R&D Contracting, Bldg 7, 2530 C Street, WPAFB OH 45433-7607

A -- RECONFIGURABLE SYSTEMS FOR TAILLESS FIGHTER AIRCRAFT (RESTORE) THIS ANNOUNCEMENT IS IN TWO PARTS. THIS IS PART 1 OF 2 SOL PRDA 96-04-FIK POC Genet Stewart, Contract Negotiator, (513) 255-5901 Lawrence W. Kopa, Contracting Officer, (513) 255-5901. A -NOTICE: THIS ANNOUNCEMENT IS IN TWO PARTS. PART 1 OF 2 PARTS. INTRODUCTION: ''RECONFIGURABLE SYSTEMS FOR TAILLESS FIGHTER AIRCRAFT (RESTORE)'' PRDA #96-04-FIK. Wright Laboratory (WL/FIKA) is interested in receiving proposals (technical and cost) on the research effort described below. Proposals in response to the PRDA shall be submitted by March 6, 1996, 1500 hours, Eastern Time, to: Wright Laboraotry, Directorate of R&D Contracting, ATTN: Genet Stewart, WL/FIKA, Bldg. 7, 2530 C Street, Wright Patterson AFB OH 45433-7607. This is an unrestricted solicitation. Small businesses are encouraged to propose on all or any part of this solicitation. Proposals submitted shall be in accordance with this announcement. Proposal receipt after the cutoff date and time specified herein shall be treated IAW restrictions of FAR 52.215-10, a copy of this provision may be obtained from the contracting point of contact. There will be no other solicitation issued in regard to this requirement. Offerors should be alert for any PRDA amendments that may be published. This PRDA may be amended to allow subsequent submission of proposal dates. There will be no formal Request for Proposal or other solicitation request in regard to this requirement. Offerors who do not already have a copy of the current Nov 92 WL guide entitled ''PRDA BAA Guide for Industry'' may request a copy from the contracting point of contact cited in this announcement. This guide was specifically designed to assist offerors in understanding the PRDA/BAA proposal process. B - REQUIREMENTS: (1) Techincal Description: The Air Force requirement for low signature high performance fighters has led to configurations with little or no vertical tail. These platforms possess a suite of new/novel effectors to generate the required yaw control power and are nominally directionally unstable. This has introduced a number of key problems. Among these is the control allocation problem since there is an unprecedented number of complex, nonlinear, coupled effectors to produce the required forces and moments. Also the effects and interactions of the new/novel effectors are not well understood. In addition to generating the required forces and moments, the effectors must be optimized to minimize control activity, structural interaction, or some other performance index. Since the configuration is likely to be unstable in 2 axes, axis prioritization becomes critical when the effectors saturate. There is also a need to keep the aircraft from exceeding the design limits (alpha, beta, flight condition, structural bending, etc.). Finally, the effects of failure/damage are amplified due to simplified actuation and a less robust effector suite. The objective of this effort is to develop a reconfigurable/adaptive control design methodology and algorithms for a class of year 2000+ low signature attack or strike fighter aircraft possessing little or no vertical control surface effectors. The key transitional products of this effort are algorithms for: 1) on-line real-time parameter estimation, 2) on-line constrained optimization, 3) on-line control design, and 4) on-line control allocation, axis prioritization, and command limiting. This class of aircraft may or may not be carrier suitable. The end result of the development effort shall be an aircraft and control system that has the following characteristics: 1) tailless or reduced vertical tail, 2) highly maneuverable, departure resistant, and capable of Level 1 Flying Qualities (FQ), 3) time to bank 90 degrees in 2.0 sec at 30 deg AOA while maintaining sideslip to +/- 6 deg, 4) capable of being landed and achieving Level 2 FQ with any one effector failure, and 5) capable of achieving Level 3 FQ with any two effector failures. The following design guidelines should be used: 1) restrict AOA to CLmax, 2) restrict investigations to 4 mission segments which can include power approach, cruise, supersonic, combat entry, combat exit, and high speed at sea level, 3) investigate the impact of any one or two control effectors failing, 4) do not address sensor and computer failures, 5) use monitors to detect and isolate actuator failures, 6) use sensors consistent with F22 or earlier fighter aircraft technology, and 7) do not investigate flutter suppression. The characteristics and guidelines listed above are not rigid specifications, but should be adhered to unless sufficient justification can be presented. The RESTORE program consists of 14 Tasks. Task 1. System requirements: Develop a set of system requirements that include: a) mission scenarios and critical mission maneuvers that will exercise the full range of nonlinearities and the entire control suite, b) required stability and performance levels after failure/damage for a failure/damage suite. The stability and performance level requirements will include Flying Quality models and Low Order Equivalent System (LOES) models for the various failure modes, c) onboard system architecture resources for implementation to include computing, max