A version of this article appears in the June 30 edition of Aviation Week & Space Technology.
New flight-control and guidance technology developed by the U.S. Navy and British researchers has been shown to allow carrier fighter pilots to land more accurately and consistently, and will be applied to both theSuper Hornet/Growler and the F‑35C Joint Strike Fighter.
Developers of the technology predict it will reduce the number of training landings needed to qualify pilots for carrier operations and reduce fatigue on airframes.
In the case of the , the new system—known as Maritime Augmented Guidance with Integrated Controls for Carrier Approach and Recovery Precision Enabling Technologies, or Magic Carpet—was shown in simulator tests to reduce pilot workload from borderline-acceptable levels to “minimal,” and it will be installed for the fighter’s long-delayed carrier trials later this year. Magic Carpet has been installed and tested without any hardware changes.
In a conventional carrier landing, the pilot follows an optical glideslope guidance from the ship, with flaps deflected to a pre-set angle. If the aircraft descends below the glideslope, the pilot has to pull the stick back and pitch the nose up to increase lift. This increases drag, so the pilot has to add power to maintain speed, then recover the original angle of attack (alpha), and throttle back to avoid over-speeding.
In a Magic Carpet approach, the pilot can engage a “Delta Path” law once the aircraft is on the glideslope. The flight-control system commands a reference flightpath, in combination with pilot-entered ship speed, which corresponds to the optical signal from the carrier. The aircraft will follow this path automatically, with the pilot correcting for any excursions. A ship-relative velocity vector is projected on the head-up display.
A major difference in the Magic Carpet approach is that the flaps are not fully deflected, and the flight control system uses them to add or reduce lift. If the aircraft falls below the glideslope, the pilot still pulls the stick back, but the control system deflects the flaps downward, reducing descent rate at a constant alpha. Once the aircraft regains the glideslope, Magic Carpet uses the flaps to readjust the vertical speed, again with no change in alpha. The auto-throttle—which on the Super Hornet is set to hold a constant alpha at an airspeed proportional to aircraft weight—will make necessary adjustments.
Both the basic/F and F-35C flight-control systems had provision for direct lift control, but the innovation in Magic Carpet is to add the Delta Path mode. In simulator tests at ’ Warton, England, site, the workload for an F-35C carrier landing was reduced from a Cooper-Harper handling qualities rating of 6 (extensive pilot workload), to 2 (minimal pilot workload), according to a Navy document.
A second element of Magic Carpet will help pilots fly through the “burble” of turbulent air behind a moving carrier. The inertial reference system and attitude sensors can be used to provide micro-corrections before the pilot can react—responding to a 0.1g departure in as little as 0.4 sec.
Magic Carpet originated at the U.S. Naval Air Warfare Center’s aircraft division (Nawcad) at the Patuxent River, Maryland, flight-test center. Team leader James Denham, a senior engineer at Nawcad, tells Aviation Week that the idea stemmed from tests of the-modified Vectored-thrust Aircraft Advanced Control (VAAC) Harrier aboard the U.K.’s aircraft carrier Illustrious, aimed at developing a shipboard rolling vertical landing mode for the F-35B.
Denham proposed a system that would give other aircraft the same rate-command flight-control capability demonstrated on the VAAC Harrier, and obtained some “seed money” from the Office of Naval Research to conduct some simulation research. The results justified follow-on funds from ONR to develop control laws for the Super Hornet, leading to flight tests in 2012.
Simulated and flight tests have shown that pilots using Magic Carpet land more consistently than pilots using conventional controls, with less variability (in terms of touchdown dispersion) between different pilots and across multiple landings. Improvements are sustained in turbulence and high sea states.
ONR predicts Magic Carpet will reduce the number of field carrier landing practice approaches that are required to requalify pilots before each cruise, reducing both direct flight hour costs and the consumption of airframe life, and estimates that Magic Carpet could save the Navy $1 billion per year.
Boeing is under contract to build Magic Carpet functions into the Super Hornet/Growler operational flight program (OFP) with the goal of making it available to the fleet in 2018. The first phase is to build a fully certifiable OFP modification, which will start tests at Patuxent River in the fall of 2014 and undergo sea trials in early 2015. That is to be followed by a second phase that adds the “anti-burble” stabilization mode head-up display symbology and integrates the air data and inertial systems more fully.