Embraer, with apologies to Pelé, is perhaps Brazil's best-known export. Since its inception in 1969, Empresa Brasileira de Aeronáutica has grown into a successful aviation manufacturer, with products in the agricultural, commercial, defence and executive sectors.
Its first offering was the EMB 110 Bandeirante turboprop, a light transport for both civil and military use. While military programmes have played a vital role in the airframer's business, it is its efforts in the civil transport sector that have thrust Embraer onto the world stage.
These have come in stages, the first being the EMB 120 Brasilia turboprop in the 1980s. This was followed in the 1990s by the ERJ series, comprising the turbojet ERJ-135, 140 and 145 models. The E-Jet family was launched at the close of the last century with first flight of the E170 in 2002. Over the years, more than 1,400 of the four-model E-Jet series (E170, 175, 190 and 195) aircraft have been delivered. Keeping pace with their 10-year-long acts, the curtain rose on the new E2 with launch of the series in 2013.
The E2s promised a step-change efficiency increase over the E-Jets. For the E190-E2, Embraer lists a 17.3% reduction in fuel burn when compared to the E190-E1. This advance was made possible by a number of factors, with the engines alone accounting for 11%. Embraer credits the new wing and aerodynamic improvements for 4.8% and the fly-by-wire control system for the remaining 1.5%.
For the E190-E2, Embraer selected the Pratt & Whitney PW1900G. The powerplant is one of several geared turbofan engines that fall into P&W's PurePower family. The high-bypass engines feature a proprietary gear system whose approximate 3:1 reduction ratio allows the fan to spin at a more efficient, slower speed than the low-pressure spool. The increased efficiency does come at a cost, as the engine weighs approximately 500kg (1,100lb) more than the GE Aviation CF34-10E on the E190 E-Jet. Additionally, the larger diameter fan of 2.01m (79in), compared with 1.35m on the older model, would drive changes to the E190-E2’s overall layout.
FRESH DESIGN
With more than 1,400 E-Jets in service with 70 airlines, Embraer sought to leverage its success as it launched the E2. One particular strength of Embraer is its large pool of young engineering talent – a resource that by some reports costs Embraer just a quarter of what would be paid by a northern hemisphere rival.
While the aircraft share a common fuselage cross-section and similar flightdeck, the E2s are essentially clean-sheet designs. With its engineering cost advantage and flexible manufacturing techniques, Embraer has been able to fashion unique wings for its aircraft. For the E-Jet series the E170 and E175 shared a common wing, as did the E190 and E195. But with the E2 series, wings are optimised for each aircraft; the E190-E2 and E195-E2 each have a unique wing, as will the E175-E2. In the quest for efficiency, the ability to offer bespoke wings is a huge advantage.
The wing is a good place to start when analysing the E190-E2's design. The GTF’s fan alone has a diameter larger by 66cm (26in) than the CF34. A simple solution would have been to increase the length of the landing gear to gain required nacelle clearances. Doing so, however, would have raised the E2's fuselage more than Embraer desired.
According to E2 programme director Fernando Antonio Oliveira, there are some sound reasons for keeping the fuselages at a similar height: shorter and lighter main landing gears, located more inboard into the wing; shorter nose landing gear; passenger and baggage doors and servicing panels at heights equivalent to those on the E-Jet.
A quick check of applicable airport planning manuals shows the E2's forward cabin door sill is, depending on weight and temperature, only around 23cm higher than the E-Jet's. Forward and aft cargo door sills are also only about 25cm higher on the E2.
Embraer was able to meet this design goal by adapting a gull-wing layout for the E2. The location and angle of the bend allows the large-fan engines to be mounted further inboard, and with shorter landing gear than would have been required with a conventional wing layout. At its most critical point, the E2's nacelles are only 5cm closer to the tarmac than the E-Jet's. In addition, their positioning further inboard reduces the yawing movement in the event of an engine failure.
The wing is of conventional construction with a span of 33.7m (111ft). According to Embraer it is the highest aspect-ratio wing of any civil transport, at slightly over 11. One interesting feature of the wing is its lack of winglets. There may be good reasons to put winglets on an aircraft: an updated legacy design or dimensional constraints such as airport gate requirements.
