Lightweight Integrated Flight Display

Our Electric Bücker Jungmann e131 project set out to modernize a classic aerobatic aircraft with an electric propulsion system. This decision immediately created a new set of requirements for cockpit instrumentation which differ substantially from conventional piston aircraft. An electric aircraft depends critically on battery status, motor control, and power management. Off-the-shelf EFIS are mainly designed for piston aircraft and are not sufficient for our needs or hard to adapt. Hence, a custom solution became necessary.

Developing custom instruments, however, is a considerable investment. Beyond the sensors and displays, a complete software framework is required. This framework must handle hardware interfaces, sensor data processing, redundancy and failover strategies and a pilot-centric user interface. Traditional (round) instruments are too heavy, and although modern EFIS systems are lighter, they still require substantial “plumbing” in the form of pressure lines, and extensive cabling.

Because a software and hardware framework had to be developed for the electric propulsion system, we decided to go one step further and design all flight and engine instruments ourselves. From this decision, the Lightweight Integrated Flight Display (LIFD) was born.

The LIFD is based on several guiding principles:

·      It is imperative for us to understand every aspect of our aircraft down to the smallest detail, not only the “nuts and bolts”. This includes among others: motor controller, battery management system, and avionics software and hardware.

·      We can build exactly what we need and nothing more, achieving significant weight savings compared to traditional instruments (“lightweight”).

·      It allows us to rethink the EFIS user experience based on Hugo’s expertise in human factors and ergonomics (HFE) and Simon’s experience in software development and interface design.

·      A consistent and optimized user experience can be tailored specifically to our aircraft and mission profile.

·      A better user experience reduces documentation and training effort (“lightweight documentation”).

·      By ignoring development time (as we also do when building the aircraft itself), the overall cost is considerably lower compared to a commercial EFIS (“lightweight costs”).

·      Wireless communication is used wherever possible. This saves weight, avoids broken, corroded, or loose contacts and reduces the risk of short circuits. For example, the airspeed and angle-of-attack sensor only needs power—no tubing and no signal wires.

·      Leverage existing pilot resources such as Electronic Flight Bag (EFB) for flight planning and navigation.

·      LIFD is an open an extensible framework and the source code will be publicly made available on github.com

·      Software is developed with DO-178 Software Considerations in Airborne Systems and Equipment Certification design-assurance objectives in mind, including verification and testing.

The LIFD therefore represents not just a new EFIS, but a new approach to avionics integration: lightweight, modular, and purpose-built.