delays, sensors, actuation, and what additional or special certification requirements would be required to ready the system for flight, d) the minimum amount of pilot interface required as a function of failures to satisfactorily complete a piloted simulation, and e) a system requirements document. A draft or preliminary version of the requirements document containing no more than 20 pages (including all attachments) shall be delivered with the proposal. Task 2. Model: Provide a fighter aircraft model (simulation) with little or no vertical tail that has a full envelope data base derived from wind tunnel and prediction data. This simulation shall be of such fidelity to be suitable for handling qualities evaluation. The model should have one or two engines, and a rich, though feasible, suite of control effectors that provide forces and moments in multiple axes. The model should contain mass variations, CG variations, actuator models, sensor models, digital effects, and turbulence and gust models. The model should also account for notch filter phase lags, structural interaction of critical modes with the control laws, and load limits. There should be little development work on the simulation, basically a variation of a previously developed future fighter model. Provide a description of the selected model in the proposal. Task 3. Failures: Define effector failure and damage effects and modify the aircraft model accordingly. Failure effects shall include, at minimum, locked and floating control effectors. Damage effects shall include, at minimum, control effectors partially and totally missing with collateral damage to surrounding area. The failure and damage effects are to be based on good engineering judgment and extrapolation from existing data. No wind tunnel testing is envisaged for this effort. Task 4. Control design: Analyze and select a control design approach from a set of 2-3 alternate control design approaches suitable for an aircraft that is unstable (or neutrally stable) in multiple axes, with particular emphasis on the directional axis. The approaches shall emphasize in-flight control design/adaptation to accommodate large variations in parameters. Dependency on fixed data bases and apriori control laws shall be minimized since the possible damage modes can not be completely defined. Particular attention shall be given to parameter estimation, since damage effects cannot be known perfectly beforehand. Fast and reliable parameter estimation is essential to maintain stability and maximize performance. Parameter estimation is used in a generic sense, since even in direct adaptive control the control parameters must be estimated. Discussions of the pros and cons of the control design approaches shall be included with the proposal. No extensive theoretical work is expected to be done on the selected design approach. Task 5. Stability: Develop tools/techniques that prove stability (or significantly contribute to confidence level) for adaptive/reconfigurable control. Task 6. Saturation: Develop approaches that rigorously prevent control power saturation in each axis and thereby improve tracking, and prevent instability and adverse pilot vehicle coupling. Task 7. Yaw power: Develop algorithms that maximize the available yaw control power to perform coordinated rolls at elevated alpha up to CLmax and during low speed landing/maneuvering tasks. Task 8. Loads: Develop on-line optimization algorithms that can perform load alleviation. Task 9. Flexibility coupling: Develop design tools and algorithms that can be easily used to modify control laws to filter out or compensate for adverse aero-servo-elastic effects. Task 10. Control allocation: Develop a dynamic on-line control power allocation technique to generate required forces and moments from a suite of effectors that generate forces and moments in multiple axes, and which also reallocates for failure and damage. Develop a prioritized list/weighting of metrics/indices to optimally allocate control power as a function of condition (failure, mission phase, maneuver, etc) or state (flight condition, rates, limits, etc). The allocation technique shall make maximum use of available control power. Load, tracking error and control activity are possible optimization indices. Stability in critical axes shall be maintained as actuators saturate. Provide a list of possible approaches in the proposal. Task 11. Axis priority: Develop a dynamic axis prioritization technique that gives priority to unstable/critical axes when control power is limited. Provide a list of possible approaches in the proposal. Task 12. Command limiting: Develop a command limiting technique. The command limiting shall be completely on-line adaptable and prevent the aircraft from exceeding it's limits. Primary among these is exceeding the available control power, exceeding the maneuver envelope (alpha, beta, etc), and exceeding the structural limits. This shall be done in such a way as to avoid/prevent integrator windup and adverse pilot-vehicle coupling. Provide a list of possible approaches in the proposal. Task 13. Non-Real-Time (NRT) simulation: Develop and perform a NRT simulation to evaluate whether the unfailed and failed performance satisfies the defined requirements. THIS IS THE END OF PART 1. (0018)

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