Experimental Assessment of Local Weather Forecasts for Small Unmanned Aircraft Flight

Estimating the Vertical Structure of Weather-Induced Mission Costs for Small UAS

“…Small-scale perturbations (characteristic scales of 1 km or 10 min) are unresolved by numerical weather models but their small size and duration means that a cruising aircraft transits many of these perturbations and their effect on the aircraft performance averages out. Large-scale perturbations have characteristic scales of hours and hundreds of kilometers, these features are resolved by weather models but with residual error similar to that observed by Glasheen et al [7]. Unlike the small perturbations, this error is correlated over scales of tens of kilometers so it can significantly impact the performance of a small UAS.…”

“…Glasheen et al evaluated high-resolution weather forecasts as a way to provide the aircraft with long-range knowledge of the environmental state [7]. Error in the position and timing of forecast phenomena makes direct comparison of high-resolution observations and forecasts challenging [8] so they compare the distributions of atmospheric properties observed by the aircraft over a mission to those forecast by a large eddy simulation.…”

Using a Balloon-Launched Unmanned Glider to Validate Real-Time WRF Modeling

“…The avionics system includes navigation and autopilot components and is capable of autonomous and beyond visual line of sight (BVLOS) operations. Location-specific weather guidance has been recommended in work comparing sUAS flights with WRF predictions limited to 250 m AGL for a 100 km 2 grid [24], which require relatively simple flight permissions. However, flying up to 25 km altitude AGL requires special authorization for flights beyond visual line of sight due to aerospace regulations.…”

“…For this study, placement of the sensors or the inlets was selected where static pressure was expected. We must note that a valid alternative is to place the motors on the wing to free the nose of the aircraft with the sensors from any propeller effects, i.e., as offered by the TTwistor sUAS [24]; (2) a powered aircraft would be unable climb to this altitude without a significantly larger and energy intensive power package, which justifies the strong need to utilize a balloon for the climb portion of the flight. For this same reason, the powered DataHawk system launched by a balloon [21] demonstrated relatively short time temperature and relative humidity data collection up to 3.6 km altitude; (3) the use of a glider saves considerable energy to be consumed in other scientific operations, and leverages the weight that a motor and battery source demand for payload needs.…”

“…Based on the power source selected, the measurements provided by the glider always last longer than the time needed for the descending flight to reach the ground; (4) finally, the glider has an efficient airfoil, which enables a slow controlled descent, compared to pure parachute-borne descent devices. Similarly, the superior airfoil for the glider rather than for existing powered aircraft such as the TTwistor [24] results in a better aerodynamic efficiency.…”