Gents, One thing about this RC airplane hobby is there never ever seems to be a day when something new or bigger or better does not hit the stores. Its a constant battle to keep the CC in the wallet if your one of those people enticed by new technology.
Well on my most recent visit to Argentina for the world F3A championships I could not help but notice the power system our good friend Sebastiano Silvestre was running. Looking at it on the ground it defied all the laws or counter rotating propellor technology and I just had to find out more about it.
What I could tell was it had the purple power
HACKER motor in it and that was powered by
FlightPower LiPo competiton packs. Looked like two 5S 5300 packs. But that is where it all stopped for me. In the wind the propellors would freely rotate as though they were not connected to anything, depending on the wind (there was plenty of course) the props would rotate alternately or just one would rotate. It obviously only had one motor and was not a dual outrunner setup so I needed to find out more.
I figured the only way to get to the bottom of this was to go find the man himself. Mr Rainer Hacker, and it was a little like looking for a needle in a haystack. But I finally tracked him down to see if we could delve deeper into the mystery of the counter rotating prop system from him. Rainer has to be one of the finest people I have ever met in this hobby by the way and he was an open book explaining how the system worked,who designed it, and why.
The motor is the standard custom made F3A competition motor but that is where all similarities end. The gearbox is double planetary free floating arrangement and that was designed and built by Michael Ramel. Now for those in the know Michael Ramel was the first guy to ever fly electrics in the world F3A championships a good few years back. Well it appears Michael has a bit of a skunk works laboratory where he secretly develops the next generation performance products for RC electric planes. But what is so great about counter rotating props. Likely nothing if they work like the rest of them but thats what this setup did not do.
Both propellors are floating and rotating opposite to each other. However the one taking the most load will run slower than the one with the least load. The floating planetary system allows the props to vary in speed separately depending on the load each one has.
Now counter rotating props make a different noise anyway but this setup makes a whole new one. If you can imagine a turbine with some sort of variable pitch fan changing speed I suppose that would describe it. I tell you what it will do though is anyone who has a hankering for a true turbo prop sound but does want to fork out the green ones for a true turbo prop??? Well this ones going to light those guys fires something awesome.
You need to hear this setup to believe it.
Does it work??? Well Sebastiano took it to 5th place in the competition, it never let him down and he told me it is one really efficient setup. Very controllable, excellent response and it seemed to handle the wind really well. Of course the big thing with it is there is no offset for torque as there is no gyroscopic effect with twin counter rotating props. You mount the motor exactly in line with the center of axis of the fuselage and it will roll round that point with no effect from a motor being setup to produce that 3 degrees and 1 down of thrust. This thing is 100% axial.
Gents I have to thank Rainer Hacker (Hacker Motor), Micheal Ramel and Colin McGinn (FlightPower) a ton for the help in describing how this system worked. The time and the amount of props Michael made to eventually get this system working sounded like the guy owns shares in a carbon fiber factory.
Also a big thanks to Seba for taking the time to unbutton the plane so we could see it in the flesh.
But in Rainer Hackers own words this was the newest advent in electric powered setups seen at the worlds so keep your eyes and ears open as these may very well be the next goody for those that need to have one.
Do I hear someone looking for an electric Tucano???
