Portland, Ore. -- European aerospace researchers have shown the first prototype of a planned "flapless" unmanned air vehicle. Similar to a remote-controlled U.S. Predator drone, the prototype UAV is an early milestone for the five-year Flapless Air Vehicle Integrated Industrial Research (Flaviir) project, which aims to produce a fully autonomous UAV with no moving control surfaces by 2009.
The completely smooth, teardrop-shaped black exterior of the envisioned autonomous craft will also be fully shielded against electromagnetic pulse (EP) attacks, whether from lightning strikes or nearby nuclear bombs, planners said.
"Our vision of future UAVs is of flapless vehicles that use fluidic thrust vectoring, where direction is changed with a secondary airflow," said Ian Postlethwaite, pro-vice-chancellor and professor of engineering at the University of Leicester, one of many U.K. institutions involved in the multidisciplinary project.
All aircraft today use control surfaces--flaps--to turn, dive and climb. By using using streams of air to control direction in its UAV, the Flaviir effort intends to take computer control one step beyond fly-by-wire aircraft, aiming at com- pletely autonomous operation (see www.flaviir.com). The goal is a low-cost, maintenance-free UAV that will fly at least as well as conventional aircraft.
The $7.4 million funding for Flaviir has been divided between a three-year research phase and follow-on, two-year demonstration phase, with $600,000 reserved for topics not considered at the outset--so-called seedcorn projects. The engineering research is divided into seven parallel efforts: aerodynamics, electronic control, electromagnetic systems, manufacturing, materials/structures, numerical simulation and integration. BAE Systems and the U.K.'s Engineering and Physical Sciences Research Council are funding the work. The recent demonstration prototype was crafted by Manchester University's Goldstein Aeronautical Research Laboratory.
"Here at the University of Leicester, we will develop the software that acts as a replacement for the pilot by autonomously flying the vehicle without collisions, even in dangerous, remote environments," said Postle-thwaite. The team has already developed an automated flight path task planner that switches among alternative planning methods in real-time to deal with uncertainty. Current work is extending the task to simultaneous management of multiple UAVs. Finally, artificial-intelligence software will be developed to detect errors and report them to a fault-tolerant flight control system that would automatically adapt for real-time failures to maintain flight performance and stability throughout a mission.
Working with Postlethwaite on the software are fellow professor Da-Wei Gu, research assistants Sarah Blaney, Kannan Natesan and Yoonsoo Kim; and research students Ihab Abou Rayan, Jianchi Chen and Samir Hassoun.
The seminal idea for the Flaviir project dates to 1930, when Romanian aerodynamicist Henri-Marie Coanda discovered that a stream of air emerging from a nozzle tends to follow a nearby curved surface. The Flaviir UAV takes advantage of the so-called Coanda effect by adding control jets that slightly alter the main airflows, thereby performing the functions of flaps but without moving parts.
Two variations are being perfected at Manchester University: control jets on the trailing edges of wings, to increase lift and thereby enable turns and deceleration, and secondary jets to control the direction of primary jets and thus enable diving and climbing.
The first method, called circulation control (CC)?226-130? replaces conventional flaps by blowing air from the trailing edge of the wing. It works by entraining the upper surface flow to yield an increase in lift in proportion to the force of the jet.