The development of our new PA Thrust® motors has followed our traditional design philosophy employed in our aircrafts; which is doing things better. Thrust® motor is one of the coolest running high performance, high-torque and high efficiency brushless motor ever produced to date. The design incorporates our latest innovation, RotorKool® which keeps the stator core material, the low resistance windings, highly permeable stator plates, high quality NMB Japan triple bearings and powerful neodymium magnets at optimum operating temperatures regardless of duration or the number of consecutive flights made*.
*provided sufficient airflow is permitted.
A little background
For a number of years, modelers have accepted the notion that in order to attain top notch performance, one has to run outrunner motors to the extreme limit with the risk of overheating. In fact, heat has become inevitable part of contemporary high performance Brushless Motors and nothing much could be done about it.
However heat is one of the main contributors to premature magnet deterioration and bearing failures leading to permanent performance degradation over time or even dangerous and catastrophic destruction due to thrown magnets.
In order to avoid unwanted heat damaging the motor, some modelers have resorted to over sizing their motors. This in turn increases the all up weight and thereby affecting wing loading and flight performance. There seems to be a no win situation and the only way to enjoy this wonderful hobby is to accept the seemingly hopeless compromise.
Motor power has always been quoted in Watts, but heat is Watts too. So, the real question is “Are all the quoted Watts being used to drive the motor, or is there a significant amount of Watts wasted in heat? To answer that just touch your motor immediately after flight and if it is hot enough to burn your finger, THAT is where the Watts went as opposed to driving your airplane.
We at PA understood that without effectively eliminating heat, all the good motor attributes already available in our motors and as well as others, contributes very little to the motor’s overall performance in service because heat building up under load means loss of efficiency, and eventually leads to detrimental effects in the electro-magnetic properties of the motor. These effects cause significant deterioration of power, thrust and eventually flight times.
We set a target to make a high performance, extreme thrust motor, which is light, runs cool and efficient for maximum flight time, is made of highest grade materials and features precision engineering and machining.
This led to rethinking the design of current brushless outrunners, their strengths and limitations and thus led to the development of a completely new line of PA Thrust® motors;
About the design
Some of the common brushless outrunner manufacturers have gone as far as incorporating high temperature magnets and exotic adhesives to circumvent the effects of the heat problem. There are myriad of crude and inefficient cooling techniques ranging from a multitude of holes, to fins, to bolt-on fans and impellers.
Unlike those, the new PA Thrust® cooling design took a complete departure in the current thinking by engineering a High Velocity Force Cool Ventilation (HVFCV) into the rotor end bell as well as taking full advantage of thermodynamic properties of the stock material itself. HVFCV is achieved through a set of solid metal turbine impeller blades painstakingly CNC milled as an integral part of the rotor end bell assembly, which not only provides the positive force cool ventilation by drawing fresh cool air through the stator and magnets, but also doubles up as a heat pump to first draw excess heat from the rotor assembly itself and then act as a heat exchanger by expelling it through the air stream contacting the solid metal turbine blades as it spins at high velocity. Micro ridges, intentionally CNC cut into the rotor, further multiples the end bell’s surface area and serve as radiators to further boost thermal dissipation achieving unparallel cooling.
There is more to the “Cool” look of the CNC exterior casing than meets the eye, and looks can be deceiving. Under the hood, is where serious engineering comes into play. With only the highest quality materials and components used in the manufacture, the new PA Thrust® motors are manufactured with the tightest tolerance making it possible to maintain the smallest air gap between the stator and shaped neodymium magnets, significantly boosting torque and Thrust®. This allows the motor to swing props of at least one size larger than any contemporary motors in its class and keeping cool in the process.