A review of thrust-vectoring in support of a V/STOL non-moving mechanical propulsion system

Abstract

Abstract:The advantages associated to Vertical Short-Take-Off and Landing (V/STOL) have been demonstrated since the early days of aviation, with the initial technolology being based on airships and later on helicopters and planes. Its operational advantages are enormous, being it in the field of military, humanitarian and rescue operations, or even in general aviation. Helicopters have limits in their maximum horizontal speed and classic V/STOL airplanes have problems associated with their large weight, due to the implementation of moving elements, when based on tilting rotors or turbojet vector mechanical oriented nozzles. A new alternative is proposed within the European Union Project ACHEON (Aerial Coanda High Efficiency Orienting-jet Nozzle). The project introduces a novel scheme to orient the jet that is free of moving elements. This is based on a Coanda effect nozzle supported in two fluid streams, also incorporating boundary layer plasma actuators to achieve larger deflection angles. Herein we introduce a state-of-the-art review of the concepts that have been proposed in the framework of jet orienting propulsion systems. This review allows to demonstrate the advantages of the new concept in comparison to competing technologies in use at present day, or of competing technologies under development worldwide.

Thrust and jet directional control using the Coanda effect

“…Mechanical deflection of the thrust involves engine nozzle deflection and, thus, physically modify of the main flow direction [3], [6,7]. In this case, complicatelly devices and actuators have to be used [8].…”

Numerical modeling of coanda effect in a novel propulsive system

“…Further, the use of thrust vectoring concept enables to control the aircraft in more controllable way. In case of military operations it can introduce an extension on aircraft controllability at high post angle of attacks, a moment where classic lifting surface lose their ability to provide the control of aircraft, creating what is called super maneuverability [45]. This technology will improve take off and landing performances.…”

“…Alternatively, fluidic thrust vectoring approach has been proposed by several researchers [45]. In contrast to mechanical thrust vectors, fluidic thrust vector uses fixed geometry.…”

“…Further, their inertia is lower thus making them faster to actuate which results in a stronger control response. Also, the complexity is reduced because they require mechanical simpler system with no moving parts, having also reduced radar cross section for stealth properties [45]. An excellent review of thrust vectoring approaches and its support in VTOL aircrafts has been presented by Pascoa et al [45].…”

“…ACHEON (Aerial Coanda High Efficiency Orienting jet Nozzle) explores the feasibility of a novel propulsive system for aircraft which is expected to overcome the main limitations of traditional systems related to typical jet deflection systems [1,41]. In particular, Project ACHEON comprises thrust vectoring propulsive nozzle named HOMER (High Speed Orientating Momentum with Enhanced Reversibility) that is supported in a patent developed at University of Modena & Reggio Emilia [41].This system also comprises a plasma actuator (boundary layer control devices) that enables to extend vector range of operations of nozzle [45] In the past, Germans used graphite control vanes in the exhaust stream of their V-2 ballistic missiles in World war 2 for some directional control of the jet [45]. Thrust vectoring in an aircraft is a relatively new practice and the concept came under use during cold war [45].…”