While the search for efficiency is to be applauded, one of my instructors from test pilot school would emphatically state: "A winglet is a sign of a poorly designed wing." It would appear that recent designs from Boeing, Gulfstream and now Embraer bear this out. The E2 series aircraft feature a raked wingtip design. I am not an aerodynamicist but this trend makes sense – I have yet to see a winglet on a bird.
Embraer has also made other improvements to the wing. Like the E-Jets, the E2 now has two flap sections per wing. The outboard flaps on both the E-Jet and E2 are single panel. With the E2, the inboard flap, however, is a single-slot design, as opposed to the E-Jet's more complicated two-slot design.
FBW IMPROVEMENTS
Some 15 years ago I was fortunate to fly the E170 E-Jet, the E190-E2's oldest direct predecessor. It was my third visit to Embraer and I was excited to experience its first FBW aircraft. While I was impressed with how the E170 E-Jet flew, joyfully flying formation with a photographic chase aircraft, I was surprised by the flight control system architecture.
For its first FBW system, Embraer developed an open-loop scheme that digitally replicated the feel of a conventional aircraft. Only at elevated angles of attack in pitch would the control loop close, to provide flight envelope protection. With its Legacy 450/500 executive jets, Embraer deployed a sidestick-controlled closed-loop control system.
During two flights in the Legacies I sampled some of their envelope protection schemes and found they were a delight to fly. In a first, for the KC-390 military transport Embraer developed in-house some of the flight-control software and fielded an active sidestick for what it calls its third-generation system. For the E190-E2, Embraer has deployed its fourth-generation FBW.
In a big step forward, Embraer has developed the flight-control software entirely in house. More than a point of pride, the in-house capability will let Embraer more rapidly and economically develop and implement system changes.
In prior flight tests I have extolled the benefits of FBW, mostly from the safety and handling qualities perspective – but the benefits can go further. One benefit is to allow for a centre of gravity further aft relative to the wing's aerodynamic centre, while still maintaining acceptable longitudinal static stability margins. A further aft centre of gravity requires less of a download on the horizontal stabiliser and results in a more fuel-efficient aircraft.
To achieve this shift in the E190-E2, Embraer moved the wing forward 0.9m from its location on the first-generation E190. This 10% aft shift also allows for a smaller horizontal stabiliser. In the case of the E190-E2, the stabiliser is the same size and aerodynamic shape as the one on the smaller E170 E-Jet.
The FBW control scheme may also allow for the downsizing of other surfaces as well, notably the vertical stabiliser and rudder. At normal take-off power, the E190-E2's engines are about 10% more powerful than those on the E190 E-Jet. Larger vertical tail surfaces might be needed, but FBW control characteristics let Embraer keep the E2's surfaces the same size and shape as those on the E-Jet: fully 15% smaller than would be needed with a conventional control system.
Embraer was also able to remove the fillet between the E-Jet's fuselage and vertical stabiliser. Overall, Embraer says the benefits of the FBW control system alone contribute to a 1.5% reduction in fuel burn.
INTERIOR EXPERIENCE
When I reported on the E170 E-Jet 15 years ago, I was impressed by the space afforded to each passenger. I especially liked the two-by-two seating configuration, as no-one really wants a middle seat. According to Embraer, each passenger had as much space as those in the A320-series aircraft. Additionally, its overhead bins could accommodate a good number of cabin baggage.
The E2 brings further improvements to the cabin environment. The overhead bins have been redesigned, increasing their volume. Each passenger can now stow an IATA-standard 56 x 45 x 25cm bag in the overhead bin. Embraer uses a different configuration for the passenger service units (PSU). Rather than a single PSU per row (two seats), each seat now has an individual PSU, improving space utilisation. While the E2 retains the E1's external fuselage diameter, thinner sidewalls net an effective increase of approximately 2.54cm to the interior cross section. In economy class, a 48.3cm aisle allows each seat to be 46.5cm wide. The updates and improvements made to the E2's passenger space will only serve to make the ride even more comfortable.
Embraer has made numerous improvements to the flightdeck. The most visible change is the forward instrument panel, where four large 10in displays provide 45% more display area than the E1's five smaller units. The Honeywell Primus Epic-based suite has been upgraded with features that improve situational awareness, as well as easing pilot workload.
