The weather in Michigan is finally giving us some actual flying weather, (13C over the weekend..) and Mike and I are taking advantage of our good fortune to get serious about testing our V4 Contra Drive prototypes.
We are running two setups. Mike is running a 6.75:1 gearset with a 1515/2.5Y Neu motor, and I am running an 8.3:1 gearset with a Kontronik Pyro 650-103 motor.
The Contra Drive itself is about 70g lighter than the V3 Drive. The Neu motor weighs 390g, and the Kontronik motor weighs 295g.
This results in a 60g saving for the Neu setup, and a 155g saving for the Kontronik setup.
The Neu setup has performance that is very similar to a comparably equipped V3 Neu motor based setup. Heat rise is also very acceptable.
The Kontronik setup has more performance. With this setup, and 22” props, I am pulling 100A max. The props are spinning at 4500 rpm, and I am drawing about 3500W from my packs. These are maximum values from my ESC log. With 20” props I am drawing close to 90A, and pulling about 3300W from my packs. Heat rise is also minimal. I am using a 130A Mezon controller, and it is running very cool. The motor itself is barely warm to the touch.
One thing that is interesting is that the spinner is actually warmer to the touch than the motor. I am ascribing this to the fact that the Drive is clamped solidly to the motor rotor shaft, and since the winding gets hotter than the motor case, the heat from the winding is conducting along the rotor shaft into the aluminum Drive., which means that the Contra Drive is essentially acting as a big heat sink, and keeping the motor winding cool.
One other thing that I noticed is that the Kontronik setup seems to be a lot more responsive at low rpm. There is no perceivable lag when the throttle is advance, and it seems to gain rpm more quickly. I am speculating that this is because the motor itself has more torque, and the gear ratio is also lower, which accelerates the props faster.
Another noticeable effect is that the throttle response in the mid range seems to be noticeably more linear than then with the V3. A click of throttle results in a predictable increase in power and speed, and this response seems to be the same over the full mid range of the motor. This required me to change my throttle curve from a non linear curve to a straight linear curve.
Mike Gaishin has built a new version of his Integer pattern plane over the winter, (See picture ...) and with his V4 setup, his all up weight is 4600g, which is good news for me, because Mike also built one for me as well, and my expectation is that my setup, with 5100mah packs, is going to get very close to a 4500g all up weight, which leaves 500g margin for me to consider using a 6500mah pack, which should be an excellent match for a Contra Drive that is pulling close to 3500W.
One final observation, the reduced weight required me to move my battery packs forward by about 6”. (See picture ...) Fortunately however, my battery tray was just long enough to accommodate this.
Brenner …
