Pushing the Envelope
You have to hand it to the Brazilians – they may have a government that is at times even worse than South Africa’s, but it has not stopped them from becoming world leaders in business jets.
Embraer achieved world beating success when its Phenom 300 become the bestselling business jet.
What to follow the phenomenal 300 with? They clearly had a gap between the small Phenoms and the airliner derived Legacy 600, so in 2008 they set out to create two clean sheet designs for the already competitive mid-size biz-jet market. But even after the success of the Phenom 300, the ‘Wichita experts’ raised a disbelieving eyebrow when Embraer said it was going to build fly-by-wire (FBW) business jets.
The thing is that unlike its more brash Wichita competitors, Embraer has something of a reputation for under-promising and over-delivering. Thus, when the mid-light (Embraer’s description) Legacy 450 was announced, the expected range was around 2,300 nm with four passengers. By the time it hit the market, the 450’s long-range cruise with four passengers had increased to a best in class 2,900 nm.
In October, the Legacy 450 arrived on its first demonstration flight in South Africa – notably just two weeks after arch-rival Cessna’s Latitude had visited. In a coup for South Africa, SA Flyer was able to sufficiently impress Embraer management with our professionalism, for them to approve the first air-to-air photo shoot outside the Americas. We pulled out all the stops to get the A-Team of pilots and photog Justin de Reuck together for an air-to-air sortie in front of the iconic Table Mountain and around the Cape Peninsula.
I met the 450 at ExecuJet Cape Town on a blustery Friday afternoon with a 30-knot Cape Doctor blowing the week’s wet weather away. In the cockpit were Embraer demo pilots Eduardo Guimares and Sydney Rodrigues, busy entering the coordinates I had sent them, for the round the Peninsula route, into the Rockwell Collins Pro Line Fusion Flight Management System (FMS).
THE CABIN’S THE THING
Biz-jets are all about the creature comforts for the boss. The Legacy 450 (and 500) have a 6-foot stand-up cabin and a flat floor. Club seating provides four fully reclining seats that convert into a pair of sleeping berths. An optional wet galley in the forward fuselage can be traded for a two-seat belted divan, which our test aircraft N801EE had. This is a cabin class jet, so Embraer supplied a welcoming local cabin attendant, Christel Vanhees, for the demo flights.
At the rear of the cabin there’s a commodious full-width toilet compartment with a solid door and a beautifully finished vanity with hot and cold running water and storage cabinet underneath the basin. The actual lavatory is an externally serviced vacuum unit which I am told is impressively quiet. A belted potty seat and 115-VAC power outlet are optional.
A popular feature is the baggage space behind the toilet compartment, which is accessible from the cabin. There’s also a large externally accessed compartment under the engines.
In flight entertainment (IFE) is provided by Honeywell’s Ovation Select cabin management system, and comes with optional high-definition video and surround-sound audio environment. Also optional is voice and Wi-Fi-enabled connectivity through Inmarsat, Gogo or Iridium platforms with inflight data speeds of up to 3.1 Mbps.
The cockpit and cabin have separate thermostats. Pressurization is fully automatic, with destination airport field elevation provided by the flight management system (FMS). Cabin altitude is 6,000 ft at the aircraft’s certified ceiling of FL450.
A measure of the intrinsic quality of the Embraer can be gauged from operating the main cabin door. The door is (wo)manually actuated and so beautifully balanced. It has a primary seal inflated with bleed-air pressure and a secondary seal inflated by cabin pressure. It has tread lights, a folding arm rail, a cabin pressure relief port and a small window to check the area below the door is clear before it’s lowered onto someone’s head. An acoustical curtain closes off the door to reduce wind noise.
The Legacy 500 and then 450 were the first business jets costing less than US$60 million to offer full fly-by-wire sidestick controls and the Rockwell Collins Pro Line Fusion avionics suite. Embraer also offers an optional enhanced-vision system (EVS) and a head-up display (HUD).
This caused Embraer some initial headaches when prime contractor Parker Hannifin got behind schedule until eventually Embraer decided to develop the FBW system in-house. When Embraer had first announced their Legacy series, Cessna responded by announcing their Latitude and Longitude as competitors. For their Latitude, Cessna rushed to market by mashing up the Sovereign wings and engines with a new fuselage and so beat Embraer in time, if not in technology.
The flight deck has a beautifully clean and uncluttered appearance and is lit by expansive cockpit windows. Immediately evident is the lack of a control column as, like Airbus, there are control sticks on the cockpit sidewalls.
Embraer’s flight deck design philosophy follows the universal standard adopted by Airbus, Boeing, Bombardier and Dassault for menu-driven, point-and-click data entry and control functions with interactive symbology. Embraer’s display colours are clean, conventional and intuitive. The four large 15.1-in EFIS displays, along with standard synthetic vision, provide great situational awareness. Any screen may be split to display multiple functions, such as PFD, MFD, EICAS and aircraft position display Jepp charts.
Because today’s flight decks are like cell phones in that they require regular software updates, the Pro Line Fusion updates via Wi-Fi or even cell data connections in as little as 15 minutes.
