Sidesticks Shine in G500 Sim Flight

 - February 20, 2015, 3:00 PM
Gulfstream’s Conceptual Advanced Simulation Environment (Case III) for the in-development G500 felt and looked real, thanks to a stunning visual display and the unique configuration of the sidesticks.

AIN’s Matt Thurber, one of the few non-Gulfstream pilots to fly the G500 Case III simulator and the first journalist to do so, reports from Savannah.

With a slight movement of my wrist, I eased back on the sidestick of Gulfstream’s new G500 to rotate at about 130 knots and we lifted off Runway 36 at Chambery Airport in France. Of course, I wasn’t flying the real airplane, but the G500 replicated in Gulfstream’s Conceptual Advanced Simulation Environment (Case III) sure felt and looked real, thanks to a stunning visual display and the unique configuration of the sidesticks.

The G500/G600 are Gulfstream’s second-generation jets with fly-by-wire flight controls, designed to fill a gap between the traditional G450/G550 and the fly-by-wire G650. The G500/G600 cabin is wider than the G450/550’s but not quite as large as the G650’s, although it shares many of the G650’s characteristics (larger windows, performance, manufacturing techniques).

The major difference between the G650 and the new models is found in Gulfstream’s Symmetry flight deck, where touchscreen controls replace a swath of switches, knobs and buttons and the pilots have an unobstructed view of the four 13- by 10-inch Honeywell displays because the large control yoke is gone, replaced by sidestick controls.

Sidesticks are not new in business aviation–the non-fly-by-wire Eclipse 500 was the first so equipped, followed by the fly-by-wire Dassault Falcon 7X and Embraer Legacy 500. But the way Gulfstream has implemented sidesticks is new for civil aviation, because the sticks are electronically interconnected and move in concert. When I pulled my stick aft, Scott Evans, project pilot advanced aircraft programs, could see exactly what I was doing with the controls because his stick was making the same motions.

The “active control sidesticks” (ACS, also known as active inceptor systems) are designed by BAE Systems and have been fielded on military designs such as the F-35 Lightning II, UH-60Mu Black Hawk, T-50 Golden Eagle, CH-53K Super Stallion and KC-390. “Gulfstream is always investigating new technology,” said Lor Izzard, director of sales engineering. The G650, while fly-by-wire, retains traditional yokes because this affords pilots a quick visual cue of flight-control inputs and position. Sidesticks are compelling from a design standpoint, greatly opening up the flight-deck real estate and eliminating a lot of weight. “Until they were available in the right technology,” he said, “we were not going to incorporate sidesticks. With this type of technology, out of the corner of your eye you’re able to see what’s going on. Even the autopilot is back-driving these sticks so you have that amount of situational awareness.”

The G500 sidesticks thus offer not only the benefits of visual feedback but also tactile feedback for the pilot flying the airplane. “It’s an unspoken language between the pilots,” said Evans. “They can see the response of the airplane. Is it something the system is doing or a dynamic response of the airplane? We fought hard to get this technology to where it is today.”

Cockpit Designed for Pilot Comfort

The impact of the G500 design isn’t apparent until one climbs into the flight deck. Before donning the Case III environment, I spent some time in the G650 integrated test facility (ITF) simulator. The difference between the G650’s flight deck and the G500’s is striking. Removal of the yokes provided vast opportunities for redesign, and Gulfstream engineers took full advantage. “We’ve done a tremendous amount of study,” said Evans, “probably more ergonomic studies than [for] any of our previous programs combined.”

Small but telling changes in the G500 include a handhold on the back of each seat for easier access and another at the corners of the glareshield. Retractable closeout screens are available to cover the forward windshield in bright sunlight. Visor rails are splined to prevent visors from wandering. A storage area that can fit a full-size iPad is located on the sidewall next to each pilot. “The goal is to make it a nicer environment for pilots,” said Izzard. “Whether it’s work tables, materials, stitching, the seat type, we put pilots into a nicer place to work.”

Starting on the left side of the flight deck, “the ACS is ground zero,” said Evans. “Once we went to the ACS, we had to move the CCDs [cursor-control devices] to the center and we needed an arm support, so we moved everything aft in support of the ACS.” Now the left sidewall is dominated by the ACS, which is fitted with an autopilot disconnect switch, pitch and roll trim, push-to-talk and HUD/EVS clear switch (left stick only). Roll trim on the controls is new for the G500/600.

The padded arm support behind the ACS is adjustable, with arm-reach locator settings so pilots know where to set the support. The ACS is mounted to match the natural resting position of the typical pilot’s hand, with three degrees of toe-out and 20 degrees of inboard tilt. The arm support moves up and down and tilts fore and aft, with more forward than aft tilt.

