The Pulitzer Air Race is an event that originated in the 1920s. The race was organised to promote the development of high-performance aircraft and to experiment with new designs. Similarly, to accelerate the advancement of high-performance, medium-range electric aviation, the National Aviation Authority (NAA) has planned to revive the Pulitzer Air Race for zero-emission electric aircraft. The race spans over four days and covers a distance of 1,000 nautical miles (1,852 km), from Eppley Airfield in Omaha, Nebraska, to Dare County Regional Airport in Manteo, North Carolina. The winner is determined by the fastest speed calculated from cumulative flight time, excluding ground maintenance, charging, or overnight stops.
The Royal Netherlands Aerospace Centre (NLR) saw an opportunity in the upcoming Pulitzer Air Race and wanted to participate in developing a sustainable electric aircraft. Group 26 taking part in the Design Synthesis Exercise (DSE) at Delft University of Technology was approached to deliver a proposal for a design that can participate in this race and win. As a result, the project objective statement for this project is to “Provide a winning design for the Pulitzer Electric Aircraft Air Race within a budget of €900,000, by 10 students in 10 weeks.”
The requirements and constraints were defined after performing a market and a stakeholder analysis, five design concepts were selected over a wide range of potential configurations and a preliminary design for each one was made. Subsequently, a trade-off was performed to select the best design. Two of the design concepts ended up in a tie, those being the conventional aircraft configuration and the Prandtl plane configuration (or box-wing aircraft), both using hydrogen and batteries as energy sources. In the end, the Prandtl plane configuration was selected as the final concept, not only because it embodies a spirit of innovation in line with the ethos of the race, but also because of its potential to be structurally lighter than conventional aircraft configurations.
During the detailed design phase, intense concurrent engineering was performed between departments, with numerous iterations occurring throughout the detailed design process. The designed aircraft has a wingspan of 7.46 m, features two counter-rotating propellers driven by a continuous power of 80 kW each and an MTOM equal to 1,163 kg, of which 115 kg are due to the fuel cell, 30 kg of hydrogen mass and 53.5 kg of batteries. The Prandtl plane has a cruise altitude of 12.5 km, a cruise speed of 163 m/s and can complete the race without any stops in 206 minutes (slightly under 3.5 hours).