Honeywell’s SmartView synthetic vision system gives a primary flight display that nearly spans an entire display, with safety-enhancing SmartRunway and SmartLanding systems standard. The E2 retains the same cursor control device as the E1 series, but it can now be used for graphical flightplanning. Another useful feature is the ADS-B-based cockpit display of traffic information system. Required navigation performance approach capability, a 3D automatic weather radar and FANS 2 controler-pilot data link communications round out significant improvements for the E2.
ORIGINAL YOKE
As detailed above, Embraer has closed the loop with the E2’s FBW control scheme to increase efficiency and safety. In a nod to commonality with the E-Jets, it has retained the M-shaped ram's horn control yoke and column. While I have come to appreciate the extra space and more open nature of a sidestick-fitted flightdeck, economics won the day. Pilots transitioning to the E2 from the E-Jets will only need 2.5 days of training, and a Class D simulator is not needed.
The underlying control schemes and protections draw heavily from the excellent work done on the Legacy 450/500 and KC-390 programmes. On the ground, the control laws are essentially stick-to-surface, control surface deflection proportional to control displacement. Once airborne, in pitch they become pitch rate command with apparent speed stability (Gamma Dot U).
This control scheme is the same as found in the Legacy 450/500 and KC-390 when they are in the landing configuration. Unlike the 450/500 and KC-390, however, the E2 retains apparent speed stability in all configurations: any speed change will require a corresponding pitch trim input.
In the lateral directional axes, Embraer again went with a P/Beta scheme. Lateral yoke deflection commands roll rate, while pedal deflection commands sideslip. The roll and yaw axes are lightly coupled, with pedal input causing a small amount of roll and yoke deflection a small amount of yaw. From a certification standpoint, Embraer sought to mimic the E-Jet's response at one particular weight and centre of gravity position. Many of the envelope protection schemes found in the Legacy 450/500 and KC-390 were retained; these features were highlighted during the preview flight.
CERTIFICATION
The smallest of the E-Jet series, the E170, first entered revenue service in 2004; the larger E195 debuted in 2006. For the E2 series, perhaps reflecting the success of the larger E-Jet models, Embraer has focused on launching the E190-E2/E195-E2 first.
After receiving certification from Brazilian, European and US agencies in February 2018, FlightGlobal was invited to take the yoke of the E190-E2, at Embraer’s São José dos Campos facility. The preview aircraft was the third E190-E2, Brazilian registration PR-ZFV. It was one of the aircraft used in the flight-test campaign, and from an aerodynamic and propulsion standpoint it was production representative.
I accompanied Embraer test pilot Gerson de Oliveira Mendes as he conducted the pre-flight walk-around inspection. I found the gull-wing design and large engine nacelles gave the E190-E2 a powerful ramp presence, much more so than the CF-34-powered E-Jet.
The wing body fairing is more prominent than the E-Jet's, allowing the main gear to be fully enclosed upon retraction, further reducing drag. The main gear itself has a trailing-arm configuration, a layout seen more on business jets than civil transport aircraft. One of advantage of this configuration is its ability to soak up excessive sink rates on landing.
That, however, is not the reason Embraer put it on the E2. As mentioned above, the FBW control scheme allowed the wing to be moved forward. A conventional oleo strut design would have placed the main wheels too far forward, with the resultant load on the nose gear too light for reliable nose wheel steering. The trailing-arm design moves the fulcrum just far enough aft to keep the nose gear firmly planted on the tarmac.
Once on board the aircraft I took a short tour of the passenger cabin. The compartment was unfinished and fitted with flight-test-specific equipment, most notably water ballast barrels and a flight-test engineer's station. Once strapped into the left seat, I surveyed the cockpit.
The flightdeck, aside from the forward instrument panel, is little changed from the E-Jet series. Four large-format displays offer plenty of real estate to present flight-critical information. Gerson loaded the FMS as I familiarised myself with yoke and thrust lever-mounted switches. After completion of pre-start flows and clearance from ground personnel, the auxiliary power unit was used to start the right, then the left engine. One concern with PurePower engines (and CFM Leaps as well) is their long start times, driven by cooling requirements. The FADEC-controlled start sequence was essentially automatic, each engine reaching IDLE in about 1min 40s. This time was much shorter than the time I observed during my CS300 preview flight (2min 50s) and on par with observed CFM Leap start times on the Boeing 737 MAX.
