DON26BZ01-NV004 TITLE: Aircraft Formation Flight Control Technology for Heterogeneous Formation Flight

COMPONENT TECHNOLOGY PRIORITY AREA(S): Advanced Computing and Software

PROJECTED CMMC LEVEL REQUIREMENT: Level 2 (Self)

The technology within this topic is restricted under the International Traffic in Arms Regulation (ITAR), 22 CFR Parts 120-130, which controls the export and import of defense-related material and services, including export of sensitive technical data, or the Export Administration Regulation (EAR), 15 CFR Parts 730-774, which controls dual use items. Offerors must disclose any proposed use of foreign nationals (FNs), their country(ies) of origin, the type of visa or work permit possessed, and the statement of work (SOW) tasks intended for accomplishment by the FN(s) in accordance with the Announcement. Offerors are advised foreign nationals proposed to perform on this topic may be restricted due to the technical data under US Export Control Laws.

OBJECTIVE: Develop an advanced flight control architecture to enable greater range and endurance through precise automatic station keeping while flying in formation and exploiting vortex-generated upwash from upstream aircraft.

DESCRIPTION: Wake surfing (i.e., flying trail in close formation within the upwash of one or several lead aircraft) has demonstrated significant fuel savings on the order of 10-20%. Researchers have conducted multiple studies and executed flight demonstrations in the past that validated performance gains. However, the adoption of an operational capability still faces challenges.

One key challenge is the technical approach for trailing aircraft to maintain precise relative position behind upstream aircraft in the optimal location to maximize efficiency. While this task can be performed through manual pilot station keeping, the task is workload intensive and is not practical for long missions. There is a need for an autopilot flight control capability to maintain the position for optimum fuel savings (i.e., the "sweet spot"), realizing this significant range/endurance benefit opportunity with minimal or zero pilot workload. Flight control architectures must be capable of precise station keeping in aircraft formations of similar/dissimilar and manned/unmanned fixed wing aircraft. Flight control architectures may include techniques to sense the location of the vortex/upwash effects both with and without explicit knowledge of aircraft relative positions.

The objective is to create robust flight control laws for trailing aircraft in similar or dissimilar formations to exploit the benefits of wake surfing. Unique aircraft hardware and modifications should be minimized to the greatest extent possible to achieve this objective. To achieve robust control law development for precision formation flight, the problem can be broken into coarse and precision tracking problems, with some interdependencies between the two. It is strongly desired that both problems be solved without additional hardware integration for participating vehicles and zero data-link demands.

For coarse acquisition and tracking, it is expected that the relative position between participating aircraft needs to be established and maintained in the general vicinity of the lead’s wing-tip vortex. Relative position must be maintained while sequencing waypoints or tracking a heading or ground track to accomplish ingress/egress mission segments. Consideration in the development of coarse acquisition and tracking capability should be given to Global Positioning System unavailability.

For precision position tracking and control, it is expected that aircraft sensors (e.g. air data, inertial, flight controls) affected by the influences of the wing tip vortex on the trail aircraft can be identified and exploited to locate optimal position. Control architecture gains and surface mixing influences necessary for acquiring and tightly tracking the optimal location in the presence of the non-linear wing tip vortices and free stream turbulence must be considered.

PHASE I: Define and develop a control law approach that provides a robust coarse and precision tracking schemes for automated formation flight to improve range. Create a control law development plan detailing the approach, rationale, schedule, key evaluations, robustness analysis, and other milestones. The plan should clearly identify expected parameters to be used for both the coarse and precision tracking loops (e.g., engine fuel flow, pitch vs Angle of Attack relationship changes, trim impacts), requirements, and rationale for their selection/derivation. Expectations for parameters sources (such as existing hardware, datalinks, or derived parameters) should be clearly documented, and any new hardware requirements should be made explicit. Control law architecture for all axes, expected gain setting, expected surface mixing approaches shall be discussed. The plan shall identify key analyses and iteration cycles to be performed in the maturation of control law algorithms. Preliminary modeling and simulation results assessing feasibility of the concept, including an accurate representation of the trailing vortex effects, are desired but not required during this Phase.

The Phase I effort will include prototype plans to be developed under Phase II.

PHASE II: Develop and implement a prototype solution for wake surfing including control algorithms (i.e., relative positioning and optimized vortex benefit positioning) evaluated and tuned for use between multiple dissimilar aircraft. Software capabilities also include: formation management algorithms, mission optimization algorithms, formation entry and exit algorithms/procedures, and displays unique to wake surfing. Implement the prototype solution in a six degree-of-freedom (6DOF) simulation environment (including pilot-in-the-loop) to demonstrate and evaluate the algorithms and displays. Produce analysis and reports describing the prototype solution and results.

The 6DOF simulation environment should include a) multiple aircraft (at least two aircraft of different type) to determine technical feasibility of the relative positioning algorithm and b) representation of the concept formation with 3+ aircraft to determine effect of larger formation sizes. The simulation must include an accurate representation of the systems that affect flight dynamic performance (actuation, latencies, hardware/sensors, etc.). Control algorithms should be able to handle different lead aircraft and aircraft sequencing inside the formation, handle a variety of maneuvers (e.g., turns and descents), enter and exit formation including failure contingency management, manage keep out zones for safety, and manage formation stability.

Navy aircraft simulation environments may be available for use and control law evaluation during Phase II.

PHASE III DUAL USE APPLICATIONS: Integrate the Phase II-developed algorithms and displays into future manned and unmanned platforms, including Collaborative Combat Aircraft Programs of Record.

Dual use applications include relative navigation without GPS aiding, UAS swarming, and robust flight control systems.

REFERENCES:

1. Niestroy, Michael; Luckner, Robert and Doll, Carsten. "Flight control systems for aircraft engaged in air wake surfing for efficiency." AIAA Scitech 2020 Forum. American Institute of Aeronautics and Astronautics, 2020. https://hal.science/hal-03224957v1/document
2. Hanson, Curtis, et al. "An overview of flight test results for a formation flight autopilot." AIAA Guidance, Navigation, and Control Conference and Exhibit, 2002. https://ntrs.nasa.gov/api/citations/20030005820/downloads/20030005820.pdf
3. Nangia, R. K. and Brown, Nelson. "Formation Flying (Air-Wake-Surfing) for Efficient Operations–NATO STO Research Task AVT-279." AIAA Scitech 2020 Forum. https://arc.aiaa.org/doi/abs/10.2514/6.2020-1001
4. Blake, William B.; Bieniawski, Stefan R. and Flanzer, Tristan C. "Surfing aircraft vortices for energy." The Journal of Defense Modeling and Simulation 12.1 (2015): pp. 31-39. https://journals.sagepub.com/doi/abs/10.1177/1548512913500734

KEYWORDS: Wake Surfing; Formation Flight; Precise Relative Navigation; Vortex; Upwash; Long Range

TPOC:
NAVAIR SBIR/STTR POC
navair-sbir@us.navy.mil