point of view, and an aileron damage, perhaps due to a kind of dynamic stall phenomenon, seems have been caused the copter fall. These problems may be avoided using particularly airfoil for the section of aileron instead of classic ones as NACA four digit series (as 00120018). These profiles may be FFA-W1-XXX series, characterised by a double curvature of camber-line.

In the present paper, after a deep analysis of operative conditions of modern combat helicopters, the aerodynamic performance of aileron section as NACA 0018 and FFA-W1-182 have been analysed and compared, and the results of tests carried out on a water table test bench are exposed and discusses.