The Airbus A380 is and remains a superlative aircraft that has set the technical bar high for future airliners. And no matter what the future holds for the aircraft in scheduled services: For the time being, the A380 is more popular with passengers than any other aircraft. Many travelers book their own flights on this aircraft, not least because they appreciate the spacious cabin and the low noise level.

Captron, a company from Olching, Germany, which has developed a sensor button for closing the hand luggage compartments and produced it in series for the A380, also demonstrates how technical innovations lead to greater comfort and customer satisfaction. The components have now proven themselves in practical use in aircraft worldwide.

But first, let's take a look at the initial situation: in many aircraft, hand luggage compartments are designed in such a way that a flap swings upwards to provide access to the actual luggage compartment. In the A380, however, a different principle is used: once the opening mechanism is activated, the entire baggage compartment moves downwards. This means that passengers do not have to stretch as far upwards and can place their luggage much more comfortably. Because the overall structure in the A380 is much larger than in other aircraft, there is also considerably more space available: The A380's luggage compartments can hold up to 50 kilograms.

On the other hand, this means that considerably more force is required to close the compartments than when simply closing a flap. This is particularly noticeable for the flight attendants, who close the compartments one after the other after check-in.

Capacitive sensor strip on the luggage compartment
This is where Captron comes in: The company has developed a solution in which a capacitive sensor strip on the luggage compartment starts the closing process with motor support. The sensor strip builds up an electric field and continuously measures the capacitance between the surface and the sensor environment. If a hand approaches the hand luggage compartment, the capacitance increases and the switching process is carried out. As there are no wearing parts in this type of design, capacitive technologies are significantly more robust and durable than their mechanical counterparts.

At Captron, every customer and every project is looked after individually until a suitable solution is found and implemented. © Captron

Captron specializes in this type of design. "For 35 years, our family business has been developing and producing special solutions based on capacitive measuring principles for industries such as mechanical engineering, bus and rail vehicle manufacturers and many other areas where precise switching operations or accurate measurement are required," explains company founder Reinhard Bellm. "We develop solutions together with our customers and make all our expertise and knowledge available for their specific requirements."

High demands in the aircraft
One challenge with the push-button variant for the A380 was the size of the baggage compartment. This meant that the button had to be designed to be correspondingly long. Extensive tests had shown that the button had to extend over the entire baggage compartment for optimum ease of use. This is the only way that all passengers and flight attendants can easily reach the compartment from any position.

This presented the Captron engineers with a challenge: As the electrodes of the push-button act electrically like an antenna, the risk of coupled interference signals is correspondingly high. Captron has solved this by intelligently arranging the electrodes with particularly good shielding and a special electronic circuit concept.

The question of what happens if, for example, a water bottle breaks in the luggage compartment also had to be clarified. In such a case, the button should not be triggered, nor should the moisture destroy the electronics. For this reason, the electronics of the buttons are encapsulated to make them watertight and the sensor strip is laminated into the luggage compartment.

Weight is of course an important factor for all aircraft components. Here, Captron had to adhere very closely to Airbus' specifications. Documentation and compliance with the various European and international standards and regulations of the aviation industry were also extremely important in this project and required a great deal of effort from Captron. This included extensive testing, for which the company developed and built some of its own test benches. Julie Dörr/as