Autolanding remains a challenging task due to changing environmental conditions and the sensitivity of conventional control methods to model uncertainties and delays. This work investigates the application of Incremental Nonlinear Dynamic Inversion (INDI) to an autoland scenario using the PH-LAB Cessna Citation aircraft model. INDI reduces the model dependency by utilising sensor-based feedback, thereby enhancing robustness to modelling inaccuracies and external disturbances. Emphasis is placed on addressing variable sensor and actuator delays, which can degrade control accuracy and stability. The proposed INDI controller integrates multiple feedback loops and Pseudo-Control Hedging (PCH), complemented by a
hybrid filter for angular acceleration estimation and a novel altitude estimator. The latter utilises linear accelerations measured by the IMU, which are subject to smaller delays than altitude measurements from the Digital Air Data Computer (DADC). This estimate is fused with the DADC altitude through a Kalman filter for improved accuracy and mitigation of cumulative errors. Simulation results demonstrate that the controller achieves safe landings under external disturbances and variable delays. Sensitivity analyses further show consistent performance across multiple scenarios, while identifying the controller’s operational
limits. ... Read more

This report entails the design of a regional passenger aircraft, serving 48 passengers and entering the market by 2035. It is known as the SRP-22 ALAR FOX, however, in general, SRP-22 is used. The propulsion system is designed with hydrogen as its fuel. The hydrogen is converted to electricity with a low-temperature proton-exchange membrane fuel cell, which in turn is used by the electric motors, to power the propellers. There are four electric motors with one six-bladed propeller each. Two propellers are located under the wing near the fuselage and deliver 80% of the total power. The remaining two propellers are positioned on the wing tips, delivering the remaining 20%. The benefit of these wingtip propellers is an expected drag reduction of around 10%, due to the attenuation of wingtip vortices.
The hydrogen is stored in a composite tank, located behind the aft pressure bulkhead. The fuel cell is placed under the cabin floor, just in front of the pressure bulkhead, such that less tubing is required to transport the hydrogen. The boil-off of the hydrogen is used to transform the hydrogen from its liquid state to its gaseous state, through the usage of glass rods. After that, the hydrogen is heated up until about 80◦C, which is the operating temperature of the fuel cell. The control system is controlled through a mechanical-powered hydraulic system. The elevator design includes horns to relieve the hinge moment.
One of the main goals was to reduce the environmental impact of the aircraft. The average temperature response of the SRP-22 is almost 83 times lower than that of the ATR 42 by 2064, which supports this goal. Noise has also been taken into account, which mainly stems from the propellers and airframe. It is found that the noise levels are well below the limits set by ICAO. The unit list price of the SRP-22 will be $19 million when using more optimistic fuel cell prices, while a least optimistic estimate results in a unit list price of $37 million. Moreover, the direct operational cost is around 10% lower than those of the ATR 72. Because of the usage of electric motors, the maintenance cost is expected to be lower than for a turboprop aircraft. ... Read more