It is well known that business needs are placing an ever-increasing demand on the aeronautics industry to develop and manufacture aircraft at lower costs, with improved flight capabilities and a reduced impact on the environment. Research efforts towards an improved understanding of the flow physics around fuselage/tail combinations remain limited. However, a successful design approach towards the development of modern transport aircraft has to include the empennage as well. Performance guarantees for future aircraft have to be granted earlier and with higher accuracy compared with former developments.
In order to cope with the current aeronautics industrial needs, which are different from what was relevant in the past, a new integrative approach was proposed, closing the gap between the current classical and the possible future unconventional empennage design. This can be achieved by bringing the current tail design to its utmost level of optimised performance with highly efficient empennage control surfaces. Thus, the improvements to be achieved by REMFI focused on three main aspects: the enhanced understanding of the tail flow physics, improved computational predictions for fuselage/tail design and analysis, and improved experimental capabilities and measuring techniques for tail flows.
These aimed at providing the means to:
- increase the empennage aerodynamic efficiency and reduce loads
- improve empennage performance and weight for optimised gap effects, including Reynolds number effects
- investigate sting mounting effects on empennage wind tunnel measurements
- enhance the current scaling methodologies to flight conditions
- reduce fuel burn (a positive effect on energy saving and reduction of emissions to the environment)
- provide novel design concepts for integrated fuselage/empennage designs with regard to significant interaction between rear fuselage and belly fairing, and
- shorten the design cycle by reducing the cost of the aerodynamic design of tail and fuselage; reduce the maintenance costs.
The REMFI project was structured into four complementary technical Work Packages plus one project management Work Package:
- Project Management and Coordination;
- Empennage improved control surfaces efficiency;
- Sting mounting arrangement interference investigation;
- Experimental verification study;
- Innovative integrated fuselage and empennage designs.
These Work Packages represented a major path each with either numerical or experimental test technology, or both activities. They contained a number of tasks and sub-tasks that reflect the logical phases of the project contents. Combined, the technical Work Packages contained all the theoretical and experimental research activities necessary for the successful qualification of state-of-the-art simulation tools. This was in order to achieve the anticipated design capability, in support of improved rear-end configurations covering:
- precise numerical simulation of tail-specific flow phenomena for full-scale aircraft on the basis of the CFD tools currently used for the aerodynamic design of wings at their design conditions;
- experimental verification study by means of high-resolution test data, including data at full-scale flight conditions;
- tail-orientated improvement of wind tunnel measurement and testing techniques; and
- integrated fuselage and empennage designs.
The following major achievements were expected:
- Fully optimised empennage design with highly efficient control surfaces with respect to:
- Elevator / rudder fuselage gaps effects on empennage performance (efficiency and hinge moments)
- Transition effects on empennage performance, efficiency and hinge moments
- Improved live-rear-end measuring technique including comprehensive understanding of:
- Split gap effects on the empennage measurement accuracy
- Twin-sting mount arrangement effects on empennage measurement accuracy
- Comprehensive set of tail-specific data advanced aircraft type configurations containing detailed flow field information up to full-scale Reynolds numbers
- Advanced CFD tools for industrial application with specific guidelines for empennage flow simulation
- Improved knowledge on scale effects up to true flight Reynolds numbers
- New and innovative designs for integrated fuselage and empennage including belly fairing
- Drag increasing devices for steep descend to reduce noise impact