WATTS INNOVATIONS PRISM R.P.A.S., Руководство по эксплуатации самолета

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PRISM FLIGHT MANUAL
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Operating in hot environments (above 35° C) will place increased strain of the chemistry of
the battery packs. As the packs are discharged during flight, they generate heat internally.
This heat generation increases as the voltage drops towards the end of the discharge cycle
when more current is required to supply the required power to the RPA.
Excessive heat can cause the cells to swell and can permanently damage the internal
chemistry, decreasing the pack’s usable life span. It also increases the waiting period while
the pack cools before it can be recharged. For these reasons the pilot should be aware
of not flying the packs down to the limit or performing power intensive maneuvers while
operating in hot conditions.
The efficiency of the motors is affected by high temperature operations. As current is
passed through the motor coils they generate the electromagnetic force that drives the
propeller. This current also heats the coils and increases their resistance to the current
being pushed through the coils.
This greater resistance increases electrical power losses in the propulsion system,
decreasing the overall efficiency. For this reason the RPA propulsion system is designed to
operate well below the maximum power capacity, keeping the motors cool and maximizing
efficiency. When the ambient temperature increases significantly, the motor temperature
will rise as a direct result and a loss of flight endurance is to be expected.
The brushless motor system also dumps excess heat through the heat sinks on the
electronic speed controllers (ESCs). In excessive ambient temperature, the heat sinks
cannot exchange thermal energy efficiently, which can cause heat to build up in the ESCs
to the point of failure.
5.3.3 PROPULSION SYSTEM