The FBW system uses no mechanical linkages between the pilot and the control surfaces, saving weight and maintenance. Embraer’s FBW operates in one of two modes: Normal Mode, in which everything is computer controlled, providing full flight envelope protection, or Direct Mode, where the 450 responds to control inputs like an old-fashioned wire and pulley controlled aircraft.
The big question every sceptic likes to ask is how do you move the controls if you have a total electric failure? It’s as the air hostess says: “In the unlikely event of …” electrical failure there are plenty of alternatives. Being an essentially electric aeroplane, the 450 has three separate power busses and three generators – one on each engine, plus the auxiliary power unit (APU). In the unlikely event of all three packing up, there is a ram air turbine (RAT) which swings out to provide electric and hydraulic power. And finally, if all else fails, there are two 24-volt DC NiCad batteries inside the pressure hull, plus two lead-acid backup batteries, one to power the flight controls and the other the fuel system.
The hydraulic system is triple-redundant: powered by two engine-driven pumps and an electric backup.
The APU provides bleed air for engine starting up to 23,000 ft, air-conditioning and pressurization up to 20,000 ft, and electrical power up to 31,000 ft. In theory, this would enable the APU to be used for air conditioning instead of the engine bleed to boost performance for hot-and-high departures. But there’s no need, because the engines are highly flat rated.
Another notable feature for this size of jet is the single point programmable refuelling with a selectable refill quantity function that is capable of filling the tanks. Alternatively, the aircraft can be refuelled using over the wing refuelling ports.
FLYING THE LEGACY 450
For the formation work for the air-to-air shoot, Embraer sent out Luis Gigo, a retired Brazilian Air Force Lt. Colonel and Mirage III pilot (callsign ‘Gigo’ and who we all just called that).
After a thorough briefing in ExecuJet’s boardroom, covering all aspects and contingencies for the sortie, we moved out to the aircraft. On the apron the Legacy has real presence, dominating the many smaller jets and turboprops.
The two Legacy models share virtually identical Honeywell HTF7500E turbofan engines, the latest versions of the engines that made their debut 14 years ago on the Challenger 300. The engines are factory rated at 7,638 lbs thrust to ISA+18 C. For the Legacy 450 they’re de-rated to 6,540 lbs at ISA+18 C to reduce stress and maintenance costs and increase reliability.
To start the engines the crew needs only to switch on hydraulic system #3, check that the throttles are at idle and twist each engine run switch to the start position. The FADEC system automatically engages the pneumatic, fuel, electrical and environmental systems for the start sequence.
In keeping with the refined simplicity of operations, there are just six items on the after-start checks. The 450 epitomises the quiet, dark cockpit design philosophy. With most knobs in the 12 o’clock position, annunciator button lights extinguished, and a few normal CAS messages displayed, the aircraft is ready to go. The systems are automated and so the checklists are remarkably short.
You steer the 450 with the rudder pedals, not a tiller, and it has a ‘steer-by-wire’ system. At 10 knots or less, the nosewheel can turn 62 degrees either way. This proved very useful for manoeuvring the largish jet within the confines of the busy ExecuJet ramp. As taxi speed increases, the amount of available turn decreases.
The basic operating weight of N801EE the day we flew it was 23,500 lbs, with four on board and 6,000 lbs of fuel. This was far below the 450’s maximum all up weight of 35,759 lbs. The FMS calculated V1 of 117 knots and with a 17-knot headwind component (from a 25-knot wind at about 45 degrees to the runway), a requirement for 3,100 feet of runway for takeoff.
After start, we taxied through the main apron to Cape Town’s Echo taxiway, and after a long wait were finally cleared for takeoff after the Seneca cameraship, flown my Mark ‘Bugs’ Hensman who generously made himself available as expert advisor and commander of the cameraship.
At the holding point, Gigo checked brake temperature on the EICAS, and verified flap, pitch, trim and park brake positions by pressing a takeoff check button on the centre console. A synthetic voice confirmed, “Takeoff okay.”
Gigo then armed the autothrottles and selected auto-brakes to rejected takeoff. Cleared for takeoff, he advanced the throttles to 40%, causing the servos to push the throttle levers to the stops. Initial acceleration was brisk. At 80 knots, the autothrottle servos disengaged, leaving the throttles in the takeoff position, but releasing the clutches to make it easy to pull them back to idle in case of a high-speed abort.
The 450 has excellent short-field performance, and, at our light weight and given the headwind component from the South Easter, it was particularly impressive. We rotated well before the Charlie intersection, just 2,400 ft from where we had started our roll.
The 450 bounded into the air and at 300 ft, so as not to catch the Seneca too soon, Gigo pulled the power back sharply, eliciting a plaintive blare from the gear warning. Gigo says that initial pitch response to sidestick inputs on rotation is crisp, but the pitch is well damped when the stick is released. When the weight comes off the wheels, the FBW transitions from pitch command mode to gamma dot, or G rate command, control law. The pilot flying can still make inputs on the sidestick to change attitude, but the flight path vector remains stable with speed and configuration changes. This makes the ride in the cabin particularly smooth.
