Variable camber is an intended feature of future aircraft wings that will change the main aerofoil’s camber, or curvature, during flight for improved fuel efficiencies and green aviation operations.
A simple example is provided in Figure 1, which indicates how the wing shape can be curved to support flight operations.
Figure 1: A simple example of Variable Camber
Source: Utah State
The 2017 IATA Technology Roadmap indicates that the Variable Camber technology would be ready for Entry Into Service (EIS) some years after 2020 and has a current Technology Readiness Level (TRL) of 5. A TRL of 5 means the Variable Camber has only been validated as a breadbox project in a relevant environment. There are still four more technology development stages to go through, in this case, to progress through to final commercial validation and application. Variable Camber technology, however, offers a 5 – 10% fuel efficiency benefit, which is quite an improvement.
Current partial approaches to Variable Camber
Some examples of variable camber-partial developments are already included in current aircraft systems, where the leading and/or trailing edge sections of the whole wing will pivot to increase the effective camber (i.e. curvature) of the wing. Modern aircraft such as the Airbus and Boeing fleets deploy these systems. As a result, the maximum lift coefficient for the aircraft is increased, which shortens the take-off run while also enhancing the aircraft’s manoeuvrability in the air. However, these leading edge/trailing edge designs are only part of successfully implementing a variable camber system.
Another limited example of camber-changing aerodynamics is through the use of flaps. Flaps in certain locations, such as a wing’s trailing or leading edge, vary the overall camber. These are sometimes described as camber–changing flaps. However, because these flaps do not alter the main lifting surface in the same way that a variable-camber wing does, they only provide a partial solution.
The following Figure 2 shows the three elements under discussion thus far in this piece. Leading edge types are indicated through the four subfigures: a static wing and the wing flaps.
Figure 2: A Presentation Of Leading Edge Types, Static Wing And Flaps
Source: Naver
Other Variable Camber mechanisms attempted
Various other variable camber mechanisms have been tried over time. These include a device that controls the location and shape of the entire upper surface of the airfoil, such as a retractable bridge that connects two separate high aspect ratio wings, turning them into a single low aspect ratio wing or with telescopic segments that could be forced out, increasing the thickness, the chord and the shape of the affected portion of the wing.
The first and only Variable Camber that was flown was in 1917 as part of the airplane development process of that era. Figure 3 shows how that wing changed during flight operations. One can conclude that this idea is challenging to implement, given that relatively limited progress has been made until recent decades.
Figure 3: Parker Variable Wing as a Fully Flexible Aerofoil.
Benefits of Variable Camber
Variable-camber control of the wing for drag reduction throughout the flight mission using existing control surfaces can provide the ability to realize modest operational savings. Variable camber is considered ideal for future aircraft because the concept calls for a complete redesign of the wing from largely a static piece to an ever-adjusting aircraft component. As a result, additional control surfaces will be able to be used throughout the flight phases. Flaps would be used for take-off and landing, with ailerons for routine turning maneuvers. Variable-camber control would be used during the cruise flight while also participating in the other flight phases mentioned earlier.
In addition to the operational savings from using variable camber technology, reduced fuel consumption results in equivalent reductions in atmospheric gas emissions, which is an increasingly important environmental issue and increasingly a focus of IATA, given that aircraft passenger rates are projected to increase dramatically in the coming decades.
IATA estimates that the demand for air travel is expected to double by 2040, growing at an annual average rate of 3.4%. Origin-destination passengers are projected to increase from around 4 billion in 2019 to just over 8 billion at the end of the forecast horizon. (IATA, June 2023)
To see a Variable Camber wing demonstration, look at the following YouTube Video from NASA. It will radically change your view of how an aeroplane’s wing can change to support the entire flight cycle.
Source: NASA
Editor’s note: We have been taking notes and segments from the 2017 IATA Technology Roadmap and translating them into developed stories by providing details of how aerospace technology is changing and what is changing in that sector.
Noted is that in this past year, IATA has updated its Technology Roadmap and boldly pointed it further to 2050. We will soon be presenting our following stories from that new TRM to continue to indicate the ever-changing nature of aerospace and how it translates its mission to support our societal imperatives, particularly with respect to green aviation.