Specifying an electric power train.

[Mike.K 60]

Hi Guys,

After nearly a couple of years of flying now having returned to the hobby after an absence of some forty years later. Boy, did I find the whole game had changed. I needed to get into a serious learning curve!

So what did I struggle with? New fangled 2.4 radio gear and electric power plants. I found myself totally out of my comfort zone. OK, the radio gear was fairly easily overcome but electric motors, UBECS and LiPo batteries were completely outside my knowledge library. To begin to bridge that gap, I resorted to taking advice from George Worley at 4-Max. I`m glad I did.

George bent over backwards to sort out my initial needs. Telling him I intended to work my way back into the hobby with a Hanger 9 60" Ultra Stick, he immediately worked out that I needed a PO5056-420Kv motor, a 60a ESC, 5a UBEC and a minimum 6S LiPo of 3700mAh capacity running a 15x6 prop. That is the combination that many people saw me practice for and gain my A-test with in May 2019. 

George later further specified a similar 5065- 360Kv motor, 70a ESC and 6S 4500mAh Lipo for my Dancing Wings Fokker Tri-Plane. As it transpired, that 360Kv motor soon transferred to the Ultra Stick to provide faster acceleration and the ability to make use of the greater torque which offered the increased ability to swing a larger propeller. The 420Kv motor taken from the Ultra Stick then transferred to a Seagull Fly Baby monoplane where fast flying really wasn`t anything like so important. Gradually then, I began to learn something about correct power unit selection.

So how does the often viewed specification seen on some out-runner cases apply to what you might see on a 4-Max motor case? As an example, if we examine the 4-Max PO5056 series motors discussed above, we can learn that the 50 refers to the metric diameter of the motor case, which in this instance equates to 50mm. The 65 refers to the motors` 65mm case length. The 360Kv or 420Kv refers to the motor performance. All this is far better explained in the link to the 4-Max site below. I certainly find the explanation found in the link to be most useful as indeed I hope it may also be to fellow club members who like me, might be struggling to understand the technicalities of electric power applications. Please take look.Microsoft Word - Working out the power train for electric aeroplanes - Version 1.2.doc - Working out the power train for electric aeroplanes - Version 1.0.pdf

Mike