Traditional Global Navigation Satellite Systems (GNSS) are subject to intentional or unintentional disturbances in the northern regions of Norway, leading to loss of critical infrastructure. The novel VHF Data Exchange System (VDES) has been suggested as an alternative positioning, navigation and timing (PNT) system for a possible GNSS contingency service, based on signal simulations and statistical estimates. However, an empirical investigation into the feasibility of such a GNSS contingency service remains to be done, and has only recently become possible after the launch of the NorSat-TD satellite with purpose-designed VDES ranging capabilities. This paper presents an analysis of the characteristics of empirical VDE-SAT range measurements and a system-level performance analysis of a GNSS-contingency system based on the signal performance of empirical ranging data gathered from NorSat-TD. Using the equated error level of the signal, the positioning performance of simulated autonomous systems of VDE-SAT PNT-sources is analysed, followed by an assessment of the combination of the empirical VDE-SAT range measurements and traditional GNSS measurements in a critical GNSS contingency scenario. In total, 236 VDE-SAT pseudorange observations obtained from eleven satellite passes recorded in July 2023 were used. Residual analysis shows that these observations have a large and constant mean error of about 416 km, with a standard deviation of 260.8 m. The previously neglected atmospheric propagation effects on a VDE-SAT range measurement is shown to be significant, and the largest effect is likely to be the time-delay due to the ionosphere. The system performance analysis shows that VDE-SAT as a PNT-source could be used as a possible future general navigation backup system, with a positioning accuracy within 1000 m. Finally, an important conclusion is that a contemporary GNSS-contingency system is possible with the measured signal performance, where NorSat-TD acting as a PNT-source can, under the correct geometric conditions, allow a positioning accuracy within 1000 m in combination with partial GNSS coverage at the user.

Bush planes are general aviation aircraft, that enable transportation to remote areas, where there is no infrastructure supporting regular aviation. Their main features are the taildragger configuration, a short take off and landing distance (STOL) and they offer the ability to land on rough terrain. Paradoxically, although they are the aircraft most directly related to nature, bush planes are often old, polluting and loud, and thus far from being environmentally friendly. To partially overcome these disadvantageous characteristics, Group 12 designed a stateoftheart bush plane, using the principle of distributed propulsion, called the Twin Puffin. In order to design a bush plane, first an understanding is required of the needs and desires of the stakeholders. For this, a market analysis is performed and from this it can be concluded that the aircraft will serve for three main purposes: transport, medical emergency missions and tourism. After obtaining the insight into the market of bush planes, all possible design options are listed. Pruning of unfeasible, unrealistic and inapplicable options is done to end up with seven aircraft concepts. From those concepts, the most suitable and promising is then selected. The aircraft is chosen to be a twin boom concept, therefore the name Twin Puffin was chosen for the design. Following, the design is worked out in detail, where all the subsystems are designed. The fuselage, the structure of the plane, the energy source, the wing, the propulsion system, the empennage, landing gear and electrical systems are designed and optimised, so the final aircraft design is finalised. Inspired by Nature, the bush plane is named the Twin Puffin. ’Twin’ following the distinctive twinboom empennage, and the ’Puffin’, from the bird with a stubby display and a master of short takeoff and landing on the ocean cliffsides, a real inspiration for a STOL aircraft. The featured twin boom empennage make aft loading of cargo or a medical stretcher easy. Furthermore, the distributed propulsion is placed on the wing’s leading edge, allowing unobstructed view during all flight phases, solving the typical visibility issues of a traditional bush plane. The distributed propellers are powered by a hybrid engine using both electricity from batteries and power generated by an internal combustion engine that can run on diesel, jet fuel, and suitable types of biofuels. This allows for an increase in available power and a local reduction in the emissions and noise during electricallypowered takeoff and landing. Furthermore, the distributed electric propulsion lead to excellent STOL characteristics, as the blown air over the wing allow for a large increase in lift at low speeds. Moreover, the Twin Puffin is primarily built of the sustainable material flax fibre composite, making the aircraft more environmentally friendly. The Twin Puffin is estimated to produce 70% less noise and 50% emission, compared to competing aircraft and is thereby a modern, impressively performing bush plane design.