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Novel findings are discussed in this paper that will be especially beneficial to designers and modelers of small-scale unmanned air vehicles and high-altitude long-endurance vehicles that both oper...

The Icing Encounter Flight Simulator is one part of the Smart Icing Systems project at the University of Illinois at Urbana-Champaign. From the Smart Icing Systems project, an ice management system was designed that would sense and characterize ice, notify the pilot, and if necessary take measures to ensure the safety of the aircraft. The icing simulator was used as a platform to integrate and test different components of the Smart Icing System. To create an Icing Encounter Flight Simulator, functionality and Smart Icing System components were added to the FlightGear flight simulator. Functionality added to FlightGear include a reconfigurable aircraft model and an icing model, and Smart Icing System components added include an envelope protection system and a glass cockpit enhanced with ice management system features. To ensure a real-time simulation, computationally intensive processes were distributed over several desktop computers linked together through a local network. In order to demonstrate the effectiveness of the Smart Icing System components, two fictional but historically motivated icing scenarios were developed and tested with a simulated DeHavilland DHC-6 Twin Otter, specifically, a tailplane stall event during a steep descent and a roll upset event during an emergency approach. Language: en

The growing use of small UAVs and MAVs has increased the interest in determining the performance of small-scale propellers that power them. These small-scale propellers operate at much lower Reynolds numbers than propellers for larger aircraft; typical Reynolds numbers for small-scale propellers are less than 100,000 based on the velocity and chord at the 75% span station. The low Reynolds numbers of the propellers make predicting the performance of these propellers difficult as the performance of the propellers generally change with Reynolds numbers. In order to understand the Reynolds number effects on small-scale propellers, the performance data of twenty-seven off-the-shelf propellers and four 3D-printed propellers were measured in both static and advancing-flow conditions. The diameters of these propellers ranged from 2.25 in to 9 in. From these tests, the performance of the propellers was shown to improve as the Reynolds number increased. This improvement was seen as either an increase in the thrust coefficient, a decrease in the power coefficient, or both. For propellers in an advancing flow, performance improvement was also seen as an increase in the propeller efficiency. Results from some of the propellers tested showed an efficiency improvement of around 10%. Nevertheless, the maximum efficiency achieved by the small-scale propellers is still low when compared to typical values of larger propellers.

This paper presents results of a study that was commissioned by the 3M Renewable Energy Division to measure the drag reduction by using riblet film on airfoils specifically designed for wind turbine applications. The DU 96-W-180 airfoil was tested with four different symmetrical V-shaped riblet sizes (44, 62, 100, and 150-μm) at three Reynolds numbers (1 × 106, 1.5 × 106, and 1.85 × 106) and at angles of attack spanning the low drag range of the airfoil. Tests were run with riblet film covering different sections of the airfoil in order to determine the optimal riblet location in terms of drag reduction. Results showed that the magnitude of drag reduction depended on the angle of attack, Reynolds number, riblet size, and riblet location. For some configurations, riblets produced significant drag reduction of up to 5%, while for others riblets were detrimental. Trends in the results indicated an optimum riblet size of 62-μm for the range of Reynolds numbers at which tests were conducted. The airfoil chord was 18 in (0.457 m). Results also showed that each riblet size performed best at a given Reynolds number with the optimal Reynolds number decreasing with an increase in riblet size.

Available performance data for micro propellers are very lacking. Prediction of micro propeller performance is made difficult due to the small Reynolds numbers (less than 50,000) at which the propellers operate. A test rig was designed and built at the University of Illinois at Urbana-Champaign in order to measure the static performance of micro propellers. A load cell and torque transducer measure the thrust and torque, respectively, created by a propeller. These results are then used to find the static thrust and power coefficients. Eighteen two-bladed propellers from different manufacturers and two threebladed propellers were tested with diameters ranging from 2.25 in. to 5 in. The hovering capabilities of the propellers were also analyzed.

The centennial of flight has brought about a renewed interest in the first airplanes and their flight characteristics. It is known that the first Wright Flyers were unstable, but history showed that they were flyable. It is the longitudinal handling ch.aracteristics that are of interest in this paper. Wind tunnel tests have been performed on the 1903 Flyer and provide limited aerodynamic data, but a higher fidelity model is needed to fully simulate the aircraft within nonlinear regions. Simulation models of the 1903 and 1905 Flyers were created by using the results of wind tunnel tests, using inviscid flow analysis, and expanding the data to include high angles of attack. The two models were simulated in the PC-based FlightGear Flight Simulator, and the results shew that both aircraft require continuous pilot input, but they are flyable with practice.