After setting the flaps to 2 and completion of before-taxi items, I released the parking brake to start the taxi to São José dos Campos airport's runway 15 for take-off. I used both the tiller and pedals to control the nosewheel steering, which allowed me to smoothly follow taxiway centrelines.
Once lined up on the runway I pushed the thrust lever-mounted TOGA button and advanced the thrust levers. As I stood the thrust levers up the auto throttle engaged and set a take-off power setting of 91.5% N1. As we briskly accelerated down the runway, Gerson called "V1", followed immediately by "rotate" at 130kt (241km/h) indicated airspeed (KIAS). Thumb-actuated pitch trim rapidly zeroed out pitch forces as we cleaned up and accelerated to our initial climb speed of 235KIAS. Gerson set the flight director's heading bug, and I followed its guidance as we turned to the south for transit to our working area.
PROTECTIONS EXAMINED
During the climb to FL240 (24,000ft), I hand flew the aircraft, to get a feel for how the closed-loop FBW E190-E2 handled. Once established in the working area, we concentrated on sampling envelope protection features found in the new flight-control system.
In the ROLL axis the E2 essentially has the same protections found in the Legacy 450/500. At angles of bank less than 33º the E2 exhibits neutral spiral stability. If the yoke is released with less than 33º angle of bank, the current bank angle will be maintained. At greater than 33º angle of bank it exhibits positive spiral stability, rolling back to and maintaining 33º angle of bank when the yoke is released.
As with the Legacy 450/500, the E2 also has additional protections in roll at high speeds. At 300KIAS I rolled the E2 into a 45º angle-of-bank left-hand turn and lowered the nose to accelerate past VMO (320KIAS). Passing VMO, the protection feature kicked in and reduced the bank angle to 33º, even though I still had full left yoke in. Next, I raised the nose and slowed the aircraft to below 320KIAS, where the flight-control logic allowed it to roll past 33º angle of bank. Finally, while at 45º angle of bank, I lowered the nose to accelerate past VMO and released the roll input. Automatically the E2 smartly rolled wings level, a great first step for recovering from what might well have been an unusual attitude.
The E2 also has envelope-protection features in the pitch axis, both at high and low speeds. At speeds exceeding VMO/MMO the flight controls will pitch the aircraft nose up, in an effort to slow to a safe speed. This nose-up motion can be overridden, as was demonstrated during the angle-of-bank protection exercises. At the low speed end of the flight spectrum the envelope protections are more robust.
The E2 has an angle of attack limiter, first implemented with the E-Jet series. The first indication of the slow speed condition is amber band on the airspeed tape starting at 1.13VSR (stall reference speed). At 1.08VSR, which is not enunciated to the pilot, angle-of-attack protection is enabled. Interestingly in the E1 series, it is the only time the flight control laws are closed loop.
Additionally, when angle of attack protection is active, the control scheme shifts from pitch rate command to angle-of-attack command. While not needed in the E2 but retained for commonality with the E-Jet, the stick shaker will activate at 1.05VSR. Finally, there is a hard limit of 1.03VSR. During the preview flight I did two approach to stall manoeuvres to test this feature: one in a clean configuration and the other in landing configuration, flaps 5.
In both cases, the thrust levers were set to IDLE and a shallow descent maintained to establish a 1kt/s bleed rate. In both cases, I ignored the “LOW SPEED” caution and continued to pull aft through shaker activation until the yoke was at its aft stop. In both configurations the E2 was rock steady, with no buffet or wing rock noted. Even at these elevated angles of attack, the aircraft was responsive to small control inputs in all three axes.
After the area work was complete, we followed air-traffic control for an instrument landing system approach to São José dos Campos runway 15. En route to LONES, where we joined the approach, I found the Cockpit Display of Traffic Information system very useful for keeping track of other traffic in the area.
