The Embraer E2 family of jets are now officially the quietest narrowbody jets in the world. Simple Flying caught up with Luis Carlos Affonso, Senior Vice President of Engineering, Technology and Corporate Strategy at Embraer, to find out exactly what went into this aircraft in order to achieve such an impressive outcome.
Designing a quiet aircraft from the outset
From the moment the next generation of E-Jet was conceived, Embraer knew they wanted to go one better in every aspect. One crucial element of this was to make the aircraft as quiet as possible, and that required some innovative design.
Speaking exclusively to Simple Flying, Luis Carlos Affonso, Senior Vice President of Engineering, Technology and Corporate Strategy at Embraer, described the importance of building in quietness from the outset. He said,
“You have to develop airplanes thinking about noise; it’s not an afterthought, it’s something that you have to design for. To design for a low noise level, before you design the airplane, you have to develop the technology. This means you have to do research and development, and in this, we have been very active.”
The first thing Embraer needed to do in order to make the E2 quieter was to understand the noise sources. Working in partnership with a number of high-profile academic institutes and using all the resources at hand, the team identified where noise could be reduced and set about designing solutions for a quieter operation.
So, where did this lead? Let’s take a look.
While the E2 isn’t a clean sheet design over the original E-Jet, there is a lot that has changed. In fact, very little is left that hasn’t been improved in some way over the original aircraft.
The first noticeable improvement is the wing. Each family member of the E2 series has its own, bespoke wing, something that is unusual in other aircraft families. Because each wing has been designed specifically for the size of aircraft it is used on, there is no compromise on size, shape, or specifications – each E2 has the very best wing for its fuselage.
In terms of design, the aspect ratio for the wings of the E2s is one of the most generous in the industry. For the size of the aircraft, the wings are incredibly long. The E195-E2, for example, has a wingspan of 35.124 m, 6.4 m wider than the original E195. It’s a smidge longer than the A220’s wing, and only 0.7 m shorter than the much larger A320neo family.
Luis Carlos explained why this is so important for the design of the E2. He said,
“This means the most efficient wing; the one that that will produce the lowest drag. Drag is inefficiency and noise. It’s all a cycle, because you use less fuel, which is great for the environment, CO2 emissions and so forth. But it’s also good for noise, because when you generate noise, you are being inefficient and you’re using more fuel.”
What, no winglets?
An unusual feature of the E2 wing is the lack of winglets at the tip. For many popular narrowbody families, the winglet has become an integral part of improving efficiency, reducing wingtip vortices and drag. But the E2 has no winglets, and this is a deliberate decision on the part of Embraer.
“We have used winglets in the in our first generation. But since then, the design tools, engineering tools, dynamic tools have all evolved significantly, and allowed us to design even more efficient wings without winglets.
“Without winglets, aircraft are more efficient and less noisy. The only reason you would use a winglet today is if you are really restricted in terms of the wingspan you can have … If you see a modern airplane without winglets, that’s the most efficient wing you can get.”
Adding winglets is always a trade-off. Not only do these structures cost the airline money, but they also add weight. There comes a tipping point when the fuel saved from adding winglets is no longer enough to counter the winglet’s additional weight. Thanks to its bespoke designed, high aspect ratio wing, Embraer has built out the need for this type of device.
Mind the gaps
With its all-new wing, the E2 design was well on its way to becoming the quietest narrowbody in the world. However, there is another design feature of the wing that invariably causes noise, and that’s the aircraft’s control surfaces.
Slats and flaps are required for control of the aircraft, particularly at low speeds, so tend to be deployed extensively during landing and takeoff. That adds to the noise experienced by the community around the airport, and was a problem Embraer was keen to tackle.
To solve this issue, Embraer designed in a sealing mechanism that fully seals the slat tracks, reducing aerodynamic noise during take-off and landing. The flaps feature side edge seals, reducing vortex sounds from these surfaces.
And that wasn’t the only place Embraer worked to fill in the gaps that typically contribute to an aircraft’s noise profile. All over the fuselage, aircraft like the E2 have a plethora of air intakes and outlets, for the APU, for the air conditioning, for the cooling of avionics and much more.
Embraer’s engineers worked to cover, protect and improve the air intakes and outlets right across the fuselage. On any E2, you’ll see a variety of covers, vents and hoods, all specifically designed to reduce the noise generated by these structures. But, as Luis Carlos was keen to point out, it’s never just about noise reduction.
“In each and every one of these intakes and outlets, we have designed solutions to reduce noise. But of course, what is good for noise is good for drag, and therefore good for fuel burn.”
What about the engines?
One of the key changes from the E-Jet to the E2 is the brand-new engine type. The E2 is powered by the Pratt & Whitney PW1900G engine, the very same used on the Airbus A220. However, thanks to the design team’s efforts at Embraer in optimizing the wings, the weights, and the range of the aircraft, the thrust required is less.
The engines themselves are extremely large for the size of the aircraft. Indeed, Embraer designed in a slight ‘gull wing’ shape to accommodate these large powerplants. But getting the right sized engine for the aircraft was key to design success, as Affonso explained,
“They are efficient because, with such a big fan, the engine pushes the air backward at lower speeds. You have a higher mass of air at lower speeds, so you have less friction against the air that is not moving. And this friction is what causes the noise.”
Quiet operation was one of the key selection criteria when Embraer was choosing an engine for the E2. But, again, with quiet comes efficiency, and the PW1900G delivered on all fronts.
The one downside of selecting such a large engine was that it required more ground clearance than the engine of the first generation. This meant a redesign of the landing gear was needed, but herein lay another opportunity to cut down noise and drag.
The new landing gear was to be housed in the usual wheel well, just like its predecessor. But rather than leaving the wheels open to the elements, Embraer designed a door to cover this area, reducing drag on the aircraft belly and cutting down noise. This came as an added cost to the aircraft’s development, but Luis Carlos believes it was an investment well made.
“The addition of the door means reduced noise and fuel consumption outside the plane. And in this case, it will also reduce the internal cabin noise. The landing gear wheel well is just below the cabin floor, so some passengers would hear some noise coming from there. On the E2, you don’t have that, so it’s also good for the internal noise level.”
From nose to tail
The final design element that has successfully reduced noise, and the associated drag and inefficiency, is the tail. Comparing the horizontal tailplane of the E2 to the original E-Jet, there is clearly a size difference to see. It is, in fact, 26% smaller than its predecessor, which means lower weight and less drag from the empennage.
So what has enabled this reduction in size? In a nutshell, the E2 features an all-new closed-loop fly-by-wire system, which effectively enhances flight stability, allowing the aircraft to fly with a much smaller tailplane. The result is another small saving in drag and noise, as Affonso explained,
“The lower weight will allow, again, for less drag and less noise from the wings, because the wings don’t need to carry as much weight from the empennage. The wings don’t need to generate as much lift, so they don’t have to pay the price in drag and noise.”
The end result of all this fine-tuning is an airplane that is officially the quietest narrowbody jet in existence. And everything that has been done to make the plane quiet also makes it more fuel-efficient too. That’s good for airlines, good for passengers, and even better for the environment.