Designing of control and expulsion equipment for the pitot-static system of passenger airplanes

The article discusses the issue of automating the serial process of bleeding and control of the pitot- static system of passenger airplanes. A functional diagram and basic design of some parts of the combined equipment are proposed. This equipment makes it possible to alternate the above-mentioned operations with great effectiveness. At the system control stage, the pressure or vacuum in it is created by a pressure-vacuum pneumatic unit. This pneumatic unit consists of a compressor and a set of electromagnetic valves that allow the compressor to be connected to the pumping or scavenging line. The value of the generated pressure is regulated by the flow rate in the pressure/scavenging channel and in the venting channel. Simulation of changes in ambient temperature is achieved due to blowing heated or cooled air over the temperature sensors of the aircraft. Pressure or vacuum in the controlled system is created in turn, in each of its lines. At the expulsion stage, a compressed-nitrogen cylinder acts as the pressure source. The pressurized gas passes through the pitot and is released into the atmosphere, cleaning out the contaminations. No manual operations are required for installing and removing connection hoses after connecting the proposed combined equipment to the pitot-static system. Remote-controlled electromagnetic valves connect the channels of the controlled system to the pressure-vacuum pneumatic unit and the source of compressed nitrogen. This reduces the duration of successive operations for the systems maintenance.

The Impacts of Horizontal Grid Spacing and Cumulus Parameterization on Subseasonal Prediction in a Global Convection-Permitting Model

Monthlong simulations targeting four Madden–Julian oscillation events made with several global model configurations are verified against observations to assess the roles of grid spacing and convective parameterization on the representation of tropical convection and midlatitude forecast skill. Specifically, the performance of a global convection-permitting model (CPM) configuration with a uniform 3-km mesh is compared to that of a global 15-km mesh with and without convective parameterization, and of a variable-resolution “channel” simulation using 3-km grid spacing only in the tropics with a scale-aware convection scheme. It is shown that global 3-km simulations produce realistic tropical precipitation statistics, except for an overall wet bias and delayed diurnal cycle. The channel simulation performs similarly, although with an unrealistically higher frequency of heavy rain. The 15-km simulations with and without cumulus schemes produce too much light and heavy tropical precipitation, respectively. Without convection parameterization, the 15-km global model produces unrealistically abundant, short-lived, and intense convection throughout the tropics. Only the global CPM configuration is able to capture eastward-propagating Madden–Julian oscillation events, and the 15-km runs favor stationary or westward-propagating convection organized at the planetary scale. The global 3-km CPM exhibits the highest extratropical forecast skill aloft and at the surface, particularly during week 3 of each hindcast. Although more cases are needed to confirm these results, this study highlights many potential benefits of using global CPMs for subseasonal forecasting. Furthermore, results show that alternatives to global convection-permitting resolution—using coarser or spatially variable resolution—feature compromises that may reduce their predictive performance.