BJR,

I'm sorry to hear that the Scorpion HK didn't turn out well on your Curare.

Not having any hands on experience with the Scorpions yet, I can't offer a second opinion other than what I already mentioned above however, it strikes me that loading up a lower kV helicopter series motor with an airplane APC prop might not be the best approach. I also feel that running our 60 size classics on 8 and 10s configurations is overkill causing the models to be overpowered and overweight at the same time. 8s might be a sensible option on the 6' 9.5+ lb 120 size birds mentioned in my previous posts but it does add a charging complexity requiring special chargers capable of 8s packs or two chargers if going 2x4s in series.

I think the sweet spot in the ~65" span model is really with the 6s packs which allows one to add "fuel" at a weight of about 25-30 oz. It's possible that over driving a helicopter motor on a classic pattern prop at high voltages might be the culprit for the vibration. 400 kV sounds low to me if one is targeting 13+K. We're talking about a nominal 37x400 = 14.8K rpm requiring the very large 10s cell count. It strikes me that if one wants to turn smaller 11" props (by e-power standards) at those rpm's, it is better to increase the kV and lower the cell count. For example, on 6s, one could achieve 14.8K nominal by using a ~650 kV motor.

If we look at the performance of the 400kV motor on 6s, one only gets 388W/17.5A/8.4K on a 10x10 e-APC. By increasing to the 630kV otherwise identical motor and prop, performance is 1300W/58A/12.6K which is actually a viable power platform for a Curare 60. Change the prop to an 11" and it will be right in the desired 2 bhp Rossi like power band. Comparing these motors to the aero S-4025-10 motor, performance on the same prop is 750W/33A/10.5K. It becomes clear that in a 6s configuration, one wants to be in the 600kV+ range of motors to turn smaller 10-11" props. Putting a small prop on a low kV motor at high voltages, achieves the desired rpm's but the power input is on the order of 2200W (!) which is suitable for a 10 lb+ bird still at over 200 W/lb. It might be that the motor is producing too much power, on too small a prop on too much voltage. Up the kV, lower the voltage and I think you'll be happy turning 11" props while keeping the model lighter. Someone here runs a 10x10 e-APC prop on a 600+ kV heli motor on 6s in a P8 and the plane moves out in spectacular fashion.

With that said, the Hanno is a 2-stroke 120 4-stroke type motor and does well turning 13" props sub 10K. In that sense it is easier to match the performance of it with an electric motor turning props in comparable diameters on manageable 6s packs.

As far as the quality of the Scorpions and accompanying hardware from an inspection standpoint, I can't say anything bad about them. The metal appears solid, the berings smooth, the collet and screws made of alloy rather than light flexible aluminum and the weld joints look well done. The accompanying X-mount looks like it might be made of the least strong material and although stout, it appears to be cast from metal that would yield in case of a crash with the intention of salvaging the motor while scrapping the X-mount. All this, of course, in reference to the Competition Series airplane motors shown above. I have bought at least 6 different brands of motors and these Scorpions rank high in quality compared to the others I have used. I just hope that they perform as well as I am optimistic about them.

The one thing that is interesting to note with these motors is that there is no paperwork that comes with them. I found that somewhat odd but in today's internet era, it is understandable - all the information is online.

David