The cursor-control stalks mounted on the sides on the G450/550/650 had to be moved to the G500’s center pedestal. Because of the position of the ACS and armrest, the nosewheel steering tiller also had to be moved, in this case farther aft, which at first seemed counterintuitive. But Evans explained that the G500’s nosewheel steering system now is opened up to 40 degrees of travel below 12 knots, so it’s no longer necessary to use the tiller for normal taxiing, just for close-quarters maneuvering.

Sitting in the pilot’s seat feels subtly different, and it’s because the seat no longer has to accommodate the aft-most movement of the yoke with a cutout in the pan. Now seat designers can take advantage of the pan’s full real estate, and it does feel more comfortable. I was even able to cross my legs in the cockpit, something that is impossible to do with a yoke unless the seat is moved all the way aft. Seats are fitted with perforated leather and heat-dissipating Aeristo VentiMesh passive seat ventilation material between the cushions and the leather.

The center pedestal appears skinnier and it is, but the big change from previous designs is the uncluttered look, and there are two cup-holders on the aft end. The glareshield is smaller, too. Gulfstream engineers have pushed the design of touchscreen controls to the max in the G500, with 11 touchscreens replacing myriad buttons, knobs, switches and controls. Besides the increased volume in the flight deck, including a retractable “work table” that slides out of the instrument panel in front of each pilot, the pedestal is sleekly absent of the traditional FMS control display units (CDUs) that occupy so much space and require so much button-pushing to accomplish simple tasks. The two CCDs in the pedestal double as palm supports for manipulating the touchscreen controllers.

Four Honeywell touchscreen controllers grace the forward flight deck, one on each outboard side and two in the pedestal replacing the CDUs. One more is placed at the jumpseat position. The overhead panel is all touchscreen now, too, with three panels made by Esterline’s Korry division. The secondary power distribution system contains electronic circuit breakers, eliminating 45 percent of typical mechanical type breakers. All told, the 11 cockpit touchscreens replace 70 percent of the switches in the typical modern Gulfstream jet. All touchscreens are surrounded by a bevel for easier hand-steadying during turbulence. I found the touchscreen controls intuitive and easy to master.

Evans had the Case team set the simulator on Runway 36 at Chambery, chosen for the dramatic mountainous landscape to highlight the superior visuals. The Vital 1100 displays from FlightSafety (which also manufactures the G500/G600 simulator using the same visual system) has five large 120-Hz screens, each fed by two powerful computers, with a 240- by 40-degree field of view (previous versions were 170 degrees). The result is extremely realistic, seamless high-definition scenery. “This thing is surreal,” said Izzard. “You will fool yourself into thinking you’re in motion,” Evans agreed.

After liftoff, the G500 accelerated quickly through Mmo as I leveled off just above the mountaintops for some fun flying that is impossible in real life. We slowed below redline then zoomed along above the peaks, and I pulled the G500 into a steep turn. The sidestick felt completely natural almost instantly. Evans explained that the sidestick is designed for wrist control, not arm movement, and indeed all it took was simple wrist movements to put the G500 right where I wanted it. From a force-feel standpoint, the stick gave plenty of feedback, telling me just how much I was loading up the wings in the tight turn.

Evans grabbed his sidestick and demonstrated how we could feel each others’ inputs when pulling in opposite directions. “There is no wondering who has control,” he said. 

We didn’t have time to explore more of the G500’s flight envelope, but the fly-by-wire system is the same as the G650’s, except for integration of the sidesticks. Turning back over Lac du Bourget toward Chambery, Evans set Vref at about 133 knots while I slowed the simulated G500. With the gear and flaps down, the G500’s flight controls felt tightly harmonized, with just slight wrist action needed to maintain the visual descent to Runway 18 over the lake. The Pratt & Whitney Canada PW800 engines responded quickly to power inputs, and we crossed the threshold on target for a smooth touchdown on the mainwheels, moving the stick forward followed by firm feet on the anti-skid brakes while powering up the thrust reversers. I taxied to the end of the runway, where I tried a tight turn with the tiller. It’s not hard to reach, but definitely only to be used for slow-speed turns.

Evans and other Gulfstream pilots have flown hundreds of hours in the Case and ITF simulators in preparation for the G500’s flight-test program, which is on track to begin this year. Gulfstream expects to receive certification for the G500 in 2017. The longer-fuselage G600 will fly in 2017, with certification following in 2018. Flying the Case simulator suggests pilots are going to appreciate Gulfstream’s move into the future of business jet design.