My Initiation into Electrics:-Baptism by Fire & Bloated Lipos

Over the years of dabbling in electrics, Ihave gone through all the methods of motorselection, made plenty of boo boos andamassed quite a collection of useless gearcooked, stuffed and fried in many imaginativeways. I had learnt electrics the hard way!

I’m sure most have at some stage or anotherexperienced the frustrating (and expensive)results of trial and error when it comes to select-ing, combining and using the many segments ina typical high power electric drive train. This ismainly due to the loosely defined airframe classand the existence of an unusually wide variantof motors, ESC and power packs. On theextreme end, motors from one single manufac-turer, for example, Feigao with their 380 classBL inrunners have gone as far as to produce ahuge range of motors in one turn increments,coupled with three different casing lengths(S,L,XL) within a single class totalling close to100 or more models to choose from. This is

entirely mind boggling even to the most experi-enced of electric enthusiast.

The last few years I have started using com-puter aided drive prediction tools and soondepended very heavily on it to select my gearfor a specific airframe. No more guess work thistime. ‘Motorcalc’ was initially quite difficult todigest and over time the field experienceallowed a more informed gear selection. It wasmy tool of choice to a point where it becamethe last word in gear selection for me. In theinterim I also tried a few combo’s recommend-ed by distributors and was really disappointedwith the conservative performance in compari-son to the videos they post. I bought quite afew lemons and it was literally a sour experi-ence indeed. That in turn vindicated my beliefin computer aided drive prediction tools. Theonly drawback I noticed over the years was thatthe gear selected appeared to be oversized andthe initial thought was more power was goodand completely ignored the overall aerodynam-ic performance and handling characteristics.

This was usually written off as “Well it’s justme behind the sticks and if the airplane behaveslike that then I am just not good enough”. Iunknowingly accepted this notion and contin-ued to fly the model as is, overweight and rela-tively poor flight times of 5 minutes and belowbecause there was nothing better and long flighttimes meant under powered performance.Throughout those times, many of my knowl-edgeable friends kept emphasizing on unpre-dictable flight characteristics associated withwing loading. However I could not reallyappreciate their attempts at enlightenment andusually dismissed the short falls to the inherentcharacteristics of a particular airplane or theclown behind the sticks. Those were the times

when I started changing airframes on a regularbasis in the pursuit of the “perfect” airplane. Ialso resented the manufacturer’s videos because“what I saw was not what I got” and I just toldmyself that I can only depend on myself to getit right and never bothered to look at combos ormanufacturer’s recommendations again.

Precision Aerobatics IntegratedPerformance Airframe-DriveSystem (iPAs)

When PA launched their Katana MD, I toldmyself that I will not repeat my mistake and gowith the flow so I bought the KMD with a PAThrust 30. I initially did not go for the full iPAsgear since I already had compatible JAS2300mAh, 20C, 158gr 3S1P Lipo packs and aCastle Creations Phoenix 35 ESC that shouldwork with the KMD as verified by Motocalc, to

be a very good setup. The AWT came out close to spec and the KMD flewlike “as seen on TV” and I was delighted at the outcome but was still verycurious about their iPAs stating that the gear was exhaustively tested onthe specific airframe to attain an optimum combination. I was quite curi-ous to know as to how far off be my setup in relation to the optimumspecified by PA. When PA recently launched their combo deal plus freeglobal shipping, it was very hard to resist and I got one along with thePA2200mAh, 18-30C Lipo pack to test things out, just to find out if thereare any significant difference in performance with the ancillary drive gearbeyond the motor.

Prior to receiving my new PA gear, I used EagleTree Micro E-logger totake flight data logs of my previous setup to establish a baseline of mycurrent performance. Motor Temperature, RPM, Current, Pack Voltage andcumulative milli-Amps were logged for each flight with a flight time setfor 8 minutes. The same would be done for the new gear from PA as Iplan to push both gears really hard without the risking unwanted LVC.

The KMD is also flown with the average 3D/Freestyle manoeuvresconsisting of harrier rolls, hovers, torque rolls, knife edge, snaps, waterfalls, inverted harriers, up-right harriers, inverted and upright spins andwalls since this was the intended flight performance of the KMD and howit should be flown.

It is very interesting to note that although the static bench test resultsappears to be relatively close, the dynamic test results shown on thegraphs clearly indicates the difference in actual flight. This indicates thatthe traditional method of using static bench test results alone is not nec-essarily a definitive indication of the drive’s performance because evi-dence shows that it does not reflect what is actually happening in flight,and what actually happens in flight matters the most and therefore cannot be accurately simulated on a bench. As such static bench test eitherconducted on the bench or derived from computer aided applicationsappears to have some limitations.

This also helps answers as to why therewas a performance difference noted betweenmy “should work” set up versus the optimumrecommended by PA and finally tells me howfar I can only go with computer aided driveprediction applications.

Testing the Effectiveness ofRotorKool™:-How cool is cool?

In order to find out the effectiveness of the PAThrust 30,s RotorKool™ features, I used an equiv-alent 100gr class Hacker A30-16M on its maxprop of 12X6E with the same ESC and motor usedin Graph 1, (i.e. Castle Creations Phoenix 35Aand JAS 3S1P 2300mAh, 20C pack) in order tokeep the playing field level as best I can. Thiswas flown on a smaller and lighter Katana Mini tobalance out the prop size limitations imposed bythe motor. Please refer to the graph for the tem-perature trace and compare to the table using thesame controller and Lipo packs. No changes weremade to the ESC programming.

As observed from the temperature trace, thenon-RotorKool™ equipped Hacker A30-16Moperates at a much higher temperature while therange within the temperature oscillation are alsomuch higher. The motor also appears to becomeprogressively hotter. When compared to Graphs1 & 2 the RotorKool™ equipped Thrust 30’s tem-perature measurements appears to be relativelyflatter with smaller oscillations and does not

appear to be getting progressively hotter. Thisindicates that motor temperature is being con-trolled by the innovative High Velocity ForceCool Ventilation (HFCV) feature and kept withina small & stable temperature range. RotorKool™also appears to help the motor operate at a muchlower temperature which indirectly implies thatthe health of the neodymium magnets will bemuch better. Therefore, I would believe that thecooler running Thrust 30 could possibly providea much longer and consistent service life in rela-tion to a much hotter running motor.

ConclusionFrom the graphs, it becomes obvious that the

performance offered by the iPAs setup is superiorto the “should work” mix and match setup as wellas the importance of dynamic flight testing. TheiPAs gear certainly appears to be optimally select-ed and provides the best performance as adver-tised. This also shows what could be achieved outof a non-iPAs, semi-iPAS and full iPAS setup.

I am convinced that the iPAs setup providesthe best option for any modeller to attain opti-mum performance. The plus side with the iPAsoption is that it allows any modeller to attainthe best performance without the need toundertake an extensive and complicated driveselection process. This appears to be truly per-formance out of the box and I would highly rec-ommend the iPAs option.

The iPAs components are available directlyfrom Precision Aerobatics and from good

hobby shops around Australia. For moredetails visit PrecisionAerobatics.comor call 02-9558 0443.