Airport congestion and increased passenger numbers are the primary drivers leading to the development of larger and larger aircraft. However as aircraft size increases, it becomes more and more difficult to achieve corresponding improvements in aircraft performance. It is believed that for large civil aircraft the “flying wing” design may offer improvements in aircraft performance that are significantly greater than those achievable by conventional aircraft.
There have been a number of successful flying wing aircraft designs developed for the military market, but no civil flying wing transports. This has been caused by the differing payload, mission and airworthiness requirements, which, in the past, have penalized the design of a civil “flying wing” aircraft. Modern conventional aircraft are “fly-by-wire” where the flight control computer produces an aircraft response to pilot control inputs that is tailored to give optimum handling characteristics. This alleviates the need to tailor the airframe shape to provide acceptable handling qualities, which may allow a more optimal aerodynamic solution.
The VELA project was aimed at the development of skills, capabilities and methodologies suitable for the design and the optimization of civil flying wing aircraft.
All work packages used two baseline configurations (VELA 1 and 2) produced in WP 1 to develop methods, tools and new solutions which were used in the final work package 6 to design an improved final flying wing configuration (VELA 3).
The two baseline configurations have been designed to establish two boundaries of the design space in placement and blending of the outboard wing (most forward, most rearward).
For radically different configurations like the flying wing aircraft, validation data was needed. Low speed wind tunnel tests have been performed to measure static and dynamic derivatives. These test results have been compared with the predictions made in advance using preliminary design tools. Aerodynamic derivatives are used to develop flight control systems. They describe the effect of the static deflection of control surfaces and the dynamic damping characteristics of anaircraft configuration.
Various optimization techniques have been enhanced and applied to maximize the efficiency of flying wing configurations. Parameters like chord length, twist angle and airfoil section shape were varied. To achieve realistic results, constraints like cabin dimensions and floor angle as well as longitudinal stability have been taken into account.
Alternative solutions for the flat pressure cabin have been developed and assessed with Finite Element models. These models were then used to derive more accurate estimates of the structural mass of the configurations.
Issues of airport integration as well as ditching and passenger evacuation have been addressed by new simulation techniques.