Initially I had the autopilot engaged, but clicked it off once we joined final. With flaps 5, the target speed of 133KIAS was easily held, the PurePower engines being fairly responsive. At about 30ft radio altitude I started retarding the thrust levers to IDLE and started the roundout. The E2 settled nicely onto the runway, where Gerson set the flaps to 2 and reset the pitch trim for the touch-and-go. Initially I advanced the thrust levers, only setting TOGA power when we were configured for take-off. Gerson called "rotate" at 133KIAS, where a gentle aft pull of the yoke lifted the E2 off the runway. Once airborne, the gear was retracted and I climbed the E2 in a left-hand turn to enter a visual downwind.
ONE ENGINE INOPERATIVE
As discussed in previous FBW aircraft reviews, each manufacturer has its own way of tailoring flight-control response in the event of an engine failure. They range from no compensation in the case of Gulfstream, to fully compensated for the Boeing 777 and 787.
For the E2, Embraer has kept the scheme deployed in the Legacy 450/500. If airborne, the flight-control system will allow some yaw to develop along with roll, up to 20º angle of bank. If an engine failure is sensed on the runway, the flight-control system will put in a rudder pulse to reduce the yaw transient. Test day limitations prevented doing a V1 cut on the preview flight, but I was able to do one in the fixed-base E2 engineering development simulator.
While V1 cuts are never fun, the E2's flight-control system allowed me to recognise the failure and stacked the deck in my favour for a successful outcome. Additionally, the E2 has two features that enhance single-engine performance. When an engine failure is sensed, the FADEC increases the operating engine's maximum thrust by up to 1,500lb (6.68kN). Finally, the slip indicator in the primary flight display turns into a beta target, allowing some side slip to optimise climb performance.
What we were able to do on the preview flight was a simulated one engine inoperative approach. Gerson retarded the right thrust lever to IDLE on the downwind, as I flew a visual circuit, capturing the ILS localiser and ground speed on final. Flaps were again set to 5, but our target speed was increased to 148KIAS.
Configured on final, very little rudder was needed to maintain co-ordinated flight, with the E2’s flight-control system allowing me to easily fly a stable on-speed approach. The approach was broken off at 400ft radio altitude, where both engines were used for the climb to downwind to set up for our final event, a maximum effort landing. The flaps were set to FULL and a target speed of 127KIAS was held on final. I flared a little lower than my first landing, with the E2 touching down about 300m from the threshold.
Maximum wheel braking was automatically applied as “HI” had been selected on the auto brake panel. Wheel braking for the E2 is enhanced as in addition to ground roll spoilers, the multifunction spoilers also extend on touchdown to better load the wheels. I barely had time to deploy the thrust reversers before we were slowed to a comfortable taxi speed. Had I pressed it, we could have made the first turnoff, just 800m from the threshold. It was a short taxi back to Embraer's ramp where once parked we waited for the engines to cool (P&W recommends 3-5min, marked from the closure of the thrust reversers) before shutting them down.
BETTER BY DESIGN
Having first flown the E-Jet 15 years ago, and many other Embraer products in the intervening years, I can firmly say the E190-E2 does not disappoint. While it carries the same type rating with the E-Jet, it is in reality almost a totally new aircraft. Larger, more efficient engines required a different wing lofting to keep desired servicing heights, and Embraer obliged with a longer higher aspect-ratio wing.
Incorporation of a full closed-loop FBW control scheme enabled further efficiencies to be achieved. The wing is mounted forward of the corresponding position on the E-Jet, allowing a more efficient aft centre of gravity. The FBW scheme allowed horizontal and vertical stabiliser sizes to be reduced, lowering drag and weight. While the E2 cannot be directly compared with the E-Jet in terms of feel, suffice to say the E190-E2 was a pleasure to fly, with precise and predictable handling qualities. While not industry leading, the enhanced flightdeck, with its four large displays will not feel dated for years to come.
By its set of metrics, Embraer makes a strong case that its E2 series is the most efficient single-aisle family of aircraft available. With its CSeries, Bombardier has in many ways set the standard with an aircraft that I for one found more enjoyable to fly. As to which family an airline should adopt? That is a question that will be debated in boardrooms for years to come. With an installed base of over 1,400 aircraft at 70 different airlines, momentum just might favour Embraer.
Source: FlightGlobal.com
