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). ... Read more

Flying characteristics of a multi-engined light general aviation (GA) aircraft during and after an engine failure is often a major safety consideration when both designing and operating the aircraft. In the meantime, the propellers, being large rotating masses, can exert considerable gyroscopic effect on the aircraft during flight, itself contributing to a coupling between the pitch and yaw axis, thus affecting flight dynamics. This study presents an investigation on the impact of propeller gyroscopic effects on the flying motion of a representative twin-engine GA aircraft. This is done using a modular flight mechanics toolbox that performs analyses in both frequency domain and time domain. A steady-state windtunnel aerodynamic and control surface model with empirically estimated unsteady aerodynamic coefficients, along with a propeller governor engine system simulation, complements the gyroscopic inertia model in the simulation setup.

Firstly, a modal analysis showed that all modes aside the spiral mode does not get discernibly affected by the rotating inertia typical to the reference aircraft’s propellers. Then, time-domain simulations of various rapid maneuvers show that gyroscopic effect does cause significant change in the angular response of the coupled axis, e.g. sideslip angle response during a pitch input only maneuver, whilst its impact on long term phugoid motion remained inconclusive due to undesired and uncontrolled roll motion. To compensate for this, maneuvers were performed again with a manually tuned simple wing leveler and results showed that pitch input maneuvers does not show much deviation in phugoid motion, whereas yaw input maneuvers such as sudden left engine failure shows discernible difference in airspeed and altitude responses, though the difference in magnitude is still small. Next, comparisons made with different powertrain responsiveness showed that in a power reducing case such as sudden one engine failure, the effect of the powertrain time delay is independent from the influence of gyroscopic effects, whereas for a power increase case, such as going around, the impact of the two is
simultaneous and intertwined. Finally, a sensitivity study on unsteady aerodynamic coefficients showed that their effects on flying motion are generally independent from the gyroscopic effect. ... Read more

Training in realistic conditions is crucial for fighter pilots. During this training, a red air team is used to represent adversary threats. Currently, the red air team is made up of friendly aircraft that mimic the tactics of the expected adversaries. However, this method has its limitations, such as that these friendly aircraft do not correctly mimic the performance and detectable emissions of the real adversary aircraft. Furthermore, using real combat aircraft has other downsides. They require active fighters and pilots that require expensive training, and using real aircraft means that these expensive combat aircraft need to spend a lot of their service life filling the role of red air instead of flying real missions. As red air flying hours are not considered to be useful training for the pilots flying them, there is no need for using combat-ready aircraft that can carry real armament, nor for a pilot in the cockpit. Using real combat aircraft has other extensive costs attached to it and is unsustainable looking at its real intended purpose. Just to have a real combat aircraft in the red air fleet requires acquisition of the aircraft, taking it away from active service that it was designed for. It needs a (ground)crew to operate it. It also needs lots of maintenance, requiring mechanics, engineers, tools, hardware, and much more. All of this and the combat aircraft is not used for its designed capabilities in flag missions when it is part of the red team. Therefore, there is a desire for a UAV that can match the performance of the real adversaries, is less expensive to operate, and is more sustainable than the current alternatives to fill the role of red air... ... Read more

The Continuous Descent Approach (CDA) offers reduced noise emissions and fuel consumption, but its main complication is the lack of predictability regarding the Estimated Time of Arrival (ETA). A suggested solution is to develop a pilot support interface for the execution of a fixed flight path angle CDA for a selected ETA, with thrust not being bounded to idle. Initially, the trajectory calculation method of CDA and the boundary cases were defined. Then, a two-fold interface was designed for planning and execution, based on Ecological Interface Design (EID), with a Vertical Situation Display (VSD) playing a central role, and it was tested by five pilots over different wind conditions. The pilots' on-time performance was satisfactory, while they worked with the cues and suggested enhancements to accommodate their strategy. The validation of this approach can lead to applying the CDA in real flight conditions, without limiting itself to low traffic times. ... Read more

Preventing Loss of Control In-flight (LOC-I) in commercial and general aviation is an active research area with numerous proposed solutions. One of these solutions aims to prevent lateral LOC-I, a special type of LOC-I, by presenting a roll-performance based minimum lateral control speed to the pilot in roll-limited situations, such as single-engine failure scenarios in multi-engine aircraft. This minimum lateral control speed is predicted by a system, named the Vc Prediction System (VPS), which continually predicts the minimum lateral control speed Vc at which an aircraft can still obtain a certain roll angle within a certain amount of time. It consists of three components; a linear model, a parameter estimation method and a Vc prediction model. These VPS components were designed for a simulation model of the Piper Seneca. This study analyzes the sensitivity of the VPS design to a change in aircraft dynamics and simulation model complexity by redesigning this system for a high-fidelity simulation model of the Fokker 50. The results show that both aircraft favor a small linear model and the Modified Kalman Method for parameter estimation. The original Vc prediction model however gives higher Vc prediction errors for the Fokker 50 than for the Piper Seneca. By simplifying the original Vc prediction model a stable, smooth and relatively accurate Vc prediction for the Fokker 50 can be obtained. ... Read more