Gigo switched the FBW flight mode from Normal to Direct to formate on the Seneca while Sydney silenced the TCAS alerts. This was clearly a very non-standard takeoff. As my experience with the aircraft was limited to the air-to-air sortie, I interviewed Embraer Senior Demo Pilot and instructor Sydney Rodrigues about normal ops. A far more typical takeoff is described by Sydney for their flight to Cape Town from Lanseria. There they took-off from Runway 07 and climbed out at 300 knots/M0.76 at 3,000 fpm all the way to FL380.
Taking off from Potchefstroom, they left a powerful impression on everyone from the Jonker Sailplane factory when they pulled the nose up to 30 degrees and pulled a steep climbing turn at 30 degrees of bank.
Sydney commented on the flight envelope protections of the FBW system in Normal Mode. He described how, with autopilot and autothrottles on, they tested the overspeed protection by pushing the nose sharply down. As the tape along the left side of the Primary Flight Display approaches the red overspeed region, the autothrottles come back and the nose pitches up to stay within the design safety parameters. When they approach the stall, the nose automatically pitches down to reduce angle of attack.
Sydney describes how pilots new to FBW will be surprised to see the aircraft simply maintain the angle of bank when they release the side-stick. They will also be surprised by the absence of a trim button because the FBW is automatically compensating for changing trim requirements.
For their flight to Cape Town, Sydney reported the cruise performance as follows: Through 37,000 feet, fuel flow dropped to 1,100 lbs per side, with a vertical speed of 1,500 fpm. Once level. At FL410, the normal cruise speed is Mach 0.80 (high speed cruise would be 0.82 and MMO 0.83). At a weight of 29,300 lbs, the aircraft stabilized at Mach 0.79, yielding 441 KTAS while burning 1,400 lbs/hour at ISA+10 C at FL450. This was in line with Embraer’s book figures of a 450 KIAS cruise while burning 1,447 lbs/hour at that weight and ISA condition.
Back to our takeoff for the air-to-air sortie: We easily caught up to the Seneca by Ysterplaat and, with Gigo hand flying in Direct Mode, we slotted into the Seneca’s 8 o’clock position for orbits around Robben Island. It was evident that even at just 140 knots, the Embraer was responsive and easy to hold in position, despite the fierce Cape Doctor roiling over Table Mountain and churning up the air over the Bay.
It’s interesting to note that even flying the aircraft in Direct Mode still leaves some pitch and yaw damping functions to reduce pilot workload and improve the ride. And when flying approaches to stalls, the stall warning is triggered at a slightly reduced angle of attack compared to the low-speed warning of Normal Mode to prompt the pilots to initiate stall recovery while the aircraft still has strong positive static pitch stability even with C of G at the aft limit.
After orbits for the cameraship, we headed south for some shots against the Twelve Apostles and then to Long Beach at Noordhoek and then off Cape Point. Finally, Justin said he was happy and we broke off the formation and headed back to FACT. Sydney switched back to Normal Mode and we flew north between Table Mountain and the airport on vectors from FACT Approach. I moved to the back of the cabin to check noise levels and found that, subjectively, it was one of the quietest jets I have ever flown in – including Bombardier’s yardstick G5000 and Challenger.
Going down and slowing down eventually requires the speedbrakes. These are variable rather than all-or-nothing and produced minimal rumble at around 275 knots. We intercepted the ILS for 19 from overhead Morningstar Airfield. Despite the howling quartering wind, the 450 flew the ILS as if on rails, with minimal control deflections and no discernible surges from the autothrottles.
The 450’s Normal Mode incorporates a speed stability function with landing gear extended and flaps 3 or full. A green bug appears on the PFD’s airspeed tape to cue the crew. Pressing the control steering button on the sidestick re-indexes the trim speed to the current airspeed.
Gigo disconnected the autopilot at minimums and produced a smooth touchdown, thanks too no doubt to the trailing link landing undercarriage. Using autobrakes, the 450’s brake-by-wire system had us briskly slowed to taxi speed in about 1,600 feet.
Parking back on the ExecuJet apron really tested the 450’s nosewheel steering, as we had to wend our way between other aircraft. Even with its sweptback wings, it was easy to see the winglets and thus avoid obstacles.
There was much celebration on the flight deck at the successful conclusion of the first air-to-air sortie conducted outside the Americas. One complication though was that, as we had used the Direct Mode, the aircraft Flight Control Computers had to be reset and Embraer’s maintenance centre notified. Embraer headquarters would be informed of our use of Direct Mode because it is automatically recorded by the aircraft’s maintenance computer and is uploaded by Wi-Fi after landing.
The sceptics have been thoroughly silenced. Embraer has produced totally modern mid-sized biz-jets that just do everything that matters better than the opposition. The fly-by-wire not only saves weight and maintenance costs, and makes it more fuel efficient – it really does give the Legacy a smoother, more comfortable ride.
It is evident that the aircraft is built to Embraer’s bulletproof airliner standards, and yet it out performs its lighter opposition in all key parameters, most notably cruise speed, range, fuel burn and runway requirements.
It deserves to do well in the demanding African market, especially now, as discussed in the accompanying article, Embraer have focussed their world-beating customer service on this market.