Update 6
Sortie 10 completed! All 3 pilots evaluated a new L1 design for a total of 7 aircraft configurations. The new design improved the CHRs obtained with the original L1 design.
Update 5
Two more flights! 1/1 landing with L1 engaged! L1 assisted the pilots in 6 failure configurations by improving aircraft HQs and preventing PIOs. Last flight scheduled for Tuesday 10th March.
Update 4
1 more flight completed on Friday March 6th! 1.5+h of HQ assessments for 7 failure configurations.. landed the airplane with L1 engaged again
Update 3
Wednesday March 4th: two more flights, 4/4 successful landings, 2 of them with failures engaged! L1 also enabled pilots to fly ‘unflyable’ aircraft configurations!
Quote of the day: “Can you please switch L1 on so that I can give you comments?!” – Pilot after flying a heinous aircraft config with L1 off
Update 2
Two sorties completed on Tuesday March 3rd, including landing with the L1 adaptive controller engaged!
Update 1
On Friday Feb 27th, two successful flights have been conducted. More flights are scheduled for the upcoming week.
At the time of writing, two members of the Advanced Controls Research Lab (ACRL) are at the Edwards AFB in Southern California to support flight testing of a Learjet augmented with an L1 adaptive flight control law. It is the first time an L1 adaptive system is tested in flight on a manned aircraft, and it represents an important step towards the introduction of this technology into commercial aviation. The goal of this collaboration is to build trust in L1 adaptive control and provide evidence for certification of this technology.
Testing consists of one week of ground checks, followed by two weeks of extensive flight testing, with 2 deployments per day, and 2 hours of uninterrupted flight per deployment. In-flight testing primarily focuses on handling-qualities assessment for various tasks, including capture and offset-to-landing tasks, as well as on analysis of the robustness margins of the L1 controller in terms of gain and time-delay margins. The main objective of the study is to investigate the ability of L1 adaptive control to maintain nominal aircraft handling qualities and prevent unfavorable aircraft-pilot interactions in the presence of aircraft failures (changes in the aerodynamics, loss of control effectiveness, coupling between control channels, shifts in the center of gravity, etc).
Testing is led by the USAF Test Pilot School (TPS), and uses Calspan’s variable stability Learjet. This aircraft implements a variable stability system (VSS) that is able to emulate changes in aircraft aerodynamics through the use of feedback loops, which are opaque to the flight control law. A total of 16 VSS configurations will be tested, with various severity levels per configuration. The tests are performed by F-16 and B-52 pilots. Over the past several months, the ACRL has been closely collaborating with Calspan to implement the L1 control law on the aircraft computers, and with the TPS to define the flight test plan.
These flight tests are a natural continuation of the tests performed by NASA Langley on the AirSTAR dynamically scaled Generic Transport Model research aircraft during 2009-2011 and the piloted simulation evaluations conducted by TUDelft on the SIMONA motion-based research simulator in 2011.
