Maukasa Humidity in Partially and Non-conditioned Compartments The ambient conditions in partially and non-conditioned compartments can range from a dry heat to a damp heat environment. Sea transportation Generally, test methods using diurnal cycles will be applicable to materiel in enclosed areas on or above deck. Normal Operational Transient Changes a. Where internal ambient temperatures or temperature levels of individual components are of concern, expected temperature levels should be estimated using thermal analysis programs incorporating the influences given above supported by specific measurements made in representative conditions. Energy and heat transfer engineering Materiel deployed externally on the aircraft may be subject to pressurised spray when the aircraft is hosed aetp during cleaning or de-icing operations in preparation for flight.
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Daill During long term ground running in hot regions, the combined effect of heat radiated from adjacent structures and operational equipment may tend to counteract the effects of the conditioned air. The heavier particles thrown up by vehicle tracks and wheels are likely to be found up to around one metre above the surface and quickly return to the ground, while fine dust can remain suspended in the atmosphere at higher altitudes for days.
Immersion, Precipitation and Spray Materiel subjected to immersion is liable to ingress of water including contained contaminants causing seepage and swelling of materials and inducing faults and failures similar to those associated with condensation and high levels of humidity see Paragraph 3.
Where it is required to determine the effects on materiel that may be subjected to immersion, AECTP Method should be used. The latter may be tempered by some form of natural or man-made shade or ventilation. Also, during take-off and landing or as a result of flight manoeuvres, rates of change of pressure far in excess of those arising from meteorological conditions may occur 3.
Similarly, condensation and ingress of moisture occur inside compartments and individual materiel during descent from altitude to ground level. Storage and Handling a. It may be assumed that when engines are running or aircraft systems are operating from external power supplies, hatches will be open and air conditioning systems will be operating, providing ventilation and a reduction in the level of moisture of the atmosphere in the previously closed aechp.
Icing may be counteracted by on-board de-icing systems during ground running. Partial And Non-Conditioned Compartments Packing density aetcp heat dissipation of components, the thermal paths to aecpt surfaces, and the incorporation of cooling systems will influence temperature severities. The vehicles include wheeled and tracked fighting vehicles, and associated trailers, used as Service platforms for materiel, or used for transportation of materiel beyond forward storage bases and on the battlefield.
ProMIL NATO Stretcher Platform Air conditioned compartments Air pressure inside compartments of a ship may be raised above the local ambient air pressure to provide a gas tight seal against the ingress of external contamination. Heating and cooling produces pressure differentials across the walls of the enclosure causing external air to be drawn in.
Thermal shock induces high rates of expansion and contraction, resulting in stress and fracture of materials, failure of bonded joints, and degraded performance of seals. Preferably, test severities should be derived from specific measurements made on the intended enclosure during representative worst-case conditions expected in service.
Some level of immersion may be experienced by internally fitted materiel dependent on the efficiency of sealing of doors and hatches. Reduced performance of batteries. Above deck on surface ships Materiel installed above deck normally will experience pressures equivalent to the local ambient air pressure at sea level. This leaflet addresses the induced climatic environmental conditions likely to be encountered by materiel deployed on, or installed in, land-based vehicles.
To assist design engineers by indicating potential failure modes that specific environmental characteristics could induce, and thereby providing pointers to monitor during design and testing.
Examples include materiel located in compartments of military vehicles, trailers and temporary covers used as command posts or for conducting covert surveillance. Extreme cases may occur during emergency situations in normally pressurised compartments when explosion or implosion of the container may occur.
Failure of bonded joints. Conversely, extremely low levels of relative humidity may exist in localised areas of equipment when dissipated heat adds to the drying effects prevailing in hot, dry regions of the world. Thus, for a sunny day, the maximum temperature of the day is aecto in the light closed cover before aect maximum meteorological temperature is reached. Aircraft Impact with Super-cooled Water Droplets Induced-icing of externally carried stores may occur during the various stages of a flight sortie caused by impact with super-cooled water droplets e.
Temperature and humidity AECTP test procedures give values of temperature and humidity for external ambient meteorological conditions and for conditions induced by storage. Conversely, such protective structures and temporary covers are afctp liable to be better radiators to the night skies than the ambient air, such that temperatures in enclosed compartments may be lower than the external ambient.
Wind Blown Sand and Dust For artificially aerated dust and sand laden open sky atmospheres, turbulent dust is the preferred method. Individual items of materiel deployed or installed on the vehicle are liable to experience a similar pattern of induced breathing and retention of moisture.
Icing Icing of storage materiel is unlikely to occur except for cold climatic zones. The dust remains in that internal atmosphere indefinitely. Most 10 Related.
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