|Innovative Control Effectors for Manoeuvring of Air Vehicles
|Applied Vehicle Technology|
Control Effectors, Flight Control, Flow control, Manoeuvre, Performance
New control effector strategies are a requirement for the survivability of future manned and unmanned military vehicles. Approaches that do not involve ‘seams’, ‘gaps’ or moving surfaces have been studied in the past and continue to evolve toward ever improving efficiency and ease of integration. The requirement to be seamless invokes a very critical characteristic – in general because control power for any one control effector is limited, a suite of control effectors are required to provide all envelope control of a vehicle. This is true even for a vehicle that only requires mild manoeuvring. Control effectors for take-off and landing requirements are a particularly difficult integration issue. There are many approaches that involve seamless geometry movement including morphing leading and trailing edges, morphable wings and wing tips, continuous mould-line technology, etc. Several of these concepts were addressed in a recent AVT Symposium on Morphing Vehicles (Evora, Portugal, April 2009, RTO-MP-AVT-168).
Likewise there are many pneumatic control approaches to create ‘virtual geometry changes’ that involve blowing or suction to increase the effectiveness of (or even replace) conventional aerodynamic control surfaces. Successfully implemented flow control technologies have the potential to revolutionise the performance and manoeuvre characteristics of modern air and maritime platforms. Flow control technologies have a wide range of uses from separation control for improving high alpha performance, to lift augmentation and full 3-axis flight control. However, to date, exploitation on production platforms has been limited, often due to the complexity, power requirements and impact on cruise performance.
A recent STO workshop (May 2013, AVT-215, Novel Control Effectors for Military Vehicles) explored many of these innovative control effector technologies including geometric, seamless and virtual (pneumatics, plasmas etc) shaping. A key objective from the workshop was to explore, assess and baseline the current state of the art in innovative control effector technologies.
The conclusion of the workshop was that the application of these novel technologies, both in isolation and in combination, to the manoeuvring of a vehicle constrained by low observability considerations offers the most promising route to raising the Technology Readiness Level (TRL) sufficiently to allow exploitation onto future NATO aircraft.
The objective of the Task Group will be to increase the TRL of the application of novel control technologies to manoeuvring through the assessment and development against key integration criteria, e.g. complexity, maintainability, reliability, etc.
The Task Group will also identify any barriers to exploitation, which may direct future research.
The topics covered by the Task Group will be as follows:
• Identify/develop a suitable vehicle model to act as a benchmark for application of the technologies. This would include:
o Functional requirements for flow control technology e.g. control power (forces and moments), linearity constraints, etc.
o Realistic systems integration constraints on the technology, e.g. guideline LO constraints, available engine bleed air, etc.
o Realistic environmental integration constraints on the technology, e.g. effect of contamination due to dust, water, etc.
o Reliability/maintainability requirements
• The research effort would then focus on implementation and evaluation of novel control concepts to provide flight control of the vehicle.
o It would be multidisciplinary with contributions from both pure aerodynamics/structures disciplines and control engineers
o The task could evaluate different actuator placements/implementations for gaining appropriate control of the vehicle, including combinations of technologies, both old and new; e.g. use of new technology to reduce the size of conventional controls.
o Pure aerodynamicists investigate the interaction of the e.g. flow control with the flow field as well as obtain the necessary aerodynamic performance data
o Aerodynamics/structures and control engineers work together to investigate the control loop including associated nonlinear behavior and time lags including under ‘off-design’ conditions
o Design investigation of integration, maintenance or improvement of LO, or improving/modifying the aerodynamics in tandem with improved performance from the novel control
• Outcomes would be:
o Insight into the impact of the novel control on the overall vehicle characteristics
o Evaluation of how a novel control technology (or technologies) can be used to control the flight of a vehicle, and how and where to place actuators for best effect.
o How the design of a may be impacted/improved through the use of flow control technology
o Understanding of the real world systems and environmental integration issues for the novel control technologies